During the academic semesters the plasma physics department hosts seminars on Tuesday at 2:30 pm.
If you have questions or want to suggest a speaker/topic, please contact Prof. Olga Rosmej or Dr. Paul Neumayer.

Plasmaphysik Seminar

Equation of state measurements of warm dense Carbon

by Dr Kateřina Falk (ELI-Beamlines, Prague, Czech Republic)

Europe/Berlin
Seminarraum Theorie (GSI Darmstadt)

Seminarraum Theorie

GSI Darmstadt

Description
Warm dense matter (WDM) is a unique state of dense plasmas common in many astrophysical objects including large gaseous planets, brown dwarfs, crusts of old stars and others. It is readily created when laser radiation heats up solid targets and during implosion of deuterium-tritium-fuel pellets during inertial confinement fusion (ICF) implosions. At moderately high temperatures at 1-100 eV, solid densities, and pressures above 1 Mbar the plasma is created both by collisional and pressure ionization resulting in a system where ions are strongly correlated and the electron population is partially or fully degenerate. Such states are challenging to study both theoretically and experimentally. A detailed knowledge of the equation of state (EOS) of light elements such as carbon is however essential to understanding of many processes in the formation and structure of these massive astrophysical objects.
Thus, a novel technique of x-ray Thomson scattering (XRTS) was developed to provide an active probing of such dense plasma states. The talk will present a new platform developed for the OMEGA laser facility to obtain a full EOS measurement of off-Hugoniot states in the WDM regime that does not rely on any theoretical models. Spatially and spectrally resolved XRTS was used to obtain accurate temperature measurement. Additional diagnostics including x-ray radiography, velocity interferometry and streaked optical pyrometry provided complementary measurements of density and pressure. This platform was used to study shock-released diamond and graphite at pressures between 1 and 10 Mbar and temperatures between 5 and 15 eV. The platform was also modified to obtain the first x-ray Thomson scattering data from shocked low density CH foams reaching five times compression and temperatures of 20–30 eV.