Patent GB-709390-A (GB)
Title: Method and circuit for producing expansion and contraction impulses for a magnetic induction accelerator with variable ultimate electron voltage
IPC: H05H11/00
Filed: 1952-06-30
Abstract: 709,390. Magnetic induction accelerators. AKT.- GES BROWN, BOVERI, & CIE. June 30. 1952 [June 29, 1951], No. 16431/52, Class 39(1) A betatron, Fig. 1, with variable ultimate electron voltage having one electron stream or two electron streams accelerated in opposite directions has expansion or contraction coils 16 and 17 which are energized by the acceleration flux from the main coils 11 and 12 via the pole shoes 14 and 15 and are connected in series with a capacitor 18 which supplies expansion or contraction pulses to the coils under the control of two discharge tubes 19 and 20 connected in inverse parallel relationship and having control grids connected in a circuit, Fig. 4, whereby tube 19 is fired periodically at an adjustable instant depending on the desired ultimate voltage, while tube 20 is fired so much after the firing point corresponding to maximum ultimate electron voltage of the second electron stream as the firing point of tube 19 lies in advance of the firing point corresponding to maximum electron voltage of the first electron stream. The circuit arrangement is as shown in Fig. 4 if the betatron has in fact only one electron stream, the second impulse in this case serving to restore the capacitor 18 to the condition necessary for interrupting the acceleration at the right instant during the acceleration period T 1  of the first electron stream. The firing point of tube 19 is arranged to lie within the period T 1  at a point corresponding to the desired ultimate electron voltage by means of a phase transformer 23 having two secondary windings 24 and 28 connected rigidly together and rotatable relative to the primary winding 29 which is connected in parallel with the energizing winding 32 of the betatron. Secondary winding 24 is connected to a doublewave rectifier system comprising tubes 25, 26 and load resistor 27. Secondary winding 28 is connected to a resistor 30 and capacitor 31 for shifting the phase of the secondary voltage by 45 degrees. The pulsating direct voltage at resistor 27 and the sinusoidal voltage at capacitor 31 are applied together to the grid of tube 19 which is fired by the peaks of the resulting curve. The second discharge tube 20 is fired during the acceleration period T 2  of the second electron stream by a voltage which has three components, firstly the voltage at capacitor 18, secondly the voltage at the secondary winding 36 of a transformer 37 whose primary winding 38 is connected to a resistor-capacitor circuit 40, 39 which shifts the voltage from the energizing winding 32 through 45 degrees, and thirdly a -bias voltage from the secondary winding 45 of a transformer 41, the primary winding 42 of which is connected to a phase-shifting resistor-capacitor circuit 43, 44 in parallel with the energizing winding 32. A rectifier 47 with a bias battery 46 is connected in parallel with the secondary winding 45 so that the third component voltage consists of a sine wave with the upper parts corresponding to the quarter period T 2  cut off, so that the tube 20 can only fire during the period T 2 . The first and second component voltages are reduced by a voltage divider 48 to the magnitude required for the control range of the grid of tube 20.