Uniformization of the transverse beam profile by means of nonlinear focusing method
Uniformization of the transverse beam profile by means of nonlinear focusing method
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DOI：
10.1103/physrevstab.10.104001
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发表时间：
2007-10
影响因子：
--
通讯作者：
Y. Yuri;N. Miyawaki;T. Kamiya;W. Yokota;K. Arakawa;M. Fukuda
中科院分区：
文献类型：
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作者：
Y. Yuri;N. Miyawaki;T. Kamiya;W. Yokota;K. Arakawa;M. Fukuda
众所周知，利用光束输运系统中的奇阶非线性聚焦可以使光束具有高斯分布的均匀化，并且最近已被用于均匀光束辐照。本文从理论上详细研究了利用多极磁体产生的非线性聚焦力对横向光束轮廓的均匀化。在多极磁体的非线性场由无穷幂级数给出的情况下，高斯光束均匀化所需的所有奇阶多极强度和由此产生的均匀区域的范围都用Twiss参数表示。我们用偶阶非线性场证明了均匀化原理。我们还实际演示了利用非线性聚焦，特别是在六极子场和八极子场的情况下，将非对称分布的光束转化为均匀分布的光束。通过粒子跟踪仿真验证了所提公式的有效性。提出了一种利用光束准直和八极聚焦实现均匀轮廓的实用方法。
It has been known that uniformization of a beam with a Gaussian profile is possible utilizing odd-order nonlinear focusing in the beam transport system, and this has recently been employed for uniform beam irradiation. Here, we have theoretically studied uniformization of the transverse beam profile using nonlinear-focusing forces produced by multipole magnets in detail. In the case where the nonlinear field of the multipole magnet is given by an infinite power series, all the odd-order multipole strengths required for uniformization of a Gaussian beam and the extent of the resultant uniform region have been expressed using the Twiss parameters. We have shown the principle of uniformization using even-order nonlinear fields. We have also actually demonstrated the transformation of a beam with an asymmetric distribution into one with a uniform distribution by utilizing nonlinear focusing, especially with the sextupole and octupole fields. The validity of the formulas presented here was confirmed through particle-tracking simulations. A practical method to realize a uniform profile using beam collimation and octupole focusing is also presented.