GB1524457A - Extractive electrode situated in the vicinity of the particle source of acceleators of the cyclitron type - Google Patents

Abstract

1524457 Cyclotrons CGR MEV 19 July 1976 [21 July 1975] 30044/76 Heading H1D In a cyclotron in which an extraction electrode is located adjacent the particle source to extract particles therefrom, the electrode is in the form of a metal prism 10 housing in its surface 12 adjacent the source S a window 14 for the entry of particles, the window opening into a notch 11 which provides a channel, defined by walls 15 and 16, for the particle beam F, such that the beam is shielded from the focusing and defocusing effects of the component of the cyclotron A.C. electric field which is perpendicular to the plane of the mean beam path. As shown, the electrode may be secured to one of the Dees 17. In the arrangement of Fig. 5, the element 35 separates the window and the notch into two channels C 3 and C 4 appropriate to operation of the cyclotron at two different harmonic frequencies. The element 35 may be adjustable, e.g. by the screw threaded rod 37, and may have surfaces which mate with the respective channels walls when the element is displaced to one or other of its extreme positions. (Figs. 9 and 10, not shown). In an alternative arrangement, the adjustable member 35 may at the window end be provided with shoulders (38, 39, Figs. 6 and 7, not shown) which engage the top and bottom surfaces of the window, the member being held in position by a locking plate (P). The surface 12 of the prism adjacent the source may be convex (Fig. 3, not shown) to permit positioning closer to the source.