CASCADED HIGH-T-C BULK SUPERCONDUCTOR LENSES (SUPERTRONS) FOR INTENSEELECTRON-BEAMS

Two-stage tubular lenses (Supertrons) focused and transported intense electron beams (similar to 2 kA, similar to 340 keV, similar to 10 ns) for lens separation of similar to 17 mm or less. In this range the se cond lens focused electron beams whose angle of incidence with the axi s of the lens was less than the critical value of similar to 34 degree s. The first and second lenses were 40 and 13 mm long, respectively, w ith an inner diameter of 20 mm and a wall thickness of similar to 1.5 mm. The lenses were made from Bi-based powder-pressed materials. Neon gas was introduced into the diode gap and into the bore of the lenses at pressures on the order of 0.1 Torr. The experimental results sugges t that adjacent lenses should be positioned closer than the value of t heir inner diameter, and are each sufficiently long in the axial direc tion if longer than the value of their radii.