Commissioning Results and Progress of a Helium Injector for Coupled RFQ and SFRFQ Project at Peking University

At Peking University (PKU) a new helium injector for coupled radio frequency quadrupole(RFQ) and separated function radio frequency quadrupole(SFRFQ) within one cavity, so called as coupled RFQ & SFRFQ, was designed recently[1]. It will provide a 30keV 10mA He beam whose emittance is less than 0.15 π.mm.mrad for the accelerator. It is a combination of a 2.45GHz PKU permanent magnet electron cyclotron resonance ion source (PMECRIS) and a 1.16 m long low energy beam transport (LEBT). Within the 1.16 m LEBT, 2 solenoids, 2 steering magnets, a space charge compensation section, a collimator, two vacuum valves, a Faraday cup and an ACCT are installed. The manufacture has been completed and the commissioning is on the way. In this paper we will address the commissioning results and its progress. INTRODUCTION For the purpose of studying the material irradiation damage effects, an accelerator-based material irradiation facility with MeV injecting energy will be very helpful. Conventional design of this kind of relatively low energy facility is composed of a RFQ and a post-RFQ acceleration structure such as DTL, H-type cavity, etc. At PKU, a new type of post-RFQ accelerating structure called SFRFQ which separates accelerating and focusing functions in one cavity has been studied since 1990s.[2] Based on former experiences accumulated by Peking University Neutron Imaging Facility (PKUNIFTY) [3], a He injector for RFQ-SFRFQ cavity is brought up at PKU. Recently, the He injector, which includes all the components before RFQ, is finished assembling, and the immediate experimental beam tests feedback very well results. In this paper we will address the general designs of the He injector in part 2. The commissioning results and beam diagnostic experiment designs would present in part 3. In part 4, the beam tests results would present. And a summary will follow at the end. PHYSICAL & MECHANICAL DESIGN The He injector comprehends 2 parts including the ion source and LEBT. The purpose of this injector is to provide qualified beam to inject into RFQ-SFRFQ cavity, and the beam qualification requirements are as Table 1. Table 1: Parameters of the Helium Injector Parameter Unit Value He beam current mA 10