Submicrometer-Gap Thermionic Power Generation Based on Comprehensive Modeling of Charge and Thermal Transport

This paper presents the comprehensive performance analysis of thermionic power generation when interelectrode vacuum gap shrinks to submicron range. Although reducing has been suggested as an effective approach mitigate space-charge accumulation in thermionic-energy-conversion (TEC) devices, previous theoretical works have predicted optimal distance single-digit micrometer However, we demonstrate that nanoscale charge and thermal interactions between electrodes, such Schottky barrier lowering due image perturbation near-field enhanced radiative heat transfer, significantly affects TEC within gap. Carefully conducted energy-balance reveals submicron-gap at $d\ensuremath{\approx}700$ nm can produce approximately fourfold increase output with a higher energy conversion efficiency than micron-gap under same operating condition. In addition, significant heating collector system be beneficially used further enhance by combining bottom-cycle engine. We believe present work provides framework for promising recycling scheme high-quality sources.