X-ray diagnostics for investigating electron distribution functions and electron potential confinements

X-ray radiation from the GAMMA 10 tandem-mirror plasmas is investigated so as to interpret the electron-velocity-distribution functions as well as the formation mechanism of plasma-confining potentials from the X-ray data. In particular, plasma-electron behavior in the thermal-barrier and the plug regions are highlighted. Two different shapes of the distribution functions (i.e., relativistic Maxwellian electrons and plateau-shaped electrons bounded by an electron-confining potential) characterize the barrier and the plug plasmas, respectively. For the X-ray-data analyses, we employ a new theory on the X-ray response of semiconductor detectors. In particular, it is noted that the use of this theory modifies analysis results from the conventional X-ray-response theory in textbooks, which was employed over this quarter of the century for plasma-electron-temperature analyses.