Transistor-based miniature microwave-drill applicator

This paper explores the microwave self-focusing effect, and examines various new applications of transistor-based microwave-drills at <;100-W microwave power range. The thermal-runaway instability is analyzed, and a drillability factor is defined heuristically for the minimal power needed to induce hotspots in specific materials. A practical transistor-based microwave-drill scheme using LDMOS-FET is introduced for delicate operations. Variants of this device are proposed for other applications, like local melting, ignition, indentation, plasma generation, and material identification by microwave induced breakdown spectroscopy (MIBS). Experimental results of glass processing, basalt melting and drilling, and thermite powder ignition are introduced as examples for future applications.