First operation of a 94 GHz, sheet beam, FEL amplifier

Abstract Millimeter wave (94 GHz) amplification has been observed in the sheet beam, planar wiggler, free electron laser. Using a 4 A sheet beam (20 mm × 1.0 mm) at an electron energy of 530 keV, injected wave power of 5 W was amplified to about 20 W at the end of the planar wiggler (56 periods with a periodicity of 9.6 mm). The peak wiggler magnetic field was 4.8 kG. The amplification was reproducible and had all the characteristics of a free electron laser interaction. Multi-megawatt cw FELs based on this design concept are judged to be achievable and would be relevant to controlled thermonuclear fusion research and development.