GB1232740A - - Google Patents

Abstract

1,232,740. Velocity - modulated tubes. FUJITSU Ltd. 15 Oct., 1969 [15 Oct., 1968], No. 50777/69. Heading H1D. In a crossed field electron gan having a non- uniform magnetic field, as disclosed in Specification 1,115,468, to cause the electrons emitted from the cathode 18 to converge on to a stable, linear orbit, the sole electrode 16, 17 is V-shaped and opens towards the anode 15, which has an axially extending convex portion 7 facing the V, such that the electric field 19 in the interelectrode space is similar to that of one quadrant of a quadrupolar system, and the electrons are laterally focused thereby. As shown, the cathode-in the form of a directly heated nickel ribbon coated with an electron emissive material, and held by a spring at one end to permit thermal expansion-is mounted in the base of the sole electrode, which is of copper or stainless steel. The magnetic field is produced by curved magnets 20, 21, and decreases in intensity towards the anode, but a decrease in the opposite sense may alternatively be employed. In a modification (Fig. 6, not shown) the base of the sole electrode, and the cathode, are inclined at an angle of 5 or 6 degrees to the tube axis, to provide an axial component of electric field, and the output end of the gun is provided with an annular accelerating electrode (24) held at the anode potential, followed by an annular magnet (25) and a second annular electrode (26).