常见场致发射阴极材料的发射特性

利用三阴极加速器平台,对不锈钢、黄铜、铝、天鹅绒和石墨等几种常见场致发射材料的电流发射能力、相对启动延迟时间及其抖动进行了实验研究。实验结果表明:在二极管电压近似恒定时,不锈钢阴极启动时间延迟抖动小于8 ns,天鹅绒阴极及石墨阴极启动时间延迟抖动小于4 ns;且材料在阴极频繁工作时启动时间加快;常见金属材料中不锈钢阴极的综合性能较好;非金属材料中,天鹅绒阴极的发射能力最强,且发射延迟时间最短,但考虑到天鹅绒材料严重的出气问题,非金属材料中以石墨阴极的性能为优。

Emission characteristics of several field emission cathode materials

The comparative studies by using a tri-cathode accelerator are presented on the cathode emission capability, relative emission delay and emission-time jitter of several common cathode materials, that is, stainless-steel, brass, aluminum, velvet and graphite. The stainless-steel has better quality than other metal cathode materials. At 300~450 kV diode voltage and 30 mm anode-cathode gap, the stainless-steel cathode emission current density is 0.78 ~1.50 kA/cm2 accordingly. With a constant diode voltage, the emission-time jitter of the stainless-steel is less than 8 ns, and both the velvet and graphite emission-time jitters are less than 4 ns. The cathode emission starting time of all those materials shortens when cathodes work shot by shot frequently.