Temporal and Spatial Characteristics of Surface Charge Deposited by He Plasma Jet with CF4 Additive

Atmospheric pressure plasma jets (APPJs) with trace active ingredients can make the material surface have the specified performance, which has a wide range of applications in the field of surface modification, biomedicine, and microelectronics. In this paper, the charge-discharge behavior of quartz glass surface acted by He-APPJ with CF4 additive was studied, and a basic photoelectric joint diagnosis system and a reflective linear electro-optical effect diagnosis platform were built. Combined with the fast surface charge density inversion algorithm, the temporal and spatial distribution of quartz surface charge density under the action of plasma was observed. Temporal and spatial variation of charge density deposited by He/CF4 APPJ on the quartz surface. The results show that the spatial distribution of positive and negative surface charges of pure He-APPJ in filamentary discharge mode has an obvious polarity effect at the initial discharge. The positive charge presents branching distribution, while the negative charge presents circular distribution, and the surface charge distribution gradually becomes stable after 20 cycles. When the concentration of CF4 increases, the positive and negative charge distribution area on the quartz surface decreases gradually, and the peak value of positive charge density first increases and then decreases, reaching the peak value at 0.5% CF4. Negative charge density peak decreases all the time; According to the distribution of charge density and total charge, it can be inferred that the addition of CF4 brings dual effects to the discharge process. First, a small amount of CF4 can aggravate the deposition of positive charges on the surface; Second, excessive addition of CF4 can inhibit the deposition of positive and negative charges, especially the accumulation of negative charges on the surface.