Frontier Research Base for Global Young Researchers, Graduate School of Engineering, Osaka University, Japan.
Phys Rev Lett. 2011 Aug 5;107(6):065002. doi: 10.1103/PhysRevLett.107.065002. Epub 2011 Aug 3.
The discharge initiation mechanism of nanosecond dielectric barrier discharges in open air has been clarified with time-dependent measurement of the discharge electric field by electric-field-induced coherent Raman scattering and optical emission. Our experimental observations have revealed that, in the prebreakdown phase of a nanosecond dielectric barrier discharge, the externally applied fast-rising electric field is strongly enhanced near the cathode due to large accumulation of space charge, which then strongly enhances ionization near the cathode. Once a sufficiently large number of ionizations take place, the location of peak ionization forms a front and propagates toward the cathode with strong optical emission, which establishes the discharge. This process is essentially different from the well-known Townsend mechanism for slower discharges.
通过电致相干拉曼散射和光发射对放电电场进行时变测量，阐明了真空中纳秒介质阻挡放电的起始机制。我们的实验观察表明，在纳秒介质阻挡放电的预击穿阶段，由于空间电荷的大量积累，外加快速上升的电场在阴极附近得到强烈增强，从而强烈增强了阴极附近的电离。一旦发生足够多的电离，峰值电离的位置就会形成一个前沿，并伴随着强烈的光发射向阴极传播，从而建立起放电。这个过程与较慢放电的著名汤森德机制有本质上的不同。
