论文标题
抑制纵向耦合束的不稳定性在碰撞中与交叉角度相撞
Suppression of the longitudinal coupled bunch instability in DA$Φ$NE in collisions with a crossing angle
论文作者
论文摘要
自1998年以来，在达芬（Dafne），Frascati $ e^+e^ - $ collider运营，创新的碰撞计划，即螃蟹腰部，在2008 - 09年度已成功实施。在Siddharta实验的操作过程中，已经观察到由梁梁碰撞引起的异常同步振荡阻尼效应。的确，当纵向反馈关闭时，由于束束的不稳定性，正电子束会变得不稳定200-300 mA的电流。纵向不稳定通过与高电流电子束（2 a的阶）碰撞正电子束来阻尼。观察到残留同步子侧带的大约-600 Hz的偏移。通过使用商业谱分析仪和纵向束反馈的诊断能力进行了精确的测量。在与螃蟹腰部碰撞期间，在达夫内首次观察到阻尼效应。我们的解释是基于理论考虑和建模模拟的，是具有较大交叉角度的横梁碰撞会产生纵向曲调的移动和扩散，从而提供了同步基因振荡的Landau阻尼。
In DAFNE, the Frascati $e^+e^-$ collider operating since 1998, an innovative collision scheme, the crab waist, has been successfully implemented during the years 2008-09. During operations for the Siddharta experiment an unusual synchrotron oscillation damping effect induced by beam-beam collisions has been observed. Indeed, when the longitudinal feedback is off, the positron beam becomes unstable with currents above 200-300 mA due to coupled bunch instability. The longitudinal instability is damped by colliding the positron beam with a high current electron beam (of the order of 2 A). A shift of about -600 Hz in the residual synchrotron sidebands is observed. Precise measurements have been performed by using both a commercial spectrum analyzer and the diagnostic capabilities of the longitudinal bunch-by-bunch feedback. The damping effect has been observed in DAFNE for the first time during collisions with the crab waist scheme. Our explanation, based both on theoretical consideration and modeling simulation, is that beam collisions with a large crossing angle produce longitudinal tune shift and spread, providing Landau damping of synchrotron oscillations.
