Study of Macroscopic Oscillations of Detachment front in the linear plasma machine

在一台带有模拟挡板偏滤器的线性等离子体装置中，观察到了分离前沿位置的振荡。伴随着偏滤器区域中性氦气体压力的显著振荡，滑脱锋沿场线来回运动的振荡。这是由于等离子体堵塞取决于脱离前沿的位置。为了弄清振荡机理，在偏滤器区域注入了Ne和氢气。随着注气流量的增加，偏滤器区域与挡板前部之间的中性压差ΔP达到最大值ΔP；max，&gt；，然后分离前锋位置ZF和ΔP开始振荡。振荡的基本性质，如ZF依赖于等离子体堵塞，对所有气体物种都是共同的。振荡的幅度和周期以霓虹灯最大，氢气最小。对于特定的气体种类，周期和幅度主要取决于小孔上的等离子体压力PP。结果表明，电离可以维持对Ne的PP的适度降低，而对氢的PP的显著降低可能是由于分子激活的复合过程。

Oscillations of the position of the detachment front have been observed in a linear plasma machine with a simulated baffled, divertor. The oscillation, with a back-and-forth motion, of the detachment front along field lines, accompanies a significant oscillation of the neutral helium gas pressure in the divertor region. This is due to the fact that plasma plugging depends on the position of the detachment front. To clarify the oscillation mechanism, neon and hydrogen gas were injected into the divertor region. As the flow rate of the gas injection is increased, the neutral pressure difference, ΔP, between divertor region and the front of the baffle reaches its maximum, ΔP_<max,> then the position of the detachment front Zf and ΔP begin to oscillate. The essential properties of the oscillation, such as Zf - dependency on plasma plugging, are common to all gas species. The amplitude and the period of the oscillations are largest for neon and smallest for hydrogen. The period and amplitude can be mostly dependent on the plasma pressure on the orifice, Pp, for the particular gas species. It was suggested that a modest reduction of Pp for neon can be sustained by ionization, and the significant reduction of Pp for hydrogen may be due to the Molecular Activated Recombination process.