The UHV system of the 10 MeV RF electron linac

• Published in: Journal of physics. Conference series 2008-05, Vol.114 (1), p.012026, Article 012026
• Main Authors: Bhattacharjee, D, Jayaprakash, D, Mishra, R L, Nimje, V T, Mittal, K C
• Format: Article
• Language: English
• Subjects: Baking; Design modifications; Diagnostic systems; Electron beams; Electron guns; Gate valves; Horns; Industrial applications; Linear accelerators; Physics; Pumps; Surface finish; Tightness
• ISSN: 1742-6596; 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/114/1/012026

A 10 MeV, 10 kW RF Electron Linac, for Industrial applications, is installed and commissioned at Electron Beam Centre (EBC), Kharghar, Navi Mumbai. The accelerator consists of the electron gun, RF Linac, Vacuum system, Beam diagnostics system, Magnetic sweep scanning system and Scan horn. The accelerator is divided into three sections with gate valves to isolate them, to enable servicing of pumps and modifications. The vacuum requirement in the accelerator is 10−7 mbar considering the breakdown parameters of the RF field within the linac. Total length of the accelerator from electron gun to the scan horn is about 5.0 meters. Vacuum plumb lines are of SS 304 pipes of nominal bores of 100 mm and 150 mm, machined internally to a surface finish of 0.8 μm. It encloses a volume of 156 litres. Total surface area exposed to vacuum is 57,500 cm2. It consists of 5250 cm2 of OFHC Copper, 51300 cm2 of SS 304 and 940 cm2 of ceramic sections. Leak-tightness of the order of 1 × 10−9mbar.l/s is ensured for the whole system, after eliminating the leaks at every stage of the assembly. Baking the plumb line and pumps at 150° C, for eight hours an ultimate vacuum of 2 × 10−7mbar is achieved in the accelerator. Modifications of the vacuum system is undertaken to suit the design changes in the gun and the diagnostic systems.