关于热电子发射理论的评述(Ⅲ)——动态表面发射中心

本文提出能解释热阴极中各种现象的动态表面发射中心模型。电子发射来源于一个原子集团。在这原子集团中,当运动着的电子具有瞬时的最高能量,或集团的原子核吸引力达到最小时,便产生电子发射。超额钡是提供高能电子的根源。氧则按其在集团中的相对数量和相对位置而分别起有益或有害的作用。虽然锶、钙、铝酸盐、钨酸盐等对发射只起次要的作用,但它们对蒸发、徙动、传递电子等却有影响。实用热阴极的发射不均匀性证明发射中心的存在,而发射的不稳定性,例如闪变噪声,显示出发射中心的动态特性。

ON THE THEORY OF THERMIONIC EMISSION (Ⅲ)——A MODEL OF DYNAMICAL SURFACE EMISSION CENTERS

A dynamical surface emission center model which can explain all observed phenomena in thermionic cathodes is proposed. The emission comes from such an aggregate of atoms that the moving electrons may have momentarily highest energy and/or the attraction from the nuclei to these electrons is momentarily least. Excess barium is the source for supplying high energy electrons, while the oxygen may play a favorable or unfavorable role to emission depending upon its relative quantity and relative position in the aggregate. Although strontium, calcium, aluminate, tungstate, etc. are minor factors to emission, yet they may have some effect on the evaporation, migration, and transition of electrons etc.. The non-uniformity of emission in practical cathodes proves the existence of such centers, while their dynamical character exhibits instability of emission e.g. flicker noise.