Formation of high-perveance thin tape electron beams in low magnetic fields

The results of investigation of high-perveance (P/sub /spl mu///spl sim/7 /spl mu/A/V/sup 3/2/) tape electron beam formation system for narrow transport channel (0.2/spl times/2 mm/sup 2/) of cyclotron protectors (CP) are presented. CP intends for work at long wave band of microwave range (/spl lambda//spl sim/10 cm) with the low level of magnetic field (B/B/sub BI//spl sim/1.5). For decreasing of the beam border defocusing and for improving the beam transportation the local magnetic inhomogenity had been put in cathode region. Peak level of the cathode magnetic field exceeds the working region magnetic field, its components vary along the width of cathode as determined dependence. The magnetic field is produced by thin concentrating cylinder placed in the center of cathode magnetic pole. There are determined the demands for concentrator profile and for its 3D orientation with respect to cathode. Investigations are made by means of 3D computer simulation.