High power seventh harmonic converter at 20 GHz

Abstract

A design is described of a 7 th harmonic converter utilizing a two-cavity system for producing RF power at 20 GHz. The converter uses a 250 kV, 20 A electron beam injected into the first cavity tuned to the TE 111 mode at 2.856 GHz. The beam is accelerated in this cavity via a cyclotron resonance interaction [1] using 8.5 MW of RF power to an energy of 670 kV with 99% efficiency. The accelerated beam passes to an output cavity tuned to the TE 711 mode where simulations predict an output power of 4 MW at 19.992 GHz.

Multi-MW 22.8 GHz Harmonic Multiplier - RF Power Source for High-Gradient Accelerator R&D

“…Simulations shown in the Phase I proposal indicated, with 50 MW of X-band drive power and 50 MW of initial beam power (280 kV, 170 A), that over 47 MW of 22.8 GHz power could be generated, namely at a 95% RF conversion efficiency and 47% electronic efficiency [1]. This source was to be used for breakdown tests and accelerator structure development under the aegis of the then-nascent US Collaboration in High Gradient (HG) R&D, with SLAC as the host laboratory, and Professor Sami Tantawi of SLAC as the spokesperson for the HG Collaboration.…”

“…The original plan was to install and operate the source at SLAC as part of its HG R&D program led by Professor Tantawi. The Marx HEPAP sub-panel [1] had just endorsed the building of standalone RF sources at frequencies different from those available at 11.424 GHz (SLAC and NRL), 17.1 GHz (MIT), and 34.3 GHz (Yale), to expand the range of frequencies for basic studies to achieve high acceleration gradients in warm structures. The proposed 22.8 GHz source would utilize an available electron gun and modulator.…”