Experimental Investigation on Breakdown Characteristics of High Temperature CO₂ Gas Using Inductively Coupled Thermal Plasma System

Dielectric strength in high temperature gas is crucial to determine the success or failure of current interruption in a gas circuit breaker. We aim to experimentally clarify the dielectric properties of high temperature gases. In our research, a unique method using inductively coupled thermal plasmas (ICTP) was applied to elevate the temperature of insulation gases. The breakdown voltage (BDV) in high-temperature CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> gas was measured, with the temperature controlled by adjusting the ICTP parameters. To verify the measured experimental results, a theoretical calculation of reduced electric field by solving the Boltzmann equation was also performed. As a result, the BDV significantly decreased at the temperatures above 5500 K, with the change in appearance of discharge. This is because, in this temperature range, the gas composition changes from CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> molecule to CO molecule and O atom dissociated, thereby changing the particles that dominate the breakdown.