Space and time structure of helium pulsed surface-wave discharges at intermediate pressures (5–50 Torr). (22nd November 2016)

• Record Type: Journal Article
• Authors: Hamdan, Ahmad; Valade, Fabrice; Margot, Joëlle; Vidal, François; Matte, Jean-Pierre
• Is Part Of: Plasma sources science & technology. Volume 26:Number 1(2017:Feb.)
• Publication Date: 2016-11-22
• Subjects: helium plasma -- microwave plasma -- pulsed surface-wave discharge -- gas temperature -- time-resolved imaging -- ionization front; Plasma (Ionized gases) -- Periodicals; 530.44
• DOI: 10.1088/0963-0252/26/1/015001
• Languages: English
• ISSNs: 0963-0252

Abstract

Abstract: In this paper, the ignition and development of a plasma created by pulsed surface wave discharges (PSWDs) was experimentally investigated using time-resolved imaging techniques and optical spectroscopy in helium at intermediate gas pressures between 5 and 50 Torr. We found that the ionization front moves at a few km s −1 during the ignition phase and decreases to hundreds of m s −1 after only some tens of µ s. Once the plasma has reached a sufficient length, a standing wave pattern is observed in the light emission of the discharge. We attribute its formation to the reflection of the surface wave on the ionization front, which results in a pattern of nodes and antinodes. We have also determined the time and space evolution of the gas temperature. It is shown that the gas temperature increases from the room temperature value to a plateau at several hundreds of degrees over a short time (typically 100 µ s). These results supports those obtained by light emission imaging and also show that the standing wave pattern does not affect the gas temperature.