发表机构
Deutsches Elektronen Synchrotron（德国电子同步加速器）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究以PETRA-IV为例，结合Vlasov求解器等方法，发现直接空间电荷诱导的工作点展宽可稳定高阶头尾模式，其分析框架可拓展至两类加速器的集体不稳定性研究。
AI 中文摘要
衍射极限电子储存环的超低横向发射度会导致束流密度升高，尽管在高能下相对论效应会抑制空间电荷作用，但直接空间电荷效应的相关性却日益凸显。本研究以PETRA-IV为代表性实例，探究直接空间电荷对横向耦合束团不稳定性的影响。研究结合Vlasov求解器、多束团粒子跟踪以及归一化相空间中的解析计算，分析耦合束团模式谱、非线性非相干工作点展宽及相关朗道阻尼。粒子跟踪模拟显示，空间电荷诱导的工作点展宽可提供足够的朗道阻尼，以稳定高阶头尾模式；由冻结双高斯束的解析工作点展宽构建的朗道稳定性图预测这些高阶模式会被稳定，与跟踪模拟结果一致。这些结果表明直接空间电荷在横向耦合束团动力学中发挥重要作用，所开发的分析框架还可拓展至电子和强子加速器的集体不稳定性研究。
英文摘要
The ultralow transverse emittance of diffraction-limited electron storage rings leads to high beam densities, making direct space-charge effects increasingly relevant despite their relativistic suppression at high energy. In this work, we investigate the impact of direct space charge on transverse coupled-bunch instabilities, using PETRA-IV as a representative example. A Vlasov solver, multi-bunch particle tracking, and analytical calculations in normalized phase space are combined to study the coupled-bunch mode spectrum, the nonlinear incoherent tune spread, and the associated Landau damping. Particle-tracking simulations show that the space-charge-induced tune spread can provide sufficient Landau damping to stabilize higher-order head-tail modes. Landau stability diagrams constructed from the analytical tune spread of a frozen bi-Gaussian beam predict the stabilization of these higher-order modes, in agreement with the tracking simulations. These results demonstrate the important role of direct space charge in transverse coupled-bunch dynamics. The analysis framework developed here can also be extended to collective-instability studies in both electron and hadron accelerators.
