GB1052220A - - Google Patents

Abstract

1,052,220. Automatic control systems. VARIAN ASSOCIATES. Dec.18, 1963 [Dec. 31, 1962], No. 50075/63. Heading G3R. [Also in Division H1] An electron beam tube, e.g. a klystron, comprises a cathode 13, a modulating anode 21 controlling the beam density, an accelerating anode 23, a collector 25 and a feedback circuit for automatically varying the accelerating voltage to maintain a constant average beam velocity. As shown, an inductor 27 has one end connected to the cathode terminal 19 and its other end connected over a power supply 31 to the accelerating anode 11. Tubes 33, 35 control the modulating voltage applied to anode 21. The beam density is detected at the collector 25 which is connected to the primary winding of a transformer 43 having a secondary winding controlling the conduction of a tube or solid state device 41; the current for tube 41 is supplied from inductor 27, the voltage drop across which changes and adds or subtracts from the accelerating voltage in dependence upon beam density variations, the arrangement being such that the average beam velocity is maintained constant. The Specification states that the accelerating voltage has a greater effect on the electrons at the surface of the beam than on those electrons at the centre of the beam, the degree of penetration becoming less as the beam density increases; variations in beam density caused by the modulating anode would thus result in variations in the average beam velocity, producing a phase shift which distorts the output signal from the beam tube. This phase shift is neutralised by the corrective feedback circuit 25, 43, 41, 27. An embodiment with a modified feedback circuit is described with reference to Fig.2 (not shown).