| 摘要 |
<p>Apparatus for acting upon charged particles has particular application in a mass analysis apparatus. An array of elongate magnetic poles (311) extends longitudinally in the direction of a longitudinal axis (350) of the array, the array having a symmetrical reference surface (320) containing the longitudinal axis and passing through the array with magnetic poles (311) on each side of the reference surface. Charged particles (314) enter into, or originate in, the field of the magnetic pole array at a position spaced from the said longitudinal axis (350). The array of magnetic poles is such as to provide between opposed poles (311A, 311B), an extended region of magnetic field in which the charged magnetic particles pass with a curved motion imposed thereon by the field, together with entry and exit regions (312A and 312B) which provide curved magnetic fields (312A, 312B), giving focusing or divergence of the beam of charged particles passing through the fringe field at an angle to the normal to the entry or exit region. The apparatus includes resolving means (332) for selecting a required species of particle from the beam by parameter dependent dispersion in a plane transverse to the reference surface (320), by focusing of the beam of particles at different focal points (331) along the general direction of propagation of the beam (314).</p> |
