High Density Plasma Productions by Hydrogen Storage Electrode in the Tohoku University Heliac

In the Tohoku University Heliac (TU- Heliac), a high-density plasma was produced by a Vanadium (V) electrode or a Titanium (Ti) electrode biased negatively. The electrode was pre-treated for hydrogen storage. In biasing experiments using the V electrode, a high-density plasma was observed in not only Ar plasmas but also He plasmas. In the case of the V electrode biasing, the radial distribution of the electron density sloped steeply at the electrode position and a strong negative radial electric field was formed outside the electrode. The E x B drift velocity was calculated from the local electric field, which was about 30 km/s, and the Mach number Mp was estimated to be Mp ? -20. In the low field discharges, the measured ? value exceeded about 0.5 % ( ? ? 0.5 %). (Author)