Observation of alpha particle loss from JET plasmas during ion cyclotron resonance frequency heating using a thin foil Faraday cup detector array.
The loss of MeV alpha particles from JET plasmas has been measured with a set of thin foil Faraday cup detectors during third harmonic heating of helium neutral beam ions. Tail temperatures of ∼ 2 MeV have been observed, with radial scrape off lengths of a few centimeters. Operational experience from this system indicates that such detectors are potentially feasible for future large tokamaks, but careful attention to screening rf and MHD induced noise is essential.
Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA. ddarrow@pppl.gov
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