Electron-optical system for a large-orbit gyrotron

An electron-optical system generating a rectilinear or helical 250 keV/4 A/10 mu s electron beam with a high compression factor is developed. For the former beam, a compression factor as high as 4400 and a current density of 25 kA/cm(2) are achieved. In the process of forming the helical beam, the electrons rotating about the system's axis (paraxial beam) acquire an initial velocity in a transverse magnetic field produced by a kicker. Their pitch factor is increased to a desired (operating) value in an adiabatically growing magnetic field. In tentative experiments with the helical beam in a large-orbit gyrotron, generation was obtained at the second cyclotron harmonic (223 GHz). (c) 2005 Pleiades Publishing, Inc.