Design of an Ion Source for ³He Fusion in a Low Pressure IEC Device

Recent developments in helicon ion sources and Inertial Electrostatic Confinement (IEC) device performance at UW-Madison have enabled low pressure (< 50 torr, 6.7 mPa) operating conditions that should allow the ³He-³He fusion reaction to be observed in an IEC device. An ion source capable of delivering a ~ 10 mA ³He ion beam into an IEC device with minimal neutral gas flow has been designed and tested. Furthermore, a new IEC device that has never been operated with deuterium has been constructed to avoid D-³He protons from obstructing the ³He-³He reaction product spectrum, and to minimize Penning ionization of deuterium by excited helium, which in the past is suspected to have limited the ionized density of He. These developments make it possible to study beam-background ³He-³He fusion reactions with > 300 mA recirculating ion currents.