Experimental and numerical studies of sheet electron beam short period planar wiggler free-electron laser amplifier

A detailed experimental and numerical studies of a free electron laser (FEL) amplifier using a sheet electron beam and short period planar wiggler are presented.; As an important step toward realizing the FEL amplifier, the behavior of propagation of the sheet beam through the planar wiggler was studied carefully. It was found that a suitably tapered magnetic field configuration at the wiggler entrance was essential to achieving good beam transport efficiency. The effects of some other techniques on beam transport efficiency were also studied, including the following: side focusing; beam transverse velocity tuning at the wiggler entrance; and, beam spread limiting. High beam transport efficiency approaching 100% was reached in some cases.; Small signal millimeter wave(94 GHz) amplification has been achieved on the sheet beam, planar wiggler, free electron laser. By using a 4 A sheet beam (20 mm by 1.0 mm) at a beam energy of 530 keV, the injected wave power 5 W was amplified to about 20 W at the end of the planar wiggler (56 period with a periodicity of 9.6 mm) with a peak wiggler magnetic field of 4.8 kG. The amplification was reproducible and had all the characteristics expected of a free electron laser interaction.; Finally, a brief discussion of an extension of the present experiment is given.