In high-intensity linear accelerators, the tune spreads induced by the space-charge forces in the radial and longitudinal planes are key parameters for halo formation and beam losses. For matched beams, they are the parameters governing the number of resonances (including coupling resonances), which affect the beam and determine the respective sizes of the stable and halo areas in phase space. The number and strength of the resonances excited in mismatched beams leading to even higher amplitude halos are also directly linked to the tune spreads. In this paper, the equations making the link between the basic linac parameters (rf frequency, zero-current phase advances, beam intensity and emittances) and the tune spreads are given. The analysis of the way these linac parameters can be chosen to minimize the tune spreads is presented. The ESS linac parameters are used as an example for this study.

中文翻译：

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选择直线加速器参数以最小化空间电荷效应

在高强度直线加速器中，由径向和纵向平面中的空间电荷力引起的调谐扩展是晕形成和光束损失的关键参数。对于匹配光束，它们是控制共振（包括耦合共振）数量的参数，它们影响光束并决定相空间中稳定区和晕区的各自大小。在导致更高振幅光晕的失配光束中激发的共振的数量和强度也与音调传播直接相关。在本文中，给出了在基本直线加速器参数（射频频率、零电流相位超前、光束强度和发射率）与调谐扩展之间建立联系的方程。介绍了可以选择这些直线加速器参数以最小化调谐扩展的方式的分析。