A triple pole piece magnetic field reversal element for generation of high rotational energy beams

This paper describes a magnetic field reversal technique enabling production of high-quality isorotational hollow beams for use in fundamental mode gyrotrons, fast/slow wave hybrids such as devices in which an E-layer rotates within a fluted waveguide, and collective effect accelerators. The method is completely magnetic and has all pole pieces external to the outer envelope of the beam. Further, a high degree of adjustability is provided by the technique so that beam quality can be readily optimized in the laboratory for each individual case.