An indirectly heated solid cathode for linear electron beam emitter assembly

The paper reports design and development of an indirectly heated solid cathode for a linear electron beam emitter assembly. The solid cathode is made of a 195 mm long 8 mm wide and 2 mm thick tantalum bar with varying cross sections along its length. The emitting surface of the cathode is 110 mm in length and 4 mm in width. Thermionic electron beams emitted from a directly heated strip shaped filament have been used to heat the cathode indirectly. The temperature of the cathode, measured by a two color pyrometer, was raised to 2500 K. The innovative design of the cathode and its holding mechanism accommodates thermal expansion at high temperature, and prevents thermal deformation of the cathode. The cathode is suitable for use in strip electron beam gun and for laboratory experiments on melting and evaporation of refractory materials.