Large Area Sterilization with Array Needle Ring Self-Excited Plasma Jet Device

With the traditional plasma jet device, a large amount of carrier gas was required, which led to a large experimental system and high experimental cost. In this paper, an array-type needle-ring self-excited plasma jet device was designed to address the above shortcomings. The device was made of seven tungsten needles of 61 mm in length and 1.1 mm in diameter, a printed circuit board (PCB) of 50 mm in length and width, and a DC high-voltage power supply. Six tungsten pins were arranged according to the six vertices of the hexagon, and one tungsten pin was placed at the center of the hexagon, combining the seven pins into an array to serve as the high-voltage electrode. A copper ring with a diameter of 6 mm and a thickness of 1.6 mm has been formed as the grounding electrode by cladding copper in the reserved holes of the PCB. The needle-ring structure was used to achieve stable and synchronous discharge of each unit. The voltage experiment shows that the device can produce a good uniformity of the jet from 8.0 kV; the rotation temperature of the plasma jet generated by the device was 300 K by fitting and comparing with the spectrum collected by the spectrometer; the sterilization experiment shows that the sterilization area can reach 703.36 mm² for 50 s at 11.5 kV and the range of the device can reach the hexagonal shape, compared with the conventional plasma device, even if the carrier gas is not injected, the sterilization effect of the device is good.