GB294408A - X-ray system - Google Patents

Abstract

294,408. Smith, F. S. Oct. 27, 1927. R÷ntgen-ray apparatus.-Relates to a system employing an incandescent-cathode ray-tube, and consists in including in the high voltage circuit an electrric valve which is made conductive periodically to permit energization of the tube. The device enables a single X-ray beam, or periodic beams, of high intensity and short duration to be produced. The apparatus comprises supply mains 6 to which circuits 1-5 are connected. Circuit 1 includes a step-down transformer 10 for heating the filament of a rectifying valve 8. The middle point of the secondary of this transformer is connected to an earthed point 12. Circuit 2 includes a transformer 16 which heats the cathode filament 14 of the X-ray tube 15. Circuit 3 includes a transformer 22 for heating the filament of a Magnetron 20, the anode 41 of which is connected, through the mid-point of the secondary of transformer 16, to the cathode 14 of the ray-tube. Circuit 4 includes a transformer 24 which insulates the supply mains from the high tension of the ray tube. The secondary of this transformer is connected to a motor 26 which drives a generator 27 and a rotary switch 28. The generator supplies current to the magnetizing solenoid 29 of the Magnetron 20, and the switch periodically short-circuits a resistance 31 which is in series with the solenoid 29 and the generator. Circuit 5 includes a step-up transformer 34 with its secondary connected to the anode 37 of the rectifying valve 8 and to a condenser 36 through a. high resistance 38 and a low resistance 39. The other side of the condenser 36 is connected to the earthed point 12 and, through the secondary 11 of the transformer 10, to the cathode 7 of the rectifier. The junction point 40 of the resistances 38, 39 is connected to the cathode 19 of the Magnetron through the secondary 23 of the transformer 22. The anode 42 of the ray-tube is connected to the earthed point 12. In operation, so long as the arm 33 of the rotating switch 28 short-circuits the resistance 31, current flows through the solenoid 29 and the magnetizing field prevents current from flowing through the Magnetron. During this time, the condenser 36 is charged by the transformer 34. When the arm 33 moves off its sectors, the resistance 31 reduces the current through the solenoid 29 to such an extent that the condenser 36 can discharge through the Magnetron and therefore through the ray-tube 15. In a modification, the rotary switch 28 may be replaced by a handoperated make-and-break switch and single X- ray beams may be produced. The Magnetron may also be replaced by a three-electrode valve, the switch 28 in this case being arranged to change the potential applied to the grid of the valve, so as to make the path between the filament and the anode alternately conductive and non-conductive. The apparatus may be used for the treatment of articles for the destruction of insects with which such articles may be infested.