SFRFQ with diaphragms linac structure

The accelerating efficiency of traditional RFQ structure is limited by transverse focusing and the drift tube structure has higher efficiency, so the Seperated Function RFQ (SFRFQ) with diaphragms was proposed in this paper, where the accelerating gaps were formed by diaphragms meanwhile keeping enough electric quadrupole focusing. The reverse fields had been found in the SFRFQ, after the electric field distribution was determined by static solver, then a structure called asymmetrical βλ/4-long diaphragm SFRFQ was developed. Afterwards a RF model had been designed to test the structure technology feasibilities. In order to value the RF efficiencies of RFQ and SFRFQ structures, the shunt impedance had been simulated in MicroWave Studio (MWS). It turned out the RF efficiency will be obviously enhanced after introducing gaps into RFQ strcture. Thus the total length of linac will be largely decreased if the accelerating gaps are introduced earlier, which was proved by the comparison between two dynamics simulations.