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- R. Ruo, L. Du, T.B. Du, X. Guan, C.-X. Tang, X.W. Wang, Q.Z. Xing, H.Y. Zhang, Q.Z. Zhang
TUB, Beijing, People's Republic of China
- Y. He, J. Li
NUCTECH, Beijing, People's Republic of China
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The 7 MeV H− linac injector of Xi‘an Proton Application Facility (XiPAF) is composed of an ECR ion source, a Low Energy Beam Transport line (LEBT), a Radio Frequency Quadrupole accelerator (RFQ) and a Drift Tube Linac (DTL). The 1.7 m-long LEBT is used for matching a 40 μs pulse width 6 mA peak current beam to the entrance of the RFQ accelerator. The peak current and pulse-width of the 50 keV H− beam extracted from the ion source is 10 mA and 1 ms respectively. In the LEBT, an adjustable aperture is used for scraping the peak current of the beam to 6 mA, and an electric chopper is used for chopping the beam pulse width to 40 μs. These elements make the space charge compensation problem more complicated. A careful simulation of the space charge compensation problem of the H− beam has been done by considering the beam particles interacting with the residual gas with the help of WARP PIC code. To achieve the requirements of the LEBT in XiPAF, the type and pressure of the residual gas is given according to the simulation results.
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