Measurement of the longitudinal microwave instability in the APS storage ring
Measurement of the longitudinal microwave instability in the APS storage ring
复制标题
APS存储环纵向微波不稳定性的测量
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
B. Yang
中科院分区：
文献类型：
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作者：
Y. Chae;L. Emery;A. Lumpkin;J. Song;B. Yang
研究了先进光子源（APS）存储环中的纵向单束不稳定性。先前的测量显示了束的显著延长，而能量扩散却没有相应的增长。由于弯曲磁体源点的小色散使能量扩散的小变化难以解决，因此我们调整晶格使色散在扇形内凸起，从而在源点提供大色散。来自色散的增强分量使我们能够更准确地测量能量扩散。当阈值电流为7.2 mA，射频电压为9.4 MV时，我们观察到能量扩散异常增长。能量扩散从9.0E-4增加到9.8E-4，高于阈值电流达10 mA。我们还观察到在超过阈值电流的同步加速器频率的四倍处出现相干信号，这表明能量扩散的增长是由纵向不稳定性引起的。
We studied a longitudinal, single-bunch instability in the Advanced Photon Source (APS) storage ring. Previous measurements showed significant bunch lengthening without a comparable growth in energy spread. Because the small dispersion at a bending magnet source point made it difficult to resolve the small change in the energy spread, we adjusted the lattice to make a dispersion bump within a sector, providing a large dispersion at the source point. The enhanced component from dispersion allowed us to measure the energy spread with greater accuracy. We observed anomalous growth in the energy spread beyond a threshold current of 7.2 mA with an rf voltage of 9.4 MV. The energy spread increased from 9.0E-4 to 9.8E-4 above the threshold current up to 10 mA. We also observed the appearance of the coherent signal at four times the synchrotron frequency beyond the threshold current, which indicates that the growth in energy spread is caused by a longitudinal instability.