189 / 2018-08-30 15:46:23

Effect of Temperature Variation on Positive Streamer Corona under Non-uniform Field

streamer corona,luminous intensity,temperature,ICCD

The constructing of Global Energy Interconnection will be expected to cross high latitude areas, and the study on pre-discharge in cold environments is of great theoretical significance. Under a positively non-uniform field, there is a stage containing both corona and streamer characteristics before DC corona, which embodies plasma channels in a branching way and a frequency. In this paper, a test chamber that can achieve a low temperature environment is established, with a wall bushing on its top to connect the negative HVDC power, and a de-moisture system provides dry air to keep the chamber a low humidity and to avoid condensation for clear observation windows. A set of rod-plate electrode arrangement is placed in the chamber to create a non-uniform field, and the rod electrode can be replaced by cylindrical or cone electrode heads of different sizes. For investigating, we use PMT (photomultiplier tube) and ICCD (intensified charge coupled device) to detect pulse signals of UV-light and streamer corona morphologies. The results show that the streamer corona will begin to launch at a certain voltage, and its frequency will first increase and then decrease until it disappears. After that, the glow corona will be observed to gradually increase on the rod electrode head before the arc. As the streamer corona is generated, there will be a current flows through the non-inductive resistor which connects the electrode and the ground, and the oscilloscope displays that the current signal has a pulse form with oscillation. As the radius of curvature of the rod head decreases, both the start and the end voltage of streamer corona decline. As the temperature falls, the start voltage and the end voltage rise. Based on PMT signals, we calculate the luminous intensity of streamer corona by the optical apparent discharge, and it shows that low temperature has a limitation effect on streamer corona. From the images captured by ICCD, we also find that the streamer corona turns gloomier as the temperature falls.