HIGH-PRESSURE HELIUM AFTERGLOW AT ROOM-TEMPERATURE
HIGH-PRESSURE HELIUM AFTERGLOW AT ROOM-TEMPERATURE
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DOI：
10.1103/physreva.13.1140
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发表时间：
1976-01-01
影响因子：
2.9
通讯作者：
LAMBERT, F
中科院分区：
文献类型：
--
作者：
DELOCHE, R;MONCHICOURT, P;LAMBERT, F
沿着决定氦余辉弛豫的重要基元过程的速率系数，确定了He 2+的电子-离子复合机制。实验数据（原子和分子离子电流的墙壁，原子和分子的亚稳浓度，电子浓度，弹性电子碰撞频率，电子辐射温度）作为时间的函数，在广泛的实验条件下获得的比较与解决方案的五个耦合偏微分方程，其中包括所有的过程中发生的氦余辉系统。一组独特的速率系数和常数被发现，允许在7个压力从5至100托的所有实验数据的精确再现。电子能量平衡和电子能量分布函数作为时间和空间的函数计算。结果表明，在我们的圆柱形实验池中，电子能量的空间分布是不均匀的，必须考虑非麦克斯韦电子的影响。He 2+的复合速率系数以形式α 2 =（α c2 + k02 n0）（Te 293 K）− x2 + ke2 ne（Te 293 K）− y2给出，其中α c2 <5 <10 − 10 cm 3/sec，k02 =（5 ± 1）× 10 − 27 cm 6/sec，ke2 =（4.0 ± 0. 5）× 10 − 20 cm 6/sec，x 2 = 1 ± 1，y 2 = 4.0 ± 0.5。这些系数对应于He 2+与电子复合的碰撞辐射模型，该模型强烈依赖于压力、电子浓度和电子温度。70%的重组分子离子产生对应于分子的较低激发态中的解离的原子能谱。实验结果表明，两个分子间电离碰撞的速率系数为β 11 =（1.5 ± 0. 3）× 10 - 9 cm 3/秒，β 22 =（1.5 ± 0. 5）× 10 − 9 cm 3/sec，β 12 =（2.5 ± 1. 5）× 10 − 9 cm 3/sec。超弹性电子亚稳速率系数为γ 1 =（4.2 ± 0. 6）× 10 − 9cm3/sec和γ 2 =（3.8 ± 0. 8）× 10 − 9 cm 3/sec。所有的速率系数与现有的理论数据进行了很好的比较。所用的方法给出了一个完整的解决方案，氦余辉在室温下。它可以在纯氦中推广到许多其他实验条件，并应用于其他纯气体或混合气体中余辉的研究。
The electron-ion recombination mechanisms of He 2+ are determined along with the rate coefficients of the important elementary processes which govern the relaxation of the helium afterglow, at room temperature. The experimental data (atomic-and molecular-ion currents to the walls, atomic and molecular metastable concentrations, electron concentration, elastic electron collision frequency, electron radiation temperature) obtained as a function of time under a wide range of experimental conditions are compared with the solutions of a system of five coupled partial differential equations which includes all the processes occurring in a helium afterglow. A unique set of rate coefficients and constants is found allowing the precise reproduction of all the experimental data obtained at seven pressures from 5 to 100 Torr. The electron energy balance and electron energy distribution function are calculated as a function of time and space. It is shown that the spatial distribution of the electron energy in our cylindrical experimental cell is not uniform and has to be taken into account, as well as the influence of the non-Maxwellian electrons. The recombination rate coefficient for He 2+, given under the form α 2=(α c 2+ k 02 n 0)(T e 293 K)− x 2+ k e 2 n e (T e 293 K)− y 2, is found to be such that α c 2< 5< 10− 10 cm 3/sec, k 02=(5±1)× 10− 27 cm 6/sec, k e 2=(4.0±0. 5)× 10− 20 cm 6/sec, x 2= 1±1, y 2= 4.0±0.5. These coefficients correspond to a collisional-radiative model for the recombination of He 2+ with electrons, which strongly depends on pressure, electron concentration, and electron temperature. 70% of the recombined molecular ions produce atomic metastables corresponding to a dissociation in the lower excited states of the molecule. The rate coefficients for ionizing collisions between metastables are found to be β 11=(1.5±0. 3)× 10− 9 cm 3/sec, β 22=(1.5±0. 5)× 10− 9 cm 3/sec, β 12=(2.5±1. 5)× 10− 9 cm 3/sec. The superelastic electron-metastable rate coefficients are γ 1=(4.2±0. 6)× 10− 9 cm 3/sec and γ 2=(3.8±0. 8)× 10− 9 cm 3/sec. All the rate coefficients compare very well with available theoretical data. The method used gives a complete solution of the helium afterglow at room temperature. It can be extended in pure helium to many other experimental conditions and applied to the study of afterglows in other pure gases or mixtures.