INFLUENCE OF NONUNIFORMITIES OF A MAGNETIC-MIRROR FIELD ON THE SPACE-TIME CHARACTERISTICS OF A LONG-PULSE RELATIVISTIC ELECTRON-BEAM

An experimental investigation is made of the influence of local nonuni formities of a mirror-configuration magnetic field on oscillations of the space charge and the structure of a long-pulse relativistic electr on beam. It is found that the outcome depends on the axial configurati on of the nonuniformity. A nonuniformity near the cathode can substant ially reduce the amplitude of the oscillations and improve the beam tr ansport. The creation of a nonuniformity far from the cathode leads to an accelerated increase in the oscillations and causes spreading of t he transverse structure of the beam. A possible explanation is given f or the mechanism responsible for the influence of these local magnetic field nonuniformities assuming reflection of the cathode plasma and e lectron flux from the magnetic mirror, and also allowing for a jump in the drift velocity. (C) 1997 American Institute of Physics.