Space-charge effects in low-energy proton synchrotrons
Space-charge effects in low-energy proton synchrotrons
复制标题
低能质子同步加速器中的空间电荷效应
DOI：
10.1016/0168-9002(91)90091-4
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
S. Machida
中科院分区：
文献类型：
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作者：
S. Machida
我们已经研究了空间电荷效应在低能质子同步加速器使用的模拟代码专门开发的超级计算机。具有几千个宏观粒子的束的跟踪是完全自洽的，从而使得可以跟随电荷分布以及作为时间的函数的束尺寸。本文考虑了用反冲力代替连续空间电荷力的问题。模拟进行了模型晶格（类似于SSC低能量助推器），有和没有半整数共振。在具有共振的晶格中，出现了实验中经常观察到的均方根发射度增长，并出现了相空间密度极限。然而，极限值并不像预期的那样与Laslett公式直接相关。如果我们观察单个粒子，存在一个空调谐区域，其中被空间电荷修改的某些粒子的真实的调谐在共振宽度内。在没有半整数共振的晶格中，均方根发射度也会增长。它与由光束本身驱动的高阶共振有关。只有光束的尾部受到共振的影响，并且在核心处的相空间密度几乎保持不变。
We have studied space-charge effects in low-energy proton synchrotrons using a simulation code developed specifically for supercomputers. The tracking of the beam with a few thousand macro particles is completely self-consistent, thus making it possible to follow the charge distribution as well as the beam size as a function of time. A proper substitution of the kick for the continuous space-charge force has been considered. The simulation is performed for a model lattice (similar to the SSC low energy booster) with and without half-integer resonances. In the lattice with the resonances, the rms emittance growth often observed in experiments occurs and the phase space density limit appears. The limiting value is, however, not directly related to the Laslett formula as expected. If we look at individual particles, there is a bare tune region where the real tune of some particles modified by space charge is within the resonance width. In the lattice without half-integer resonances, the rms emittance growth also occurs. It is associated with higher-order resonances driven by the beam itself. Only the tail of the beam is affected by the resonance, and the phase space density at the core remains almost unchanged.