Simulating the Highly Coupled Physics of Electron Emission
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Field emission [1] is at the heart of many promising applications such as 3D portable medical imaging [2], FLASH cancer therapy [3], and high-resolution scanning electron microscopy [4] among others. Despite its apparent potential, there are few examples of commercially available field emission devices, especially where an array of field emitters is needed. This is due to the complex nature of field emission and the lack of capable simulations tools, which makes design and manufacture challenging. Although field emission is notionally a surface effect, it has to be understood alongside the dynamics of the bulk material and vacuum. Thus, it requires a highly coupled Multiphysics approach in which electrostatics (at high field strength), thermal effects, mechanical stress, and molecular dynamics; must be considered together. Here we present out efforts to develop a robust and general computational tool to model field emission while including thermal effects from metals and semiconductors. The physics of field emission, and their interconnection, is explained. We introduce our general tool to calculate the current density emitted from a surface under high field (GETELEC) [5], how GETELEC has been integrated within COMSOL to simulate the static behaviour of field emitters, and the thermal run away of field emitters at high temperatures (FEMMOCS) [6]. We also discuss current limitations of our models and future research paths.
