A spatially resolved relaxation method for pLTE plasma diagnostics in free-burning arcs

摘要

We report on a relaxation method to determine the electron-to-gas temperature ratio in the near-cathode region of a low-current free-burning arc operated in argon under atmospheric pressure. We used an intensified CCD camera to record the relaxation process after a fast power-interruption of the discharge with a time resolution better than 1 µs. For the CCD images we applied an ABEL inversion procedure yielding 3D information about the temperature ratio ? := Te/Tg with a spatial resolution of 50 µm. We deduced spatially resolved values of ? from the relaxation experiment using independently measured values of Te and ne, so we could determine all free parameters in the partial LTE model.