A submillimeter free-electron laser experiment

A free-electron laser (FEL) Raman-backscattering oscillator, using a
\frac{1}{2}-1
MeV, 20 kA electron beam pumped with a weak (∼ 250g) periodic (8 mm) transverse magnetic field, is operated as a source of high power millimeter and submillimeter radiation, with lasing developing during the 150 ns beam pulse. Measurements of lasing operation are described at 1.0 and 0.6 mm. The temporal behavior of cavity radiation is considered and effective gain is measured and compared with theory.