Experiments on the critical ionization velocity limit effect in MCX

Magnetized rotating plasmas rely on large, supersonic plasma rotation velocity to achieve centrifugal confinement. Previous experiments in MCX documented the existence of a hard rotation velocity at or below the Alfven velocity. In addition, plasma voltage is seen to be limited in the Ordinary mode (O mode) to a value consistent with the critical ionization velocity limit. CIV has been documented in experiments on magnetized rotating plasmas since early 1960's. Current work at MCX shows that the limit on maximum plasma velocity in the O mode is consistent with neutral-plasma interaction at the end insulator. Presented will be various ways of overcoming the CIV limit during the O mode. Results from the diagnostics placed near the insulator (spectrometer, interferometer, hydrogen-alpha line detectors) will be discussed.