Milliampere He2+ beam generator using a compact GHz ECRIS

Multi-charged helium ion beam He²⁺ is useful for helium accelerator to obtain a higher energy with lower cost and for deuterium accelerator to avoid neutron activation during machine commissioning. An attempt to generate milliampere multi-charged helium He²⁺ ion beam with a 2.45 GHz electron cyclotron resonance ion source (ECRIS) was tested recently. A design using a specfic permanent magnet 2.45 GHz ECRIS (PMECRIS) source (ERCIS) is reported and the He²⁺ beam production ability is described. With this source, we produced a total helium beam of 40 mA at 40 kV with 180 W of net microwave power and a gas flow of less than 0.5 sccm. At steady state the He²⁺ beam intensity is 4.4 mA, that being the fraction of multi-charged helium ion beam is at approximately 11%.