Experimental development of a millimeter wave free electron laser

A 1 MW (cw), millimeter wave FEL ({lambda}{sub 3} {approximately} 0.5 mm)is currently under development with an application for heating fusion plasmas. Two salient features of the FEL are the use of a short-period wiggler {ell}{sub w} {le} 10 mm electromagnet and a mildly relativistic (E{sub beam} {le} 1 MeV) sheet electron beam. The FEL has been designed to operate in the high-gain regime and uses a tapered wiggler. The wiggler provides beam focusing as well as the magnetostatic pump wave. The effectiveness of wiggler focusing is being investigated. Planned experiments will address the critical issues of beam interception and stable single-mode operation. 12 refs., 1 tab.