Development of multi-ampered D− source for fusion applications

Abstract

Large current and high current density deuterium negative ion sources are investigated on the MANTIS test bed with the objective of producing several amperes of D− beams, at an accelerated current density in the range 10–20 mA/cm2, for possible application in future neutral beam injectors, e.g. ITER. As a first step, the DRAGON source, which was built by Culham Laboratory was tested on the MANTIS test bed in order to test this large source using only ‘‘pure volume’’ production of negative ions. The accelerated negative ion current is found to be a strong function of the source operating pressure and the arc power, and a significant isotopic effect is observed. The maximum accelerated currents are 1.3 A of H− (3.3 mA/cm2) and 0.5 A (1.3 mA/cm2) at 110 kW of arc power. Cesium injection from a non conventional dispenser together with an improved extraction system, have significantly improved the D‐current. A maximum of 14 mA/cm2 of D−1 are accelerated at 30 kV, which corresponds potentially, to more than 5 A for a full aperture extraction with an arc power of 140 kW (2250 A of arc current).