Beam test of the negative ion source for the high intensity proton accelerator

The high intensity proton accelerator facility project which is conducted jointly by JAERI and KEK is to irradiate a proton beam onto a target and to use the secondary particles produced by nuclear spallation for various science studies. A negative hydrogen ion source for the accelerator is required to extract a peak beam current of more than 60 mA with a duty factor of 2.5%. In addition, the ions should be negatively charged in order to improve the capture efficiency of the beam injected into a synchrotron. At JAERI, a negative ion source for the project has been developed with various technologies based on the large negative ion source for the nuclear fusion application. As a result of the beam test, the negative ion beam current and the rms normalized emittance of 72 mA and 0.15 πmm·mrad were achieved in the cesium seeded operation, respectively. A waveform of the pulsed beam current was sensitive to the operation gas flow rate, and became to have a good flatness at about 16 SCCM. These results show that the basic performance of the ion source satisfies the requirement of the ion source for the project. (author)