1. A device for producing a non-thermal atmospheric-pressure plasma, the device comprising:a piezoelectric transformer;
an activating circuit configured to apply an AC voltage at an activating frequency to the piezoelectric transformer as an input voltage; and
a field probe configured to measure a field strength of an electric field produced by the piezoelectric transformer,
wherein the activating circuit is configured to adapt the activating frequency based on the measurement results of the field probe in such a way that the field strength is maximized when the device is switched on.