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

The dependence of hydrogen plasma parameters on magnetic field configuration and neutral pressure was investigated in the radio-frequency (RF) plasma source DT-ALPHA. It was found that higher electron density was obtained when the lower hybrid resonance condition was satisfied near the RF antenna. It was also found that use of lower hydrogen neutral pressure yielded higher electron density plasma. By optimizing the resonance condition and neutral pressure, the hydrogen plasma of Te ∼ 10 eV and ne > 1 × 1017 m−3 was achieved.