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 ITER 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 attenuation and intense bremsstrahlung emission. A 5 GW (e.g., 100 keV, 50 kA) 1 mu s duration beam would increase the charge exchange recombination signal by 10(3) compared to a conventional 5 MW beam. (C) 1997 American Institute of Physics.