基于石墨烯纳米材料的爆炸式场发射阴极关键技术研究

Explosive field emission electron beam cathode is the core of high power microwave, accelerator and free electron laser devices. High emission current density and high uniform electron beam would dramatically improve their properties. Most recently, we found that due to the high field enhancement factor and high specific area, graphene can be a potential high properties and high uniform explosive emission cathode. The program is proposed here to make up the shortcoming of other cathode materials, which have insufficient emission capability and make fluctuant emission current pulse. The researches would include electronic and thermionic properties of graphene in high electric filed to find out the mechanism of plasma. Trying to find out the key technology to improve the onset speed, electron emission current density, emission uniformity and repeat emission ability of graphene cathodes. Then develop the effective method to prepare high properties graphene explosive field emission cathodes. These researches would provide a new material for explosive emission cathode and also be a reference for provide a reference for understanding of the electronics and thermal properties of graphene, and also the Physics of graphene in the plasma fields.

爆炸式强流电子束阴极是高功率微波、加速器、自由电子激光等器件的核心部件，高电流密度和高发射均匀性的强流电子束阴极能有效提高器件的性能。最近我们研究发现由于石墨烯具有很强的尖端效应和极大比表面积，采用石墨烯作为爆炸式阴极可以提高阴极发射能力、启动速度和发射均匀性。因此本项目针对目前爆炸式强流阴极由于发射能力不足、发射不均而导致的发射电流脉冲宽度小、毛刺多、难以形成平顶电流波形的问题，提出采用石墨烯制备爆炸式场发射阴极，提高爆炸式阴极的电子发射能力和均匀性。通过研究二维结构石墨烯在强场下的电子学、热力学性质，分析石墨烯爆炸发射形成等离子体的物理机理；探索提高阴极启动速度、发射电流密度，发射均匀和的发射重复频率的关键技术；发展制备高效石墨烯爆炸式阴极的制备方法；本研究可以提供一种新的爆炸式发射阴极材料，也为进一步理解石墨烯这种新型纳米材料的电子学、热学特性及其在等离子体场下的物理学性质提供参考。

本项目针对目前爆炸式强流阴极由于发射能力不足、发射不均而导致的发射电流脉冲宽度小、毛刺多、难以形成平顶电流波形的问题，采用石墨烯二维材料制备爆炸式场发射阴极，通过研究石墨烯阴极在强场下的等离子体形成机制和运动过程，研究石墨烯阴极爆炸发射机理；采用化学剥离法制备分离大面积石墨烯；并通过石墨烯和碳管等其他材料复合的方法分别实现解决石墨烯阴极在发射过程中与阴极基底结合力的困难，为实现超低开启场、快速启动、长脉冲发射、高重复寿命的石墨烯爆炸式阴极提供理论基础和实验方法，并将制备的石墨烯爆炸式阴极应用于相对论磁控管中进行验证，结果表明，该阴极能有效提高脉冲电流持续时间，提高微波器件的启动速度，可以为强流电子器件提供一种全新的爆炸式发射阴极材料，也为进一步提高强流电子器件的性能提供技术基础。