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  • 1.
    Alvarez-Asencio, Ruben
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Note: Determination of torsional spring constant of atomic force microscopy cantilevers: Combining normal spring constant and classical beam theory (vol 84, 096102, 2013)2014In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 85, no 7, article id 079901Article in journal (Refereed)
  • 2.
    Alvarez-Asencio, Rubén
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden.
    Note: Determination of torsional spring constant of atomic force microscopy cantilevers: Combining normal spring constant and classical beam theory2013In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 84, no 9, p. 096102-096102-3Article in journal (Refereed)
    Abstract [en]

    A technique has been developed for the calculation of torsional spring constants for AFM cantilevers based on the combination of the normal spring constant and plate/beam theory. It is easy to apply and allow the determination of torsional constants for stiff cantilevers where the thermal power spectrum is difficult to obtain due to the high resonance frequency and low signal/noise ratio. The applicability is shown to be general and this simple approach can thus be used to obtain torsional constants for any beam shaped cantilever.

  • 3.
    Amann, Peter
    et al.
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Degerman, David
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Lee, Ming-Tao
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Alexander, John D.
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Shipilin, Mikhail
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Wang, Hsin-Yi
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Cavalca, Filippo
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Weston, Matthew
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Gladh, Jorgen
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Blom, Mikael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Bjorkhage, Mikael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Löfgren, Patrik
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Schlueter, Christoph
    Deutsch Elektronen Synchrotron DESY, Photon Sci, Notkestr 85, D-22607 Hamburg, Germany..
    Loemker, Patrick
    Deutsch Elektronen Synchrotron DESY, Photon Sci, Notkestr 85, D-22607 Hamburg, Germany..
    Ederer, Katrin
    Deutsch Elektronen Synchrotron DESY, Photon Sci, Notkestr 85, D-22607 Hamburg, Germany..
    Drube, Wolfgang
    Deutsch Elektronen Synchrotron DESY, Photon Sci, Notkestr 85, D-22607 Hamburg, Germany..
    Noei, Heshmat
    Deutsch Elektronen Synchrotron DESY, DESY NanoLab, D-22607 Hamburg, Germany..
    Zehetner, Johann
    Univ Appl Sci, Res Ctr Mikrotechnol, Hsch Str 1, A-6850 Dornbirn, Austria..
    Wentzel, Henrik
    KTH, School of Engineering Sciences (SCI).
    Ahlund, John
    Scienta Omicron AB, POB 15120, SE-75015 Uppsala, Sweden..
    Nilsson, Anders
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    A high-pressure x-ray photoelectron spectroscopy instrument for studies of industrially relevant catalytic reactions at pressures of several bars2019In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 90, no 10, article id 103102Article in journal (Refereed)
    Abstract [en]

    We present a new high-pressure x-ray photoelectron spectroscopy system dedicated to probing catalytic reactions under realistic conditions at pressures of multiple bars. The instrument builds around the novel concept of a "virtual cell" in which a gas flow onto the sample surface creates a localized high-pressure pillow. This allows the instrument to be operated with a low pressure of a few millibar in the main chamber, while simultaneously a local pressure exceeding 1 bar can be supplied at the sample surface. Synchrotron based hard x-ray excitation is used to increase the electron mean free path in the gas region between sample and analyzer while grazing incidence <5 degrees close to total external refection conditions enhances surface sensitivity. The aperture separating the high-pressure region from the differential pumping of the electron spectrometer consists of multiple, evenly spaced, micrometer sized holes matching the footprint of the x-ray beam on the sample. The resulting signal is highly dependent on the sample-to-aperture distance because photoemitted electrons are subject to strong scattering in the gas phase. Therefore, high precision control of the sample-to-aperture distance is crucial. A fully integrated manipulator allows for sample movement with step sizes of 10 nm between 0 and -5 mm with very low vibrational amplitude and also for sample heating up to 500 degrees C under reaction conditions. We demonstrate the performance of this novel instrument with bulk 2p spectra of a copper single crystal at He pressures of up to 2.5 bars and C1s spectra measured in gas mixtures of CO + H-2 at pressures of up to 790 mbar. The capability to detect emitted photoelectrons at several bars opens the prospect for studies of catalytic reactions under industrially relevant operando conditions.

  • 4. Arnalds, U. B.
    et al.
    Agustsson, J. S.
    Ingason, A. S.
    Eriksson, A. K.
    Gylfason, Kristinn B.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Gudmundsson, J. T.
    Olafsson, S.
    A magnetron sputtering system for the preparation of patterned thin films and in situ thin film electrical resistance measurements2007In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 78, no 10, p. 103901-Article in journal (Refereed)
    Abstract [en]

    We describe a versatile three gun magnetron sputtering system with a custom made sample holder for in situ electrical resistance measurements, both during film growth and ambient changes on film electrical properties. The sample holder allows for the preparation of patterned thin film structures, using up to five different shadow masks without breaking vacuum. We show how the system is used to monitor the electrical resistance of thin metallic films during growth and to study the thermodynamics of hydrogen uptake in metallic thin films. Furthermore, we demonstrate the growth of thin film capacitors, where patterned films are created using shadow masks.

  • 5. Attard, Phil
    et al.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231). Ytkemiska Institutet, Sweden.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231). Ytkemiska Institutet, Sweden.
    Thermal calibration of photodiode sensitivity for atomic force microscopy2006In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 77, no 11Article in journal (Refereed)
    Abstract [en]

    The photodiode sensitivity in the atomic force microscope is calibrated by relating the voltage noise to the thermal fluctuations of the cantilever angle. The method accounts for the ratio of the thermal fluctuations measured in the fundamental vibration mode to the total, and also for the tilt and extended tip of the cantilever. The method is noncontact and is suitable for soft or deformable surfaces where the constant compliance method cannot be used. For hard surfaces, the method can also be used to calibrate the cantilever spring constant.

  • 6.
    Banuazizi, S. Amir Hossein
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Åkerman, Johan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics. Univ Gothenburg, Dept Phys, S-41296 Gothenburg, Sweden..
    Microwave probe stations with throw-dimensional control of the magnetic field to study high-frequency dynamic in nanoscale devices2018In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 89, no 6, article id 064701Article in journal (Refereed)
    Abstract [en]

    We present two microwave probe stations with motorized rotary stages for adjusting the magnitude and angle of the applied magnetic field. In the first system, the magnetic field is provided by an electromagnet and can be adjusted from 0 to similar to 1.4 T while its polar angle (theta) can be varied from 0 degrees to 360 degrees. In the second system the magnetic field is provided by a Halbach array permanent magnet, which can be rotated and translated to cover the full range of polar (theta) and azimuthal (phi) angles with a tunable field magnitude up to similar to 1 T. Both systems are equipped with microwave probes, bias-Ts, amplifiers, and spectrum analyzers, to allow for microwave characterization up to 40 GHz, as well as software to automatically perform continuous large sets of electrical and microwave measurements.

  • 7.
    Banuazizi, Seyed Amir Hossein
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Åkerman, Johan
    Microwave probe stations with three-dimensional control of the magnetic field to study high frequency dynamics in nanoscale devices2018In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623Article in journal (Refereed)
    Abstract [en]

    We present two microwave probe stations with motorized rotary stages for adjusting the magnitude and angle of the applied magnetic field. In the first system, the magnetic field is provided by an electromagnet and can be adjusted from 0 to ~ 1.4 T while its polar angle (θ) can be varied from 0o to 360o. In the second system the magnetic field is provided by a Halbach array permanent magnet, which can be rotated and translated to cover the full range of polar (θ) and azimuthal (φ) angles with a tunable field magnitude up to ~ 1 T. Both systems are equipped with microwave probes, bias-Ts, amplifiers, and spectrum analyzers, to allow for microwave characterization up to 40 GHz, as well as software to automatically perform continuous large sets of electrical and microwave measurements.

  • 8.
    Batistoni, Paola
    et al.
    ENEA, Dept Fus & Technol Nucl Safety & Secur, I-00044 Frascati, Rome, Italy..
    Bergsåker, Henric
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Garcia-Carrasco, Alvaro
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Hellsten, Torbjörn
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Johnson, Thomas
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Menmuir, Sheena
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Rachlew, Elisabeth
    KTH, School of Engineering Sciences (SCI), Physics.
    Ratynskaia, Svetlana
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Stefanikova, Estera
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Ström, Petter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Tholerus, Emmi
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Olivares, Pablo Vallejos
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Weckmann, Armin
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Zhou, Yushun
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics. KTH, Fusion Plasma Phys, EES, SE-10044 Stockholm, Sweden..
    Zychor, I.
    Natl Ctr Nucl Res, PL-05400 Otwock, Poland..
    et al.,
    Calibration of neutron detectors on the Joint European Torus2017In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 88, no 10, article id 103505Article in journal (Refereed)
    Abstract [en]

    The present paper describes the findings of the calibration of the neutron yield monitors on the Joint European Torus (JET) performed in 2013 using a Cf-252 source deployed inside the torus by the remote handling system, with particular regard to the calibration of fission chambers which provide the time resolved neutron yield from JET plasmas. The experimental data obtained in toroidal, radial, and vertical scans are presented. These data are first analysed following an analytical approach adopted in the previous neutron calibrations at JET. In this way, a calibration function for the volumetric plasma source is derived which allows us to understand the importance of the different plasma regions and of different spatial profiles of neutron emissivity on fission chamber response. Neutronics analyses have also been performed to calculate the correction factors needed to derive the plasma calibration factors taking into account the different energy spectrum and angular emission distribution of the calibrating (point) Cf-252 source, the discrete positions compared to the plasma volumetric source, and the calibration circumstances. All correction factors are presented and discussed. We discuss also the lessons learnt which are the basis for the on-going 14 MeV neutron calibration at JET and for ITER.

  • 9.
    Belova, Liubov M.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Hellwig, Olav
    Dobisz, Elizabeth
    Dahlberg, E. Dan
    Rapid preparation of electron beam induced deposition Co magnetic force microscopy tips with 10 nm spatial resolution2012In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 83, no 9, p. 093711-Article in journal (Refereed)
    Abstract [en]

    Magnetic force microscope Co spike tips with lateral magnetic resolution of 10 nm have been prepared. The Co spikes are grown by electron beam induced deposition of Co from Co-2(CO)(8) gas precursor. The high resolution Co spikes are fabricated at the spot of a tightly focused electron beam on the tip of commercial atomic force microscope cantilevers. Qualitative investigations indicate that a spike grown on a planar base of Co improves the signal to noise.

  • 10.
    Belyayev, S. M.
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Dudkin, F. L.
    Minimization of nanosatellite low frequency magnetic fields2016In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 87, no 3, article id 034705Article in journal (Refereed)
    Abstract [en]

    Small weight and dimensions of the micro- and nanosatellites constrain researchers to place electromagnetic sensors on short booms or on the satellite body. Therefore the electromagnetic cleanliness of such satellites becomes a central question. This paper describes the theoretical base and practical techniques for determining the parameters of DC and very low frequency magnetic interference sources. One of such sources is satellite magnetization, the reduction of which improves the accuracy and stability of the attitude control system. We present design solutions for magnetically clean spacecraft, testing equipment, and technology for magnetic moment measurements, which are more convenient, efficient, and accurate than the conventional ones. (C) 2016 AIP Publishing LLC.

  • 11. Bernardo, J.
    et al.
    Bergsåker, Henric
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Elevant, Thomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Garcia-Carrasco, Alvaro
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Hellsten, Torbjörn
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Ivanova, Darya
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Jonsson, Thomas
    KTH, Superseded Departments (pre-2005), Alfvén Laboratory. KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Menmuir, Sheena
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Rachlew, Elisabeth
    KTH, School of Engineering Sciences (SCI), Physics.
    Rubel, Marek
    KTH, Superseded Departments (pre-2005), Alfvén Laboratory. KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Ström, Petter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics. KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Tholerus, Simon
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Weckmann, Armin
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Zychor, I.
    et al.,
    Ion temperature and toroidal rotation in JET's low torque plasmas2016In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 87, no 11, article id 11E557Article in journal (Refereed)
    Abstract [en]

    This paper reports on the procedure developed as the best method to provide an accurate and reliable estimation of the ion temperature T-i and the toroidal velocity v(phi) from Charge-eXchange Recombination Spectroscopy (CXRS) data from intrinsic rotation experiments at the Joint European Torus with the carbon wall. The low impurity content observed in such plasmas, resulting in low active CXRS signal, alongside low Doppler shifts makes the determination of Ti and v(phi) particularly difficult. The beam modulation method will be discussed along with the measures taken to increase photon statistics and minimise errors from the absolute calibration and magneto-hydro-dynamics effects that may impact the CXRS passive emission.

  • 12.
    Berntsen, Magnus H.
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Götberg, Olof
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Tjernberg, Oscar
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    An experimental setup for high resolution 10.5 eV laser-based angle-resolved photoelectron spectroscopy using a time-of-flight electron analyzer2011In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 82, no 9, p. 095113-Article in journal (Refereed)
    Abstract [en]

    We present an experimental setup for laser-based angle-resolved time-of-flight photoemission. Using a picosecond pulsed laser, photons of energy 10.5 eV are generated through higher harmonic generation in xenon. The high repetition rate of the light source, variable between 0.2 and 8 MHz, enables high photoelectron count rates and short acquisition times. By using a time-of-flight analyzer with angle-resolving capabilities, electrons emitted from the sample within a circular cone of up to +/- 15 degrees can be collected. Hence, simultaneous acquisition of photoemission data for a complete area of the Brillouin zone is possible. The current photon energy enables bulk sensitive measurements, high angular resolution, and the resulting covered momentum space is large enough to enclose the entire Brillouin zone in cuprate high-T(c) superconductors. Fermi edge measurements on polycrystalline Au shows an energy resolution better than 5 meV. Data from a test measurement of the Au(111) surface state are presented along with measurements of the Fermi surface of the high-T(c) superconductor Bi(2)Sr(2)CaCu(2)O(8+delta) (Bi2212).

  • 13.
    Berntsen, Magnus H.
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Palmgren, P.
    Leandersson, M.
    Hahlin, A.
    Åhlund, J.
    Wannberg, B.
    Mansson, M.
    Tjernberg, Oscar
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    A spin- and angle-resolving photoelectron spectrometer2010In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 81, no 3Article in journal (Refereed)
    Abstract [en]

    A new type of hemispherical electron energy analyzer that permits angle and spin resolved photoelectron spectroscopy has been developed. The analyzer permits standard angle resolved spectra to be recorded with a two-dimensional detector in parallel with spin detection using a mini-Mott polarimeter. General design considerations as well as technical solutions are discussed and test results from the Au(111) surface state are presented.

  • 14.
    Bertilsson, Michael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Takman, Per
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Holmberg, Anders
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Laboratory arrangement for soft x-ray zone-plate efficiency measurements2007In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 78, no 2, p. 026103-Article in journal (Refereed)
    Abstract [en]

    We demonstrate a laboratory-scale arrangement for rapid and accurate measurements of the absolute and local efficiency of soft x-ray micro zone plates in the water window. This in-house instrument is based on a single-line lambda=2.88 nm liquid-jet laser-plasma source. Measurements are performed by a simultaneous comparison of first diffraction-order photon flux with the flux in a calibrated reference signal. This arrangement eliminates existing source emission fluctuations. The performance of the method is demonstrated by the result from measurements of two similar to 55 mu m diameter nickel micro zone plates, showing a groove efficiency of 12.9%+/- 1.1% and 11.7%+/- 1.0%. Furthermore, we show that spatially resolved efficiency mapping is an effective tool for a detailed characterization of local zone plate properties. Thus, this laboratory-scale instrument allows rapid feedback to the fabrication process which is important for future improvements.

  • 15. Bohm, P.
    et al.
    Aftanas, M.
    Bilkova, P.
    Stefanikova, E.
    Mikulin, O.
    Melich, R.
    Janky, F.
    Havlicek, J.
    Sestak, D.
    Weinzettl, V.
    Stockel, J.
    Hron, M.
    Panek, R.
    Scannell, R.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Fassina, A.
    Naylor, G.
    Walsh, M. J.
    Edge Thomson scattering diagnostic on COMPASS tokamak: Installation, calibration, operation, improvements2014In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 85, no 11, p. 11E431-Article in journal (Refereed)
    Abstract [en]

    The core Thomson scattering diagnostic (TS) on the COMPASS tokamak was put in operation and reported earlier. Implementation of edge TS, with spatial resolution along the laser beam up to similar to 1/100 of the tokamak minor radius, is presented now. The procedure for spatial calibration and alignment of both core and edge systems is described. Several further upgrades of the TS system, like a triggering unit and piezo motor driven vacuum window shutter, are introduced as well. The edge TS system, together with the core TS, is now in routine operation and provides electron temperature and density profiles.

  • 16.
    Borgani, Riccardo
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Haviland, David B.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Intermodulation spectroscopy as an alternative to pump-probe for the measurement of fast dynamics at the nanometer scale2019In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 90, no 1, article id 013705Article in journal (Refereed)
    Abstract [en]

    We present an alternative approach to pump-probe spectroscopy for measuring fast charge dynamics with an atomic force microscope (AFM). Our approach is based on coherent multifrequency lock-in measurement of the intermodulation between a mechanical drive and an optical or electrical excitation. In response to the excitation, the charge dynamics of the sample is reconstructed by fitting a theoretical model to the measured frequency spectrum of the electrostatic force near resonance of the AFM cantilever. We discuss the time resolution, which in theory is limited only by the measurement time, but in practice is of order 1 ns for standard cantilevers and imaging speeds. We verify the method with simulations and demonstrate it with a control experiment, achieving a time resolution of 30 ns in ambient conditions, limited by thermal noise.

  • 17. Cherigier-Kovacic, L.
    et al.
    Ström, Petter
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Lejeune, A.
    Doveil, F.
    Electric field induced Lyman-alpha emission of a hydrogen beam for electric field measurements2015In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 86, no 6, article id 063504Article in journal (Refereed)
    Abstract [en]

    Electric field induced Lyman-alpha emission is a new way of measuring weak electric fields in vacuum and in a plasma. It is based on the emission of Lyman-alpha radiation (121.6 nm) by a low-energy metastable H atom beam due to Stark-quenching of the 2s level induced by the field. In this paper, we describe the technique in detail. Test measurements have been performed in vacuum between two plates polarized at a controlled voltage. The intensity of emitted radiation, proportional to the square of the field modulus, has been recorded by a lock-in technique, which gives an excellent signal to noise ratio. These measurements provide an in situ calibration that can be used to obtain the absolute value of the electric field. A diagnostic of this type can help to address a long standing challenge in plasma physics, namely, the problem of measuring electric fields without disturbing the equilibrium of the system that is being studied.

  • 18.
    Craciunescu, Teddy
    et al.
    Natl Inst Laser Plasma & Radiat Phys, Magurele, Romania..
    Bergsåker, Henrik
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Craciunescu, T.
    Natl Inst Laser Plasma & Radiat Phys, Magurele, Romania..
    Elevant, Thomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Garcia Carrasco, Alvaro
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Hellsten, Torbjörn
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Ivanova, Darya
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics. KTH, EES, Fus Plasma Phys, SE-10044 Stockholm, Sweden..
    Johnson, Thomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Menmuir, S.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Petersson, P
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Rachlew, Elisabeth
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Ström, Petter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Tholerus, Emmi
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Weckmann, Armin
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Zychor, I.
    Inst Plasma Phys & Laser Microfus, PL-01497 Warsaw, Poland..
    et al,
    Evaluation of reconstruction errors and identification of artefacts for JET gamma and neutron tomography2016In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 87, no 1, article id 013502Article in journal (Refereed)
    Abstract [en]

    The Joint European Torus (JET) neutron profile monitor ensures 2D coverage of the gamma and neutron emissive region that enables tomographic reconstruction. Due to the availability of only two projection angles and to the coarse sampling, tomographic inversion is a limited data set problem. Several techniques have been developed for tomographic reconstruction of the 2-D gamma and neutron emissivity on JET, but the problem of evaluating the errors associated with the reconstructed emissivity profile is still open. The reconstruction technique based on the maximum likelihood principle, that proved already to be a powerful tool for JET tomography, has been used to develop a method for the numerical evaluation of the statistical properties of the uncertainties in gamma and neutron emissivity reconstructions. The image covariance calculation takes into account the additional techniques introduced in the reconstruction process for tackling with the limited data set (projection resampling, smoothness regularization depending on magnetic field). The method has been validated by numerically simulations and applied to JET data. Different sources of artefacts that may significantly influence the quality of reconstructions and the accuracy of variance calculation have been identified.

  • 19.
    Dal Molin, A.
    et al.
    Univ Milano Bicocca, Dipartimento Fis G Occhialini, Milan, Italy..
    Bergsåker, Henric
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Garcia-Carrasco, Alvaro
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Hellsten, Torbjörn
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Johnson, Thomas
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Menmuir, Sheena
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Rachlew, Elisabeth
    KTH, School of Engineering Sciences (SCI), Physics.
    Ratynskaia, Svetlana
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Stefanikova, Estera
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Ström, Petter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Tholerus, Emmi
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Olivares, Pablo Vallejos
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Weckmann, Armin
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Zhou, Yushun
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Zychor, I.
    Natl Ctr Nucl Res, PL-05400 Otwock, Poland..
    et al.,
    Development of a new compact gamma-ray spectrometer optimised for runaway electron measurements2018In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 89, no 10, article id 10I134Article in journal (Refereed)
    Abstract [en]

    A new compact gamma-ray spectrometer was developed in order to optimise the measurement of bremsstrahlung radiation emitted from runaway electrons in the MeV range. The detector is based on a cerium doped lutetium-yttrium oxyorthosilicate (LYSO:Ce) scintillator coupled to a silicon photomultiplier and is insensitive to magnetic fields. Adedicated electronic board was developed to optimise the signal readout as well as for online control of the device. The detector combines a dynamic range up to 10 MeV with moderate energy non-linearity, counting rate capabilities in excess of 1 MHz, and an energy resolution that extrapolates to a few % in the MeV range, thus meeting the requirements for its application to runaway electron studies by bremsstrahlung measurements in the gamma-ray energy range.

  • 20.
    Davidson, Ian A.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics. Stockholm Univ, Sweden.
    Azzouz, Hatim
    Hueck, Klaus
    Bourennane, Mohamed
    A highly versatile optical fibre vacuum feed-through2016In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 87, no 5, article id 053104Article in journal (Refereed)
    Abstract [en]

    Coupling light into a vacuum system is a non-trivial problem, requiring the use of a specialized feed-through. This feed-through must be both leak tight and offer a low optical loss if it is to be suitable for general use. In this paper, we report on the development of an extremely simple yet versatile, low cost, demountable optical fiber vacuum feed-through based on the modification of a standard optical fiber bulkhead connector. The modified connector was found to have a leak rate of 6.6 +/- 2.1 x 10(-6) mbar l/s and an optical loss of -0.41 +/- 0.28 dB, making it suitable for use in high vacuum applications.

  • 21. De Angeli, M.
    et al.
    Castaldo, C.
    Ratynskaia, Svetlana
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Grosso, G.
    Almaviva, S.
    Caneve, L.
    Colao, F.
    Maddaluno, G.
    Note: Simultaneous electrical and optical detection of expanding dense partially ionized vapour clouds2011In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 82, no 10, p. 106101-Article in journal (Refereed)
    Abstract [en]

    The scheme and construction of an electro-optical probe able to collect charge and detect optical emission from expanding dense partially ionized vapour clouds are reported. The instrument can be applied to phenomena such as dust impact ionization and solid target laser ablation. First, results of measurements of expanding plasma cloud formed upon ablating W target are presented. Use of the instrument in different experimental facilities, including tokamak, is discussed.

  • 22. de Groot, J.
    et al.
    Johansson, G. A.
    Hertz, Hans M.
    KTH, Superseded Departments, Physics.
    Capillary nozzles for liquid-jet laser-plasma x-ray sources2003In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 74, no 8, p. 3881-3882Article in journal (Refereed)
    Abstract [en]

    We describe a method to fabricate tapered glass nozzles suitable for liquid-jet-target generation in laser-plasma soft x-ray and extreme ultraviolet sources. In the method, a tapered nozzle is formed as an integral part of a flexible capillary glass tubing. The method makes use of inert materials, extending the possible choice of target liquids compared to current nozzles. It also provides flexibility as regards nozzle diameter and pressure, thereby allowing optimization of the target size and extending the range of applicability for the liquid-jet-target laser plasmas.

  • 23.
    Delabie, E.
    et al.
    EUROfus Consortium, JET, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.;FOM Inst DIFFER, NL-3430 BE Nieuwegein, Netherlands..
    Bergsåker, Henric
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Elevant, Thomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Garcia-Carrasco, Alvaro
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Hellsten, Torbjörn
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Ivanova, Darya
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Johnson, Thomas
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Menmuir, Sheena
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Rachlew, Elisabeth
    KTH, School of Engineering Sciences (SCI), Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Ström, Petter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Tholerus, Emmi
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Weckmann, Armin
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Zychor, I.
    Annan organisation.
    et al.,
    In situ wavelength calibration of the edge CXS spectrometers on JET2016In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 87, no 11, article id 11E525Article in journal (Refereed)
    Abstract [en]

    A method for obtaining an accurate wavelength calibration over the entire focal plane of the JET edge CXS spectrometers is presented that uses a combination of the fringe pattern created with a Fabry-Perot etalon and a neon lamp for cross calibration. The accuracy achieved is 0.03 angstrom, which is the same range of uncertainty as when neglecting population effects on the rest wavelength of the CX line. For the edge CXS diagnostic, this corresponds to a flow velocity of 4.5 km/s in the toroidal direction or 1.9 km/s in the poloidal direction.

  • 24. Delahaye, P
    et al.
    Barton, C J
    Connell, K
    Fritioff, T
    Kester, O
    Lamy, T
    Lindroos, M
    Sortais, P
    Tranströmer, Göran
    KTH, School of Engineering Sciences (SCI), Physics.
    Wenander, F
    Recent results with the Phoenix booster at ISOLDE2006In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 77, no 3, p. 03B105-Article in journal (Refereed)
    Abstract [en]

    At ISOLDE, CERN the development of charge breeding techniques is one of the key points for numerous future experiments. We report in this article on the latest online tests of the Daresbury Phoenix booster at ISOLDE. The performances of the continuous mode were investigated for different injected stable beams. Preliminary results were obtained with the afterglow pulsing method and two injected noble gas isotopes. These latter tests are of particular interest for the postacceleration of ISOL-type beams.

  • 25. Demidov, V. I.
    et al.
    Ratynskaia, Svetlana V.
    Rypdal, K.
    Electric probes for plasmas: The link between theory and instrument2002In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 73, no 10, p. 3409-3439Article, review/survey (Refereed)
    Abstract [en]

    Electric probe methods for diagnostics of plasmas are reviewed with emphasis on the link between the appropriate probe theories and the instrumental design. The starting point is an elementary discussion of the working principles and a discussion of the physical quantities that can be measured by the probe method. This is followed by a systematic classification of the various regimes of probe operation and a summary of theories and methods for measurements of charged particle distributions. Application of a single probe and probe clusters for measurements of fluid observables is discussed. Probe clusters permit both instantaneous and time-averaged measurements without sweeping the probe voltage. Two classes of applications are presented as illustrations of the methods reviewed. These are measurements of cross sections and collision frequencies (plasma electron spectroscopy), and measurements of fluctuations and anomalous transport in magnetized plasma.

  • 26. Demidov, V. I.
    et al.
    Ratynskaia, Svetlana V.
    Rypdal, K.
    Reducing influence of ion current on measurements of electron energy distributions in collisional plasmas2001In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 72, no 11, p. 4106-4109Article in journal (Refereed)
    Abstract [en]

    A method for reducing the influence of ion current on probe measurements of electron velocity distributions in plasmas has been developed and tested in noble gas afterglow plasmas. It is valid for diffusive transport of ions to the probe. Experiments have demonstrated high accuracy of the proposed method.

  • 27. Denysenkov, V. P.
    et al.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Broadband ferromagnetic resonance spectrometer2003In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 74, no 7, p. 3400-3405Article in journal (Refereed)
    Abstract [en]

    The continuous wave ferromagnetic resonance (FMR) spectrometer operating in multioctave (0.05-40 GHz) frequency range has been built to investigate the magnetic properties of thin ferromagnetic films in the temperature range of 4-420 K. The spectrometer has two probeheads: one is the X-band microwave reflection cavity used to perform express room temperature measurements and the other is an in-cryostat microstrip line probe to carry out FMR experiments covering the entire frequency range offered by the microwave source. Very uniform and stable magnetic field up to 2.4 T, temperature 4 K-420 K, and continuous frequency scan performed by an HP8722D vector network analyzer provide various modes of operation. Both probe heads are equipped with two-circle high precision goniometers to ensure accurate characterization of magnetic anisotropy and magnetostatic waves spectra recording. Use of the phase sensitive detection, utilized by magnetic field modulation at audio frequency and computer triggering of the network analyzer, enables broadband spectrometer sensitivity to be as high as 1.3x10(11) spins/Oe.

  • 28.
    Eriksson, Tore
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Sylwan, Christopher
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Measurement method for finding gas adsorption equilibrium isotherms by employing a gas chromatograph and using its integrator in a new way2005In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 76, no 4, p. 044102-Article in journal (Refereed)
    Abstract [en]

    A method for measuring the adsorption ability of zeolites has been developed. The adsorption can be accurately measured over a wide range of pressures and temperatures. The range usually covered is partial pressures ranging from 0.2 to 20 bar (a) and temperatures from 10 to 50 degrees C. However, it may be extended to 0.1-25 bar (a) and -40-80 degrees C. When a partial pressure below 2 bar (a) is to be used, the gas is diluted with helium. The method is built around a gas chromatograph (GC) equipped with a thermal conductivity detector (TCD) and having a programming and peak integrating unit. It also has an option using liquid nitrogen to allow work below ambient temperature. The GC has been modified with two special columns to be used alternately for purging with helium and as test chamber for the measurements. It is also equipped with a separate external flow and pressure-handling unit. The GC is used, not as a chromatograph, but instead to integrate suitably interrupted breakthrough curves. The primary measured data are evaluated using a program written in BASIC, which separates the part of the primary measured results that originates from the adsorption from the part that is induced by the measuring equipment. Using a calibration file that can easily be updated from within the program, this separation has achieved a high degree of accuracy. Using the adsorption data from these measurements, Langmuir-type isotherm equations are fitted, which accurately represent the adsorption of the tested gas both with respect to pressure and to temperature. It has been found that adsorption data measured in this way can achieve a standard deviation between measured and calculated data that typically varies around 1% over the whole measured range. In order to do this, however, in the case of nitrogen adsorption the sum of two Langmuir isotherms has to be used. This is not needed with oxygen or argon adsorption.

  • 29. Fedosseev, V. N.
    et al.
    Berg, Lars-Erik
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Fedorov, D. V.
    Fink, D.
    Launila, Olli J.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Losito, R.
    Marsh, B. A.
    Rossel, R. E.
    Rothe, S.
    Seliverstov, M. D.
    Sjödin, A. M.
    Wendt, K. D. A.
    Upgrade of the resonance ionization laser ion source at ISOLDE on-line isotope separation facility: New lasers and new ion beams2012In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 82, no 2, p. 02A903-Article in journal (Refereed)
    Abstract [en]

    The resonance ionization laser ion source (RILIS) produces beams for the majority of experiments at the ISOLDE on-line isotope separator. A substantial improvement in RILIS performance has been achieved through a series of upgrade steps: replacement of the copper vapor lasers by a Nd:YAG laser; replacement of the old homemade dye lasers by new commercial dye lasers; installation of a complementary Ti:Sapphire laser system. The combined dye and Ti:Sapphire laser system with harmonics is capable of generating beams at any wavelength in the range of 210-950 nm. In total, isotopes of 31 different elements have been selectively laser-ionized and separated at ISOLDE, including recently developed beams of samarium, praseodymium, polonium, and astatine.

  • 30. Ferreira, Diogo R.
    et al.
    Bergsåker, Henric
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Elevant, Thomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Garcia-Carrasco, Alvaro
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Hellsten, Torbjörn
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Ivanova, Darya
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Johnson, Thomas
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Menmuir, Sheena
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Rachlew, Elisabeth
    KTH, School of Engineering Sciences (SCI), Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Ström, Petter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Tholerus, Emmi
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Weckmann, Armin
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Zychor, I.
    Robust regression with CUDA and its application to plasma reflectometry2015In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 86, no 11, article id 113507Article in journal (Refereed)
    Abstract [en]

    In many applications, especially those involving scientific instrumentation data with a large experimental error, it is often necessary to carry out linear regression in the presence of severe outliers which may adversely affect the results. Robust regression methods do exist, but they are much more computationally intensive, making it difficult to apply them in real-time scenarios. In this work, we resort to graphics processing unit (GPU)-based computing to carry out robust regression in a time-sensitive application. We illustrate the results and the performance gains obtained by parallelizing one of the most common robust regression methods, namely, least median of squares. Although the method has a complexity of O(n(3) log n), with GPU computing, it is possible to accelerate it to the point that it becomes usable within the required time frame. In our experiments, the input data come from a plasma diagnostic system installed at Joint European Torus, the largest fusion experiment in Europe, but the approach can be easily transferred to other applications.

  • 31.
    Fokine, Michael
    KTH, Superseded Departments, Physics.
    High temperature miniature oven with low thermal gradient for processing fiber Bragg gratings2001In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 72, no 8, p. 3458-3461Article in journal (Refereed)
    Abstract [en]

    A miniature oven for processing fiber Bragg gratings in excess of 1000 degreesC has been projected and evaluated. The dimensions and the design of the oven allow rapid insertion and removal of the fiber during heating and minimizes mechanical degradation of the fiber. The 22 mm long oven has a flat zone at 1000 degreesC of 16 mm with a temperature variation of less than 2% and 20 mm with a temperature variation of 10%. The long term stability (hours) is +/- 20 degreesC measured at the center of the oven at 1000 degreesC. Rapid heating is possible, and heating optical fibers to 1000 degreesC shows a delay of approximately 400 ms before the core reaches thermal equilibrium.

  • 32. Forsberg, J.
    et al.
    Duda, L. C.
    Olsson, A.
    Schmitt, T.
    Andersson, J.
    Nordgren, J.
    Hedberg, J.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Aastrup, T.
    Wallinder, D.
    Guo, J. H.
    System for in situ studies of atmospheric corrosion of metal films using soft x-ray spectroscopy and quartz crystal microbalance2007In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 78, no 8Article in journal (Refereed)
    Abstract [en]

    We present a versatile chamber (atmospheric corrosion cell) for soft x-ray absorption/emission spectroscopy of metal surfaces in a corrosive atmosphere allowing novel in situ electronic structure studies. Synchrotron x rays passing through a thin window separating the corrosion cell interior from a beamline vacuum chamber probe a metal film deposited on a quartz crystal microbalance (QCM) or on the inside of the window. We present some initial results on chloride induced corrosion of iron surfaces in humidified synthetic air. By simultaneous recording of QCM signal and soft x-ray emission from the corroding sample, correlation between mass changes and variations in spectral features is facilitated.

  • 33. Franz, P.
    et al.
    Gadani, G.
    Pasqualotto, R.
    Marrelli, L.
    Martin, P.
    Spizzo, G.
    Brunsell, Per
    KTH, Superseded Departments, Alfvén Laboratory.
    Chapman, B. E.
    Paganucci, F.
    Rossetti, P.
    Xiao, C.
    Compact soft x-ray multichord camera: Design and initial operation2003In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 74, no 3 II, p. 2152-2156Article in journal (Refereed)
    Abstract [en]

    The design and initial operation of a compact soft x-ray (SXR) multichord camera was studied. The line integrity emissivity was measured along up to 20 lines of sight using an array of miniaturized silicon photodiodes. The application of the diagnostic to a gas-fed magnetoplasma dynamic thruster (MPDT) with an external magnetic field was also discussed.

  • 34.
    Frassinetti, Lorenzo
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Beurskens, M. N. A.
    Scannell, R.
    Osborne, T. H.
    Flanagan, J.
    Kempenaars, M.
    Maslov, M.
    Pasqualotto, R.
    Walsh, M.
    Spatial resolution of the JET Thomson scattering system2012In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 83, no 1, p. 013506-Article in journal (Refereed)
    Abstract [en]

    The instrument function of the high resolution Thomson scattering (HRTS) diagnostic in the Joint European Torus (JET) has been calculated for use in improved pedestal profile analysis. The full width at half maximum (FWHM) of the spatial instrument response is (22 +/- 1) mm for the original HRTS system configuration and depends on the particular magnetic topology of the JET plasmas. An improvement to the optical design of the laser input system is presented. The spatial smearing across magnetic flux surfaces is reduced in this design. The new input system has been implemented (from JPN 78742, July 2009) and the HRTS instrument function corresponding to the new configuration has been improved to approximately FWHM = (9.8 +/- 0.8) mm. The reconstructed instrument kernels are used in combination with an ad hoc forward deconvolution procedure for pedestal analysis. This procedure produces good results for both the old and new setups, but the reliability of the deconvolved profiles is greatly reduced when the pedestal width is of the same order as, or less than the FWHM of the instrument kernel.

  • 35. Giacomelli, L.
    et al.
    Hjalmarsson, A.
    Källne, J.
    Hellesen, C.
    Tardocchi, M.
    Gorini, G.
    Van Eester, D.
    Lerche, E.
    Johnson, Thomas J.
    EURATOM-UKAEA Association, Culham Science Centre, OX14 3DB Abingdon, United Kingdom .
    Kiptily, V.
    Conroy, S.
    Sundén, A.
    Ericsson, G.
    Johnson, G.
    Sjöstrand, H.
    Weiszflog, M.
    Neutron emission spectroscopy results for internal transport barrier and mode conversion ion cyclotron resonance heating experiments at JET2008In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, ISSN 0034-6748, Vol. 79, no 10, p. 10E514-Article in journal (Refereed)
    Abstract [en]

    The effect of ion cyclotron resonance heating (ICRH) on ((3)He)D plasmas at JET was studied with the time of flight optimized rate (TOFOR) spectrometer dedicated to 2.5 MeV dd neutron measurements. In internal transport barrier (ITB) plasma experiments with large (3)He concentrations (X((3)He)>15%) an increase in neutron yield was observed after the ITB disappeared but with the auxiliary neutral beam injection and ICRH power still applied. The analysis of the TOFOR data revealed the formation of a high energy (fast) D population in this regime. The results were compared to other mode conversion experiments with similar X((3)He) but slightly different heating conditions. In this study we report on the high energy neutron tails originating from the fast D ions and their correlation with X((3)He) and discuss the light it can shed on ICRH-plasma power coupling mechanisms.

  • 36.
    Hansson, B. A. M.
    et al.
    KTH, Superseded Departments, Physics.
    Hemberg, O.
    KTH, Superseded Departments, Physics.
    Hertz, Hans M.
    KTH, Superseded Departments, Physics.
    Berglund, Magnus
    KTH, Superseded Departments, Physics.
    Choi, H. J.
    KTH, Superseded Departments, Physics.
    Jacobsson, Björn
    KTH, Superseded Departments, Physics.
    Janin, E.
    KTH, Superseded Departments, Physics.
    Mosesson, Sofia
    KTH, Superseded Departments, Physics.
    Rymell, L.
    KTH, Superseded Departments, Physics.
    Thoresen, J.
    KTH, Superseded Departments, Physics.
    Wilner, M.
    KTH, Superseded Departments, Physics.
    Characterization of a liquid-xenon-jet laser-plasma extreme-ultraviolet source2004In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 75, no 6, p. 2122-2129Article in journal (Refereed)
    Abstract [en]

    A liquid-xenon-jet laser-plasma source for extreme-ultraviolet (EUV) and soft-x-ray generation has been characterized. Being a source candidate for EUV lithography (EUVL), we especially focus on parameters important for the integration of the source in EUVL systems. The deep-ultraviolet (DUV) out-of-band radiation (lambda=120-400 nm) was quantified, to within a factor of two, using a flying-circus tool together with a transmission-grating spectrograph resulting in a total DUV conversion efficiency (CE) of similar to0.33%/2pisr. The size and the shape of the xenon plasma was investigated using an in-band-only EUV microscope, based on a spherical Mo/Si multilayer mirror and a charge-coupled device detector. Scalability of the source size from 20-270 mum full width at half maximum was shown. The maximum repetition-rate sustainable by the liquid-xenon-jet target was simulated by a double-pulse experiment indicating feasibility of >17 kHz operation. The xenon-ion energy distribution from the plasma was determined in a time-of-flight experiment with a Faraday-cup detector showing the presence of multi-kilo-electron-volt ions. Sputtering of silicon witness plates exposed to the plasma was observed, while a xenon background of >1 mbar was shown to eliminate the sputtering. It is concluded that the source has potential to meet the requirements of future EUVL systems.

  • 37. Ingesson, L. C.
    et al.
    Campbell, D. J.
    Cecconello, Marco
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Ciattaglia, E.
    Dirken, P.
    Hawkes, N.
    Walsh, M.
    von Hellermann, M.
    Kalvin, S.
    McCarthy, P.
    Neubauer, O.
    Petrizzi, L.
    Progress on common aspects of the EU-supplied ITER diagnostics and prediction of diagnostic performance2006In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 77, no 10, p. 10F502-Article in journal (Refereed)
    Abstract [en]

    The European Union will supply a number of diagnostics for ITER. Significant progress has been made on the design and integration of these diagnostics. Specific topics, in common for several of the diagnostics, discussed are port-plug integration, simplification of labyrinths against neutron streaming, and design measures to protect and to be able to replace sensitive optical components. Performance analysis to predict the likely capability of the diagnostics to meet the ITER measurement requirements will be an important aspect of the design process. The interpretation of the measurement requirements, specifically of spatial resolution in the case of indirect measurements, is discussed on the basis of two examples, and methods of performance analysis are compared.

  • 38.
    Jacobsen, A. S.
    et al.
    Culham Sci Ctr, EUROfus Consortium, JET, Abingdon OX14 3DB, Oxon, England.;Max Planck Inst Plasma Phys, Garching, Germany.;Tech Univ Denmark, Dept Phys, Bldg 309, DK-2800 Lyngby, Denmark..
    Bergsåker, Henric
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Garcia-Carrasco, Alvaro
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Hellsten, Torbjörn
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Johnson, Thomas
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Menmuir, Sheena
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Rachlew, Elisabeth
    KTH, School of Engineering Sciences (SCI), Physics.
    Ratynskaia, Svetlana
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Stefanikova, Estera
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Ström, Petter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Tholerus, Emmi
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Olivares, Pablo Vallejos
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Weckmann, Armin
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Zhou, Yushun
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Zychor, I.
    Natl Ctr Nucl Res, PL-05400 Otwock, Poland..
    et al.,
    Velocity-space sensitivities of neutron emission spectrometers at the tokamaks JET and ASDEX Upgrade in deuterium plasmas2017In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 88, no 7, article id 073506Article in journal (Refereed)
    Abstract [en]

    Future fusion reactors are foreseen to be heated by the energetic alpha particles produced in fusion reactions. For this to happen, it is important that the energetic ions are sufficiently confined. In present day fusion experiments, energetic ions are primarily produced using external heating systems such as neutral beam injection and ion cyclotron resonance heating. In order to diagnose these fast ions, several different fast-ion diagnostics have been developed and implemented in the various experiments around the world. The velocity-space sensitivities of fast-ion diagnostics are given by so-called weight functions. Here instrument-specific weight functions are derived for neutron emission spectrometry detectors at the tokamaks JET and ASDEX Upgrade for the 2.45 MeV neutrons produced in deuterium-deuterium reactions in deuterium plasmas. Using these, it is possible to directly determine which part of velocity space each detector observes.

  • 39. Jakubowska, Katarzyna
    et al.
    De Bock, M. F. M.
    Jaspers, Roger
    Von Hellermann, M. G.
    Shmaenok, Leonid A.
    Motional Stark Effect Diagnostic on TEXTOR2004In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 75, no 10, p. 3475-3477Article in journal (Refereed)
    Abstract [en]

    A motional Stark effect diagnostic at the tokamak TEXTOR has been constructed and brought recently into operation. In contrast to diagnostics used on other tokamaks, this diagnostic reveals the direction of the magnetic field from the intensity ratio of the pi and sigma components of the emitted Balmer-alpha and not from a polarization measurement of a single line. Moreover, the complete spectrum is measured which allows determining the radial position of the measurement, and in principle the radial electric field.

  • 40.
    Jansson, Per
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ultich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Liquid-nitrogen-jet laser-plasma source for compact soft x-ray microscopy2005In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 76, no 4, p. 043503-Article in journal (Refereed)
    Abstract [en]

    We describe a liquid-nitrogen-jet laser-plasma source with sufficient brightness, uniformity, stability, and reliability to be suitable for compact water-window soft x-ray transmission microscopy. A cooled capillary nozzle arrangement allows long-term operation and avoids previously reported jet instabilities. The source is quantitatively characterized by calibrated slit-grating spectroscopy and zone-plate imaging. The absolute photon number in the major spectral lines (lambda=2.48 nm and lambda=2.88 nm) is 1.0x10(12) photons/(pulsexsrxline). The source diameter is similar to 20 mu m (full width at half maximum) and the spatial stability is better than +/- 2 mu m. Within an area with uniformity of 20%, the average source brightness is 4x10(8) photons/(pulsexsrx mu m(2)xline), which allows operation of a compact soft x-ray transmission microscope with exposure times of a few minutes.

  • 41. Johansson, G. A.
    et al.
    Berglund, M.
    Eriksson, F.
    Birch, J.
    Hertz, Hans M.
    KTH, Superseded Departments, Physics.
    Compact soft x-ray reflectometer based on a line-emitting laser-plasma source2001In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 72, no 1, p. 58-62Article in journal (Refereed)
    Abstract [en]

    We describe a compact soft x-ray reflectometer for in-house characterization of water-window multilayer optics. The instrument is based on a line-emitting, liquid-jet, laser-plasma source in combination with angular scanning of the studied multilayer optics. With a proper choice of target liquid and thin-film filters, one or a few lines of well-defined wavelength dominate the spectrum and multilayer periods are measured with an accuracy of 0.003 nm using a multi-line calibration procedure. Absolute reflectivity may also be estimated with the instrument. The typical measurement time is currently 10 min. Although the principles of the reflectometer may be used in the entire soft x-ray and extreme ultraviolet range, the current instrument is primarily directed towards normal-incidence multilayer optics for water-window x-ray microscopy, and is thus demonstrated on W/B4C multilayers for this wavelength range.

  • 42. Johansson, G. A.
    et al.
    Holmberg, Anders
    KTH, Superseded Departments, Physics.
    Hertz, H. M.
    Berglund, M
    Design and performance of a laser-plasma based compact soft x-ray microscope2002In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 73, no 3, p. 1193-1197Article in journal (Refereed)
  • 43. Karlsson, H S
    et al.
    Chiaia, G
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    System for time- and angle-resolved photoelectron spectroscopy based on an amplified femtosecond titanium:sapphire laser system1996In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 67, no 10, p. 3610-3615Article in journal (Refereed)
    Abstract [en]

    A system for time- and angle-resolved photoelectron spectroscopy based on an amplified femtosecond titanium:sapphire laser system is described. Using this type of system, angle-resolved photoemission is extended to include the possibility of following the time development of excited electrons at and near a solid surface. Time resolution is accomplished by using pump-and-probe technique and the photoemitted electrons are energy analyzed in a time-of-fight detector. In order to perform photoemission, the near-infrared light from the titanium:sapphire laser is frequency up-converted to the vacuum ultraviolet range. This is accomplished by using the high peak power pulses from the laser system to produce short-wavelength radiation by means of harmonic generation. The system described uses cascaded frequency doubling and tripling, reaching a photon energy close to 10 eV. (C) 1996 American Institute of Physics.

  • 44. Kim, Yong-Su
    et al.
    Jeong, Youn-Chang
    Sauge, Sebastien
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Makarov, Vadim
    Kim, Yoon-Ho
    Ultra-low noise single-photon detector based on Si avalanche photodiode2011In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 82, no 9, p. 093110-Article in journal (Refereed)
    Abstract [en]

    We report operation and characterization of a lab-assembled single-photon detector based on commercial silicon avalanche photodiodes (PerkinElmer C30902SH, C30921SH). Dark count rate as low as 5Hz was achieved by cooling the photodiodes down to -80 degrees C. While afterpulsing increased as the photodiode temperature was decreased, total afterpulse probability did not become significant due to detector's relatively long deadtime in a passively-quenched scheme. We measured photon detection efficiency >50% at 806 nm.

  • 45.
    Krawczyk, N.
    et al.
    Inst Plasma Phys & Laser Microfus, Hery 23, PL-01497 Warsaw, Poland.;Inst Plasma Phys & Laser Microfus, Hery 23, PL-01497 Warsaw, Poland..
    Bergsåker, Henric
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Garcia-Carrasco, Alvaro
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Hellsten, Torbjörn
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Johnson, Thomas
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Menmuir, Sheena
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Rachlew, Elisabeth
    KTH, School of Engineering Sciences (SCI), Physics.
    Ratynskaia, Svetlana
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Stefanikova, Estera
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Ström, Petter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Tholerus, Emmi
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Olivares, Pablo Vallejos
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics.
    Weckmann, Armin
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Zhou, Yushun
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Fusion Plasma Physics. KTH, Fusion Plasma Phys, EES, SE-10044 Stockholm, Sweden..
    Zychor, I.
    Natl Ctr Nucl Res, PL-05400 Otwock, Poland..
    et al.,
    Application of the VUV and the soft x-ray systems on JET for the study of intrinsic impurity behavior in neon seeded hybrid discharges2018In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 89, no 10, article id 10D131Article in journal (Refereed)
    Abstract [en]

    This paper reports on impurity behavior in a set of hybrid discharges with Ne seeding-one of the techniques considered to reduce the power load on reactor walls. A series of experiments carried out with light gas injection on JET with the ITER-Like-Wall (ILW) suggests increased tungsten release and impurity accumulation [C. Challis et al., Europhysics Conference Abstracts 41F, 2.153 (2017)]. The presented method relies mainly on the measurements collected by vacuum-ultra-violet and soft X-ray (SXR) diagnostics including the "SOXMOS" spectrometer and the SXR camera system. Both diagnostics have some limitations. Consequently, only a combination of measurements from these systems is able to provide comprehensive information about high-Z [e.g., tungsten (W)] and mid-Z [nickel (Ni), iron (Fe), copper (Cu), and molybdenum (Mo)] impurities for their further quantitative diagnosis. Moreover, thanks to the large number of the SXR lines of sight, determination of a 2D radiation profile was also possible. Additionally, the experimental results were compared with numerical modeling based on integrated simulations with COREDIV. Detailed analysis confirmed that during seeding experiments, higher tungsten release is observed, which was also found in the past. Additionally, it was noticed that besides W, the contribution of molybdenum to SXR radiation was greater, which can be explained by the place of its origin.

  • 46.
    Kuldkepp, Matias
    et al.
    KTH, Superseded Departments, Physics.
    Rachlew, Elisabeth
    KTH, Superseded Departments, Physics.
    Hawkes, N.C.
    Schunke, B.
    First mirror contamination studies for polarimetry motional Stark effect measurements for ITER2004In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 75, p. 3446-3448Article in journal (Refereed)
    Abstract [en]

    The motional Stark effect (MSE) diagnostic on the International Thermonuclear Experimental Reactor will need to guide the light through a labyrinth of mirrors to provide neutron shielding. Knowledge of how the mirrors change the polarization is essential for accurate determination of the q profile. The optical properties of the plasma facing mirror are also expected to change with time due to deposition/erosion. For the purpose of examining this experimentally a detector system, identical to the JET MSE system, using twin photoelastic modulators was constructed. Measurements have been performed on freshly prepared mirrors, on mirrors after exposure to plasmas in Tore Supra, and labyrinth designs. The result shows a significant effect on the optical properties and demonstrate the need for in situ monitoring. The measured properties of the labyrinth closely follow the Mueller matrix formalism. With a correct choice of material the angle change introduced by the four mirrors furthest away from the plasma will be below 1 degrees.

  • 47.
    Kuldkepp, Matias
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Walsh, M.J.
    Carolan, P. G.
    Conway, N. J.
    Hawkes, N. C.
    McCone, J.
    Rachlew, Elisabeth
    KTH, School of Engineering Sciences (SCI), Physics.
    Wearing, G.
    Motional Stark effect diagnostic pilot experiment for MAST2006In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 77, no 10, p. 10E905-Article in journal (Refereed)
    Abstract [en]

    Exploiting the motional Stark effect (MSE) in the low magnetic fields of spherical tokamaks such as MAST is complicated by the Doppler smearing of the relatively closely spaced Stark components. Extensive modeling of MSE spectra and the subsequent polarized fraction (similar to 20%) of spectrally filtered light and signal to noice ratios have been performed taking account of real experimental conditions including neutral beam parameters, port sizes, optical losses, filter characteristics, etc. A design is selected which uses high throughput interference filters (0.1 nm bandpass ) for separation of the spectral components. An accuracy of similar to 0.5 degrees S compared with typically 15 degrees is estimated for field angle measurements. The design allows for early implementation, starting with a pilot two chord system, and for an economic expansion to a multiplicity of chords. Matching the Doppler shifted D-alpha from the beam neutrals will be accomplished by a combination of filter selection and fine-tuning of the beam voltage. Avoiding filter tuning in the design greatly simplifies the diagnostic. Calibration results of the diagnostic support the calculations.

  • 48.
    Kwak, Sehyun
    et al.
    JET, Culham Sci Ctr, EUROfus Consortium, Abingdon OX14 3DB, Oxon, England.;Korea Adv Inst Sci & Technol, Dept Nucl & Quantum Engn, Daejeon 34141, South Korea..
    Svensson, J.
    JET, Culham Sci Ctr, EUROfus Consortium, Abingdon OX14 3DB, Oxon, England.;Max Planck Inst Plasma Phys, D-17491 Greifswald, Germany.;Teilinst Greifswald, Max Planck Inst Plasmaphys, D-17491 Greifswald, Germany..
    Ghim, Y. -c.
    JET, Culham Sci Ctr, EUROfus Consortium, Abingdon OX14 3DB, Oxon, England.;Korea Adv Inst Sci & Technol, Dept Nucl & Quantum Engn, Daejeon 34141, South Korea..
    Bergsåker, Henric
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Elevant, Thomas
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Garcia Carrasco, Alvaro
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Hellsten, Torbjörn
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Ivanova, Darya
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Johnson, Thomas
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Menmuir, Sheena
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Rachlew, Elisabeth
    KTH, School of Engineering Sciences (SCI), Physics, Atomic and Molecular Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Ström, Petter
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Tholerus, Simon
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Weckmann, Armin
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Zychor, I.
    Inst Plasma Phys & Laser Microfus, PL-01497 Warsaw, Poland..
    Bayesian modelling of the emission spectrum of the Joint European Torus Lithium Beam Emission Spectroscopy system2016In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 87, no 2, article id 023501Article in journal (Refereed)
    Abstract [en]

    A Bayesian model of the emission spectrum of the JET lithium beam has been developed to infer the intensity of the Li I (2p-2s) line radiation and associated uncertainties. The detected spectrum for each channel of the lithium beam emission spectroscopy system is here modelled by a single Li line modified by an instrumental function, Bremsstrahlung background, instrumental offset, and interference filter curve. Both the instrumental function and the interference filter curve are modelled with non-parametric Gaussian processes. All free parameters of the model, the intensities of the Li line, Bremsstrahlung background, and instrumental offset, are inferred using Bayesian probability theory with a Gaussian likelihood for photon statistics and electronic background noise. The prior distributions of the free parameters are chosen as Gaussians. Given these assumptions, the intensity of the Li line and corresponding uncertainties are analytically available using a Bayesian linear inversion technique. The proposed approach makes it possible to extract the intensity of Li line without doing a separate background subtraction through modulation of the Li beam.

  • 49.
    Larsson, Daniel H.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Takman, Per A.C.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    A 24 keV liquid-metal-jet x-ray source for biomedical applications2011In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 82, no 12, p. 123701-Article in journal (Refereed)
    Abstract [en]

    We present a high-brightness 24-keV electron-impact microfocus x-ray source based on continuous operation of a heated liquid-indium/gallium-jet anode. The 30–70 W electron beam is magnetically focused onto the jet, producing a circular 7–13 μm full width half maximum x-ray spot. The measured spectral brightness at the 24.2 keV In Kα line is 3 × 109 photons/(s × mm2 × mrad2 × 0.1% BW) at 30 W electron-beam power. The high photon energy compared to existing liquid-metal-jet sources increases the penetration depth and allows imaging of thicker samples. The applicability of the source in the biomedical field is demonstrated by high-resolution imaging of a mammography phantom and a phase-contrast angiography phantom.

  • 50. Lawson, K. D.
    et al.
    Barnsley, R.
    Maggi, C. F.
    Tyrrell, S.
    Beldishevski, M.
    Brzozowski, Jerzy
    KTH.
    Buckley, M.
    Cass, G.
    Elevant, Thomas
    KTH.
    Griph, S.
    Heesterman, P.
    Hogben, C.
    Jennison, M.
    Stamp, M. F.
    Williams, J.
    Zastrow, K. -D
    Enhancements to the JET poloidally scanning vacuum ultravioletvisible spectrometers2012In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 83, no 10, p. 10D536-Article in journal (Refereed)
    Abstract [en]

    Enhancements to the JET poloidally scanning spectrometers are presented, which will aid the exploitation of the recently installed ITER-like wall in JET. They include the installation of visible filterphotomultiplier tube assemblies and spectrometers and the replacement of large rotating mirrors in the JET vacuum with small oscillating mirrors outside. The upgrade has resulted in a more robust and reliable diagnostic than before, which is described. Drifts in the mirror angle reconstructed from quadrature encoder signals are found, a reference signal being required. The use of the small scanning mirrors necessitated the inclusion of focusing mirrors to maintain throughput into the vacuum ultraviolet spectrometers. The mirror design has taken account of the extreme sensitivity of the focusing to the grazing angle of incidence, an aspect of importance in the design of grazing incidence focusing components on future machines, such as ITER. The visible system has been absolutely calibrated using an in-vessel light source.

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