以闪光二号加速器为研究平台，实验研究了前沿80 ns和34 ns脉冲电压下的二极管工作稳定性，通过对比实验结果和数值模拟结果，分析了脉冲前沿对二极管启动时间、阴极发射均匀性和阻抗重复性的影响，探讨了脉冲前沿对平面阴极二极管工作状态的影响机制。实验结果表明：脉冲前沿、二极管启动时间增加时，二极管的阻抗重复性降低; 平面阴极易于在中心位置形成强区域发射，等离子体覆盖整个阴极发射面的时间随脉冲前沿增大而增加; 屏蔽效应对阴极发射的影响随前沿增加而变大，进而导致阴极表面不均匀强点发射，等离子体运动速度增加，阴极有效发射面积减小，在等离子体运动速度和阴极有效发射面积共同作用下，二极管工作稳定性下降。

Stability of high current diode under pulse voltage with 80 ns and 34ns rise time was studied on flash II accelerator. Influence of rise time of diode voltage on startup time and cathode emission uniform and impedance of diode was analyzed by comparing the experimental results with numerically simulated results, and the Influence mechanism was discussed. The startup time of diode increased with the addition of rise time of voltage, and the repeatability of impedance of diode decreased.Discal plane cathode was prone to emit intensely in center area, the time that plasma covered surface of cathode would be increased and shielding effect had more effect on cathode emission according to the increase of the rise time. Local intense emission on the cathode would increase expansion speed of plasma and reduce the effective emission area. The stability of characteristic impedance of diode under pulse voltage with slower rise time was decreased by the combined action of expansion speed of plasma and effective emission area.