Free electron laser with small period wiggler and sheet electron beam: A Study of the feasibility of operation at 300 GHz with 1 MW CW output power

Abstract

The use of a small period wiggler (Cw < 1 cm) together with a sheet electron beam has been proposed as a low cost source of power for electron cyclotron resonance heating (ECRH) in magnetic fusion plasmas. Other potential applications include space-based radar systems. We have experimentally demonstrated stable propagation of a sheet beam (18 A. 1 mm x 20 mm) through a ten-period wiggler electromagnet with peak field of 1.2 kG. Calculation of microwave wall heating and pressurized water cooling have also been carried out. and indicate the feasibility of operating a near-millimeter, sheet beam FEL with an output power of 1 MW CW (corresponding to power density into the walls of 2 kW/cm*). Based on these encouraging results, a proof-of-principle experiment is being assembled, and is aimed at demonstrating FEL operating at 120 GHz with 300 kW output power in 1 ^s pulses: electron energy would be 410 keV. Preliminary design of a 300 GHz. 1 MW' FEL with an untapered wiggler is also presented.