447 / 2017-05-02 08:09:30

Study on the development process of the ejected plasma used as a trigger method in gas spark switch

13818,13819,13820,13821

Ejected plasma used in gas spark switch has been proved efficient as a trigger method, and gas spark switch can be triggered reliably even when the work coefficient is lower than 10%. However, the development and trigger mechanism are still to be revealed. In this paper, a novel switch structure with an ejected plasma actuator was tested. Ejected plasma is generated by a pulse voltage acting on the needle electrode in the actuator and leading to discharge of the main gas gap. An experimental platform was built to investigate the influence of trigger pulse energy and polarity on the space-time shape evolution characteristics and the ejecting characteristic of plasma by capturing images via a nanosecond framing camera. The results indicate that the head of the plasma would depart from its body leading to the separation of the head and tail of ejected plasma. Furthermore, some branches could be observed in the following few microseconds. Especially when negative pulses with higher energy were applied onto a gas gap, the ejected plasma seemed to be brighter and larger. As for the ejecting characteristics of the plasma, the height of the plasma was of the order of mm, and the velocity was of the order of 10e5mm/μs. Not only the height but also the velocity was higher when larger pulse energy and negative pulse were applied.