A corrosion study on vacuum brazed joints of LINAC

A 10 MeV, S-band electron linac has been developed at RRCAT for industrial applications. At present, the in-house fabricated accelerating structure, is under continuous operation and has been tested at beam power more than 4.2 kW. The accelerating structure of electron linac comprises RF couplers, buncher section and regular section. The accelerating structure is made of OFE copper and is fabricated by vacuum brazing of cavities and coupler components using BVAg-8 and Palcusil-5 as braze filler metals (BFM). During accelerator operation, RF power is dissipated on cavities surface and the resultant heat is removed by circulating low conductivity water (LCW) in cooling jackets built around the accelerating structure whose inner part is maintained under vacuum. Corrosion characteristics of OFE copper brazed joints in LCW environment is of utmost importance towards development of reliable industrial linac. Therefore, a study has been undertaken to investigate corrosion possibilities in the cooling circuit which can limit the life of accelerating structures