Tune and Chromaticity Control During Snapback and Ramp in 2015 LHC Operation
Tune and Chromaticity Control During Snapback and Ramp in 2015 LHC Operation
复制标题
2015 年大型强子对撞机运行中快速回升和斜坡期间的调谐和色度控制
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
J. Wenninger
中科院分区：
文献类型：
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作者：
M. Schaumann;M. Juchno;M. Lamont;M. S. Camillocci;E. Todesco;J. Wenninger
由于超导电缆上的电流重新分布，大型强子对撞机 (LHC) 中超导磁体的磁场谐波分量在低场注入平台期间表现出衰减。这导致光束的调谐和色度变化。在斜坡的最初几秒内，磁场的原始磁滞状态恢复，磁场快速恢复。这些快速的动态场变化会导致强烈的调谐和色度偏移，如果控制不当，会引起光束损失并可能触发光束收集器。前馈系统在注入平台期间和斜坡的第一部分应用预测校正，以避免光束条件的剧烈变化。本文讨论了 2015 年观察到的调谐和色度的快速恢复，以及斜坡期间光束参数的控制。它还评估所应用的前馈校正的质量及其再现性。
Because of current redistribution on the superconducting cables, the harmonic components of the magnetic fields of the superconducting magnets in the Large Hadron Collider (LHC) show decay during the low field injection plateau. This results in tune and chromaticity variations for the beams. In the first few seconds of the ramp the original hysteresis state of the magnetic field is restored the field snaps back. These fast dynamic field changes lead to strong tune and chromaticity excursions that, if not properly controlled, induce beam losses and potentially trigger a beam dump. A feed-forward system applies predicted corrections during the injection plateau and to the first part of the ramp to avoid violent changes of beam conditions. This paper discusses the snapback of tune and chromaticity as observed in 2015, as well as the control of beam parameters during the ramp. It also evaluates the quality of the applied feed-forward corrections and their reproducibility.