Multiple-shell structures of laser-cooled 24Mg+ ions in a quadrupole storage ring
Multiple-shell structures of laser-cooled 24Mg+ ions in a quadrupole storage ring
复制标题
四极存储环中激光冷却 24Mg 离子的多壳层结构
作者：
G. Birkl;S. Kassner;H. Walther
通过电子和激光冷却在高能储存环中产生有序离子束的可能性开辟了加速器物理学的新纪元。在这样的系统中，增强的亮度和抑制的动量扩散创造了最高的相空间密度。第一个实验结果是通过将Li+束冷却到几个开尔文甚至亚开尔文温度3，4获得的，并且已经通过分子动力学方法从理论上研究了有序结构5 -7。在低能量四极储存环8和线性陷阱9中已经观察到了最低离子密度的预测配置。最近，我们表明，在稍高的离子密度螺旋结构获得10。本文介绍了四极储存环中离子有序结构的一系列新的实验结果。按照离子数增加的顺序，可以观察到线性离子链、锯齿形结构、螺旋结构和最后的多个同心壳。实验结果与分子动力学计算结果一致。
THE possibility of creating ordered ion beams in high-energy storage rings1,2 by means of electron and laser cooling has opened up a new era in accelerator physics. The enhanced luminosity and suppressed momentum spread in such systems create the highest possible phase-space density. The first experimental results were obtained by cooling 7Li+ beams to temperatures of a few kelvin or even to sub-kelvin temperatures3,4, and the ordered structures have been studied theoretically5–7 by methods of molecular dynamics. Predicted configurations for the lowest ion densities have been observed in low-energy quadrupole storage rings8 and linear traps9. Recently we showed that at slightly higher ion densities helical structures are obtained10. Here we present a series of new experimental results on ordered ion structures in a quadrupole storage ring. In order of increasing ion number, a linear chain of ions, a zig-zag structure, helical structures and finally multiple concentric shells could be observed. The experimental results agree with molecular dynamics calculations.