放电室长径比与磁体间距对离子推力器原初电子约束性能的影响

电子约束效率为反映环尖型离子推力器放电性能的重要参数之一,一般采用原初电子的平均约束长度来表征。对于离子推力器,放电室长径比与磁体间距会影响磁场分布,进而影响电子约束效率。放电室长径比与磁体间距的最佳状况是原初电子在放电室中保持尽量长的时间。以二维轴对称的离子推力器放电室为几何模型,发展了计算原初电子运动情况的代码。通过求解Maxwell方程和电子运动方程得到磁场和电子的运动轨迹,从而得到原初电子的平均约束长度。对放电室长径比与磁体间距对原初电子约束性能的影响进行了参数化研究,总结了只考虑原初电子约束时放电室长径比与磁体间距的选取原则。

Effect of Chamber Length-Diameter Ratio and Magnet Separation on Primary Electron Confinement in Ion Thrusters

Electron confinement efficiency generally characterized by average primary electron confinement length is one of the most important parameter that reflects the discharge performance of direct current ring-cusp ion thruster. For the design of ion thruster the chamber length-diameter ratio and magnet separation are key parameters that influence the magnetic field and sequentially effect electron confinement efficiency. The criterion for optimal confinement efficiency is the value that keeps the primary electrons in the discharge chamber for the longest time. A computer code was developed and utilized to study the motion of primary electrons in a two-dimensional, axisymmetric discharge chamber of an ion engine. Maxwell equations were solved to determine the magnetic field and the equations of motion were solved to determine the trajectory of the primary electrons and average primary electron confinement length. Parametric effect of length-diameter ratio and magnet separation on primary electron confinement were studied using the code. Summarized in this paper were comments on rules of thumb for magnetic separation and length-diameter ratio considering the primary electron confinement only.