Electric field vector measurements in a surface ionization wave discharge
Electric field vector measurements in a surface ionization wave discharge
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DOI：
10.1088/0963-0252/24/5/055017
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发表时间：
2015-09
影响因子：
3.8
通讯作者：
B. Goldberg;P. Böhm;U. Czarnetzki;I. Adamovich;W. Lempert
中科院分区：
文献类型：
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作者：
B. Goldberg;P. Böhm;U. Czarnetzki;I. Adamovich;W. Lempert
这项工作展示了短脉冲持续时间（半峰全宽 60 ns）、使用皮秒四波混合技术的氢气表面电离波放电的时间分辨电场矢量测量结果。使用在水平和垂直平面中线性偏振的泵浦光束和斯托克斯光束以及放置在红外探测器前面的偏振器单独测量电场矢量分量。在放电间隙的三个不同位置以及氧化铝陶瓷电介质表面上方的三个不同高度（约 100、600 和 1100 μm）（总共九个不同位置）测量时间分辨电场矢量。结果表明，击穿后，放电发展为电离波，以平均速度 1 mm ns−1 沿介质表面传播。表面电离波在高压电极附近形成，靠近电介质表面（~100 μm）。波前的特征是垂直和水平电场矢量分量的显着超调。在波前后面，垂直场分量迅速减小。当波沿着电介质表面传播时，它也会进一步远离电介质表面，在接地电极附近可达约 1 毫米。波前后面的水平场分量仍然相当重要，以维持流向高压电极的电子流。波到达接地电极后，水平场分量经历准直流放电的二次上升，维持沿近表面等离子体片的电流。测量结果表明，由于放电中的高电流密度，在接地电极附近形成了阴极层，并且阴极电压显着下降，约 3 kV。表面电离波中的峰值还原电场为 85-95 Td，与根据氢的帕邢曲线估计的直流击穿场一致。本组表面电离波放电电场分布数据为验证动力学模型和评估其预测能力提供了实验参考。
This work presents the results of time-resolved electric field vector measurements in a short pulse duration (60 ns full width at half maximum), surface ionization wave discharge in hydrogen using a picosecond four-wave mixing technique. Electric field vector components are measured separately, using pump and Stokes beams linearly polarized in the horizontal and vertical planes, and a polarizer placed in front of the infrared detector. The time-resolved electric field vector is measured at three different locations across the discharge gap, and for three different heights above the alumina ceramic dielectric surface, ~100, 600, and 1100 μm (total of nine different locations). The results show that after breakdown, the discharge develops as an ionization wave propagating along the dielectric surface at an average speed of 1 mm ns−1. The surface ionization wave forms near the high voltage electrode, close to the dielectric surface (~100 μm). The wave front is characterized by significant overshoot of both vertical and horizontal electric field vector components. Behind the wave front, the vertical field component is rapidly reduced. As the wave propagates along the dielectric surface, it also extends further away from the dielectric surface, up to ~1 mm near the grounded electrode. The horizontal field component behind the wave front remains quite significant, to sustain the electron current toward the high voltage electrode. After the wave reaches the grounded electrode, the horizontal field component experiences a secondary rise in the quasi-dc discharge, where it sustains the current along the near-surface plasma sheet. The measurement results indicate presence of a cathode layer formed near the grounded electrode with significant cathode voltage fall, ≈3 kV, due to high current density in the discharge. The peak reduced electric field in the surface ionization wave is 85–95 Td, consistent with dc breakdown field estimated from the Paschen curve for hydrogen. The present set of data on electric field distribution in a surface ionization wave discharge provides an experimental reference for validation of kinetic models and assessing their predictive capability.