Effect of Voltage Pulse Duration on Electrophysical and Thermal Characteristics of Cold Atmospheric Plasma Jet

The desirable properties of a cold atmospheric plasma jet (CAPJ) for medical applications are high efficiency of the treatment and low thermal effects. To meet these requirements, we propose to use the CAPJ generated with the positive pulsed (PP) voltage. In our experiments and fluid model simulations, it is shown that a change of the pulse duration allows us to control precisely the intensity of interaction of the plasma jet with the target and the heating of the contact zone. The helium CAPJ is formed with 13-30 kHz PP voltage frequencies with the pulse duration of 7-20 mu s. The enhancement of plasma-target interaction is analyzed with the measured discharge current and calculated ionization rate near the target surface. The temperature measurements in the plasma-target active zone show that the heating by CAPJ excited with the PP voltage is generally less than in the case of AC voltage. The efficacy of treatment is tested on A549 cancer cells exposed to CAPJ ignited with the positively pulsed voltage with different pulse duration and with AC voltage.