| 摘要 |
<p>The beam deflection system includes two dipole magnets for deflecting a charged particle beam in a deflection plane. The first magnet bends the beam in a path having a radius rho 1 and a deflection angle theta 1 greater than 180 DEG . The first magnet has an effective exit edge at an angle (90 DEG - eta 1) with respect to the beam path. The second magnet further bends the beam in a path having a radius rho 2 and a deflection angle theta 2 where 225 DEG </=( theta 1+ theta 2)</=280 DEG . The effective entry edge of the second magnet is at an angle of (90 DEG - eta 2) to the beam path. In the usual practical case the effective interior edges of the two magnets are roughly parallel, that is, eta 1 &persp& - eta 2 and the doubly achromatic properties are obtained to first order when the angles satisfy the following formula: eta 1 APPROX - eta 2 2 eta 2 APPROX theta 2-( theta 1-180 DEG ), and when the distance D between the effective edges of the two magnets is set so that the dipoles produce equal beam dispersion in the drift distance between them. For the case of 270 DEG total bend with rho 2= rho 1 this occurs at a distance D, given by <IMAGE></p> |
