Emittance measurements of the J-PARC RF-driven H- ion source.

In order to satisfy the Japan Proton Accelerator Research Complex (J-PARC) 2nd stage requirements of an H- ion beam current of 60mA within normalized emittances of 1.5πmm·mrad both horizontally and vertically, a flat top beam duty factor of 1.25% (500μs×25Hz) and a life-time of more than 50days, a cesiated RF-driven H- ion source using a internal-antenna developed at the Spallation Neutron Source (SNS) was developed. The horizontal and vertical emittances were measured by using two double (W) slit emittance monitors for several different conditions. Although the measured normalized rms emittances are more than 1.4-times larger than those of a J-PARC H- ion source driven with two tungsten (W) filaments probably due to the RF field around extraction gap, the J-PARC 2nd stage requirement of the 60mA beam within 1.5πmm·mrad was satisfied if a beam more than 66mA were extracted. [ABSTRACT FROM AUTHOR]