摘要
要成功获得相干(衍射)的参数X-射线辐射(PXR)光源,粒子的运动必须是稳定的。但是由于衰减、晶格热振动、电子多重散射和相互作用势的非线性等因素的影响,系统将产生退道、分叉、混沌等不稳定现象,从而对PXR的反射、衍射、聚焦和谱分布产生直接影响。在经典力学框架内和偶极近似下,引入正弦平方势,把粒子在弯晶中的运动方程化为具有常数力矩的摆方程。利用Jacobian椭圆函数和椭圆积分分析了系统的相平面特征,并用能量法讨论了系统的稳定性,在相空间密度均匀分布的假设下,导出了系统的退道系数。以硅单晶为例,计算了能量为1.0 GeV的质子运动在曲率半径为1 m的(110)面沟道的退道系数η=0.3。
For obtaining coherent PXR source, the particle motion must be stable. However because of the effects such as attenuation, thermal vibration of lattices, electron multi-scattering and the non-linearity of interaction potential, instabilities of dechanneling, bifurcation and chaos will appear in the system, thus effecting the reflection, diffraction, focusing and spectral distribution of PXR. Based on the classical mechanics framework and the dipole approximation, the particle motion equation in bent crystal is deduced to a pendulum equation with a constant moment by exploring the sine-squared potential. The phase planar properties are analysed by using Jacobian elliptic function and the elliptic integral, and the stability of the system is discussed with the energy method. By assuming a homogeneous distribution of phase space density, the dechanneling factor is derived. Taking silicon single crystal for example,its dechanneling factor η is 0.30 when a proton with energy E=1. 0 GeV moved in the channel of Si（110） with a curvature radius of R=1m.
出处
《半导体光电》
CAS
CSCD
北大核心
2009年第2期220-223,253,共5页
Semiconductor Optoelectronics
