Thermal analysis for wire scanners in the CSNS Linac

• DOI: 10.1016/j.nima.2014.05.061
• Publication Date: 2014-05-27T08:34:34Z
• Authors: Tao Yang; Shinian Fu; Taoguang Xu; Zhihong Xu; Ming Meng; Ruiyang Qiu; Jianmin Tian; Lei Zeng; Peng Li; Fang Li; Biao Wang
• Keywords: Spallation Neutron Source; Thermionic emission

3 MeV H beam from the Radio Frequency Quadrupole (RFQ) will be accelerated to 80 MeV in the CSNS (China Spallation Neutron Source) linear accelerator (Linac). The wire scanner is used to measure the transverse beam profile and the emittance, and the carbon or tungsten wire is considered to use. Thermal analysis of the wire scanners in the Linac is presented in this paper. The maximum temperature (T,) of the wire decreases as the beam energy increases, and we also calculate the influence of all possible parameters on T-m. T-m, of carbon wire is significantly lower than tungsten wire if both the beam parameters and wire geometric parameters are set to the same, which can be attributed to its higher heat capacity and radiant emissivity. In addition, we present the results of sublimation rate of the wire, which show that tungsten wire has a much lower evaporation rate than carbon wire in the same temperature, which can be attributed to the different vapor pressures of the two materials. To limit the thermionic emission, the maximum beam frequency approximately has an exponential relationship with beam rms size at a certain beam pulse width. (C) 2014 Elsevier B.V. All rights reserved.