Localized Rapid Heating by Low-Power Solid-State Microwave Drill

Abstract

This paper presents a theoretical and experimental study of a locally induced microwave-heating effect implemented by a low-power transistor-based microwave drill. A coupled thermal-electromagnetic model shows that the thermal-runaway instability can be excited also by relatively low microwave power, in the range ~ 10-100 W, hence by solid-state sources rather than magnetrons. Local melting then occurs in a millimeter scale within seconds in various materials, such as glass, ceramics, basalts, and plastics. The experimental device employs an LDMOS transistor in an oscillator scheme, feeding a miniature microwave-drill applicator. The experimental results verify the rapid heating effect, similarly to the theoretical model. These findings may lead to various material-processing applications of local microwave heating implemented by solid-state devices, including local melting (for surface treatments, chemical reactions, joining, etc.), delicate drilling (e.g., of bones in orthopedic operations), local evaporation, ignition, and plasma ejection (e.g., in microwave-induced breakdown spectroscopy (MIBS) for material identification).