Machining of cavities for travelling wave LINAC

A Traveling Wave (T.W.), 2π/3 mode electron linear accelerator of 2856 MHz is under development at CAT for radiation processing of agricultural products. This LINAC consists of a thermionic triode electron gun, TW buncher section and Regular Section. Machining of input/output couplers, regular section cells and disc were carried out using CNC lathe LAL- 2 BT and CNC milling machine BMV - 40. This paper highlights the dimensional and geometrical requirements of cavities, problems encountered during machining of OFE copper and their solutions to achieve high precision with ultrahigh surface finish. The performance of Linac depends upon a number of factors such as operating vacuum level, accuracies of cavity dimensions, materials, and surface finish of cavities comprising the LINAC. Each of these depends upon material and fabrication techniques used for manufacturing OFE copper of higher purity has been used since they offer lower surface resistivity and lower power losses. With CNC tuning and milling machines, the high surface finish has been achieved with higher dimensional and geometrical accuracies