带电粒子在磁场中的运动区及其模型实验

本文讨论了带电粒子在电磁场中的运动区域.在计算过程中假定磁场是有势的,并且势函数分别考虑为轴对称与平面函数.计算结果表明:当磁场足够强时,粒子运动区的边界与磁力线是相似的.这个结果表明,我们可以根据磁力线图形确定带电粒子的运动区.此外,还将上述计算结果与模型实验做了对此,在磁场中的辉光放电实验里,放电中的辉光区部分相当于粒子的运动区,暗区部分相当于粒子禁区.对比结果表明,辉光区的边界与磁力线相似,其中有以下几个结果:（1）当磁场是一个偶极磁场,并且其磁短的大小大于其临界值时,则放电辉光将被捕获于偶极磁场中,其边界近似于磁力线;（2）当偶极磁场受到扰动时,设扰动场分别考虑为与赤道面上的偶极磁场方向相反的均匀磁场,以及位于捕获区之外在赤道面上的电流环磁场时,则偶极磁场磁力线将向外伸长,实验观测到被捕获于偶极磁场中的辉光将同时伸长,并且辉光区边界的变化与磁力线的变化是相似的;（3）根据中性线磁场中的辉光放电实验表明,辉光区的边界仍然与中性楱磁场的磁力线相似.由于气体放电中的现象比较复杂,因此要进行定量的计算是比较困难的,为此我们引进了一些简化假定,定量计算了辉光区在上进各种磁场中的边界,计算出来的辉光边界的大小和形状与实验结果是相同的.

THE ALLOWED REGIONS OF CHARGED PARTICLES MOVING IN THE MAGNETIC FIELD AND THE MODEL EXPERIMENT

The allowed regions of a single charged particle moving in the various field of force is investigated assuming that the magnetic field has a potential,which in the present investigation two types of assumed magnetic potential are considered:（1） the magnetic potential is axial symmetric,（2）the magnetic potential is a two dimensional function. The result of the calculation shows that the boundary of the allowed regions is similar to the magnetic lines when special condition is fulfilled,and the allowed regions can be studied from the figure of the magnetic line. The results of calculation are also compared with the model experiment,in which glow regions in the gaseous discharge correspond to the allowed regions and the dark regions correspond to the forbidden regions.The comparison results are:（1） In the terrella experiment,the glow is trapped in the dipole field,when the magnetic moment of the terrella is greater than a critical value.（2） When the dipole field is disturbed by a uniform field which is antiparallel to the dipole field at the equatorial plane,or a field originated from a ring current situated outside the trapped region at the equatorial plane;the dipole magnetic lines are stretched and expanded,and the glow will also extended.The variation of the boundary of the glow is similar to the variation of the magnetic lines.（3） In the gasous discharge experiment around the neutral line in the magnetic field,the boundary of the glow is also similar to the magnetic lines. Since many phenomena in gaseous discharge is very complicated,it is very difficult to compare the result of calculation with the experiment quantitatively,therefore we used some simplified and calculated the boundary of the glow regions.The result is very similar with the experiment.