Ion heating in the HELIX helicon plasma source

Efficient ion heating in a steady-state helicon plasma source is observed w ith two external loop antennae just above the ion cyclotron frequency. The ion velocity space distribution is measured by laser induced fluorescence i n an argon plasma. The measured bulk ion heating is highly anisotropic (the perpendicular temperature increase is ten times the parallel temperature i ncrease) even though the plasma is moderately collisional. Measurements of the perturbed distribution function with laser induced fluorescence suggest that an electrostatic ion cyclotron wave is launched. (C) 1999 American In stitute of Physics. [S1070-664X(99)02212-0].