Calabazas Creek Research, Inc. is involved in two research programs in the high energy physics area. One program is the development of multiple beam electron guns for high power RF sources. The next generation of high energy accelerators will require RF sources producing output power levels in the range of 50–150 MW at frequencies of 10.0 GHz and higher. One of the major cost drivers for these devices is the high operating voltage. One way to avoid high operating voltage is to use a klystron with a multiple beam electron gun to raise the effective perveance. In the multiple beam gun, the cathode emits a number of ‘beamlets’ that traverse the tube in separate beam tunnels. This reduces space charge forces that drive the voltage requirement. This paper describes progress in the development of a high convergent multiple beam electron gun for a 75 MW klystron operating at 150 kV. The second program involves development of high power windows and waveguide components capable of operating at power levels from 10...