Improvements in and relating to High Vacuum Electronic Valves

1,184,532. Magnetrons. PATELHOLD PATENTVERWERTUNGS - UND ELEKTRO-HOLDING A.G. 13 March, 1968 [15 March, 1967], No. 12282/68. Heading H1D. A high vacuum electronic valve comprises an elongate control electrode 1 surrounded by an anode 4 which has a number of spaced elongate recesses 7 extending parallel to the control electrode, an elongate cathode 9 disposed in each recess, an arrangement (not shown) for generating a magnetic field to reduce the number of electrons reaching the control electrode, and a pair of plate-like separator electrodes 31, one located either side of the cathode 9 in each recess. The penetration A of the separator electrodes 31 into the space between the anode and control electrode is set by the requirement that when there is no current flowing, the desired valve amplification factor is equal to the ratio of the electric field strength generated at the cathodes per unit control voltage to the electric field-strength generated at the cathodes per unit anode voltage. As shown, the separator electrodes 31 are formed by a single U-shaped cylindrical unit, each fastened to a rod 16 which forms a part of the cathode tensioning frame comprising plates 10 to 14 and rods 15 to 17 and a spring 23 to hold the cathodes under axial tension. To provide the magnetic field a solenoid coil may be coaxially disposed around the anode 4, and the valve may be cooled by a coolant, e.g. water, flowing in the annular gap between the solenoid coil and the anode 4, which may have cooling fins. An additional grid-shaped control electrode (41), Fig. 4 (not shown), may be arranged between each cathode and the control electrode in the region between the separator electrodes of a respective cathode. An alternative embodiment, Fig. 3 (not shown), has two concentric cylindrical control electrodes, one inside and the other outside the anode, with the anode recesses extending through the anode wall and extended plate separator electrodes so that an electron stream is emitted from either side of the cathode.