A novel flexible plasma array for large-area uniform treatment of an irregular surface

In this work,we demonstrate a flexible multi-pin plasma generator with movable electrodes,which can change the shape of the electrode array freely,and then provide a large-area uniform plasma for the treatment of surfaces of different shapes.Discharge characteristics including U-I waveforms and discharge images and sterilization performance under three different electrode configurations(flat-flat,flat-curve,curve-curve)are investigated.Very similar results are acquired between the flat-flat configuration and the curve-curve configuration,which is much better than that under flat-curve configuration.This flexible multi-pin plasma generator offers a simple method to treat different irregularly shaped surfaces uniformly with a single device.Moreover,this device provides a foundation for developing a self-adaption large-scale uniform plasma generator by further introducing automatic adjustment of the position of every electrode driven by motors with discharge current feedback in the following study.Thus it will promote the applications of atmospheric-pressure cold plasmas significantly.

A non‐equal gap distance dielectric barrier discharge:Between cone‐shape and cylinder‐shape electrodes

A non‐equal gap distance dielectric barrier discharge(DBD)between cone‐shape and a cylinder‐shaped electrodes is reported.The DBD is driven by a nanosecond voltage pulse.When the pulse frequency is 500 Hz or lower,ladder‐shape plasma with multiple plasma layers is generated within the gap,with a distance increasing from 1 to 7 mm.According to high‐speed photographs of the plasma captured by an intensified charge‐coupled camera detector camera,the ladder‐shaped plasma is formed owing to propa-gation of ring‐shaped plasma from the region of the short‐gap distance to the region of long‐gap distance with regular variations in its propagation speed.The propagation speed drops to zero and lasts for about 20-30 ns at the region of each plasma layer,which results in bright plasma layers.The electric field of the plasma layer at the region of the different gap distance is evaluated according to the optical emission intensity ratio R_(391)/_(394)of N_(2)^(+)at 391 nm and N_(2) at 394 nm.The obtained electric field drops from 8.1 to 6.4 kV/mm when the plasma is propagated from regions of gap distance of 2-5 mm.When the pulse frequency is increased to 1 kHz or higher,the discharge changes into a filamentary mode and the multiple‐layer plasma disappears.