Development of negative ion sources for fusion produced alpha particle diagnostics

Abstract

Status of the development of the negative ion sources designed for diagnostics of alpha particles confined in a thermo‐nuclear fusion plasma is reported. A lithium vapor produced by a laser induced desorption was found useful to produce a lithium plasma suitable for extracting negative ions of lithium. This method creates a beam of Li for duration about 1 msec, which can be utilized for phase sensitive detection of alpha particle. Production of negative helium ions can be realized with the efficiency close to 3% by converting a low energy positive helium ion beam with Rb vapor charge exchange cell.