Temperature and density measurement by using a double probe of pseudospark discharge plasma jet

摘要

We have been doing research on the new type of plasma jet. Plasma jet is device that makes high temperature and high-density plasma flow at high speed In this research, we investigate the application of pseudospark discharge (PSD) to high power plasma jet in particular. PSD is low-pressure gas discharge. Electrodes have a hole on the center axis of parallel plane electrode and cathode has cylindrical hollow cavity behind the circular hole. Characteristics of PSD axe as follows. When discharge is formed by using this hollow cathode and on the condition in the low pressure region on the left hand side of the lowest point of a Paschen's curve, discharge current becomes large because breakdown voltage is high. Moreover in this low-pressure region, since discharge dose not formed along the short discharge path but the long one, discharge path passes through the center hole from reverse side of electrodes. As a result, the points of the discharge to the cathode spread to the back surface in the hollow cathode. Due to the hollow cathode effect, discharge is kept on the glow mode at the high current discharge, resulting that damage on electrode will be small. To spout the high temperature and high-density plasma in PSD, geometric structure of electrode of PSD is modified. Due to the modification of the PSD electrodes, plasma is spouted from anode hole by the power of the Lorentz power.