Status and plans for the development of a RF negative ion source for ITER NBI

IPP Garching is currently developing a RF driven negative ion source for the ITER neutral beam injection system as an alternative to the present design with filamented sources. This paper reports an overview on the present status and the further prospects of the RF source development. Current densities of 26mA/cm2 and 15mA/cm2 have been achieved for hydrogen and deuterium, respectively, at a pressure of less than 0.5Pa and an electron/ion ratio of 1. Size scaling experiments indicate a maximum extraction area which can be illuminated by a driver without losses of beam quality and uniformity. The preparation of a test facility for pulse lengths of up to 3600s is proceeding; commissioning is expected end of 2004. As an intermediate step tests of a large source with the half size of the ITER source are foreseen to be commissioned in 2005.