强流AVF型迴旋加速器中的空间电荷效应和束晕

Effects of the Space Charge Forces and the Beam Halo in an AVF Cyclotron with Intense Beam Currents

详细推导了AVF型旋加速器中束团粒子在曲线坐标系中的动力学方程 (考虑和不考虑空间电荷相互作用力两种情况 ) .在假定动力学方程中各参数值的前提条件下 ,用Lunge Kutta方法对考虑空间电荷时的动力学方程进行了数值计算 .结果表明 ,束晕的形成和发展同样也是强流旋加速器中束流损失的一个主要原因 .但束晕形成的机制不同于直线加速器的情况 ,它不是由共振和混沌引起 ,而是由于粒子的排斥运动和束团内粒子的涡流运动引起的 .

The equations of motion of particles in an AVF cyclotron in a curvilinear coordinate system are derived for the cases with and without space charge forces. Assuming a set of the parameter values in the equations, numerical calculations are carried out by using Lunge Kutta methods in the case with space charge forces. The results show that the formation of the beam halo is also a main reason of the beam losses, but the mechanism here is different from that in a linear accelerator. It is not given rise by resonance and chaos but the outward repellent motion and the vortex motion of the particles in the bunch.