Effect OF ground electrodes ON stability of plasma jet

Summary form only given. Plasma jet is one kind of atmospheric pressure discharge which has been studied extensively. The stable /unstable states of plasma jets have been demonstrated in previous studies¹. And the plasma jet which can keep in stable stage is important for application. In this study, we are focus on the influence of grounding electrode for the stage of plasma jet.The coaxial-type plasma generator is used, the powered inner electrode is made of a screw like stainless steel metallic rod with uniform threads on the surface, the glass tube with the in ner diameter and thickness of 7mm and 0.5mm, respecitively, the outer electrode is a circular metal structure and the diamet er is 7.1mm, it can move smoothly along the axis of the glass tube, the driving voltage is a high-voltage a.c. power supply a t a frequency of 45kHz. The plasma working gas is argon (wi th a purity of 99.999%). The applied voltage is measured by using the high-voltage probe. Through the resistor, the discha rge current is converted into the voltage signal. SONY digital camera is used to capture the discharge images. As shown in Fig.1, when grounding electrode close to the fro nt end of inner electrode (Position B and C), the initial voltag e are low, 2.36kV and 2.12kV; When grounding electrode is away the front end of inner electrode (Position A and D), the i nitial voltage are higher, 3.08kV and 3.40kV; In position A, p lasma jet can be kept in stable stage in a narrow range of driv ing voltage. In position B and C, plasma jet can be kept in sta ble stage in a wide range of driving voltage. In position D, th e voltage range is decreased. In conclusion, the position of gr ounding electrode can affect the stage of plasma jet, especiall y the initial value and the voltage range of stable stage.