High density hydrogen helicon plasma in a non-uniform magnetic field

A high density (1019 m−3) hydrogen plasma has been sustained successfully in axially non-uniform static magnetic field configurations for frequencies both above and below the high density limit of the lower hybrid resonance frequency (LH-HD). Wave field measurements suggest several modes are coupling to generate these helicon plasmas. The dependence of the plasma density on the static magnetic field strength for a fixed geometry can be explained by waves, with wavelength close to the antenna length, that couple to the fundamental radial mode for frequencies below the LH-HD frequency and to the second radial mode for frequencies above the LH-HD frequency.