Multi-harmonic RF test stand for RF breakdown studies

Abstract

Abstract.A multi-harmonic RF test stand is under construction at Yale Beam Physics Laboratory. It includes a frequency multiplier which can generate high power harmonics efficiently that are phase locked to the fundamental drive frequency. In a bi-modal asymmetric cavity powered by this RF source, the cavity may experience reduced exposure time to peak fields and sweeping of peak fields across their surfaces, and strong asymmetry between surfaces that may experience cathode-and anode-like fields; these phenomena are to be assessed for their influence on RF breakdown probabilities.

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

“…It seems that three output cavities covering the range between 20 and 25.7 GHz could all be designed and driven using the S-band driver system. In addition, as shall be described below, a 2 nd harmonic output cavity at 5.712 GHz has also been designed and built for confirming the high predicted conversion efficiency (88%) at this low harmonic, and for installation as part of a two-frequency test stand described elsewhere [11].…”

“…As stated above, the 2 nd harmonic device is being built (a) to confirm the predicted exceptionally high (88%) RF-to-RF conversion efficiency for this two-cavity interaction; and (b) to be available together with fundamental power at 2.856 GHz to constitute a two-frequency multi-MW phase coherent test stand with variable amplitudes and phases for both frequenciesfor tests of RF breakdown rates in two-frequency cavities [11], and for powering a twofrequency RF gun [12]. In paragraphs that follow, details are provided on these hardware items.…”