Calculation of Space Charge Effects in Isochronous Cyclotrons
Calculation of Space Charge Effects in Isochronous Cyclotrons
复制标题
等时回旋加速器中空间电荷效应的计算
DOI：
10.1109/tns.1985.4333962
复制
发表时间：
1985
影响因子：
1.8
通讯作者：
S. Adam
中科院分区：
文献类型：
--
作者：
S. Adam
本文介绍了等熵回旋加速器中空间电荷计算的有关问题，提出了一种新的纵向空间电荷效应的计算机模拟模型。新模型使用解析变换将三维简化为二维，并使用粒子单元法计算电荷分布随时间的变化。新的计算机程序使我们能够研究“螺旋不稳定性”，它可以引起与粒子的能量和RF相位相关的相平面中的不稳定性。虽然这种不稳定性在低能量下是最重要的，但在加速期间，束脉冲中的能量扩展也稳定增加。此外，该第二效应导致提取时的射束损失增加，因此两者都可以限制可以处理的射束电流。
An introduction to the problems related to space charge calculations in isochronous cyclotrons is followed by the presentation of a new computer simulation model for the longitudinal space charge effects. The new model uses an analytical tansformation to reduce from three to two dimensions and a particle-in-cell method to calculate the charge distribution as a function of time. The new computer program enabled us to study the "spiralling instability", which can evoke filamentation in the phase-plane related to energy and RF-phase of the particles. While this instability is most important at low energies, there is also a steady increase of energy spread in the beam pulses during the acceleration. Also this second effect causes an increase of the beam losses at extraction, therefore both can limit the beam current that can be handled.