Patent GB-736774-A (GB)
Title: Improvements in or relating to target structures for electromagnetic separators
Inventor: HALL ROGER NORMAN
IPC: H01J49/30
Filed: 1950-10-06
Abstract: 736,774. Heavy ion beam tubes. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. Sept. 5, 1951 [Oct. 6, 1950], No.'24451/50. Class 39 (1). The target structure of an electromagnetic separator comprises a plurality of cavities 34, 35, 36, Fig. 2, with closely adjacent slots, a carbon plate 12 with corresponding slots 31, 32, 33 spaced according to the relative mass numbers of the isotopes to be separated, and a recording arrangement comprising a flexible foil (not shown) mounted on rotatable drum 23. The target supporting arrangements comprise tube 3 which can slide and rotate relatively to collar 6, the latter being movable about pivot pins 4, 5. Flange 1 is bolted to one side of the vacuum container. Vacuum seals are formed by spherical surface 7 and ring 8, and sealing ring 9. The target drum 16 has split sections 17, 18 clamped together by screws 19, 20, is carried in bearing plates 21, 22 from bracket 10, and is driven by gear train 23, 24, 25, 26, 27 from shaft 28. Additional bearings 29, 30 may carry a small drum near carbon plate 12 and a shaft and idler pulley respectively. Screws 19, 20 have spring screening bands 19a, 20a. The carbon plate 12 has three slots for corresponding ion beams to pass to three separate cavities 34, 35, 36 divided by inclined copper plates 41, 42, the two outer cavities 34, 36 having tungsten covers and water-cooled copper base plates. The water cooling system comprises inlet pipe 68, annular manifold 69, duct 70, pipe 71 which passes through aperture 72 into head 2, and a similar return system. Inlet pipe 71 and outlet pipe 84 have a twist to allow for thermal expansion. At the left hand end of shaft 28 there is double vacuum seal 47 fed by grease along the hollow interior of the shaft from grease cap 49, and driving means for the shaft comprising gearing 48, 51, 52, 53 associated with electric motor 54. The tube 3 can be rotated through a small angle by a flexible drive transmitted through a coupling bar, shaft and eccentric confined by prongs attached to the tube and is moved axially by shaft 61, coupling bar 62, pinion (Fig. 3, not shown) and spur wheel 64 which engages tube 3 in a threaded manner; 66 is a thrust race. The prongs prevent rotation of the tube during axial movement thereof. To collect a specified isotope the slots in carbon plate 12 are spaced according to the relative mass numbers of the isotopes. The total ion current is measured by deflecting the head 2 about pivot pins 4, 5 so that none of the beam passes through the slots. The head is then adjusted to give maximum current from the drum and two outer cavities which have separate leads and minimum current from plate 12. A foil for the deposition of the isotope may be clamped at its ends between drum parts 17, 18. In a modification the drum may be directly water cooled. A plurality of rotating drums may be used to deposit isotopes from a common source on separate foils thereon. The foils may be narrow in the axial direction to obtain deposits of uniform density. The Provisional Specification refers in addition to application of the invention to " other kinds of low pressure discharge devices wherein material is deposited on to a target from a beam of ions."