Abstract: The present disclosure generally relates to photonic crystals, for example, for thermophotovoltaic power generation, or other applications, and to systems and methods for bonding metals or other materials together. Certain aspects are generally drawn to tantalum or other refractory metals that are bonded to Inconel or another metal superalloy. The tantalum or other refractory metals may be used as a photonic crystal in certain instances, e.g., to produce emissions when heated. In other aspects, other materials can also be used. In some cases, there may be substantially no gaps present between the materials, which may facilitate heat transfer between the materials. In some embodiments, the materials can be forced to or bonded together by heating the materials such that one material is unable to expand without exerting a force on the other material.

Abstract: The present disclosure generally relates to fuel burners, for example, for use with photonic crystals as part of thermophotovoltaic power generators or with other thermal power generators. In certain aspects, fuel is supplied into a reaction tube and mixed between swirling streams of gases moving in opposite directions (e.g., clockwise and counterclockwise) within the tube. This may allow for rapid mixing and relatively complete oxidation or combustion of the fuel. Heat may be extracted from the heated exhaust and may be supplied to a thermal power generator to produce power. For example, the heat may be supplied to an emitter comprising a photonic crystal, which can be used to direct electromagnetic radiation to a thermophotovoltaic cell to produce power. In addition, certain embodiments are directed to relatively small burners, e.g., that can burn fuel at less than 20 ml/min to produce power.