A Two-Stage Ion Heating Obtained in a Rapid Theta-Compression Experiment. I

抄録

The ion heating process of a kilovolt plasma obtained by a rapid magnetic compression is studied experimentally. The initial plasma for compression is produced by the encounter of two deuterium plasma streams. For the spectroscopic evaluation of the ion temperature, a small quantity of helium is added to the deuterium gas. According to time-resolved measurements of Doppler profiles of a HeII line, the ion heating process is divided into two stages: phase I up to 240 ns from the ignition of the compression and phase II hereafter. In phase I, most of measured Doppler profiles take the Gaussian forms and the heating rate is 1∼2 eV/ns. In phase II, each profile from 250 ns to 500 ns shows a two-temperature distribution. The ion temperature is 1.7 keV at 700 ns and the heating rate is 4 eV/ns around this time. Finally, the ion temperature reaches 3∼4 keV.