NUMERICAL STUDY OF RELATIVISTIC ELECTRON-BEAM ELECTROSTATIC PUMPING BY ANODE APERTURE

Quality and pumping of an electron beam by means of the inhomogeneous electrostatic field at an anode aperture are investigated using numeri cal simulation. A specially developed relativistic particle-in-cell co de, described here, is employed. The longitudinal velocity spread and the pitch ratio of the beam electrons are derived for different apertu re radii and cathode-aperture distances. The presented results could b e practically useful for operation of high-power cyclotron resonance m asers with a sharpened cathode and an anode aperture. The beam pumping in such devices is typically achieved by more complicated systems (pu mping magnet, adiabatically changing magnetic field, etc.). The numeri cal simulations show a significant pumping effect coming from the anod e aperture itself.