Basalt melting by localized-microwave thermal-runaway instability

This paper presents an experimental and theoretical study of the thermal-runaway instability induced by localized microwaves in basalt stones. This effect leads to the inner melting of the basalt core, and further to its eruption similarly to a volcanic burst. The experiments are conducted in a single-mode cavity at 2.45 GHz, 0.9 kW. The microwave-induced miniature volcano exhibits hotspots, bursts and eruption of lava, and solidification of lava flows to volcanic glass (obsidian), similarly to real volcanic phenomena. The numerical simulation, taking into account the temperature dependence of the basalt properties, is compared to the experimental measurements. The results may lead to the development of new means for mining and construction in basalt, as well as for demonstrating volcanic phenomena in laboratories, schools and museums.