弱电离大气等离子体电子碰撞能量损失的理论研究

在前期计算电子能量分布函数的基础上, 求出弱电离大气等离子体中各碰撞反应过程的电子能量损失. 由于在弹性碰撞中电子-重粒子能量交换很少, 同时氮气、氧气分子又有很多能量阈值较低的转动、振动能级存在, 因此在大气等离子体中弹性碰撞电子能量损失所占份额很小(直流电场下小于6%). 研究发现, 弱电离大气等离子体中在不同能量区间占主导的能量损失过程不同. 随着有效电子温度(或约化场强)增加, 占主导的电子能量损失过程依次为转动激发、振动激发、电子态激发、碰撞电离、加速电离产生的二次电子. 在约化场强E/N=1350 Td (或有效电子温度为14 eV)附近, 平均电离一个电子所需的能量最小, 约为57 eV. 因此可以根据不同的需求调节电场强度, 从而达到较高的能量利用率. 关键词： 弱电离大气等离子体 碰撞反应过程 电子能量损失

Theoretical study on the energy loss induced by electron collisions in weakly ionized air plasma

The energy loss induced by electron collisions in weakly ionized air plasma is calculated based on the electron energy distribution function that we obtained. Since there are a lot of low-energy-threshold molecular rotation and vibration excitations and the electron-molecule energy transfer is inefficient in elastic collision, the fraction of energy loss for electron elastic collision (less than 6%) is negligible. Among different collision processes the electron energy loss is dominant in different energy regions. As the effective electron temperature (or the reduced electric field) increases, the dominant energy loss process becomes sequentially rotational excitation, vibrational excitation, electronic excitation, collisional ionization, and accelerating ionized electrons. When E/N=1350 Td (or T_e=14 eV), the average energy loss per ion-electron pair reaches a minimum value of 57 eV. By controlling the electric field according to the requirement in applications, we can control the electric field to achieve a higher energy efficiency.
Keywords： weakly ionized air plasma electron collision electron energy loss