45 MW, K-band second-harmonic multiplier for testing high-gradient accelerator structures

A relatively simple and inexpensive two-cavity 45 MW, 22.8 GHz second-harmonic multiplier to be used as an RF source for high-gradient experiments is described. The design is based on use of an existing SLAC electron gun, such as the XL-4 gun. RF drive power would be supplied from a 50 MW SLAC klystron and modulator, and a second modulator would be used to power the gun in the multiplier. An important feature of the harmonic multiplier is use of a TE₀₁ circular waveguide for output RF power extraction fed through the beam collector.