六极装置电场分布及对CH_3Cl分子束选态会聚的模拟

Simulation of electrostatic field distribution and state-selected CH_3Cl beam focus in a hexapole

通过数值获得的六极装置内部电势分布数值解,拟舍得出电势分布公式中的系数,给出各项系数随着装置参数ρ_o/r_o的变化规律及拟合函数形式,结果表明ρ_o/r_o=0.5516时,六极装置的电场分布最接近理想六极电场.对于其它ρ_o/r_o值时,推导出电势、电场更精确的计算公式.并利用这些公式,在ρ_o/r_o不满足最优配置时给出了对CH_3Cl分子转动态的会聚所需的实验参数.这些方法为利用六极装置对分子束会聚和转动态选择的理论模拟及试验提供了更准确的理论依据.

The fitted function of the parameter ρo/ro are given in a hexapole from the solution of electric potential obtained by numerical calculation method. The results show that the electric field distribution is almost the same with that in ideal hexapole when ρ0/r0= 0.5516. For other value of ρ0/r0, the more accurate formula for potential and electric field magnitude can be achieved and thus the focus curve for rotational states of CH3C1 beam is described by the method here correctly. Therefore, these formula can be used to guide experiment of beam focus and rotational states selection in a hexapole.