The U.S. electron ion collider will utilize high current electron and ion storage rings with many bunches and large rf systems. Because of the dissimilarity of the two rings, the rf transients created by gaps or variations in the current distributions will be very different in the two rings. These transients cause a shift in the synchronous phase of the beams as a function of rf bucket position, can impact the luminosity through shifts in longitudinal position of the IP, will affect the performance of the rf and LLRF control loops, and may require significant rf power overhead to control. A machine design that uses superconducting crab cavities will also have sensitivity to gap transients and synchronous phase variations along the bunch train with variations in crab cavity voltage seen by each bunch, since the high $Q$ of the crab cavities precludes modulating them to compensate for the time of arrival shifts caused by the gap transients in the main rf systems. All these effects make the problem of managing gap transients crucial to the operation of the EIC. This work presents methods to study the dynamics of the rf and LLRF systems for these heavily beam loaded facilities. An illustrative machine design example is presented and used to investigate the expected magnitudes of the rf gap transients, and exploration of various possible remedies to match the gap transients in the two dissimilar EIC rings. In addition to the study of the power required and gap transients, this work also estimates longitudinal coupled-bunch instabilities due to the baseline cavity fundamental impedance. The work is motivated to emphasize the importance of tools and methods to estimate these effects as part of the early design phase of the Electron-Ion Collider or any high current storage ring design.

中文翻译：

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电子离子对撞机大电流存储环中的束隙瞬态分析和缓解

美国电子离子对撞机将利用具有许多束和大型射频系统的高电流电子和离子存储环。由于两个环的不相似性，两个环中由间隙或电流分布变化产生的射频瞬变将非常不同。这些瞬变会导致光束同步相位随射频铲斗位置的变化而变化，会通过IP的纵向位置的变化影响光度，会影响射频和LLRF控制回路的性能，并可能需要很大的射频。电源开销来控制。使用超导蟹腔的机器设计还将对沿束流的间隙瞬变和同步相位变化具有敏感性，因为每束蟹腔的电压都会发生变化，因为$问$对蟹腔的任何一种都无法对其进行调制，以补偿由主要射频系统中的间隙瞬变引起的到达时间偏移。所有这些影响使得管理间隙瞬变的问题对于EIC的运行至关重要。这项工作提出了研究这些重载梁设施的rf和LLRF系统动力学的方法。给出了一个说明性的机器设计示例，用于研究射频间隙瞬变的预期幅度，并探索各种可能的补救措施以匹配两个不同的EIC环中的间隙瞬变。除了研究所需的功率和间隙瞬变之外，这项工作还估计了由于基线腔基本阻抗而引起的纵向耦合束不稳定性。