Shaped emitters are of interest to a broad range of applications in vacuum electronic devices. In particular, thermionic energy converters (TECs) take advantage of shaped emitters to increase the local surface field, thereby extracting more current for a given cathode temperature and applied voltage. However, modeling these devices is challenging; Warp [J.-L. Vay, D. P. Grote, R. H. Cohen, and A. Friedman, Comput. Sci. Discov. 5, 014019 (2012)] is a fully 3D particle-in-cell code capable of handling a wide range of physics problems and is well suited to modeling TECs. Additionally, recent improvements to Warp have enabled the accurate modeling of emitters with arbitrary curved surfaces. Specifically, the inclusion of subgrid resolution for computing the electrostatic potential and the ability to apply mesh refinement for specific areas of interest allow for a more accurate solution to the fields on these surfaces. These improvements coupled with Warp’s ability to handle variable particle weights make it an ideal candidate for simulating these complex devices. In this paper, the authors study the applicability of different subgrid configurations for simulating shaped emission surfaces and field convergence for different mesh-refinement techniques. They then implement a custom weighting algorithm that allows for uniform sampling of emission surfaces with a large variation in the surface electric field. They then use this algorithm to study emission for curved emitters in both the field-enhancement regime and the space-charge regime.

中文翻译：

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场增强热电子发射的高级建模

成形发射器在真空电子设备中的广泛应用中受到关注。特别是，热离子能量转换器 (TEC) 利用成形发射器来增加局部表面场，从而在给定的阴极温度和施加的电压下提取更多的电流。然而，对这些设备进行建模具有挑战性。翘曲 [J.-L. Vay、DP Grote、RH Cohen 和 A. Friedman，Comput。科学。发现 5, 014019 (2012)] 是一种完全 3D 的细胞内粒子代码，能够处理各种物理问题，非常适合对 TEC 进行建模。此外，最近对 Warp 的改进使得可以对具有任意曲面的发射器进行精确建模。具体来说，包含用于计算静电势的子网格分辨率以及对特定感兴趣区域应用网格细化的能力，可以更准确地解决这些表面上的场。这些改进与 Warp 处理可变粒子权重的能力相结合，使其成为模拟这些复杂设备的理想选择。在本文中，作者研究了不同子网格配置在模拟不同网格细化技术的成形发射表面和场会聚方面的适用性。然后，他们实施自定义加权算法，允许对表面电场变化较大的发射表面进行均匀采样。然后，他们使用该算法来研究场增强区和空间电荷区中弯曲发射器的发射。