Plasma candle with a hollow dielectric cylinder for a wide and stable jet
Ayman A. Abdelaziz1, 2, *, Nozomi Takeuchi3, Yoshiyuki Teramoto1, and Hyun-Ha Kim1, *
* The author to whom correspondence should be addressed.
1 National Institute of Advanced Industrial Science and Technology (AIST), Environmental Management Research Institute, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
2 Faculty of Science, Assiut University, Assiut 71516, Egypt
3 Department of Electrical and Electronic Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Tokyo 152-8552, Japan
Abstract
Expanding a nonthermal plasma jet to treat a large area is considered as one of the big challenges for industrial applications. Unlike conventional upscaling methods using multi-tubes, this work reports a new approach to obtain a stable, largevolume, wide-area, and long plasma plume from a single tube. The wide plasma jet is achieved using a hollow dielectric cylinder (HDC) embedded perpendicular to the flow of helium inside a wide glass tube (diameter: 26 mm). In addition to the capability of the developed device to launch long and wide plasma plumes, it exhibits low operating power that makes the plasma plume maintain at a temperature close to the room temperature. Furthermore, the jet has a flickering pattern resembling a candle flame, similar to the observed phenomenon in the recently developed plasma candle device utilizing a microporous disc. Additionally, the millimeter-sized hollows in the HDC prevent any pressure drop across it, offering a distinct advantage over plasma candle devices. The investigation revealed that the narrow channels within the HDC intensify the electric field in the device, which is necessary to overcome the comparatively weak electric field in the wide tube. To gain deeper insights into the pivotal factors contributing to launching a stable plasma jet, the plume was monitored using a high-speed camera under different configurations of the developed device. It is found that the arrangement of the HDC locations and the electrodes inside the glass tube are important to form a stable plasma jet; two distinct plasma zones are observed inside the developed device and optimizing their ratio is a crucial parameter contributing to launching a strong, stable, and wide plasma jet. The presented techniques and findings can be applied to improve the uniformity of plasma jets launched from conventional multi-tube devices.
Keywords - Plasma candle, jet diameter expansion, hollow dielectric cylinder (HDC), narrow gas channels, single tube.