Characteristics of in-liquid plasma in water under higher pressure than atmospheric pressure

The excitation temperature, electron density, temperature of OH, and behavior of bubbles generated by a 27.12 MHz in-liquid plasma are investigated in water under pressures ranging from 0.1 to 0.4 MPa. The excitation temperature decreases as the pressure increases and, conversely, the temperature of OH and the electron density increase. Since the plasma can be generated stably even under high-pressure conditions and the liquid provides a cooling effect, the electrode is not damaged by the heat. The bubbles generated from the tip of the electrode have a fixed relationship between their diameter and departure frequency. The in-liquid plasma can be stably generated even under high pressures and it maintains a high superheated state of a few thousand K. A boiling phenomenon in the in-liquid plasma uses the plasma itself as a heat source.