A theoretical study on electon-capture process by multiply-charged ion in external magnetic field

1.本文建立了外磁场影响下离子原子碰撞中电子捕获过程的半经典紧密耦合方程，其中磁场方向对入射弹丸速度是任意的。这个公式已经应用到一些系统,即,(B ^ < 4 + > + H), (^ < 2 + > + H), (^ < 3 + > + H),和(他^ < 2 + > + H)。这些计算得到的主要结果如下：(1)一般情况下，磁场使电子捕获加速，但在某些状态和/或在一定角度下，也有截面减小的情况。(2)由于磁场与旋转耦合的协同作用，当磁场方向垂直于碰撞面时，磁场效应最强。(3)磁场与入射速度之间的角积截面随磁场的增大而缓慢增大。(4)碰撞能量越低，磁场越有效。我们研究了极化效应，即多电荷离子运动时极化靶与磁场相互作用的效应。然而，这种影响在我们的案例中是相当小的。He^<2+>+H (1s)*He^+ (2l) +H^+对应于共振情况，并预测了磁场混沌效应的可能性。然而，在这种情况下，发生了两种类型的转变，一种是由于斯塔克混合相和另一种是由于旋转耦合。在很大的核间距上的跃迁使得跃迁机制非常复杂。我们编制了一个程序，正在用它进行计算。

1.A semiclassical close-coupling equation is formulated for the electron-captureprocess in ion-atom collisions under the influence of an external magnetic field where the field direction was arbitrary to the incident projectile velocity. This formula has been applied to some systems, i.e., (B^<4+>+H), (Be^<2+>+H), (Be^<3+>+H), and (He^<2+>+H). The main results obtained by these calculations are as follows.(1) In general, the magnetic field make the electron capture accelerate, but for some states and/or at certain angle there are cases also where the cross sections decrease.(2) The magnetic field effect is the most strong when the direction of the magnetic field is perpendicular to the collision plane, because of the cooperetive action of magnetic field and rotational coupling.(3) The cross sections integrated over angle between the magnetic field and the incident velocity increase slowly with magnetic field.(4) The lower the collision energy becomes, the more effective the magnetic field becomes.2.We investigated the polarization effect, that is, the effect of the interaction between polarized target by moving multiply charged ion and magnetic field. However, this effect is pretty small in our cases.3.The process, He^<2+>+H (1s)*He^+ (2l) +H^+, is corresponding to a resonance case and the possibility of chaos-like effect of magnetic field is predicted. However, in this case, there occurs two-type transitions, one is that due to phase by the Stark mixing and the other is that due to the rotational coupling. The transition at very large internuclear distance makes the transition mechanism very complex. We have made a proguram and are now performing calculatious using it.