Production of superthermal electrons and ion cyclotron waves in a reversed‐field‐pinch plasma

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Abstract
Production of superthermal electrons through kinetic interactions with electromagneticfluctuations is studied to account for observations of fast electrons and ion cyclotron waves in reversed field pinch plasmas. Low‐frequency Alfvénic (torsional) modes can interact with electrons through the Landau resonance when the wavelength perpendicular to the magnetic field is as small as the ion gyroradius. Such kinetic Alfvén waves induce simultaneous diffusion (double diffusion) in the coordinate and velocity spaces, and produce a field aligned superthermal electron beam in the edge region. Microinstabilities are driven by the electron‐beam and ion cyclotron waves are excited. Through these precesses the fluctuation energy in the low‐frequency regime may be transported to the ion cyclotron frequency regime.