The question of interplay of coherent and incoherent space charge driven resonances and of their Landau damping has found some interest in beam dynamics of modern high-intensity synchrotrons. We revisit the theoretical and simulation models describing coherent half-integer parametric resonances, analyze their Landau damping in 2D beams on the basis of simulated tune spectra and conclude that above second order (envelope modes) they play no role in realistic, Gaussian-like beam models. We also analyze incoherent resonance effects in the beam core regions and find that their role has been underestimated in part of the literature, in particular with regard to the very long-term beam evolution as in synchrotrons. We conclude that for such time scales more careful analysis of realistic simulation models—including the incoherent frozen space charge approximations—is needed to support synchrotron design and evaluation of experiments.

中文翻译：

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重新审视空间电荷的相干和非相干共振

相干和非相干空间电荷驱动共振及其朗道阻尼的相互作用问题在现代高强度同步加速器的束动力学中引起了一些兴趣。我们重新审视了描述相干半整数参数共振的理论和模拟模型，基于模拟的调谐谱分析了它们在 2D 梁中的朗道阻尼，并得出结论，以上二阶（包络模式）它们在现实的类高斯梁中不起作用楷模。我们还分析了光束核心区域的非相干共振效应，发现它们的作用在部分文献中被低估了，特别是在同步加速器中的非常长期的光束演化方面。