HIRFL-CSRm冷却束流寿命

Research of the cooling beam lifetime in HIRFL-CSRm

实验研究了HIRFL-CSRm中电子冷却装置对C6+,Ar15+两种束流寿命的影响。首先,通过对比实验的测量确定电子冷却可以有效提高束流寿命;其次,探究了电子冷却装置中的各项参数(主要是电子束密度分布、流强、能量、绝热展开因子)是如何影响束流寿命的,通过改变电子束参数,测量束流寿命的变化趋势和规律,并且结合电子冷却相关理论对实验结果给予解释,最终通过实验优化和确定最佳的冷却装置参数,使束流在HIRFL-CSRm上获得了较高的寿命,从而提高HIRFL-CSRm束流累积过程中的流强增益。

The main Cooling Storage Ring （CSRm） of HIRFL-CSR is used to accumulate, accelerate and extract the charged ion beam to experimental terminal.During accumulation in CSRm, the Multiple Multiturn Injection method with electron cooling is applied at the injection energy to increase beam intensity.Theoretical analysis suggests that the cooling rate and beam lifetime have a strong influence on the beam intensity.On the one hand, electron cooling can quickly shrink the size, divergence and the momentum spread of stored ion beams, which is also used to reduce beam loss caused by Intra Beam Scattering （IBS）.On the other hand, the recombination effects between electrons and ions will result in the beam loss.Some experiments on C6＋ beam and Ar15＋ beam were carried out in CSRm to investigate the relationship between electron cooling and beam lifetime.The beam lifetime was remarkably increased when electron cooling was applied.The effects of the electron beam parameters （density, current, energy and expansion factor） on the ion beam lifetime were measured.The results of the measurement were analyzed based on the electron cooling and recombination theory, and how the electron cooling affect the beam lifetime was studied.According to the measurement results and the analysis, the electron beam parameters were optimized to increase the beam lifetime and the ion beam intensity could be increased to a high level accordingly.