强流发射纳米碳管阴极研究

项目名称： 强流发射纳米碳管阴极研究

项目编号： No.10876001

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 原子能技术

项目作者： 张跃

作者单位： 北京科技大学

项目金额： 34万元

中文摘要： 直线感应加速器是军事和武器系统中的重要设备，强流电子束阴极是其核心部件。本研究通过化学气相沉积和涂敷/印刷法分别制备了大面积碳纳米管阵列和薄膜冷阴极，并采用水热法制备了氧化锌纳米棒阵列阴极，阴极直径均为2英寸。在直线感应加速器的脉冲电场下研究了碳纳米管阴极的强流发射性能。在强流发射过程中产生了等离子体，阴极等离子体的面积和亮度决定了发射电流强度。碳纳米管和氧化锌纳米棒阵列阴极的等离子体膨胀速率分别为11.93和10.97 cm/μ#12290;碳纳米管阵列阴极的发射电流随阵列高度的增加而降低。通过在基片预镀铁膜后，提高了碳纳米管薄膜阴极的发射电流强度。碳纳米管阵列和薄膜阴极的最高发射电流密度分别达到176.93A/cm2和343.88A/cm2，阴极的强流发射性能满足了直线感应加速器的使用要求。碳纳米管阴极的发射电流高于氧化锌纳米棒阵列阴极的发射电流，但发射均匀性和稳定性差于氧化锌纳米棒阵列阴极。研究了碳纳米管冷阴极的强流发射过程，发现在发的过程中存在场致发射和等离子体发射两个过程，建立了碳纳米管阴极发射强流电子束的机理。研制的大面积碳纳米管冷阴极可作为强流电子束源在高能微波器件上提升装备性能。

中文关键词： 碳纳米管；阴极；强流发射；等离子体；发射机理

英文摘要： Linear induction accelerator (LIA) is an important apparatus in the armament and weapon system, and the cathodes emitting intense-current electron beams are the key component of LIA. In this study, the carbon nanotube (CNT) array cathodes were synthesized by chemical vapor deposition method and large area CNT film cathodes were fabricated by screen-printing and dip-coating. The ZnO nanorod array cathodes were prepared by low temperature hydrothermal method. The diameters of fabricated 1D nanomaterial cold cathode were 2 inch. The intense-current emission properties of large-area CNT cathodes were investigated under the high-voltage pulse electric field of LIA. Plasma formed on the cathode surface during the intense-current emission of CNT cathodes, and the area and brightness of plasma are in direct proportion to the intensity of emission current. The average plasma expansion velocities of CNT array cathodes and ZnO nanorod array cathodes were 11.93 and 10.97 cm/μrespectively. The emission currents of CNT array cathodes were decreased with the increase of the nanotube height. As to the CNT film cathodes, the emission currents were improved effectively by depositing Fe film on the substrates in advance. The maximum emission current density of CNT array and film cathodes are 176.93 A/cm2 and 343.88 A/cm2 respectively. The intense-current emission properties of CNT cathodes meet the usage demand of LIA. The CNT cathodes have higher emission current than ZnO nanorod array cathodes, but have worse emission uniformity and stability than the ZnO nanorod array cathodes. The intense-current emission process of the cathodes was analyzed. During the intense-current emission of 1D nanomatereial cold cathodes, there were two different electron emission mechanisms which included field emission and plasma-induced emission. There has been a transformation from the field emission to the plasma-induced emission. The emission mechanism of the cathodes under high-voltage pulse electric field was proposed. The fabricated CNT cathodes can be used as intense electron beams source and applied in the field of high-power devices, and it will enhance the properties of equipments.

英文关键词： Carbon nanotubes; Cathodes; Intense-current electron emission; Emission mechanisms