Rising-bucket heating in helicons

Summary form only given. Accelerating phase-space buckets, a well-known concept in particle accelerator physics, was explored theoretically and predicted to be an effective means of heating plasma by intense microwaves in a tokamak. The observed r.f. absorption in the MTX tokamak was consistent with this mechanism. An increasing phase velocity vs. distance was reported recently for helicon experiments at ANU and test-particle calculations showed that wave trapping and heating can occur for these experiments. We use analytic techniques developed previously to specify the conditions under which this mechanism can be significant for helicon plasmas, and obtain a model for such a heating rate that can be used in transport codes.