Morrison J T, Willis C, Freeman R R, Van Woerkom L
Physics Department, The Ohio State University, Columbus, Ohio 43210, USA.
Rev Sci Instrum. 2011 Mar;82(3):033506. doi: 10.1063/1.3556444.
Thomson parabola spectrometers are used to characterize MeV ion beams produced in high intensity laser interactions. These spectrometers disperse multiple ion species according to their charge to mass ratio through the use of parallel electric and magnetic fields. Analytical solutions for ion deflection in electric and magnetic fields have been used to extract ion spectra with the assumption that fringing effects are negligible. Experimental space restrictions and dynamic range requirements necessitate designs that stress the analytical assumptions. Depending on design parameters, the error in the analytical assumption can be comparable to the energy resolution. Estimates are provided to approximate the error on the total ion deflection. A method for modeling ion trajectories including fringing effects is presented using software freely available or in common use. The magnetostatic fields are modeled in 3D, including material properties of nearby magnetic materials using RADIA. Electrostatic fields are modeled in 2D for a spectrometer implementing angled plates using the partial differential equation toolbox in MATLAB(®). Using these models to calculate the ion trajectory allows for analysis of a Thomson parabola spectrometer with an arbitrary field configuration.
汤姆逊抛物线光谱仪用于表征高强度激光相互作用中产生的兆电子伏离子束。这些光谱仪通过使用平行电场和磁场，根据离子的荷质比来分离多种离子种类。在忽略边缘效应的假设下，已使用电场和磁场中离子偏转的解析解来提取离子光谱。实验空间限制和动态范围要求使得设计需要强调解析假设。根据设计参数，解析假设中的误差可能与能量分辨率相当。提供了估计值以近似总离子偏转的误差。提出了一种使用免费或常用软件对包括边缘效应的离子轨迹进行建模的方法。静磁场在三维中建模，使用RADIA考虑附近磁性材料的材料特性。对于使用MATLAB（®）中的偏微分方程工具箱实现倾斜极板的光谱仪，静电场在二维中建模。使用这些模型计算离子轨迹可以分析具有任意场配置的汤姆逊抛物线光谱仪。
