Time structure of an accelerated beam using a ratio-frequency quadrupole linac with direct plasma injection scheme

Kashiwagi, Hirotsugu; Okamura, Masahiro*; Jameson, R. A.*; Hattori, Toshiyuki*; Hayashizaki, Noriyosu*

The relation between ion current from a laser ion source and accelerated beam using direct plasma injection scheme was studied. Accelerated beam time-structure was well reproduced by series of analysis: evaluating beam current at extraction from a measured plasma parameters using a scaling law, beam emittance at the entrance of acceleration electrode region by ion extraction simulation, and the beam acceleration simulation. The extraction simulation revealed the time variation of the injected beam parameter to the RFQ linac. It is proved that time-structure of accelerated beam was different to that of injection beam because degree of the matching between the injected beam emittance and the RFQ acceptance varied with time.