Experiments investigating microwave beat-wave Raman scattering in inductively coupled plasma

Non-linear wave coupling can develop in plasma perturbed by powerful EM waves. These effects can arise in microwave interactions in fusion plasma, cool plasma, radio propagation in ionospheric plasma and laser-plasma interactions. Understanding these dynamics can inform new methods to introduce energy into plasma, manipulate plasma conditions or to mitigate undesirable consequences induced by such instabilities. Cool plasmas with critical frequencies in the low microwave range are relatively easier to diagnose. Experiments are therefore underway investigating the dynamics of microwave beams propagating in an inductively coupled plasma formed in a recently commissioned source with a diameter of 1m and length of 3m. Operating in He gas with pressures in the range of <!--[if gte msEquation 12]>≈ 10^-3 mbar – 10^-1 mbar it achieves plasma frequencies in the range a few hundred MHz and bulk temperatures of <1eV (a tenuous hotter population is also present) when driven by a 10-200W RF source at 14MHz, ideal for microwave parametric scattering experiments. The plasma is being modulated by counter propagating microwave beams in the range of 10GHz, with power between 7 and 15kW injected as Gaussian beams using a pair of Satoh horn antenna. Progress on this experiment will be reported.