Retarding field analysis of a 75kV variable current electron beam with Wiggler and axial magnetic fields

A 5 microsecond, 75 kV, variable current square output pulse is produced by a 3-stage, crowbarred, Marx generator. The electron gun contains a lanthanum hexaboride cathode which is heated by electron bombardment in a Pierce electron-gun geometry. The cathode is immersed in a collimating axial field of 1.1 kG which extends over the entire length of the beam. The electromagnetic bifilar wiggler has a period of 4.0 cm and is 7 wavelengths long. A newly-developed retarding potential velocity analyzer has been used to study the effect of the wiggler on the beam velocity distribution.