The role of temperature on the existence of negative differential conductivity (NDC) is investigated using Boltzmann equation calculations of electron swarms in gaseous nitrogen. This effect has been observed previously in both experimental results and calculations, with the important role of superelastic rotational collisional processes in this phenomenon being examined in this work. A simple analytic model cross-section set is employed to elucidate the role of de-excitation processes in NDC, with complementary physics identified in N-2. The criterion of Robson (1984 Aust. J. Phys. 37 35) for predicting the occurrence of NDC using only knowledge of the collisional cross-sections is utilised for both the model system and N-2, and found to be in excellent agreement with our simulated appearance of NDC. Finally, we also report on the impact of anisotropy in the very low threshold scattering channels on the transport coefficients, examine the finite difference collision operator of Frost and Phelps (1962 Phys. Rev. 127 1621) for the inelastic channel, in particular its neglect of recoil, and assess other assumptions utilised in existing Boltzmann equation solvers.

中文翻译：

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N ₂和 N ₂类气体中电子群的热诱导 NDC ：温度和碰撞算子近似值的作用

温度对负微分电导率 (NDC) 的存在的作用使用气态氮中电子群的玻尔兹曼方程计算来研究。之前在实验结果和计算中都观察到了这种效应，在这项工作中研究了超弹性旋转碰撞过程在这种现象中的重要作用。一个简单的分析模型横截面集被用来阐明去激过程在 NDC 中的作用，并在 N-2 中确定了补充物理学。Robson (1984 Aust. J. Phys. 37 35) 仅使用碰撞截面知识来预测 NDC 发生的标准被用于模型系统和 N-2，并发现与我们模拟的 NDC 外观。最后，