PROGRESS TOWARD A MICROSECOND DURATION, REPETITIVELY PULSED, INTENSE-ION BEAM FOR ACTIVE SPECTROSCOPIC MEASUREMENTS ON ITER

We describe the design of an intense, pulsed, repetitive, neutral beam based on magnetically insulated diode technology for injection into I TER for spectroscopic measurements of thermalizing alpha particle and thermal helium density profiles, ion temperature, plasma rotation, and low Z impurity concentrations throughout the confinement region. The beam is being developed to enhance low signal-to-noise ratios expected with conventional steady-state ion beams because of severe beam atten uation and intense bremsstrahlung emission. A 5 GW (e.g., 100 keV, 50 kA) 1 mu s duration beam would increase the charge exchange recombinat ion signal by 10(3) compared to a conventional 5 MW beam. (C) 1997 Ame rican Institute of Physics.