场致爆炸发射阴极表面微凸起热效应的数值研究

研究场致发射电流密度与阴极表面微凸起顶部的温度之间的高度非线性关系,用数值方法计算在外加宏观电场条件下,不同顶底半径比微凸起的热效应.结果表明:当微凸起顶底半径比值不同时,由于微凸起的微观电场增强因子不同,当微凸起顶部温度达到阴极材料的熔点时,微凸起内部温度分布差异显著;当外加宏观电场相同时,微凸起的顶底半径比越小,爆炸发射延迟时间越短;对于顶底半径比确定的微凸起而言,爆炸电子发射延迟时间随外加宏观电场强度的减小而成指数规律增长.

Numerical Investigation on Thermal Effects of Field-Induced Explosive Emission Cathode Microprotrusion

To study non-linear relations between field emission current density and temperature at top surface of a cathode microprotrusion, thermal effects on cathode microprotrusion are investigated numerically at various applied electric fields. Enhancement factor of electric field at top surface of microprotrusion is different as ratio of top radius to bottom radius is changed. It leads to obvious difference in temperature distribution in microprotrusion when temperature at microprotrusion peak reaches melting point of cathode material. At a given applied electric field, the smaller the ratio of top radius to bottom radius of microprotrusion, the shorter the time delay of explosive emission. Time delay of explosive emission increases exponentially with decrease of applied electric field.