Patent GB-460288-A (GB)
Title: Improvements in or relating to discharge tubes using electrons and/or positive ions
IPC: H01J29/48
Filed: 1935-04-23
Abstract: 460,288. Discharge apparatus. ROGOWSKI, W., and MALSCH, F. April 23, 1935, Nos. 12277 and 12278. Convention dates, April 19, 1934 and Jan. 7, 1935. [Class 39 (i)] To secure concentrated electron beams from large surface cathodes in oscillographs &c., at least part of a beam of ions or electrons is caused to reverse in direction by an axially symmetrical counterfield and is thus concentrated towards the axis. Electrons from a cathode 1, Fig. 1, are focused by a lens 2, 3 to form a beam passing through an aperture 4 in the anode 2 into the retarding field of an electrode 5 slightly negative with respect to the cathode 1. An accelerating electrode 6 attracts axial rays through the aperture 7 in the electrode 5 but rays 8 at greater than a given angle to the axis reverse their direction and move towards the axis as shown. It is stated that electrons pass to-and-fro through the aperture 4 and move towards the axis to increase the intensity of the beam finally drawn through the aperture 7. In a modification, Fig. 4, a large-surface, thermionic cathode 21 and a curved grid anode 24 are arranged in an axially symmetrical, box-like, negatively charged electrode 22 with a central aperture 23 through which the electron beam is drawn off by the electrode 25. Electrons passing through the anode 24 towards the walls of the electrode 22 are reversed and concentrated towards the axis so that electrons pass to-and-fro through the electrode 22 towards the axis, to increase the electron concentration near the axis and the intensity of the beam emerging from the aperture 23. The walls of the electrode 22 may be covered with emissive substance. In other modifications, electron beams are projected at points symmetrical to the axis into an axially symmetrical counter-field which reverses their direction and bring them to the axis to form a combined beam. The original beams may be parallel to the axis and moved towards the axis by the counter-field, Fig. 3 (not shown), or the counter-field may be homogeneous and the original beams inclined to the axis to take parabolic paths 36, Fig. 6, to emerge as a beam 38 from the aperture 7. The inclination of the beams at the apertures 4 may be produced by cylindrical deflecting electrodes 42, 43 or by inclining the electrodes 1, 2 producing the beams. To produce a homogeneous counter-field, the electrodes 34, 35 are large or lateral walls joining the electrodes 34, 35 are of low-conductivity and take current between the electrodes 34, 35 to produce a linear voltage drop over the walls. The cathode may be one or more axially symmetricol rings, and the beams 36 may be focused to form an image of the cathode in the aperture 4 or in the aperture or at an intermediate point. In other modifications, cylindrical counter-field electrodes such as 5, Fig. 1, are slotted around their centre and the slot is surrounded by a biassed electrode producing a lens effect. The intensity of the beam may be controlled by varying the potentials of this biassed electrode or of the deflecting electrodes 42, 43. Ionic beams may be similarly controlled. and thus concentrated on to a cathode to produce an electron beam. In one such arrangement, Fig. 7 (not shown), canal rays pass through apertures in an electrode of an auxiliary discharge and are reversed in direction to strike a central cathode giving an electron beam which may be controlled in intensity by controlling the auxiliary discharge or by an electrode modifying the counter-fields. The Specification as open to inspection under Sect. 91 comprises also the arrangements described in Specification 460,397 and other arrangements in which the cathode 14, Fig. 11 (Cancelled), is spherical and pivotally mounted to allow part of its surface aged by disintegration to be replaced by a new surface. The spherical or other cathode is arranged with its emitting surface near the plane of an aperture in an electrode 16 bounding a space for a gas-discharge producing the beams. " Ion tubes " generally are referred to. This subjectmatter does not appear in the Specification as accepted.