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  • 301.
    Hadinia, Baharak
    et al.
    KTH, Tidigare Institutioner                               , Fysik.
    Cederwall, Bo
    KTH, Tidigare Institutioner                               , Fysik.
    Lagergren, Karin
    KTH, Tidigare Institutioner                               , Fysik.
    Blomqvist, Jan
    KTH, Tidigare Institutioner                               , Fysik.
    Bäck, Torbjörn
    KTH, Tidigare Institutioner                               , Fysik.
    Johnson, Arne
    KTH, Tidigare Institutioner                               , Fysik.
    Liotta, Roberto
    KTH, Tidigare Institutioner                               , Fysik.
    et al.,
    First identification of gamma-ray transitions in 107Te2004Ingår i: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 70, nr 6, s. 064314-1-064314-4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Gamma-ray transitions in Te-107 have been identified for the first time. The experiment, which utilized the recoil decay tagging technique, was performed at the accelerator laboratory of the University of Jyvaskyla, Finland. Prompt gamma rays produced in Ni-58(Cr-52,3n)Te-107(*) reactions were detected by the JUROGAM gamma-ray spectrometer. The gamma rays belonging to Te-107 were selected based on the recoil identification provided by the RITU gas-filled recoil separator and the GREAT focal plane spectrometer. A first excited state at 90 keV, tentatively of g(7/2) character, is proposed.

  • 302. Hagberg, Johan
    et al.
    Morozov, Evgeny
    Furo, Istvan
    KTH, Tidigare Institutioner (före 2005), Kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Centrum för Industriell NMR-teknik. KTH, Tidigare Institutioner (före 2005), Fysik.
    Lindbergh, Göran
    KTH, Tidigare Institutioner (före 2005), Kemiteknik.
    Inequality of Axial and Radial Diffusion of Inserted Lithium Ions in Carbon Fibres as Revealed by Pulsed-Field Gradient NMRManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Nuclear Magnetic Resonance (NMR) studies has characterized lithiated polyacrylonitrile-based carbon fibres. The local dynamics has been probed by spin-lattice and spin-spin relaxation measurements and long range motion (diffusion) by pulsed field gradient NMR. Differences in fibre orientation was investigated by axially and radially aligned samples. One single peak related to lithium insertion was observed around 12-25 ppm, increasing with lithium load. A small effect of fibre orientation was observed on the relaxation behavior. The diffusion though was found to be around three times higher in axial compared to radial direction of the carbon fibres. This is believed to be due to the microstructure, with oriented crystallites along the carbon fibres contributing more in the axial direction to the average measured diffusion. The diffusion coefficients varied from around 10-12 m2/s to 4·10-12 m2/s, increasing with lithium load.

  • 303. Haggkvist, R.
    et al.
    Lundow, Per Håkan
    KTH, Tidigare Institutioner                               , Fysik.
    The Ising partition function for 2D grids with periodic boundary: Computation and analysis2002Ingår i: Journal of statistical physics, ISSN 0022-4715, E-ISSN 1572-9613, Vol. 108, nr 04-mar, s. 429-457Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Ising partition function for a graph counts the number of bipartitions of the vertices with given sizes, with a given size of the induced edge cut. Expressed as a 2-variable generating function it is easily translatable into the corresponding partition function studied in statistical physics. In the current paper a comparatively efficient transfer matrix method is described for computing the generating function for the nxn grid with periodic boundary. We have applied the method to up to the 15 x 15 grid, in total 225 vertices. We examine the phase transition that takes place when the edge cut reaches a certain critical size. From the physical partition function we extract quantities such as magnetisation and susceptibility and study their asymptotic behaviour at the critical temperature.

  • 304. Haggkvist, R.
    et al.
    Rosengren, Anders
    KTH, Tidigare Institutioner, Fysik.
    Andren, D.
    Kundrotas, Petras
    KTH, Tidigare Institutioner, Fysik.
    Lundow, Per Håkan
    KTH, Tidigare Institutioner, Fysik.
    Markstrom, K.
    Computation of the Ising partition function for two-dimensional square grids2004Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics: Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, ISSN 1063-651X, E-ISSN 1095-3787, Vol. 69, nr 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An improved method for obtaining the Ising partition function of nxn square grids with periodic boundary is presented. Our method applies results from Galois theory in order to split the computation into smaller parts and at the same time avoid the use of numerics. Using this method we have computed the exact partition function for the (320x320) grid, the (256x256) grid, and the (160x160) grid, as well as for a number of smaller grids. We obtain scaling parameters and compare with what theory prescribes.

  • 305. Hakansson, P.
    et al.
    Westlund, P. O.
    Lindahl, E.
    Edholm, Olle
    KTH, Tidigare Institutioner                               , Fysik.
    A direct simulation of EPR slow-motion spectra of spin labelled phospholipids in liquid crystalline bilayers based on a molecular dynamics simulation of the lipid dynamics2001Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 3, nr 23, s. 5311-5319Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    EPR line shapes can be calculated from the stochastic Liouville equation assuming a stochastic model for the reorientation of the spin probe. Here we use instead and for the first time a detailed molecular dynamics (MD) simulation to generate the stochastic input to the Langevin form of the Liouville equation. A 0.1 mus MD simulation at T = 50 degreesC of a small lipid bilayer formed by 64 dipalmitoylphosphatidylcholine (DPPC) molecules at the water content of 23 water molecules per lipid was used. In addition, a 10 ns simulation of a 16 times larger system consisting of 32 DPPC molecules with a nitroxide spin moiety attached at the sixth position of the sn2 chain and 992 ordinary DPPC molecules, was used to investigate the extent of the perturbation caused by the spin probe. Order parameters, reorientational dynamics and the EPR FID curve were calculated for spin probe molecules and ordinary DPPC molecules. The timescale of the electron spin relaxation for a spin-moiety attached at the sixth carbon position of a DPPC lipid molecule is 11.9 x 10(7) rad s(-1) and for an unperturbed DPPC molecule it is 3.5 x 10(7) rad s(-1).

  • 306.
    Hammar, M.
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Gauthier, Y.
    Göthelid, M.
    Karlsson, U. O.
    Flodström, S. A.
    Rosengren, A.
    Scanning tunnelling microscopy studies of Pt80Fe 20(110)1993Ingår i: Journal of Physics: Condensed Matter, ISSN 09538984 (ISSN), Vol. 5, nr 18, s. 2837-2842Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Results of scanning tunnelling microscopy (STM) show that two different kinds of surface structures coexist on the (110) surface of Pt 80Fe20. The predominant structure corresponds well to the missing row type (1*2) reconstruction previously observed on, for example Pt(110), whereas the minority domains show a faintly buckled structure with approximately (1*1) geometry. Based on the STM images, the authors propose that the two domains have different surface chemical compositions and correspond to two different metallurgical phases known for the PtFe system at this composition.

  • 307.
    Hammar, M.
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Göthelid, M.
    Karlsson, U. O.
    Flodström, S. A.
    Initial growth of silver on Ge(111) studied by scanning tunneling microscopy1993Ingår i: Physical Review B, ISSN 01631829 (ISSN), Vol. 47, nr 23, s. 15669-15674Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Scanning tunneling microscopy (STM) has been used to study the Ge(111) surface after submonolayer depositions of Ag. At the lowest coverages a (4×4) reconstruction, with small insets of a (3×1) edge structure, is observed. Based on the STM images we propose a mixed Ag and Ge adatom structure for the (4×4) reconstruction, in which the adatoms have local (1×1) and (2×2) arrangements corresponding to a Ag coverage of 6/16 monolayers. The (3×1) structure appears to have a configuration similar to the Si(111)/Ag-(3×1) reconstruction, although in this case it has a much more limited extension, restricted to a few unit cells in the near vicinity of step edges and phase boundaries. At higher coverages, after the completion of a full (4×4)/(3×1) surface, a (3 × 3) R30°structure appears showing STM images similar to those previously published for the Si(111)/Ag system. © 1993 The American Physical Society.

  • 308.
    Hammar, M.
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Göthelid, M.
    Karlsson, U. O.
    Flodström, S. A.
    Håkansson, K. L.
    Johansson, L. I.
    Morphology and atomic structure of the sputtered and annealed Mo3Si and Cr3Si (110) surfaces1994Ingår i: Physical Review B, ISSN 01631829 (ISSN), Vol. 50, nr 23, s. 17639-17642Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Scanning tunneling microscopy was used to study the sputtered and annealed (110) surfaces of Mo3Si and Cr3Si. Both surfaces show extended and atomically flat terraces, but in the case of Mo3Si there is also a uniform distribution of Mo crystallites. This difference in morphology is discussed in terms of different preferential sputtering effects. In both cases, measured step heights show that the ideally bulk-truncated surfaces are either purely Si or metal terminated. Atomically resolved images suggest that the Mo3Si surface is Si terminated, but although no atomic resolution could be obtained for the Cr3Si surface, there are indications that this surface is instead metal terminated. © 1994 The American Physical Society.

  • 309.
    Hammar, M.
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Steele, B. E.
    Tsong, I. S. T.
    Impact-collision ion-scattering spectrometry studies of the VC0.8(111)-(8 × 1) surface1994Ingår i: Nuclear Inst. and Methods in Physics Research, B, ISSN 0168583X (ISSN), Vol. 85, nr 1-4, s. 429-434Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use impact-collision ion-scattering spectrometry (ICISS) to verify that the (8 × 1) reconstructed surface of VC0.8(111) arises from the superposition of a rectangular surface vanadium layer on top of the hexagonal bulk, in agreement with a surface structure proposed earlier in a scanning tunneling microscopy (STM) study. However, a major discrepancy with the STM results is the absence of any pronounced buckling within the surface unit cell. The ICISS results suggest that the vanadium layer on the surface is perfectly planar. © 1994.

  • 310.
    Han, Shunhui
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Andersson, Magnus
    KTH, Tidigare Institutioner, Fysik.
    The upper critical-field of pb doped BI-SR-CA-CU-O compounds1991Ingår i: Physica scripta. T, ISSN 0281-1847, Vol. 44, nr 11, s. 69-70Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The upper critical field H(c2) of four Bi-(Pb)-Sr-Ca-Cu-O superconductors with the 110 K phase has been measured as a function of temperature. H(c2) exhibited a (T(c) - T)alpha-temperature dependence with alpha > 1 f two impure samples, but showed a linear temperature dependence for the purest sample, which is not expected according to current theories and other experiments.

  • 311.
    Han, Shunhui
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Andersson, Magnus
    KTH, Tidigare Institutioner, Fysik.
    Thermodynamic fluctuation in doped BiSrCaCuO superconductors with 110K phase1994Ingår i: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 194-196, s. 1513-1514Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The resistivity has been carefully measured for four sintered samples of Pb and Pb/Sb doped Bi-Sr-Ca-Cu-O superconductors with the 110 K phase from zero resistance temperature up to 300 K. The thermodynamical fluctuation have been fitted on the form DELTAsigma is-proportional-to epsilon(x) (epsilon=(T-T(c))/T(c)) in the regions -4 < In epsilon < -2. By choosing T(c) in different ways, it is shown that consistent results only could be obtained when T(c) is defined according to the Lawrence-Doniach theory.

  • 312.
    Han, Shunhui
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Andersson, Magnus
    KTH, Tidigare Institutioner, Fysik.
    Hegedüs, Zsolt
    Arrheniuslaboratoriet, Stockholms Universitet.
    Study of the upper critical magnetic field HC2 of YBA2CU3O7-DELTA compounds1992Ingår i: Solid State Communications, ISSN 0038-1098, E-ISSN 1879-2766, Vol. 82, nr 5, s. 379-380Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Careful resistive measurements of the upper critical field H(c2) have been made on high quality polycrystalline YBa2Cu3O7-delta samples in magnetic fields up to 12 T. The data have been fitted on the form H(c2) infinity (T(c)-T)alpha to compare with theoretical models. A cusp is found in the H(c2) (T) curve for both of the samples. Different exponents-alpha are obtained depending on the temperature range used in the fitting procedure.

  • 313.
    Han, Shunhui
    et al.
    KTH, Tidigare Institutioner, Fysik. KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Axnäs, Johan
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Zhao, B R
    Rapp, Östen
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Fluctuation conductivity at high temperatures in polycrystalline Hg, Tl-1223 - Is there ID fluctuation behavior?2004Ingår i: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 408, s. 679-680Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Detailed resistivity measurements were made for polycrystalline Hg1-xTlxBa2Ca2Cu3O8+delta (x = 0.2) in zero field and in the temperature region from zero resistance up to 300 K. The fluctuation conductivity Deltasigma was analyzed as a function of is an element of equivalent to In(T/Tc-mf) in the range -5.5 < Inc < -0.5. 1D behavior Of fluctuation conductivity was found at high temperatures (above the 2D regime) with a crossover temperature T-1*, above which the critical exponent was found to be -1.5.

  • 314.
    Han, Shunhui
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Hegedüs, Zsolt
    Arrheniuslaboratoriet, Stockholms Universitet.
    Andersson, Magnus
    KTH, Tidigare Institutioner, Fysik.
    Nygren, Mats
    Arrheniuslaboratoriet, Stockholms Universitet.
    Rapp, Östen
    KTH, Tidigare Institutioner, Fysik.
    Yan, Y.F.
    Dept. Physics, Chinese Academy of Sciences, Beijing.
    Chen, Q.
    Dept. Physics, Chinese Academy of Sciences, Beijing.
    Wei, Y.N.
    Dept. Physics, Chinese Academy of Sciences, Beijing.
    He, Y.S.
    Dept. Solid state physics, Quinghua University, Beijing.
    Study of upper critical field Hc2(T) in doped Bi-Sr-Ca-Cu-O superconductors with 100 K phase1990Ingår i: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 169, nr 3-4, s. 250-256Artikel i tidskrift (Refereegranskat)
  • 315.
    Hansen, Patricia
    KTH, Tidigare Institutioner, Fysik.
    A new measurement of the mu(+) and mu(-) spectra at several atmospheric depths with CAPRICE982004Ingår i: Relativistic Astrophysics And Cosmology / [ed] Shapiro, MM; Stanev, T; Wefel, JP, 2004, Vol. 13, s. 217-226Konferensbidrag (Refereegranskat)
    Abstract [en]

    A new measurements of the mu(+) and mu(-)spectra at several atmospheric depths in the momentum range 0.3-20 GeV/c was made by the balloon-borne experiment CAPRICE98. The data were collected during the ascent of the payload on the 28 May 1998 from Fort Summer, New Mexico, USA. This apparatus consists of a magnet spectrometer, with a superconducting magnet and a drift-chamber tracking device, a time of flight scintillator system, a silicon-tungsten imaging calorimeter and a gas ring imaging Cherenkov detector. This gas RICH radiator made it possible to safely identify mu(+) up to 20 GeV/c. This is the first time that the mu(+) component has been measurement over a wide momentum range.

  • 316.
    Hansen, Patricia
    KTH, Tidigare Institutioner                               , Fysik.
    A new measurement of&#956+ and&#956- spectra at several atmospheric depths2003Doktorsavhandling, monografi (Övrigt vetenskapligt)
  • 317.
    Hansson, B. A. M.
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Hemberg, O.
    KTH, Tidigare Institutioner, Fysik.
    Hertz, Hans M.
    KTH, Tidigare Institutioner, Fysik.
    Berglund, Magnus
    KTH, Tidigare Institutioner, Fysik.
    Choi, H. J.
    KTH, Tidigare Institutioner, Fysik.
    Jacobsson, Björn
    KTH, Tidigare Institutioner, Fysik.
    Janin, E.
    KTH, Tidigare Institutioner, Fysik.
    Mosesson, Sofia
    KTH, Tidigare Institutioner, Fysik.
    Rymell, L.
    KTH, Tidigare Institutioner, Fysik.
    Thoresen, J.
    KTH, Tidigare Institutioner, Fysik.
    Wilner, M.
    KTH, Tidigare Institutioner, Fysik.
    Characterization of a liquid-xenon-jet laser-plasma extreme-ultraviolet source2004Ingår i: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 75, nr 6, s. 2122-2129Artikel i tidskrift (Refereegranskat)
    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.

  • 318.
    Hansson, B. A. M.
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Hertz, Hans M.
    KTH, Tidigare Institutioner, Fysik.
    Liquid-jet laser-plasma extreme ultraviolet sources: from droplets to filaments2004Ingår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 37, nr 23, s. 3233-3243Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The laser plasma is one of the major contenders as a high-power source for future high-volume-manufacturing extreme ultraviolet lithography systems. Such laser-plasma sources require a target system that allows high-repetition-rate operation with low debris and manageable thermal load at the required high laser power. In this paper, we review the development of the liquid-jet target laser plasmas, from droplets to filaments, with special emphasis on its applicability for high-power extreme ultraviolet generation. We focus on two target systems, the liquid-xenon-jet and the liquid-tin-jet.

  • 319. Hansson, B. A. M.
    et al.
    Rymell, L.
    Berglund, M.
    Hertz, Hans M.
    KTH, Tidigare Institutioner                               , Fysik.
    A liquid-xenon-jet laser-plasma X-ray and EUV source2000Ingår i: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 53, nr 04-jan, s. 667-670Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We describe a laser-plasma soft-x-ray source based on a cryogenic-xenon liquid-jet target. The source is suitable for extreme ultraviolet (EUV) projection lithography and proximity x-ray lithography (PXL). Absolute calibrated spectra in the 1-2 nm range and uncalibrated spectra in the 9-15 nm range are obtained using a free-standing transmission grating and a CCD-detector.

  • 320.
    Hansson, Björn
    KTH, Tidigare Institutioner                               , Fysik.
    Laser-Plasma Sources for Extreme-Ultraviolet Lithography2003Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis describes the development and characterizationof a liquidxenon- jet laser-plasma source forextreme-ultraviolet (EUV) radiation. It is shown how thissource may be suitable for production-scale EUV lithography(EUVL).

    EUVL is one of the main candidates to succeeddeep-ultraviolet (DUV) lithography for large-scalemanufacturing of integrated circuits (IC). However, a majorobstacle towards the realization of EUVL is the currentunavailability of a source meeting the tough requirements onespecially power and cleanliness for operation in an EUVLstepper. The liquid-xenon-jet laser-plasma concept has keyadvantages that may make it suitable for EUVL since, e.g., itsplasma consists only of the inert noble gas xenon and since theliquidjet target technology enables plasma operation at largedistances from the source-hardware thereby reducing sputteringand to allowing for high-power operation.

    At the beginning of the work described in this thesis, aspatial instability of the liquid-xenon-jet made stableoperation of a plasma at practical distances from the nozzleorifice dicult. However, an invention of a stabilization methodbased on applying localized heating to the tip of thejet-forming nozzle, resulted in stable jet operation. Thelongitudinal droplet stability of a liquid-droplet laser-plasmasource has also been investigated and improved.

    Continuous improvements of especially the laser-power toEUV-radiation conversion eciency (CE) and the stability oflaser-plasma operation at large distances (several centimeter)from the nozzle are reported for the liquidxenon- jet laserplasma source. Furthermore, this source is characterizedregarding many parameters relevant for EUVL operationincluding, ion emission from the plasma and related sputteringof nearby components, source size and shape, therepetition-rate limit of the source and non-EUV emission fromthe plasma.

    Although the main focus of the thesis has been thedevelopment and characterization of a liquid-xenon-jetlaser-plasma source for production-scale EUVL, the source mayalso be suitable for small field applications that benefit fromthe high potential brightness of the source. A method to scanthe plasma and thus minimize the photon losses whilemaintaining the object plane uniformity was developed.Furthermore, the first operation of a liquidtin- jet laserplasma is reported. Quantitative EUV flux measurements yieldrecord CE, but quantitative contamination measurements alsoindicate that a liquid-tin-jet laser plasma is not likely to beapplicable as a source for EUVL.

  • 321.
    Hansson, Björn A. M.
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Mosesson, Sofia
    KTH, Tidigare Institutioner, Fysik.
    Hertz, Hans M.
    KTH, Tidigare Institutioner, Fysik.
    Improved emission uniformity from a liquid-jet laser-plasma extreme-ultraviolet source2004Ingår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 43, nr 29, s. 5452-5457Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many modern compact soft-x-ray and extreme-ultraviolet (EUV) imaging systems operate with small fields of view and therefore benefit from the use of small high-brightness sources. Such systems include water-window microscopes and ELTV lithography tools. We show that the photon losses in such systems can be minimized while uniformity of object-plane illumination is maintained by controlled scanning of the source. The improved collection efficiency is demonstrated both theoretically and experimentally for a scanned laser-plasma source compared with static sources. A prospective aerial image microscope and a liquid-xenon-jet laser-plasma source are offered as examples of modem imaging tools that may benefit from such scanning of the source.

  • 322.
    Hansson, Björn
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Berglund, Magnus
    KTH, Tidigare Institutioner, Fysik.
    Hemberg, Oscar
    KTH, Tidigare Institutioner, Fysik.
    Hertz, Hans M.
    KTH, Tidigare Institutioner, Fysik.
    Stabilization of liquified-inert-gas jets for laser-plasma generation2004Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 95, nr 8, s. 4432-4437Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate the hydrodynamic properties of liquified-inert-gas jets in a vacuum with a special emphasis on their stability. Such jets have applications as targets for laser-plasma generation of soft-x-ray and extreme-ultraviolet (EUV) radiation. An important example is the liquid-xenon-jet laser-plasma source, one of the source candidates for EUV lithography. A simple hydrodynamic model in not sufficient to explain experimental observations of jet stability. Evaporation-induced cooling explains observed in-flight freezing of the jet and may be a key factor influencing jet stability. It is shown how the jet stability, and, thus, the stability of the laser-plasma x-ray and EUV emission, are improved by applying localized heating to the tip of the jet-generating nozzle.

  • 323. Hansson, G.
    et al.
    Karlsson, H.
    Laurell, Fredrik
    KTH, Tidigare Institutioner, Fysik.
    Unstable resonator optical parametric oscillator based on quasi-phase-matched RbTiOAsO42001Ingår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 40, nr 30, s. 5446-5451Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate improved signal and idler-beam quality of a 3-mm-aperture quasi-phase-matched RbTiOAsO4 optical parametric oscillator through use of a confocal unstable resonator as compared with a plane-parallel resonator. Both oscillators were singly resonant, and the periodically poled RbTiOAsO4 crystal generated a signal at 1.56 mum and an idler at 3.33 mum when pumped at 1.064 mum. We compared the beam quality produced by the 1.2-magnification confocal unstable resonator with the beam quality produced by the plane-parallel resonator by measuring the signal and the idler beam M-2 value. We also investigated the effect of pump-beam intensity distribution by comparing the result of a Gaussian and a top-hat intensity profile pump beam. We generated a signal beam of M-2 approximate to 7 and an idler beam of M-2 approximate to 2.5 through use of an unstable resonator and a Gaussian intensity profile pump beam. This corresponds to an increase of a factor of approximately 2 in beam quality for the signal and a factor of 3 for the idler, compared with the beam quality of the plane-parallel resonator optical parametric oscillator.

  • 324. Hansson, G.
    et al.
    Karlsson, H.
    Wang, S. H.
    Laurell, Fredrik
    KTH, Tidigare Institutioner, Fysik.
    Transmission measurements in KTP and isomorphic compounds2000Ingår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 39, nr 27, s. 5058-5069Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The optical biaxial nature of crystals in the potassium titanyl phosphate (KTP) family result in anisotropic transmission that depends on the polarization direction of the transmitted radiation with respect to the fundamental crystal axes. Knowledge of the polarization-dependent crystal transmission is important for all wavelength-conversion applications and in particular is the only limitation on possible combinations of wavelengths when one uses the quasi-phase-matching techniques recently developed for the KTP family materials. In this study, polarized transmission spectra of KTiOPO4 (KTP), RbTiOPO4, RbTiOAsO4 (RTA), and KTiOAsO4 were measured over the 0.3-6-mu m wavelength range with a spectrophotometer and a Fourier-transform infrared spectrometer. Seven crystal samples were studied, including four samples of KTP crystals of different origins. Variations in spectral transmission on the short- and long-wavelength edges, as well as visible-wavelength transmission and OH- absorption properties, are presented and discussed. The transmission of one sample of RTP and of RTA was also measured before and after periodic electric field poling.

  • 325.
    Hansson, Göran
    KTH, Tidigare Institutioner                               , Fysik.
    Studies on coherent mid-infrared solid state sources for lidar and countermeasure applications2001Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 326.
    Hansson, Peter
    KTH, Tidigare Institutioner                               , Fysik.
    Optical characterization of paper structures and print defects1999Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 327. Haraldsson, H. O.
    et al.
    Li, H. X.
    Yang, Z. L.
    Dinh, Truc-Nam
    KTH, Tidigare Institutioner                               , Fysik.
    Sehgal, B. R.
    Effect of solidification on drop fragmentation in liquid-liquid media2001Ingår i: Heat and Mass Transfer, ISSN 0947-7411, E-ISSN 1432-1181, Vol. 37, nr 4-5, s. 417-426Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents results of experimental and analytical investigation on molten alloy drop fragmentation in water pool. Emphasis is directed towards delineating the roles which melt to coolant heat transfer and melt solidification play in the fragmentation process. The strong impact of coolant temperature upon fragmentation process is addressed. A set of 23 drop fragmentation experiments were performed, in which 8 experiments employed a low melting point alloy, cerrobend-70 and 15 experiments using Pb-Bi eutectic alloy as drop fluid. The results show strong impact of coolant temperature on particle size distribution of the fragmented drops. A linear stability analysis of the interface between the two liquid fluids with thin crust growing between them, is performed. A modified dimensionless Aeroelastic number, for Kelvin-Helmholtz instability, is obtained and used as a criteria for fragmentation of molten drops penetrating into another liquid coolant media with lower temperature. The nondimensionalized mean diameter of the fragmented particles is correlated with the Aeroelastic number.

  • 328.
    Haviland, David B.
    et al.
    KTH, Tidigare Institutioner                               , Fysik.
    Andersson, K.
    Agren, P.
    Superconducting and insulating behavior in one-dimensional Josephson junction arrays2000Ingår i: Journal of Low Temperature Physics, ISSN 0022-2291, E-ISSN 1573-7357, Vol. 118, nr 06-maj, s. 733-749Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Experiments on one-dimensional small capacitance Josephson Junction arrays are described. The arrays have a junction capacitance that is much larger than the stray capacitance of the electrodes, which we argue is important for observation of Coulomb blockade. The Josephson energy can be tuned in situ and an evolution from Josephson-like to Coulomb blockade behavior is observed. This evolution can be described as a superconducting to insulating, quantum phase transition. In the Coulomb blockade state, hysteretic current-voltage characteristics are described by a dynamic model which is dual to the resistively shunted junction model of classical Josephson junctions.

  • 329.
    Haviland, David B.
    et al.
    KTH, Tidigare Institutioner                               , Fysik.
    Andersson, K.
    Agren, P.
    Johansson, J.
    Schollmann, V.
    Watanabe, M.
    Quantum phase transition in one-dimensional Josephson junction arrays2001Ingår i: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 352, nr 04-jan, s. 55-60Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We describe experiments on one-dimensional arrays of small capacitance Josephson junctions which show how the Coulomb blockade of Cooper pair tunneling is influenced by changing the Josephson coupling energy in situ with an externally applied magnetic flux. We show how the zero bias resistance of the array is affected by the length of the array, and we use the length scaling of this resistance to infer that a quantum phase transition occurs as the Josephson coupling energy is changed. The data are qualitatively analyzed in terms of a theoretical model of the quantum phase transition which uses a mapping to the two-dimensional XY model.

  • 330.
    Haviland, David B.
    et al.
    KTH, Tidigare Institutioner                               , Fysik.
    Chow, E.
    Delsing, P.
    Quantum-phase transition in 1D Josephson junction arrays2000Ingår i: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 284, s. 1808-1809Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One-dimensional arrays of small capacitance SQUIDs have been studied experimentally. The effective Josephson coupling between neighboring electrodes is tunable in situ. The arrays can be tuned from a Josephson-like state, with low resistance and sharp critical current, to a Coulomb blockade state, with infinite resistance and sharp threshold voltage. A quantum phase transition occurs at the crossover between these two types of behavior, which is evident from an analysis of the temperature dependence of the zero bias resistance.

  • 331. Hawkes, N. C.
    et al.
    Andrew, Y.
    Challis, C. D.
    DeAngelis, R.
    Drozdov, V.
    Hobirk, J.
    Joffrin, E.
    Lotte, P.
    Mazon, D.
    Rachlew, Elisabeth
    KTH, Tidigare Institutioner                               , Fysik.
    Reyes-Cortes, S.
    Sattin, F.
    Solano, E.
    Stratton, B. C.
    Tala, T.
    Valisa, M.
    Efda Jet Workprogramme,
    The formation and evolution of extreme shear reversal in JET and its influence on local thermal transport2002Ingår i: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 44, nr 7, s. 1105-1125Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In JET discharges where lower hybrid heating and current drive (LHCD) is applied early during the current ramp, a region of the plasma with zero current density is formed near the axis. At the boundary of this region the current density is large and B-theta increases rapidly over a small distance. In the central region the safety factor, q, is effectively infinite, but this falls steeply in the boundary region. Outside the boundary region q reaches a minimum, where the magnetic shears equivalent to r/q (dq/dr) becomes zero. The formation of this region of zero current is dependent on both the heating and the current drive effects of the LHCD. When LHCD is switched off the current profile begins to relax towards the resistive peaked current distribution of fully inductive tokamak operation. If LHCD is not used in the current rise then these current profiles are not established. Although the physical mechanism exists to drive the central plasma current below zero, in most cases it appears to be prevented from going negative. At least one MHD mechanism has been identified which could be responsible for this. The presence of the zero central current is closely linked to the periodic relaxation events seen in these discharges. In these discharges, internal transport barriers have been observed with additional heating powers substantially below the values required to obtain barriers in monotonic q profile cases.

  • 332. Hawkes, N. C.
    et al.
    Stratton, B. C.
    Tala, T.
    Challis, C. D.
    Conway, G.
    DeAngelis, R.
    Giroud, C.
    Hobirk, J.
    Joffrin, E.
    Lomas, P.
    Lotte, P.
    Mailloux, J.
    Mazon, D.
    Rachlew, Elisabeth
    KTH, Tidigare Institutioner                               , Fysik.
    Reyes-Cortes, S.
    Solano, E.
    Zastrow, K. D.
    Observation of zero current density in the core of JET discharges with lower hybrid heating and current drive2001Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 8711, nr 11, s. art. no.-115001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Simultaneous current ramping and application of lower hybrid heating and current drive (LHCD) have produced a region with zero current density within measurement errors in the core (r/a less than or equal to 0.2) of JET tokamak optimized shear discharges. The reduction of core current density is consistent with a simple physical explanation and numerical simulations of radial current diffusion including the effects of LHCD. However, the core current density is clamped at zero, indicating the existence of a physical mechanism which prevents it from becoming negative.

  • 333.
    Hedqvist, Anders
    KTH, Tidigare Institutioner                               , Fysik.
    Diagnostics of the EXTRAP-T2 reversed field pinch by visible and VUV spectroscopy1998Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 334.
    Hedqvist, Anders
    KTH, Tidigare Institutioner                               , Fysik.
    Quantitative plasma spectroscopy in a resistive shell reversed-field pinch1999Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 335.
    Hedqvist, Anders
    et al.
    KTH, Tidigare Institutioner, Fysik.
    O'Mullane, Martin
    Nordquist, Jonas
    KTH, Tidigare Institutioner, Fysik.
    Rachlew-Källne, Elisabeth
    KTH, Tidigare Institutioner, Fysik.
    Zastrow, Klaus-Dieter
    JET Joint Undertaking, United Kingdom .
    Contributions of thermal charge exchange excitation to the Rydberg series of Cl16+2000Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 33, nr 3, s. 375-382Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spectra from the Rydberg series 1s-np for the principal quantum numbers n greater than or equal to 8 of Cl16+ are observed on the JET tokamak. Individual lines up to n = 15 are resolved. The line intensity of n = 10 is enhanced, relative to the underlying 1/n(3) scaling, due to charge exchange collisions with neutral deuterium in the ground state. The observations are compared with predictions based on available partial charge exchange cross section data. There is generally good agreement, however, some details of the predicted n-shell distribution are different from those observed in the experiment.

  • 336.
    Hegedüs, Zsolt
    et al.
    Arrheniuslaboratoriet, Stockholms Universitet.
    Nygren, Mats
    Arrheniuslaboratoriet, Stockholms Universitet.
    Andersson, Magnus
    KTH, Tidigare Institutioner, Fysik.
    Rapp, Östen
    KTH, Tidigare Institutioner, Fysik.
    On the preparation of the high temperature superconductor YBa2Cu4O81991Ingår i: ICMAS-91: International conference on modern aspects of superconductivity, Paris, 7-8 octobre 1991 / [ed] B. Raveau, K. Wasa and R. Suryanayanan, Gournay-sur-Marne: Institute for Industrial Technolog Transfer (IITT) , 1991, s. 107-111Konferensbidrag (Refereegranskat)
  • 337. Hegyesi, G.
    et al.
    Imrek, J.
    Kalinka, G.
    Molnár, J.
    Novák, D.
    Végh, J.
    Balkay, L.
    Emri, M.
    Molnár, G.
    Trón, L.
    Bagaméry, I.
    Bükki, T.
    Rózsa, S.
    Szabó, Z.
    Kerek, Andras
    KTH, Tidigare Institutioner, Fysik.
    Development of an FPGA-based data acquisition module for small animal PET2004Ingår i: 2004 IEEE Nuclear Science Symposium Conference Record, 2004, s. 2957-2961Konferensbidrag (Refereegranskat)
    Abstract [en]

    We report on the design of a DAQ module for a small animal PET camera developed at our institutes. During the design an important guideline was to develop a system which is built up from strictly identical DAQ modules, and which has no built-in hardware limitation on the maximum number of modules. The developed DAQ module comprises of an LSO scintillator crystal block, a position sensitive PMT, analog signal conditioning circuits, a digitizer, an FPGA for digital signal processing and a communication module through which the collected data is sent to a cluster of computers for post processing and storage. Instead of implementing hardware coincidence detection between the modules we attach a precise time-stamp to each event in our design, and the coincidence is determined by the data collecting computers during the post processing. The digital CFD algorithm implemented in the FPGA gives a time resolution of 2 to 3 ns FWHM for real detector signals.

  • 338. Hellstrom, J.
    et al.
    Clemens, R.
    Pasiskevicius, Valdas
    KTH, Tidigare Institutioner, Fysik.
    Karlsson, H.
    Laurell, Fredrik
    KTH, Tidigare Institutioner, Fysik.
    Real-time and in situ monitoring of ferroelectric domains during periodic electric field poling of KTiOPO42001Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 90, nr 3, s. 1489-1495Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate a photographic method to view the inversion of ferroelectric domains during the periodic electric field poling of KTiOPO4 by taking advantage of the electro-optic effect and a high speed charge coupled device (CCD) camera. The method is noninvasive and allows monitoring in situ and in real time. The high speed CCD camera opens up the possibility to observe the dynamics of the domains during poling and to probe the samples afterwards to evaluate the grating formed in the material. This monitoring method should be applicable to other ferroelectric crystals, as well.

  • 339. Hellstrom, J.
    et al.
    Karlsson, G.
    Pasiskevicius, Valdas
    KTH, Tidigare Institutioner, Fysik.
    Laurell, Fredrik
    KTH, Tidigare Institutioner, Fysik.
    Optical parametric amplification in periodically poled KTiOPO4 seeded by an Er-Yb: glass microchip laser2001Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 26, nr 6, s. 352-354Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An optical parametric amplifier based on periodically poled KTiOPO4 was used to generate 3-ns pulses at 1.544 mum. The device was pumped by a Q-switched Nd:YAG laser, and the signal output-pulse energy reached 71 muJ; the maximum gain was 66 dB. The seed source was an Er-Yb:glass microchip laser. A theoretical fit to experimental data gave an effective nonlinear coefficient of 9.7 pm/V, close to the highest values reported for periodically poled KTiOPO4. Furthermore, the broad parametric gain observed could be used for broadband pulse amplification.

  • 340. Hellstrom, J.
    et al.
    Pasiskevicius, Valdas
    KTH, Tidigare Institutioner, Fysik.
    Karlsson, H.
    Laurell, Fredrik
    KTH, Tidigare Institutioner, Fysik.
    High-power optical parametric oscillation in large-aperture periodically poled KTiOPO42000Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 25, nr 3, s. 174-176Artikel i tidskrift (Refereegranskat)
  • 341. Hellström, J.
    et al.
    Pasiskevicius, Valdas
    KTH, Tidigare Institutioner, Fysik.
    Karlsson, H.
    Tellefsen, J. A.
    Laurell, Fredrik
    KTH, Tidigare Institutioner, Fysik.
    High-power parametric oscillator with large-aperture periodically poled KTiOPO42000Ingår i: OSA Trends in Optics and Photonics, ISSN 1094-5695, Vol. 34, s. 275-279Artikel i tidskrift (Refereegranskat)
  • 342.
    Hellström, J.
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Pasiskevicius, Valdas
    KTH, Tidigare Institutioner, Fysik.
    Karlsson, Håkan
    KTH, Tidigare Institutioner, Fysik.
    Laurell, Fredrik
    KTH, Tidigare Institutioner, Fysik.
    Efficient nanosecond optical parametric oscillators based on periodically poled KTiOPO4, emitting in 1.8-2.5 µm spectral region1999Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 24, s. 1233-1235Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The use of periodically poled KTiOPO4 as a gain medium in efficient nanosecond optical parametric oscillators pumped by a flash-lamp-pumped 𝑄‐switched Nd:YAG laser is demonstrated. Parametric radiation in the 1.8–2.5‐µm spectral region was achieved when the crystal temperature was tuned from 10 to 100 °C. A maximum total output energy of 1.8 mJ was obtained at a pump level of 3.5 mJ. Stable operation was achieved, with conversion efficiencies reaching 50%. No gray tracking or laser damage was observed, even for pump intensities of 450 MW/cm2.

  • 343.
    Hellström, Jonas
    KTH, Tidigare Institutioner                               , Fysik.
    Nanosecond optical parametric oscillators and amplifiers based on periodically poled KTiOPO42001Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Optical parametric oscillators (OPOs) and optical parametricamplifiers (OPAs) constitute a class of optical frequencyconverting devices that have many possible applications, e.g.in range finding, molecular spectroscopy and medicine. They canconvert the frequency of the incident pump field with highefficiency, and generate two waves at new frequencies that willbe continuously tuneable over a wide spectral range. Virtuallyany wavelengths within the transparency region of the nonlinearmaterial can be generated if the material can bequasi-phasematched (QPM). In addition, QPM gives thepossibility to utilise the largest nonlinear tensor element ofthe material and allows walk-off free interaction between thewaves.

    The aims of this thesis have been to investigate thepossibility to use QPM KTiOPO4crystals as nonlinear material in nanosecond OPOsand OPAs operating at room-temperature, and to explore theadvantages and shortcomings of these devices. The technique ofelectric field poling has been employed to implement the QPMstructure in flux grown KTiOPO4(KTP).

    The main conclusion is that periodically poled KTP (PPKTP)is a suitable material to use in nanosecond OPOs and OPAs. Thematerial properties that foremost make KTP into an attractivenonlinear material are: The large value of the nonlinearcoefficient d33, the high resistance to optically inducedbreakdown, the low susceptibility to grey-track formation, theinsensitivity to the photorefractive effect, the widetransparency and the low coercive field.

    The thesis shows that it is possible to pole large volumesof KTP with a high quality of the QPM structure. Highlyefficient nanosecond OPOs have been constructed during thisproject. Maximum conversion efficiencies have reached 45 % inthe case of a singly resonant OPO (SRO) built around a 3 mmthick PPKTP crystal. Total pulse energies for both the signal(1.72 µm) and the idler (2.8 µm) of up to 18 mJ wasreached and an average output power of 2 W was obtained forthis sample. However, up to 24 W was produced in a doublyresonant OPO operating close to degeneracy. The efficiencyreached 48 % for that case. Truly continuous and very widespectral tuning has also been demonstrated, as well as a narrowbandwidth OPO operating on one single longitudinal mode.

    Keywords:optical parametric oscillators, opticalparametric amplifiers, quasi-phasematching, KTiOPO4, nonlinear optics, frequency conversion, periodicelectric field poling, ferroelectrics, high-order secondharmonic generation, electro-optic effect.

  • 344.
    Hellström, Jonas
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Karlsson, Gunnar
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Pasiskevicius, Valdas
    KTH, Tidigare Institutioner, Fysik.
    Laurell, Fredrik
    KTH, Tidigare Institutioner, Fysik.
    An optical parametric amplifier based on periodically poled KTiOPO4, seeded by an Er-Yb: glass microchip laser2001Ingår i: ADVANCED SOLID-STATE LASERS, PROCEEDINGS, 2001, Vol. 50, s. 650-655Konferensbidrag (Refereegranskat)
    Abstract [en]

    We report on an optical parametric amplifier in periodically poled KTiOPO4 at 1.54 mum, with an Er-Yb:glass microchip seed laser. The signal pulses reached 71 muJ, with pulse duration of 3 ns, corresponding to 66 dB gain.

  • 345.
    Helm, Johannes
    KTH, Tidigare Institutioner                               , Fysik.
    A confocal scanning laser microscope for cell physiological research1997Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 346. Hemberg, O.
    et al.
    Hansson, B. A. M.
    Berglund, M.
    Hertz, Hans M.
    KTH, Tidigare Institutioner                               , Fysik.
    Stability of droplet-target laser-plasma soft x-ray sources2000Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 88, nr 9, s. 5421-5425Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The spatial stability of microscopic target droplets used for laser-plasma soft x-ray generation in vacuum is investigated. A long-term drift in drop position is characterized with an ultrafast laser-diode imaging system. The drift is experimentally and theoretically shown to be due to a temperature-induced increase in target-liquid viscosity as a result of evaporation. Finally, the drift is compensated for and stable, long-term unattended operation of the source is demonstrated with an automatic phase-delay drop-to-laser synchronizing system. This is important for future compact lithography and microscopy systems.

  • 347.
    Hemberg, Oscar
    KTH, Tidigare Institutioner, Fysik.
    Compact Liquid-Jet X-Ray Sources2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis describes the development, characterization andoptimization of compact, high-brightness, liquid-jet-targetx-ray sources. Two different source types have been developedfor different wavelength regions and applications.

    A laser-plasma source for generating soft x-ray andextreme-ultraviolet radiation has been further developed forsoft x-ray microscopy and extreme-ultraviolet lithography. Thiswork focused on improved target stability, increased conversionefficiency and decreased debris production. For x-raymicroscopy applications using carbon-containingliquid-jetdroplet targets, the droplet stability has beeninvestigated and a method for source stabilization introduced.This source has also been optimized in terms of flux per debriswith respect to target material and size. Forextreme-ultraviolet lithography applications, aliquid-xenon-jet-target laser-plasma source system has beengreatly improved, especially in terms of stability andconversion efficiency. This source has also been characterizedin terms of, e.g., source size, angular distribution, andrepetition-rate capability. For extremeultraviolet lithography,the possible use of tin as a target material has also beenstudied and conversion efficiency and debris measurementsperformed.

    A new anode concept for electron-impact hard x-ray sourcesbased on high-speed liquidmetal jets has been introduced.Initial calculations show that this new target concept couldpotentially allow more than a hundred-fold increase in sourcebrightness compared to existing state-of-the-art technology. Alow-power, proof-of-principle, experiment has been performed,verifying the basic source concept. Scaling tohigh-poweroperation is discussed and appears plausible. A main obstaclefor high-power operation, the generation of a microscopichigh-speed jet in vacuum, is investigated usingdynamic-similarity experiments and shown to be feasible.Finally, initial medium-power experiments, approaching currentstate-of-the-art sources in terms of brightness, have beenperformed.

  • 348.
    Hemberg, Oscar
    et al.
    KTH, Tidigare Institutioner                               , Fysik.
    Hertz, Hans
    KTH, Tidigare Institutioner                               , Fysik.
    Otendal, Mikael
    KTH, Tidigare Institutioner                               , Fysik.
    Liquid-Metal-Jet Anode Electron-Impact X-Ray Source2003Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 83, s. 1483-1485Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A liquid-metal-jet anode for improved brightness in compact electron-impact x-ray source was investigated. The generated x-ray flux and brightness was quantitatively measured in the 7-50 keV spectral region and found to agree with the theory. Applications such as mammography, angiography, and diffraction would benefit from a compact high-brightness source.

  • 349.
    Hemberg, Oscar
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Otendal, Mikael
    KTH, Tidigare Institutioner, Fysik.
    Hertz, Hans M.
    KTH, Tidigare Institutioner, Fysik.
    The liquid-metal-jet anode x-ray source2004Ingår i: Proceedings of The International Society for Optical Engineering, 2004, s. 421-431Konferensbidrag (Refereegranskat)
    Abstract [en]

    We introduce a novel electron-impact x-ray source based on a high-speed liquid-metal-jet anode. Basic thermal power load calculations indicate that this new anode concept potentially could increase the achievable brightness in compact electron-impact x-ray sources by more than a factor 100 compared to current state-of-the-art rotating-anode or microfocus sources. A first, successful, low-power proof-of-principle experiment is described and the feasibility of scaling to high-brightness and high-power operation is discussed. Some possible applications that would benefit from such an increase in brightness are also briefly described.

  • 350.
    Hemberg, Oskar
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Otendal, Mikael
    KTH, Tidigare Institutioner, Fysik.
    Hertz, Hans M.
    KTH, Tidigare Institutioner, Fysik.
    A Liquid-Metal-Jet Anode X-Ray Tube2004Ingår i: Optical Engineering: The Journal of SPIE, ISSN 0091-3286, E-ISSN 1560-2303, Vol. 43, nr 7, s. 1682-1688Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We describe a novel electron-impact x-ray source based on a high-speed liquid-metal-jet anode. Thermal power load calculations indicate that this new anode concept potentially could increase the achievable brightness in compact electron-impact x-ray sources by more than a factor 100 compared to current state-of-the-art rotating-anode or microfocus sources. A first, successful, low-power proof-of-principle experiment is described and the feasibility of scaling to high-brightness and high-power operation is discussed. Some possible applications that would benefit from such an increase in brightness are also briefly

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