Dynamic Control of a Cusped Plasma near the Ion Cyclotron Frequency

An r f electric field near the ion cyclotron frequency is applied perpendicularly to the magnetic field of cusp regions in order to plug up cusp ends and to heat ions. A helium plasma is steadily fed from one of point cusps into the containment region whose density is varied from 1×10 8 to 1×10 11 cm -3 . For the line cusp loss good plugging is satisfied up to 1×10 11 cm -3 , but for the point cusp loss it is not obtained for the density above 1×10 10 cm -3 . Under the resonance condition the ion energies consist of two components both of which display Maxwellian-like distribution of T i of about 40eV and 150∼200eV respectively when E r f =100V/cm.