Periodic permanent magnet field-transported relativistic electron beams

Abstract

The utility of periodic permanent magnet (PPM) focusing for transporting relativistic electron beams (REB) was demonstrated experimentally and these results were supported by REB trajectory simulations. The PPM field was made by a series of permanent toroidal Sm-Co magnets and pure iron-made spacers of alternate magnetic orientation along the axis of the REB. When a foilless beam diode was operated at a pressure of approximately 0.2 Torr of nitrogen gas with an applied voltage of 420 kV, the PPM focused and transported the REB (200 keV, 1.2 kA, 10-ns pulse width). About 12% of the energy charged at the high-voltage generator was converted to the REB. Optimization of the beam diode and PPM configuration was not attempted.