NEGATIVE-ION PRODUCTION WITH THE PACODA SOURCE

A 1 MV, 0.1 A, 10 mA cm(-2) current density, multi-second D- ion beam acceleration project called SINGAP is scheduled to start at the end of 1994 at Cadarache. This experiment will be equipped with a PAGODA ion source for which experimental results are presented here. The negative ion beam was accelerated with a three-electrode system to up to 65 keV and measured calorimetrically on a target located 3 m from the ion source. With the full extraction area (240 cm(2)) and with caesium seeding in the source, a total D- transmitted current of 1 A was obtained. By masking some parts of the plasma grid consisting of five segments, various ion beam extraction areas were utilized, and higher current densities were obtained from smaller extraction surfaces. With 1/5th of the extraction area (central segment), a transmitted D- mean current density of 10 mA cm(-2) was measured at a filling pressure of 0.65 Pa with caesium seeding in the ion source, which meets the SINGAP requirements. Spectroscopic and caesium deposition measurements were also performed. The energetic electron leaks were measured and compared with the predictions of a Monte Carlo code.