High power, high frequency lasertron RF sources

High power RF sources have historically been limited to frequencies at which intense electron beams could be efficiently modulated. The power, frequency, and efficiency limitations associated with the use of lasertrons for generating modulated beams were explored and these beams were used as high power microwave sources. This effort is an extension of wake field accelerator development, and will proceed as part of the Argonne Wakefield Accelerator construction and use. In the lasertron the electron beam is produced from the photoelectric effect at the photocathode, thus the electron pulse closely resembles the laser pulse in density and spatial extent. One configuration for this device is where a dielectric Cerenkov coupler is used to transfer power from the electron beam to the RF field. Operation at high power and high frequencies, (approximately GW, approximately greater than THz) seems possible using laser optics to compensate electron aberrations due to geometrical optics and space charge. In this paper we show results of simulations that indicate electron pulse lengths of the order of 0.25 ps can be produced if other aberrations are controlled, describe an optical system to compensate aberrations and generate pulse trains from a short pulse laser, discuss design constraints and limitations of RF couplers, and describe constraints on the system as a whole.