The Cadarache negative ion experiments

Up to energies of 140 keV neutral beam injection (NBI) based on positive ions has proven to be a reliable and flexible plasma heating method and has provided major contributions to most of the important experiments on virtually all large tokamaks around the world. As a candidate for additional heating and current drive on next step fusion machines (ITER) it is hoped that NBI can be equally successful. The ITER NBI parameters of 1 MeV 50 MW D/sup 0/ demand primary D/sup -/ beams with current densities of at least 15 mA/cm/sup 2/. Although considerable progress has been made in the area of negative ion production and acceleration the high demands still require substantial and urgent development.