Energetic particle physics in JET

Results achieved on JET during the 1997-1999 experimental campaigns in the physics of energetic ions and runaway electrons are reviewed. Heating of de uterium-tritium (DT) plasmas by fusion born alpha particles is found to be similar to that achieved by comparable ICRF heating of deuterium plasmas. T he stability of alpha particle driven Alfven eigenmodes (AEs) in the highes t fusion power ELM-free H mode discharges is shown to be consistent with th e existing theoretical analysis for AEs. Direct measurements of the trapped alpha particle and knock-on deuteron distribution functions by a neutral p article analyser (NPA) are described, New ICRF heating scenarios tested in JET DT plasmas are presented in view of the possible use of the ICRF heatin g of ITER-like DT plasmas on route to ignition. The energetic ion pinch in the presence of toroidally asymmetric ICRF waves is studied experimentally on JET. Recent experimentally observed effects of ICRF accelerated ions on sawteeth in JET are reviewed. Detailed time and space resolved X ray images of the electron runaway beam in flight spontaneously generated by disrupti ons on JET are described.