热离子能量转换器扩散工况的电流饱和特性

Characteristic of Saturation of Current for Thermionic Energy Converter Operating on Diffusion Mode

为阐明热离子能量转换器扩散工况下的饱和电流存在条件及其机理,通过修正电弧工况低温等离子体输运方程的电离项,建立了适用于扩散工况的输运方程,并依据发射离子裕度选择鞘层边界条件。基于牛顿迭代法实现了模型的数值求解,结果表明,采用输运理论获得的伏安特性与实验值符合较好,饱和电流的存在性可根据热发射的中和状态来判定,分析发射极鞘层电子势能分布可阐述其机理;接收极鞘层的电子势能分布随输出电流的增大发生跃变方向的改变,并不影响饱和电流的存在性。

In order to illuminate the characteristic of saturation of current for thermionic energy converter(TEC) operating on diffusion mode, transport equations in the interval of the electrodes applied to diffusion mode were built with amending the ionization items of the low-temperature plasma for ignited model. And the boundary conditions were selected according to the ion-richness ratio in the emitter plasma sheath. Then, the model was solved numerically based on Newton iteration method. It is found that the calculated U-I characteristic accords with lecture results. The existence of saturation current can be decided by the neutralization condition of emission and the distribution of electron potential energy can account for its principle. The orientation of potential jump in the collector sheath changes with the increase of current, which doesn’t influence the existence of saturation current.