Testing of a high current DC ESQ accelerator

A high current DC electrostatic quadrupole (ESQ) accelerator is being developed for negative-ion-based neutral beam heating and current drive on the next generation tokamak. Beam energy and current will eventually be in the megaelectronvolt and multiampere range. This constant-current variable-voltage (CCVV) accelerator uses a series of identical ESQ modules. The authors have successfully tested a prototype CCVV accelerator up to 200 keV with a 100-mA He/sup +/ beam (with space charge equivalence of 140 mA of D/sup -/) for a pulse length of 1 s. Testing was also done with a 42-mA H/sup -/ beam (H/sup -/ beam current was limited by source performance). There was almost no beam loss in the ESQ accelerator.<
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