Narrow Results

The thermal plasma conditions under a practical use could be affected by the insertion of a solid, cold probe severely. In this study, we calculated flowing thermal plasmas with two different sizes of a Langmuir probe into an argon free burning arc system and investigated the thermal and flow disturbances caused by the metallic probe. From the results, the severe disturbance of a large part of the thermal plasma, especially the axial velocity field, by the inserted probe has been found. Therefore, it might be a practical solution to use a Langmuir probe which has sufficiently small diameter for avoiding such a severe disturbance.

In this study, we predicted the thermal breakdown of high-voltage interrupter with the characteristics of thermal plasmas such as temperature, pressure and concentration of the ablated material by using a commercial CFD program. The results showed that the pressure build-up inside the chamber was proportional to the magnitude of applied current because the quantities of heat energy and ablated mass also increase together with the current during the compression process. During the decompression process, the reverse flow found did not coincide with the magnitude of current due to the compressibility of the gas through backflow channel. The present method is expected to be useful for the design of guideline and interruption capacity on the thermal breakdown of a PASB chamber.