GB682504A - Improvements in the ejection or injection of electrons in magnetic induction accelerators - Google Patents

Abstract

682,504. Magnetic induction accelerators. AKT.- GES. BROWN BOVERI, & CIE. Oct. 11, 1948 [Oct. 11, 1947], No. 26405/48. Class 39(i) Ejection or injection of electrons in magnetic induction accelerators is obtained by forces which influence the electrons in a direction at right angles to their velocity and over not more than a quarter of the orbit, additional forces being provided for influencing the electrons in the opposite sense. Excitation coils 1, 1<SP>1</SP> produce a magnetic flux in magnet iron 8, a part 3 of this flux flowing by way of the inner poles 2, 2<SP>1</SP> to give an accelerating field, and a part 4 flowing by way of external control poles 5, 51 to cause the electrons to execute a circular movement in the vacuum tube 7. An electrode pair 9, 91 exerts deflective forces over a small portion of the orbit, whilst the electrode pair 10, 10<SP>1</SP> produces forces in the opposite direction. Coils 6, 6<SP>1</SP> produce an additional magnetic field for enlarging the electron orbit. The deflective and opposing deflective forces can be produced by special coils which only surround the control coil. One of the forces can be obtained by altering the ratio of the control field to that of the inductive field by iron saturation or phase displacement. Fig. 4 shows the effect of a deflective force F<SP>1</SP> on the electron orbit and of a counter force F<SP>2</SP> applied over the major portion of the orbit, a peak S being produced such that upon expansion of the orbit by means of coils 6, 6<SP>1</SP> electrons are ejected at that point. Other symmetrical and asymmetrical combinations are described. The forces may be given a component perpendicular to the radial direction by inclining the coils or electrodes, and in Fig. 9, the electrons 20 may be brought between the plates 21, 21<SP>1</SP> of a condenser placed outside the orbit 19, 191 and given a further deflection to remove them finally from the acceleration channel of the vacuum tube. Similar methods for injecting the electrons are also described in Figs. 10 and 11 (not shown), the latter comprising two linked coils producing the deflective force and opposed force respectively to give a parallel displacement.