准周期聚焦–加速耦合系统的均温设计方法

强流质子直线加速器要求严格控制束流损失和束流发射度增长.理论已经证明,强的空间电荷作用在不同自由度之间的耦合,会因为其间的温度差异,通过束流的相干不稳定性,使束流发射度增长.因此,有必要按照均温的原则设计强流加速器.但是,由于质子直线加速器的各种加速结构均为准周期耦合系统,使得均温设计十分繁琐而难以达到完全均温.我们利用国际上通用的束流动力学软件TRACE3-D,给它补充了均温设计功能,通过与PARMILA程序的配合使用,可以方便地在加速器设计中实现均温条件.本文将介绍我们对TRACE3-D的修改补充,并以强流质子直线加速器设计实例,说明均温设计的必要性.

Equipartitioning Design Method of a Quasi-Periodic Focusing-Accelerating Coupled System

Intense-leam proton linac sets a very severe requirement on the control of beam loss and emittance growth. Beam physics theory demonstrates that coupling of the strong space charge effect between different freedoms with different temperature will surely increase the beam emittance in the way of beam coherent instability. Therefore it is necessary to design an intense beam accelerator in accordance with the equipartitioning principle. However, this design is too tedious to reach full equipartitioning because the real proton linac is a quasi-periodic coupling system. Thus, we made a few modifications to TRACE3-D, which is a popular code in beam dynamics, and added the equipartitioning design function to it. When the modified TRACE3-D is used together with the PARMILA code, it is easy to realize equipartitioning. This paper will introduce the modification to TRACE3-D code, and then illustrate its application to the design of a DTL linac section, which shows the importance of equipartitioning design in the intense beam linac.