A theoretical study of the spatial relaxation characteristics of the mean electron energy in a uniform electric field in He, Ne, Ar, Kr, Xe and a mixture of He:Xe was performed. Calculations were carried out with the use of the Monte Carlo technique. Electrons were launched at some point z = 0, and the electron energy distribution function and the mean electron energy u _m(z) were calculated at various distances from the source. According to calculations, for pure gases in a wide range of the electric field strength E, the dependence u _m(z) has the form of damped oscillations. At that, the relaxation length L and the oscillation period Λ are almost independent of the form of the energy spectrum of the electron source. It is shown that for all pure gases the calculated dependences L(E) have the shape of a hump, and for each gas the position of the maximum corresponds to such E values at which the energy lost by electrons in elastic collisions is about 4%–8%. For the case of Xe we also studied the variation of L(E) depending on the set of cross sections used in the calculations. It was also shown that for the same E value, the relaxation length in He:Xe mixture differs significantly from that in pure He or Xe. Moreover, u _m(z) in a certain range of parameters (E and percentage of Xe in the gas mixture) is characterized by the sum of two damped oscillations with different spatial periods.

对He，Ne，Ar，Kr，Xe和He：Xe混合物中的均匀电场中平均电子能量的空间弛豫特性进行了理论研究。使用蒙特卡洛技术进行计算。在z = 0的某个点发射电子，并在距源不同距离处计算出电子能量分布函数和平均电子能量u _m（z）。根据计算，对于大范围电场强度E中的纯气体，依赖性u _m（z）具有阻尼振荡的形式。那时，松弛长度L振荡周期Λ和振荡周期Λ几乎与电子源的能谱形式无关。结果表明，对于所有纯净气体，计算得出的相关性L（E）具有驼峰形状，并且对于每种气体，最大值的位置对应于这样的E值，在该E值下，弹性碰撞中电子损失的能量约为4％ –8％。对于Xe，我们还研究了L（E）的变化，具体取决于计算中使用的横截面集。还表明，对于相同的E值，He：Xe混合物中的弛豫长度与纯He或Xe中的弛豫长度显着不同。而且，u _m（z在一定参数范围内（E和混合气体中Xe的百分比）的特征是具有不同空间周期的两个阻尼振荡之和。