模拟离子在缓冲气体中运动的硬球碰撞模型

On the Hard-Sphere Collision Model Used to Simulate the Ion's Motion in Buffer Gas

为了研究RFQ冷却聚束器、彭宁阱等核物理实验设备中离子的运动情况,从大学物理课本中的理想气体的微观模型出发,建立了用于模拟离子在气体分子中运动的硬球碰撞模型.该模型通过计算离子在运动过程中与气体分子的碰撞概率、碰撞后的运动速度,以及大量次数的模拟来研究离子在气体中的运动情况.通过比较模拟结果和实验数据,得出模型适用于离子能量较低(低于约5eV/u)的情况,这是因为模型中离子与气体分子的作用仅被当作弹性碰撞来处理.RFQ冷却聚束器、彭宁阱等核物理实验设备中离子的入射能量在模型的适用范围内,因此使用硬球碰撞模型并考虑设备所产生的电磁场对离子的作用,可研究离子在这些设备中的运动情况.

In order to study the ion's motion in Radio frequency quadrupole(RFQ)cooler and buncher and Penning trap,a hard sphere collision model was built base on the ideal gas's microscopic model. The model can be used to simulate and study the ion's motion in gas by calculating the probability of col-lision,velocity after the collision and a large number of simulations.By comparing the simulated data with experimental data,it found that the model should be used when the ion's energy is less than 5 eV/u,because the effect of ion and gas was treated as elastic collision.The energy of ions in RFQ cooler and buncher and Penning trap is in range of the model's application,so the model can be used to study the ion's motion in these equipments after considering the effect of the electromagnetic field produced by e-quipment.