Bremsstrahlung and line spectroscopy of warm dense aluminum plasma heated by xuv free-electron-laser radiation.

We report the creation of solid-density aluminum plasma using free-electron laser (FEL) radiation at 13.5nm wavelength. Ultrashort pulses were focused on a bulk Al target, yielding an intensity of 2x10;{14}Wcm;{2} . The radiation emitted from the plasma was measured using an xuv spectrometer. Bremsstrahlung and line intensity ratios yield consistent electron temperatures of about 38eV , supported by radiation hydrodynamics simulations. This shows that xuv FELs heat up plasmas volumetrically and homogeneously at warm-dense-matter conditions, which are accurately characterized by xuv spectroscopy.

[1]  O. Landen,et al.  The physics basis for ignition using indirect-drive targets on the National Ignition Facility , 2004 .

[2]  Paul Gibbon,et al.  Short-pulse laser - plasma interactions , 1996 .

[3]  D. Saumon,et al.  Modeling pressure-ionization of hydrogen in the context of astrophysics , 1999, astro-ph/9909168.

[4]  B. L. Henke,et al.  X-Ray Interactions: Photoabsorption, Scattering, Transmission, and Reflection at E = 50-30,000 eV, Z = 1-92 , 1993 .

[5]  Marta Fajardo,et al.  Hydrodynamic simulation of XUV laser-produced plasmas , 2004 .

[6]  D Sertore,et al.  Generation of GW radiation pulses from a VUV free-electron laser operating in the femtosecond regime. , 2002, Physical review letters.

[7]  Ryszard S. Romaniuk,et al.  Operation of a free-electron laser from the extreme ultraviolet to the water window , 2007 .

[8]  Justin S. Wark,et al.  Plasma-based studies with intense X-ray and particle beam sources , 2002 .

[9]  H. Mendlowitz,et al.  Optical Constants of Aluminum in Vacuum Ultraviolet , 1962 .

[10]  K. Witte,et al.  Isochoric Heating of Solid Aluminum by Ultrashort Laser Pulses Focused on a Tamped Target , 1999 .

[11]  J. Meyer-ter-Vehn,et al.  VUV-heating of plasma layers and their use as ultrafast switches , 2005 .

[12]  G. Chandler,et al.  X-ray absorption spectroscopy measurements of thin foil heating by Z-pinch radiation. , 2002, Physical review. E, Statistical, nonlinear, and soft matter physics.

[13]  et al,et al.  Thomson scattering from near-solid density plasmas using soft x-ray free electron lasers , 2006, physics/0611274.

[14]  Gilbert W. Collins,et al.  Absolute equation of state measurements of shocked liquid deuterium up to 200 GPa (2 Mbar) , 1997 .

[15]  R. Redmer,et al.  Ab Initio Equation of State Data for Hydrogen, Helium, and Water and the Internal Structure of Jupiter , 2007, 0712.1019.

[16]  Raymond F. Smith,et al.  Picosecond-resolution soft-x-ray laser plasma interferometry. , 2003, Applied optics.

[17]  Gilbert W. Collins,et al.  Broadband dielectric function of nonequilibrium warm dense gold. , 2006, Physical review letters.

[18]  T E Cowan,et al.  Isochoric heating of solid-density matter with an ultrafast proton beam. , 2003, Physical review letters.

[19]  O. Landen,et al.  Demonstration of spectrally resolved x-ray scattering in dense plasmas. , 2003, Physical review letters.

[20]  Y. Ping,et al.  Optical properties in nonequilibrium phase transitions. , 2006, Physical review letters.

[21]  M. Rosen,et al.  Ultrafast X-ray Pulses from Laser-Produced Plasmas , 1991, Science.

[22]  Herrmann,et al.  X-ray generation in a cavity heated by 1.3- or 0.44- microm laser light. I. Time-integrated measurements. , 1988, Physical review. A, General physics.

[23]  A. Dobryakov,et al.  Laser-Induced Nonequilibrium Electron Distribution in Metals on a Femtosecond Time Scale , 1999 .

[24]  Bremsstrahlung vs. Thomson scattering in VUV-FEL plasma experiments , 2006, physics/0601212.

[25]  Gilbert W. Collins,et al.  Temperature measurements of shock compressed liquid deuterium up to 230 GPa. , 2001, Physical review letters.

[26]  J. Bearden.  X-Ray Wavelengths , 1967 .

[27]  R. Redmer,et al.  COMPTRA04 – a Program Package to Calculate Composition and Transport Coefficients in Dense Plasmas , 2005 .

[28]  O. Landen,et al.  Observations of plasmons in warm dense matter. , 2006, Physical review letters.

[29]  W. C. Martin,et al.  Wavelengths and Energy Level Classifications for the Spectra of Aluminum (Ali through Alxiii) , 1991 .

[30]  LaGattuta.  Multiphoton ionization rates for atomic hydrogen: Linear and circular polarization compared. , 1991, Physical review. A, Atomic, molecular, and optical physics.

[31]  H. Kramers,et al.  XCIII. On the theory of X-ray absorption and of the continuous X-ray spectrum , 1923 .

[32]  Tommy Ao,et al.  Single-State Measurement of Electrical Conductivity of Warm Dense Gold , 2004 .

[33]  P. R. Woodruff,et al.  HELIOS-CR – A 1-D radiation-magnetohydrodynamics code with inline atomic kinetics modeling , 2006 .

[34]  Davidson,et al.  Absorption experiments on x-ray-heated mid-Z constrained samples. , 1996, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[35]  T. Nishikawa,et al.  Transient observation of extended x-ray absorption fine structure in laser-melted Si by using femtosecond laser-produced-plasma soft x ray , 2005 .

[36]  J. Bergmann,et al.  A single‐shot spectrograph for the soft x‐ray region , 1994 .

[37]  F. Schäfer,et al.  Soft x‐ray spectra produced by subpicosecond laser‐double‐pulses , 1991 .

[38]  Weber,et al.  Electron Density Measurements of High Density Plasmas Using Soft X-Ray Laser Interferometry. , 1995, Physical review letters.

[39]  S. Toleikis,et al.  Investigations of ultrafast phenomena in high-energy density physics using X-ray FEL radiation , 2005 .

[40]  Robert Cook,et al.  Review of indirect-drive ignition design options for the National Ignition Facility , 1999 .