Devices and methods for treating skin tissue using cold plasma

Disclosed herein is a system for treating skin and/or nails with cold plasma. The system includes a discharge device, which includes a handle and an applicator mounted thereon, and control infrastructure, which includes a waveform generator. The applicator includes an elongated tube housing therein a cathode. The handle includes a flyback amplifier. The waveform generator is configured to induce the flyback amplifier to establish a voltage at the cathode. The voltage produced by the flyback amplifier is configured to allow generating a self-sustaining Townsend avalanche when a distal end of the tube is positioned sufficiently near a target site on a skin surface or a nail of a subject, such as to produce a cold plasma discharge directed at the target site and having an average power between about 0.1 μW and about 10 μW, so that the target site is not heated.