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arXiv 1709.07071physics.plasm-ph
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射频氢放电的整体增强振动动力学模型及其在强流负氢离子源模拟中的应用

A Global Enhanced Vibrational Kinetic Model for Radio-Frequency Hydrogen Discharges and Application to the Simulation of a High Current Negative Hydrogen Ion Source

Sergey N. Averkin

摘要:

针对Busek公司研制的新型强流负氢离子源(HCNHIS),建立了全局增强振动动力学(GEVKM)模型。和伍斯特理工学院HCNHIS由一个高压射频放电(RFD)室,其中产生的氢分子的高振动态,旁路系统,喷嘴,和一个低压负氢离子产生区域,其中$\text{H}^-$产生的低能量电子的离解连接到旋转振动激发的氢分子。GEVKM是从用于电感耦合RFD室的圆柱形几何形状的Wang Chang-Uhlenbeck方程导出的多温度化学反应等离子体的矩方程发展而来的。模型中包含的物种为$\text{H}(n), n=0-3, \text{H}_2(v), v=0-14, \text{H}^+, \text{H}_2^+, \text{H}_3^+, \text{H}^-$和$e$。将体积平均稳态连续性方程与电子能量方程、总能量方程和腔壁传热方程耦合求解,得到等离子体组分的体积平均数密度、电子温度、重粒子温度和腔壁温度。GEVKM的补充是一套全面的表面和体积化学过程的振动和电离动力学的氢等离子体。为旁路管和喷嘴中的流动开发的分析边界条件考虑了稀疏效应,并通过将RFD室中的压力预测与压力测量值进行比较来验证。GEVKM在不同等离子体反应器的宽压力和吸收功率范围内进行了验证和确认,并用于HCNHIS的RFD室的参数研究,氢气入口流量为5-1000 sccm,吸收功率为200-1000 W。

英文摘要:

A Global Enhanced Vibrational Kinetic (GEVKM) model is presented for a new High Current Negative Hydrogen Ion Source (HCNHIS) developed by Busek Co. Inc. and Worcester Polytechnic Institute. The HCNHIS consists of a high-pressure radio-frequency discharge (RFD) chamber where high-lying vibrational states of the hydrogen molecules are produced, a bypass system, a nozzle, and a low-pressure negative hydrogen ion production region where $\text{H}^-$ are generated by the dissociative attachment of low energy electrons to rovibrationally excited hydrogen molecules. The GEVKM is developed from moment equations for multi-temperature chemically reacting plasmas derived from the Wang Chang-Uhlenbeck equations for a cylindrical geometry of an inductively coupled RFD chamber. The species included into the model are $\text{H}(n), n=0-3, \text{H}_2(v), v=0-14, \text{H}^+, \text{H}_2^+, \text{H}_3^+, \text{H}^-$, and $e$. The volume-averaged steady-state continuity equations coupled with the electron energy equation, the total energy equation and heat transfer to the chamber walls are solved simultaneously to obtain the volume-averaged number densities of the plasma components, the electron, heavy-particle and wall temperatures. The GEVKM is supplemented by a comprehensive set of surface and volumetric chemical processes governing vibrational and ionization kinetics of hydrogen plasmas. Analytic boundary conditions developed for the flow in the bypass tubes and in the nozzle take into account rarefaction effects and are validated by comparing pressures predictions in the RFD chamber with the pressure measurements. The GEVKM is verified and validated in the wide range of pressures and absorbed powers of different plasma reactors and is used in a parametric investigation of the RFD chamber of the HCNHIS with hydrogen inlet flow rates 5-1000 sccm and absorbed powers 200-1000 W.

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