Heating and Acceleration in Helicon Plasmas Measured via 3D Thomson Scattering

Helicon discharges are frequently used as plasma sources in laboratory experiments thanks to their high ionization rate and electron temperature. We directly measure the helicon wave phase-sorted electron velocity distribution functions and electron temperature anisotropy to distinguish between the possible particle-field interactions in helicon plasmas. However, it remains elusive how electrons are heated and interact with helicon waves. A new 3D Thomson Scattering apparatus has been developed to measure electron velocity distribution functions in the helicon source as well as in the PHAse Space MApping (PHASMA) experiment. The new Thomson Scattering collection optics are modular, so that it can be moved to different locations in PHASMA. Preliminary measurements of the RF phase-resolved parallel electron velocity distribution function in the helicon source will be presented.