Design and Testing of Faraday’s Cup for Nsls-ii Linac and Booster

Content Provider	Semantic Scholar
Author	Fernandes, Huston Belkacem, B. Cheng, Weixing Kosciuk, B. N. Rank, Jim Sharma, S. Singh, O. Tanabe, Tsuyoshi Wang, Guimei
Copyright Year	2013
Abstract	NSLS-II will provide 500 mA, 3 GeV beam of 1 nm emittance. It’s planned to have top-off operation. To ensure bunch uniformity and constant current, the precise measurement of the charge becomes necessary. There are three Faraday Cup’s at the end of the transport line in the Linac and Booster transport lines which serve this purpose. The details of the design consideration are presented in this paper. The Diagnostic group at NSLSII, designed, prototyped and tested the Faraday Cup (FC). Power density calculations and FEA simulations were carried out for the three cases. INTRODUCTION At NSLS-II, the FC’s serve as a beam dump and a charge measuring device, therefore we have three such devices at the end of each of the test beamlines. The beam energy in the Linac area is 200 MeV [1]. The beam size at FC1 and FC2 in the Linac transport line was found to be 0.2 mm horizontally and 0.5 mm vertically. Figure1 below indicates the location of FC1 and FC2 in the Linac area. Figure 2 indicates FC3 in the Booster area. The beam energy in the Booster area is 3 GeV with a beam size of 2.3 mm in the horizontal direction and 0.27 mm in the vertical direction. Figure 1: Location of Faraday’s Cup in the linac area. Figure 2: Location of the Faraday’s Cup in booster area. Different devices are used to measure beam current. One way to measure the total charge of the beam in normal operation is by non intercepting devices such as current transformers (ICT, and DCCT). This non destructive method is independent of beam energy. These devices have to be calibrated to a device that will collect the totality of the electrons. For this reason an FC have to be installed close to the device to be calibrated (unknown losses between the two instruments introduce systematic errors). Another method to measure the charge is by using FCs. In this case, we need to stop and dump the electron beam for a certain period, preferably at full energy and bunch repetition rate. FCs are installed at the end of the transport lines. The beam will be sent to the FC during beam tune ups. Beam stops are used to absorb the entire beam.
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Language	English
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Resource Type	Article