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  • 1.
    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.

  • 2. 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.

  • 3. 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.

  • 4.
    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.

  • 5.
    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.

  • 6.
    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.

  • 7.
    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.

  • 8.
    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).

  • 9.
    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.

  • 10.
    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.

  • 11. 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.

  • 12. 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.

  • 13.
    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.

  • 14. 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.

  • 15. 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.

  • 16. 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.

  • 17. 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.

  • 18. 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.

  • 19. 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.

  • 20.
    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.

  • 21. 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.

  • 22.
    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.

  • 23. Fokine, Michael
    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.

  • 24. 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.

  • 25. 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.

  • 26.
    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.

  • 27. 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.

  • 28.
    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.

  • 29. 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.

  • 30. 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.

  • 31.
    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.

  • 32. 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.

  • 33. 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)
  • 34. 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.

  • 35. 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.

  • 36.
    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.

  • 37.
    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.

  • 38.
    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.

  • 39. 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.

  • 40. Legall, H.
    et al.
    Stiel, H.
    Vogt, Ulrich
    Schonnagel, H.
    Nickles, P. V.
    Tummler, J.
    Scholz, F.
    Scholze, F.
    Spatial and spectral characterization of a laser produced plasma source for extreme ultraviolet metrology2004In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 75, no 11, p. 4981-4988Article in journal (Refereed)
    Abstract [en]

    We present a laser produced plasma (LPP) source optimized for metrology and the results of its radiometric characterization. The presented (LPP) source can be used for reflectometry and spectroscopy in the soft x-ray range. For these applications, stable operation with high spectral photon yields high reliability in continuous operation and, to reach high spectral resolution, a small source size and high source point stability is necessary. For the characterization of the source, special instruments have been designed and calibrated using the soft x-ray radiometry beamline of the Physikalisch-Technische-Bundesanstalt at BESSY. These instruments are an imaging spectrometer, a double multilayer tool for in-band power measurements, a transmission slit grating spectrograph, and a pinhole camera. From the measurements a source size of 30 mumx55 mum (2sigma, horizontal by vertical) and a stability of better than 5 mum horizontally and 9 mum vertically were obtained. The source provides a flat continuous emission in the extreme ultraviolet (EUV) range around 13.4 nm and a spectral photon flux of up to 1*10(14)/(s sr 0.1 nm) at a pump laser pulse energy of 650 mJ. The shot-to-shot stability of the source is about 5% (1sigma) for laser pulse energies above 200 mJ. It is shown that an Au-LPP source provides spectrally reproducible emission with sufficient power at low debris conditions for the operation of a laboratory based EUV reflectometer and for spectroscopy.

  • 41. Leyland, M. J.
    et al.
    Beurskens, M. N. A.
    Flanagan, J. C.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Gibson, K. J.
    Kempenaars, M.
    Maslov, M.
    Scannell, R.
    Edge profile analysis of Joint European Torus (JET) Thomson scattering data: Quantifying the systematic error due to edge localised mode synchronisation2016In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 87, no 1, article id 013507Article in journal (Refereed)
    Abstract [en]

    The Joint European Torus (JET) high resolution Thomson scattering (HRTS) system measures radial electron temperature and density profiles. One of the key capabilities of this diagnostic is measuring the steep pressure gradient, termed the pedestal, at the edge of JET plasmas. The pedestal is susceptible to limiting instabilities, such as Edge Localised Modes (ELMs), characterised by a periodic collapse of the steep gradient region. A common method to extract the pedestal width, gradient, and height, used on numerous machines, is by performing a modified hyperbolic tangent (mtanh) fit to overlaid profiles selected from the same region of the ELM cycle. This process of overlaying profiles, termed ELM synchronisation, maximises the number of data points defining the pedestal region for a given phase of the ELM cycle. When fitting to HRTS profiles, it is necessary to incorporate the diagnostic radial instrument function, particularly important when considering the pedestal width. A deconvolved fit is determined by a forward convolution method requiring knowledge of only the instrument function and profiles. The systematic error due to the deconvolution technique incorporated into the JET pedestal fitting tool has been documented by Frassinetti et al. [Rev. Sci. Instrum. 83, 013506 (2012)]. This paper seeks to understand and quantify the systematic error introduced to the pedestal width due to ELM synchronisation. Synthetic profiles, generated with error bars and point-to-point variation characteristic of real HRTS profiles, are used to evaluate the deviation from the underlying pedestal width. We find on JET that the ELM synchronisation systematic error is negligible in comparison to the statistical error when assuming ten overlaid profiles (typical for a pre-ELM fit to HRTS profiles). This confirms that fitting a mtanh to ELM synchronised profiles is a robust and practical technique for extracting the pedestal structure.

  • 42.
    Linnarsson, Margareta K.
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Åström, J.
    Primetzhofer, D.
    Legendre, S.
    Possnert, G.
    New beam line for time-of-flight medium energy ion scattering with large area position sensitive detector2012In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 83, no 9, p. 095107-Article in journal (Refereed)
    Abstract [en]

    A new beam line for medium energy ion mass scattering (MEIS) has been designed and set up at the Angstrom laboratory, Uppsala University, Sweden. This MEIS system is based on a time-of-flight (ToF) concept and the electronics for beam chopping relies on a 4 MHz function generator. Repetition rates can be varied between 1 MHz and 63 kHz and pulse widths below 1 ns are typically obtained by including beam bunching. A 6-axis goniometer is used at the target station. Scattering angle and energy of backscattered ions are extracted from a time-resolved and position-sensitive detector. Examples of the performance are given for three kinds of probing ions, H-1(+), He-4(+), and B-11(+). Depth resolution is in the nanometer range and 1 and 2 nm thick Pt layers can easily be resolved. Mass resolution between nearby isotopes can be obtained as illustrated by Ga isotopes in GaAs. Taking advantage of the large size detector, a direct imaging (blocking pattern) of crystal channels are shown for hexagonal, 4H-SiC. The ToF-MEIS system described in this paper is intended for use in semiconductor and thin film areas. For example, depth profiling in the sub nanometer range for device development of contacts and dielectric interfaces. In addition to applied projects, fundamental studies of stopping cross sections in this medium energy range will also be conducted.

  • 43. Magnus, Fridrik
    et al.
    Gudmundsson, Jon Tomas
    University of Iceland, Iceland.
    Digital Smoothing of the Langmuir Probe I-V Characteristic2008In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 79, no 7, article id 073503Article in journal (Refereed)
    Abstract [en]

    Electrostatic probes or Langmuir probes are the most common diagnostic tools in plasma discharges. The second derivative of the Langmuir probe I-V characteristic is proportional to the electron energy distribution function. Determining the second derivative accurately requires some method of noise suppression. We compare the Savitzky-Golay filter, the Gaussian filter, and polynomial fitting to the Blackman filter for digitally smoothing simulated and measured I-V characteristics. We find that the Blackman filter achieves the most smoothing with minimal distortion for noisy data.

  • 44. Malaquias, A
    et al.
    von Hellermann, M
    Tugarinov, S
    Lotte, P
    Hawkes, N
    Kuldkepp, Mattias
    KTH, Superseded Departments, Physics.
    Rachlew, Elisabeth
    KTH, Superseded Departments, Physics.
    Gorshkov, A
    Walker, C
    Costley, A
    Vayakis, G
    Active beam spectroscopy diagnostics for ITER: Present status (invited)2004In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 75, no 10, p. 3393-3398Article in journal (Refereed)
    Abstract [en]

    An overview is given of the present design of the active beam spectroscopy diagnostics for the ITER. Present spatial resolution and signal-to-noise indicate that, in principle, all proposed measurements are possible covering the entire plasma minor radius. Calculations show that the mirror based periscopes and the impurity coating of the first mirror affect the signal strength and the polarization characteristics of the measured spectra having an impact in the measurement accuracy. On-line calibration techniques and methods to access the first mirror status are addressed.

  • 45.
    Menmuir, Sheena
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Giroud, C.
    Biewer, T. M.
    Coffey, I. H.
    Delabie, E.
    Hawkes, N. C.
    Sertoli, M.
    Carbon charge exchange analysis in the ITER-like wall environment2014In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 85, no 11, p. 11E412-Article in journal (Refereed)
    Abstract [en]

    Charge exchange spectroscopy has long been a key diagnostic tool for fusion plasmas and is well developed in devices with Carbon Plasma-Facing Components. Operation with the ITER-like wall at JET has resulted in changes to the spectrum in the region of the Carbon charge exchange line at 529.06 nm and demonstrates the need to revise the core charge exchange analysis for this line. An investigation has been made of this spectral region in different plasma conditions and the revised description of the spectral lines to be included in the analysis is presented.

  • 46. Mogg, S.
    et al.
    Chitica, N.
    Plaine, G.
    Hammar, Mattias
    Absolute reflectance measurements by a modified cavity phase-shift method2002In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 73, no 4, p. 1697-1701Article in journal (Refereed)
    Abstract [en]

    This article reports on a modified cavity phase-shift (CAPS) method for accurate and reliable characterization of high reflectance mirrors. Our approach relies on using a directly modulated Fabry-Perot laser to circumvent the difficulties encountered in previous attempts with the CAPS method. The Fabry-Perot laser diode ensures a constant coupling between the probe laser and test cavity modes. This results in a stable beam intensity transmitted through the test cavity allowing for accurate measurements of the phase shift from which the absolute reflectance can be determined. The experimental arrangement presented in this article is versatile and easy to use. The method is nondestructive and especially suited for the characterization of distributed Bragg reflectors (DBRs) employed in vertical-cavity optoelectronic devices. A premium feature of this method is its capability to probe a relatively small area of less than 1 mm which can be positioned anywhere across the surface of the wafer. We demonstrate the use of the method by measuring the absolute reflectance of metalorganic vapor-phase epitaxy grown AlAs/GaAs DBRs for 1.3 mum vertical-cavity lasers.

  • 47. Murari, A.
    et al.
    Alper, B.
    Bertalot, L.
    Brzozowski, Jerzy H.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Coad, P.
    Conroy, S.
    De la Luna, E.
    Ericsson, G.
    Esser, H. G.
    Hacquin, S.
    Kaellne, J.
    Kiptily, V.
    Lawson, K.
    O'Mullane, M.
    Philipps, V.
    Sharapov, S.
    Zastrow, K. D.
    New diagnostic techniques and technologies at JET (invited)2006In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 77, no 10Article in journal (Refereed)
    Abstract [en]

    The European Fusion Development Agreement's mission for JET is the development of ITER scenarios exploiting the specific properties of the device. This task requires significant improvements in the measuring techniques. The most innovative diagnostic upgrades are in the fields of edge measurements, detection of fast magnetohydrodynamics modes and burning plasma diagnostics. The importance of plasma-wall interactions, and, in particular, the issue of tritium inventory promoted the development of the quartz microbalance, a detector with improved time resolution to measure material redeposition in the remote areas of the inner divertor. Measurement of Alfven cascades with unprecedented spectral resolution, reaching a toroidal n number of up to 16, was obtained using an O-mode microwave reflectometer as an interferometer. For the diagnosis of the fusion products, a new approach is being developed to measure the He ash based on double charge exchange between thermalized particles and neutrals from JET beams. There have been several upgrades of the neutron diagnostic systems, one of which, the new time of flight neutron spectrometer designed for high counting rates is described.

  • 48.
    Månsson, Martin
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Claesson, Thomas
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Karlsson, Ulf O.
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Tjernberg, Oscar
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Pailhés, Stephane
    Laboratory for Neutron Scattering, ETH Zürich.
    Chang, Johan
    Laboratory for Neutron Scattering, ETH Zürich.
    Mesot, Joël
    Laboratory for Neutron Scattering, ETH Zürich.
    Shi, Ming
    Swiss Light Source, Paul Scherrer Institut, Villigen.
    Patthey, Luc
    Swiss Light Source, Paul Scherrer Institut, Villigen.
    Momono, Naoki
    Department of Physics, Hokkaido University, Sapporo.
    Oda, Migaku
    Department of Physics, Hokkaido University, Sapporo.
    Ido, Masayuki
    Department of Physics, Hokkaido University, Sapporo.
    On-board sample cleaver2007In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 78, no 7, p. 076103-Article in journal (Refereed)
    Abstract [en]

    An on-board sample cleaver has been developed in order to cleave small and hard-to-cleave samples. To acquire good cleaves from rigid samples the alignment of the cleaving blade with respect to the internal crystallographic planes is crucial. To have the opportunity to mount the sample and align it to the blade ex situ has many advantages. The design presented has allowed us to cleave very tiny and rigid samples, e.g., the high-temperature superconductor La(2-x)SrxCuO4. Further, in this design the sample and the cleaver will have the same temperature, allowing us to cleave and keep the sample at low temperature. This is a big advantage over prior cleaver systems. As a result, better surfaces and alignments can be realized, which considerably simplifies and improves the experiments.

  • 49. Müller, L.
    et al.
    Hartmann, G.
    Schleitzer, S.
    Berntsen, M. H.
    KTH.
    Walther, M.
    Rysov, R.
    Roseker, W.
    Scholz, F.
    Seltmann, J.
    Glaser, L.
    Viefhaus, J.
    Mertens, K.
    Bagschik, K.
    Frömter, R.
    De Fanis, A.
    Shevchuk, I.
    Medjanik, K.
    Öhrwall, G.
    Oepen, H. P.
    Martins, M.
    Meyer, M.
    Grübel, G.
    Note: Soft X-ray transmission polarizer based on ferromagnetic thin films2018In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 89, no 3, article id 036103Article in journal (Refereed)
    Abstract [en]

    A transmission polarizer for producing elliptically polarized soft X-ray radiation from linearly polarized light is presented. The setup is intended for use at synchrotron and free-electron laser beamlines that do not directly offer circularly polarized light for, e.g., X-ray magnetic circular dichroism (XMCD) measurements or holographic imaging. Here, we investigate the degree of ellipticity upon transmission of linearly polarized radiation through a cobalt thin film. The experiment was performed at a photon energy resonant to the Co L3-edge, i.e., 778 eV, and the polarization of the transmitted radiation was determined using a polarization analyzer that measures the directional dependence of photo electrons emitted from a gas target. Elliptically polarized radiation can be created at any absorption edge showing the XMCD effect by using the respective magnetic element. 

  • 50.
    Olson, Jonas
    et al.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Brenning, Nils
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Whalund, J.-E.
    Swedish Institute of Space Physics, Uppsala.
    Gunell, H.
    Belgian Insitute for Space Aeronomy, Brussels, Belgium.
    On the interpretation of Langmuir probe data inside a spacecraft sheath2010In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 81, no 10, p. 105106-1-105106-8Article in journal (Refereed)
    Abstract [en]

    If a Langmuir probe is located inside the sheath of a negatively charged spacecraft, there is a risk that the probe characteristic is modified compared to that of a free probe in the ambient plasma. We have studied this probe-in-spacecraft-sheath problem in the parameter range of a small Langmuir probe (with radius r(LP)<<lambda(D)) using a modified version of the orbit motion limited (OML) probe theory. We find that the ambient electron contribution I-e(U-LP) to the probe characteristic is suitably analyzed in terms of three regions of applied probe potential U-LP. In region I, where the probe is negatively charged (i.e., U-LP<U-1, where U-1 is the potential in the sheath at the probe position), the probe characteristic I-e(U-LP) is close to that of OML theory for a free probe in the ambient plasma. In the probe potential range U-LP>U-1, there is first a transition region II in applied potential, U-1<U-LP<U-2, in which the key factor to determine the shape of I-e(U-LP) is a potential minimum U-M between the probe and the ambient plasma. This minimum gives the depth U-pl-U-M of a potential barrier that prevents the lowest energy ambient electrons from reaching the probe. For a high enough positive probe potential, in region III, the barrier becomes small. Here, I-e(U-LP) again approaches OML theory for a free probe. The boundary U-2 between regions II and III is somewhat arbitrary; we propose a condition on the barrier, U-pl-U-M << k(B)T(e)/e, as the definition of region III. The main findings in this work are qualitative rather than quantitative. The existence of the transition region points to that special care must be taken to extract plasma parameters from measured I(U-LP) as the probe characteristic is likely to depart from usual OML in crucial respects: (1) the ambient plasma potential U-pl falls into the transition region, but there is no obvious knee or other feature to identify it, (2) there is in this region no exponential part of I-e(U-LP) that can be used to obtain T-e, instead, (3) the probe size is important in determining the curve shape. We have tentatively applied our simplified probe-in-sheath model to real probe data from the Cassini spacecraft, taken in the dense plasma of Saturn's magnetosphere. We propose that our model gives a better description than OML of measured Langmuir probe sweeps in space plasmas where the Langmuir probe is situated within the spacecraft sheath, i.e., for long Debye lengths. The understanding of these probe sweep effects in such regions may improve by self-consistent particle simulations of the spacecraft environment.

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