Lopatin I V, Akhmadeev Yu H, Koval N N
Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, 2/3 Akademichesky Avenue, 634055 Tomsk, Russia.
Rev Sci Instrum. 2015 Oct;86(10):103301. doi: 10.1063/1.4932543.
The performance capabilities of the PINK, a plasma generator with a thermionic cathode mounted in the cavity of a hollow cathode, depending for its operation on a non-self-sustained low-pressure gas discharge have been investigated. It has been shown that when a single-filament tungsten cathode 2 mm in diameter is used and the peak filament current is equal to or higher than 100 A, the self-magnetic field of the filament current significantly affects the discharge current and voltage waveforms. This effect is due to changes in the time and space distributions of the emission current density from the hot cathode. When the electron mean free path is close to the characteristic dimensions of the thermionic cathode, the synthesized plasma density distribution is nonuniform and the cathode is etched nonuniformly. The cathode lifetime in this case is 8-12 h. Using a cathode consisting of several parallel-connected tungsten filaments ∼0.8 mm in diameter moderates the effect of the self-magnetic field of the filament current and nearly doubles the cathode lifetime. The use of this type of cathode together with a discharge igniting electrode reduces the minimum operating pressure in the plasma generator to about one third of that required for the generator operation with a single-filament cathode (to 0.04 Pa).
研究了PINK（一种等离子体发生器，其热电子阴极安装在空心阴极腔内，依靠非自持低压气体放电运行）的性能。结果表明，当使用直径为2毫米的单丝钨阴极且峰值灯丝电流等于或高于100安时，灯丝电流的自磁场会显著影响放电电流和电压波形。这种效应是由于热阴极发射电流密度的时空分布变化所致。当电子平均自由程接近热电子阴极的特征尺寸时，合成的等离子体密度分布不均匀，阴极蚀刻也不均匀。在这种情况下，阴极寿命为8至12小时。使用由几根直径约0.8毫米的并联钨丝组成的阴极，可以减轻灯丝电流自磁场的影响，并使阴极寿命几乎延长一倍。将这种类型的阴极与放电点火电极一起使用，可将等离子体发生器的最低工作压力降低至单丝阴极运行所需压力的约三分之一（降至0.04帕）。
