Patent GB-294409-A (GB)
Title: X-ray system
IPC: H05G1/20
Filed: 1927-10-27
Abstract: 294,409. Smith, F. S. Oct. 27, 1927. R÷ntgen-ray apparatus.-A system employing a ray-tube with an incandescent cathode is provided with means for periodically passing through the cathode a current having a steep wave front in order to bring the filament to incandescence rapidly to produce an intense X-ray beam of relatively short duration. The apparatus may be used for treating materials such as cereals, furs and tobacco for the destruction of insects with which the materials may be infested. The apparatus is supplied with low voltage alternating current by means of supply mains A, B to which circuits 1-6 are connected. Circuit 1 comprises a step-up transformer 9 having its secondary earthed at one end while the other end is connected to the cathode 24 of a, rectifying valve 10 and to the anode of a second rectifying valve 11. The anode of the rectifier 10 is connected through a high resistance 12 with one plate of a condenser 14, the other plate being earthed at 15. The cathode of the rectifier 11 is connected through a high resistance 16 with one plate of a condenser 18, the other plate of which is earthed at 15. The resistance 12 is also connected with the cathodes of two X-ray tubes 20, 21, and the resistance 16 is connected with the anticathodes of the tubes. Circuits 2 and 3 comprise step-down transformers 23, 26. respectively, for heating the filaments of the rectifying valves. Circuit 4 comprises a motor 29 which drives a pump for circulating water through the anticathodes of the ray-tubes and through a radiator 38. Circuit 5 comprises a motor 39 which drives a direct current generator 42 one terminal of which is connected, through a low resistance 43, with one plate of a condenser 44 and to the filaments of the ray-tubes 20, 21. The filaments are connected also to one ball, 50, of a spark gap, the other ball, 51, being connected to the other plate of the condenser 44. The other terminal of the generator 42 is connected to a ring sector 53<a> of a switch 53, another sector 52a being connected with the condenser 44 and the ball 51. The switch also includes a rotating arm 56, of insulating material which is driven by the motor 39 and carries a contact 54 and a metal ball 57. Circuit 6 comprises a step-down transformer 58 having its secondary connected at one end to the cathode 24 of the rectifier 10 and at the other end to one plate of a condenser 59. The other plate of the condenser is connected to the ball 50 and to the resistance 12. The seoondary is also connected to a ball 60 of a spark gap, the other ball 61, being connected to the ball 51, the two spark gaps thus being in series with one another. Operation. When the contact 54 bridges the segments 52<a>, 53<a>, the different condensers are being charged. The condenser 44 is charged by the generator 42, and the condenser 59 is charged by the transformer 58 through the rectifier 10. The condensers 14, 18 are also charged by the transformer 9 through the rectifiers 10, 11. When the contact 54 rides off the segments, the ball 57 passes into the spark gap 60, 61 so that the condenser 59 discharges through the spark gaps 60. 61 and 50, 51. This discharge causes ionization of the air between the balls 50, 51 thus closing the discharge circuit of the condenser 44. The condenser discharges through the cathodes of the ray-tubes and brings them rapidly to incandescence The condensers 14, 18 then discharge through the tubes and produce an X-ray discharge of high intensity. The constants of the circuits of the condensers are so chosen that the discharge is dead beat.