<b>Divertor Plasma Simulation Experiment Using Hydrogen Ionizing </b><b>Plasma and Helium Ion Beam in an RF Plasma Source </b><b>DT-ALPHA</b>

Abstract

A helium ion beam was injected into hydrogen ionizing plasma using a radio-frequency plasma source to study divertor plasma. Optical emissions from the hydrogen Balmer series and Fulcher-α band were collected. The emissions of the hydrogen Balmer series clearly increased following the onset of the ion beam injection. The behavior of excited hydrogen atoms slightly depend on its excitation energy. In addition to the Balmer series, the emission from hydrogen molecules increased under the existence of energetic ions. These results indicate that the energetic ion collision affects the population density of the excited hydrogen atoms and molecules.

Dependence of Plasma Parameters in Hydrogen Discharges on Magnetic Field Configuration and Neutral Pressure in the DT-ALPHA Device

“…In Ref. [9], the LHR condition was satisfied at lower n e because the magnetic field strength near the RF antenna edge was larger than that in this study. Although the RF heating power was smaller than that in this study, the reason for lower n e is considered to be mainly the un-optimized LHR condition.…”

“…However, n e of argon plasma can exceed 10 18 m −3 even though the LHR condition is not satisfied. Previously obtained n e in hydrogen plasma was approximately 10 16 m −3 [9]. LHR frequency depends on n e , and resonance density decreases as magnetic field strength increases.…”