Results from mm-Wave Accelerating Structure High-Gradient Tests

We show high power test progress for 110 GHz high-gradient accelerating structures. The purpose of this work is to study the physics of particle accelerators in the mm-wave regime, as well as ultrahigh vacuum RF breakdown in such structures. The setup under investigation consists of a single-cell standing-wave accelerating cavity operated in the n-mode and fed via the TMm mode in a circular waveguide, which is in turn fed through a Gaussian horn. The cavities will be powered with nanosecond pulses from a MW gyrotron oscillator, allowing it to reach a peak accelerating gradient of 400 MeV/m.