Plasma electron acceleration in a non-resonant microwave heating scheme below the electron cyclotron frequency

Abstract Microwave heating of over-dense plasmas is routinely achieved in the stellarator TJ-K. In contrast to usually applied scenarios tokamaks or stellarators, an operational regime described where occurs well below electron cyclotron frequency but still above lower hybrid frequency. energy deposited at so-called O-resonance, accompanied by a small population high-energy electrons with up 100 keV. These are responsible for significant toroidal net current and occurrence hard x-rays. Requirements achieving this together novel scheme plasma-electron acceleration.