| 摘要 |
<p>1413741 Ion beam apparatus CGR-MEV 29 Jan 1973 [31 Jan 1972] 4460/73 Heading H1D A beam of accelerated particles, e.g. deuterons from a cyclotron, translated in position by electromagnets E 1 or E 2 and deflected by an electromagnet E 3 is brought to a point focus on a target C by suitable selection of the parameters r, R, #,α, #, d, L or l. A triple focus, i.e. a momentum focus in two mutually perpendicular planes can be achieved. Mathematical relationships between the parameters which must be satisfied to achieve a print focus are set out, together with graphs (Fig. 3, not shown) from which suitable values can be selected. It is shown that an accurate point focus cannot be achieved with a parallel incident beam. A slightly convergent beam is necessary, and the form of the incident beam and the angle which it makes with the entry face A1 of the first electromagnet E1 may be adjusted by a known arrangement of three quadripolar lenses. The electromagnets each comprise two parallel plates separated by an air gap. A deuteron beam may be directed on to the target to produce a neutron beam.</p> |
