A novel method for generating high-temperature gas using a tandem-type inductively coupled thermal plasma (Tandem-ICTP), composed of two vertically arranged coils, was proposed to experimentally evaluate the dielectric properties of hot gases. The dielectric properties of high-temperature insulation gases are critical for determining the success or failure of current interruption in gas circuit breakers (GCBs). In this study, we focused on the detailed investigation of the high-temperature gas field generated by Tandem-ICTP. The temperature of \(\hbox {CO}_2\) gas, heated by varying the lower-coil input power in the Tandem-ICTP system, was estimated using spectroscopic measurements at the electrode position, applying the Boltzmann plot method. Additionally, an electromagnetic thermofluid simulation was conducted to support the experimentally measured temperatures and to estimate the mole concentration of \(\hbox {CO}_2\) gas between the electrodes. The results revealed that the temperature of the \(\hbox {CO}_2\) gas could exceed 3800 K using the Tandem-ICTP and could be adjusted by approximately 2600 K by modifying the input power of lower-coil. Furthermore, the mole concentration of high-temperature \(\hbox {CO}_2\) gas between the electrodes was found to be approximately 40 \(\%\) , as determined by numerical simulation. This method demonstrates that a dielectric test can be conducted in the wide range of high-temperature gas fields above 3000 K by controlling parameters such as the input power of lower-coil in the Tandem-ICTP system.
