Temperature measurement through detailed balance in x-ray Thomson scattering

The plasma conditions in isochorically heated beryllium are measured by collective x-ray Thomson scattering. The collectively scattered Cl Ly-α x-ray line at 2.96 keV shows up- and down-shifted plasmon signals. From the detailed balance relation, i.e., the ratio of the up-shifted to the down-shifted plasmon intensities, the plasma temperature can be determined independent of model assumptions. Results are shown for an experiment in which a temperature of 18 eV was measured. Using detailed balance for temperature measurement will be important to validate models that calculate the static ion–ion structure factor S_ii(k).