【摘要】 为了提高扫描电镜等设备的探针束流，设计了磁浸没式热场发射电子枪，可对电子枪阴极发射电子进行有效收集，提高有效的发射束流。对磁浸没热场发射电子枪的电子光学特性进行了理论分析，仿真对比了单极靴、双极靴轴向间隙、双极靴径向间隙3种结构的磁透镜性能。基于双极靴轴向间隙结构的透镜设计了磁浸没式电子枪，仿真分析了束斑、束流、角束流密度、亮度等参数随浸没透镜的变化情况。基于实验平台对浸没透镜的磁场分布与磁浸没式电子枪的有效发射束流进行了测试。实验结果表明：浸没透镜磁场实际分布值与仿真值基本一致；在相同光阑尺寸下，磁浸没式电子枪的有效发射束流在3.3 kV低加速电压下为44.97 nA,23.5 kV高加速电压下为638.12 nA，与普通热场发射电子枪相比提高了约4倍。更多还原

【Abstract】 To enhance the probe beam current of scanning electron microscopes and related devices, a thermal field electron gun immersed in a magnetic lens field was designed to collect electrons emitted from the cathode and increase the effective emitted beam current. The optical properties of the magnetic fieldimmersed thermal field electron gun were theoretically analyzed, and the performance of three magnetic lens configurations—single polepiece, double polepiece with axial gap, and double polepiece with radial gap—was simulated and compared. A magnetic field-immersed electron gun was subsequently developed based on the double polepiece with axial gap lens, and the variations in beam spot size, beam current, and angular current density in response to the magnetic immersion lens were examined. Experimental measurements of the magnetic field distribution of the immersion lens and the effective emitted beam current of the magnetic field-immersed electron gun were conducted using a dedicated platform. Results demonstrate that the measured magnetic field distribution closely matches simulation predictions. The effective emitted beam current reached 44. 97 nA at a low acceleration voltage of 3. 3 kV and 638. 12 nA at a high acceleration voltage of 23. 5 kV, representing an approximate fourfold increase compared with conventional thermal field electron guns.更多还原