139 research outputs found
Self-consistent Spectral Function for Non-Degenerate Coulomb Systems and Analytic Scaling Behaviour
Novel results for the self-consistent single-particle spectral function and
self-energy are presented for non-degenerate one-component Coulomb systems at
various densities and temperatures. The GW^0-method for the dynamical
self-energy is used to include many-particle correlations beyond the
quasi-particle approximation. The self-energy is analysed over a broad range of
densities and temperatures (n=10^17/cm^3-10^27/cm^3, T=10^2 eV/k_B-10^4
eV/k_B). The spectral function shows a systematic behaviour, which is
determined by collective plasma modes at small wavenumbers and converges
towards a quasi-particle resonance at higher wavenumbers. In the low density
limit, the numerical results comply with an analytic scaling law that is
presented for the first time. It predicts a power-law behaviour of the
imaginary part of the self-energy, Im Sigma ~ -n^(1/4). This resolves a long
time problem of the quasi-particle approximation which yields a finite
self-energy at vanishing density.Comment: 28 pages, 9 figure
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Thomson Scattering at FLASH - Status Report
The basic idea is to implement Thomson scattering with free electron laser (FEL) radiation at near-solid density plasmas as a diagnostic method which allows the determination of plasma temperatures and densities in the warm dense matter (WDM) regime (free electron density of n{sub e} = 10{sup 21}-10{sup 26} cm{sup -3} with temperatures of several eV). The WDM regime [1] at near-solid density (n{sub e} = 10{sup 21}-10{sup 22} cm{sup -3}) is of special interest because, it is where the transition from an ideal plasma to a degenerate, strongly coupled plasma occurs. A systematic understanding of this largely unknown WDM domain is crucial for the modeling and understanding of contemporary plasma experiments, like laser shock-wave or Z-pinch experiments as well as for inertial confinement fusion (ICF) experiments as the plasma evolution follows its path through this domain
Electron-ion temperature relaxation in warm dense hydrogen observed with picosecond resolved X-Ray scattering
Angularly resolved X-ray scattering measurements from fs-laser heated hydrogen have been used to determine the equilibration of electron and ion temperatures in the warm dense matter regime. The relaxation of rapidly heated cryogenic hydrogen is visualized using 5.5 keV X-ray pulses from the Linac Coherent Light (LCLS) source in a 1 Hz repetition rate pump-probe setting. We demonstrate that the electron-ion energy transfer is faster than quasi-classical Landau-Spitzer models that use ad hoc cutoffs in the Coulomb logarithm
X-ray Thomson scattering diagnostics of impact ionization in laser-driven carbon foils
We have studied the light–matter interaction of ultra-short, intense optical laser fields with thin carbon foils via particle-in-cell simulations. Especially, the influence of additional impact ionization on the density and temperature of the generated plasma and on the corresponding Thomson scattering spectra was investigated. We predict a pump–probe experiment at the free electron laser FLASH in order to verify the importance of this effect in the laser–matter interaction on ultra-short time scales and to check our predictions quantitatively
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