石墨-金刚石复合阴极的强流脉冲性能

High-current Pulsed Emission Performance of Graphite-diamond Composite Cathodes

为满足高功率微波系统对电子束质量的要求,对相对论返波管现用石墨阴极通过涂覆掺氮超纳米金刚石(UNCD)薄膜进行改性处理,以提升石墨阴极的强流脉冲发射性能。采用场发射扫描电子显微镜(FESEM)和Raman光谱仪及X射线光电子能谱仪(XPS)详细分析了掺氮UNCD薄膜的微观形貌和组成成分,在自制相对论返波管上完成强流脉冲性能测试。结果表明,与原始石墨阴极相比,石墨-金刚石复合阴极的电流发射密度提升25%,放气率最大可降低60%,说明用掺氮UNCD薄膜表面涂覆改性石墨阴极是一种提升阴极性能的有效途径。

In order to meet the requirements of electron beam quality in high-power microwave systems,a surface treatment technique using nitrogen-doped ultrananocrystalline(UNCD)films was applied for the conventional graphite cathode to the enhancement of its high-current pulsed emission performance.The microstructure and composition of the nitrogen-doped UNCD films on graphite cathode were analyzed by field-emission scanning electron microscopy(FESEM),Raman spectroscopy and X-ray photoelectron spectroscopy(XPS).High-current pulsed emission performance test was performed on a self-made relativistic backward-wave tube.The results show that the current emission density of the graphite-diamond composite cathode was increased by25%,and the largest gas release rate was reduced by60%,by comparison with that of conventional graphite cathode.This study demonstrates that surface treatment using nitrogen-doped UNCD films is an effective method to improve the high-current pulsed emission performance of conventional graphite cathode.