title: Non-local-thermodynamical-equilibrium effects in the x-ray emission of radiatively heated materials of different atomic numbers.
abstract: X-ray self-emission of radiatively heated materials with different values of Z has been investigated. Thin foils were uniformly heated by a 120-eV Hohlraum radiation of 400-ps duration in order to study the self-emission of a homogeneous, optically thin material. The x-ray emission spectra were followed for more than 2 ns. The spectrally integrated emission shows not only a strong Z dependence, but different temporal behaviors for different values of Z. The lower is the value of Z of the x-ray heated matter, the longer is the duration of self-emission. Theoretical comparison with a hydrocode and FLY post-processing shows a non-local-thermal equilibrium behavior caused by direct photoionization due to the thermal pumping radiation, which has a higher brightness temperature than the matter temperature of the heated material.
authors.affiliation: KFKI-Research Institute for Particle and Nuclear Physics, Association EURATOM, H-1525 Budapest, POB. 49, Hungary.
authors.forename: I B
authors.initials: IB
authors.lastname: Földes
authors.forename: K
authors.initials: K
authors.lastname: Eidmann
authors.forename: G
authors.initials: G
authors.lastname: Veres
authors.forename: J S
authors.initials: JS
authors.lastname: Bakos
authors.forename: K
authors.initials: K
authors.lastname: Witte