Is There Existing A Gaseous Process During the Propagation of Streamer in the Natural Ester?

The ingredient existed in the streamer channel is the critical factor for studying discharge in the dielectric liquid. In this paper, the dual-needle/plate electrode and shadowgraph technique are used in the experiment. The propagation and gaseous characteristics of the streamer in natural ester are discussed during the lightning impulse voltage. Results show that the polarity of the voltage significantly affects the streamer patterns and the initial field strength of adjacent needle electrodes. Besides, there is only a single breakdown channel for both positive and negative streamers, and the position and pattern of the negative streamer can be changed under the influence of the breakdown channel. An expansion phenomenon of the non-breakdown negative streamer channels is recorded under the heat and light generated by the breakdown channel. The expansion phenomenon of the streamer is the growth process of microbubbles in the streamer channel. Results provide a new way to discuss the existence of microbubbles in the streamer channel and believe microbubbles play a vital role in the formation and propagation of the streamer.