GB715389A - Improvements in electron discharge devices - Google Patents

Abstract

715,389. Magnetron amplifiers. COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. Aug. 2, 1951 [Aug. 12, 1950], No. 18366/51. Class 39(1) In travelling wave amplifiers in which an electron beam gives up energy to a wave travelling along a delay line in a region of crossed electric and magnetic fields, the emission from the cathode of the gun is space charge limited and the profile and potential of the focusing and accelerating electrodes are such that the potential at the beam edges and the potential gradient at the beam edges normal to the edges is the same as it would be in a beam of infinite cross-section. The potentials of the focusing and accelerating electrodes lie within the range cathode potential to the potential of the most positive electrode in the crossed field region, and increase with increased distance of the electrodes from the cathode. The shape of the electrodes which are of non-magnetic material may be found by calculation or by electrolytic tank experiments. In one form, Fig. 2, the gun has cathode 21, Wehnelt electrode 22 making an angle of 67.5 degrees with the beam and profiled focusing and accelerating electrodes 23, 24, 27, 28. In Fig. 3 (not shown), electrode 27 is a filter type circuit having a plurality of cavity resonators and with end slots for input and output couplings, and electrode 31 is supported by a flat insulator from the tube wall. In a modification, Fig. 5, the crossed field travelling wave tube is bent into circular form, and has cathode 3, Wehnelt control electrode 10, I profiled accelerating and focusing electrodes 18, 19, 20, and delay line 9. The electron flow is controlled by varying the potential of the cathode or of an 'auxiliary electrode'. It is stated that the space charge limited beams have reduced shot noise as compared for example with known tubes with saturated or unsaturated emission.