HOT-ELECTRON PRODUCTION AND WAVE STRUCTURE IN A HELICON PLASMA SOURCE

Energetic wave-trapped electrons of similar to 20 eV, moving at the 13 .56 MHz helicon wave phase velocity, are directly measured with a 3 ns response-time retarding-potential analyzer. The rf axial wavelength i s measured with B-dot probes scanned axially. Changes in the axial mag netic field or the rf power cause order of magnitude changes in the en ergetic electron current. The current correlates with either a transit ion from partially propagating to nearly pure standing waves or quanti zed jumps in the number of half wavelengths between the two azimuthal antenna straps.