Simulation of nanoscale high-efficiency thermionic converters

The design and fabrication of vacuum nano-electronic devices is essential to the present and future US economy and energy sources. Highly-resolved 3D electrostatic particle-in-cell (PIC) simulations are required to correctly model and optimize their fabrication and operation; however, the associated run-time and complexity of such HPC codes is prohibitive. The Scientific Discovery through Advanced Computing (SciDAC) program has contributed to the development of Warp, an open source multi-species 3D PIC code that scales efficiently to many cores and includes many state-of-the-art algorithms, including mesh refinement. With code hardening, and some additional physics and design capabilities, Warp will profoundly impact the vacuum nano- electronics industry.We are developing a commercial quality GUI for cloud-based execution of Warp on HPC servers, with CAD integration for complex geometries, and with specialized capabilities to design and optimize vacuum nano-electronic devices, emphasizing thermionic converters for electricity generation. We are demonstrating the capabilities of this interface by optimizing the design of thermionic converters for industrial application.RadiaSoft has developed a browsed-based GUI for cloud-based execution of Warp for 2D electrostatic devices. We have improved the dielectric and quasi-static solvers to permit faster and more accurate simulations of devices using dielectric support structures. We demonstrated integration of STL file formats with Warp for 3D rectilinear objects. Finally, we performed nonlinear optimization of 3D rectilinear thermionic converter designs using both gradient-based and evolutionary algorithms.We will extend our interface to support the design, simulation, and optimization of realistic 3D devices. To do this, we will extend our GUI to support 3D design and visualization, the submission of jobs at supercomputers, as well as the use of nonlinear optimization toolkits. We will enhance Warp's underlying grid geometries to support non-conformal device geometries. Finally, we will further explore non-steady state physics, including ionization, external-biasing, and lifetime effects. With these new tools, we will demonstrate the optimization of realistic devices, including a diverse array of energy loss channels. The RadiaSoft commercialization strategy is to provide highly-skilled scientific and engineering R&D consulting and subscription-based HPC support services across a broad range of submarkets including nanoelectronics.