Apparatus and method for generating a non-thermal atmospheric pressure plasma

1. An apparatus for generating a non-thermal atmospheric-pressure plasma comprising:

a first piezoelectric transformer;

a second piezoelectric transformer; and

a drive circuit configured to apply an input voltage to the first piezoelectric transformer and a second input voltage to the second piezoelectric transformer,

wherein the input voltage applied to the first piezoelectric transformer is phase-shifted by 90° in relation to the input voltage applied to the second piezoelectric transformer, and

wherein a frequency resulting from a mean value of resonant frequencies of the first and second piezoelectric transformers is chosen for the drive circuit.

2. The apparatus according to claim 1 , wherein the first and second piezoelectric transformers are arranged at a distance of less than 5 cm from one another.

3. The apparatus according to claim 1 , wherein the drive circuit is configured in such a way that both input voltages have the same frequency.

4. The apparatus according to claim 1 , wherein the apparatus comprises more than two piezoelectric transformers, and wherein the drive circuit is configured to apply input voltages to the piezoelectric transformers in such a way that the input voltages of immediately adjacent piezoelectric transformers are each phase-shifted by 90° with respect to one another.

5. The apparatus according to claim 4 , wherein the piezoelectric transformers are arranged parallel to one another and form a single row.

6. The apparatus according to claim 4 , wherein the piezoelectric transformers are arranged parallel to one another and form an array with at least two rows and at least two columns, and wherein the drive circuit is configured to apply the input voltages to the piezoelectric transformers in such a way that the input voltages at the piezoelectric transformers that are arranged on one and the same diagonal of the array are each phase-shifted by 0° with respect to one another.

7. The apparatus according to claim 1 , wherein the first and the second piezoelectric transformers are arranged in such a way that their output-side front faces are opposite one another.

8. The apparatus according to claim 1 , wherein a first group of piezoelectric transformers comprises the first piezoelectric transformer and further first piezoelectric transformers that are arranged parallel to one another and form a single row, wherein a second group of piezoelectric transformers comprises the second piezoelectric transformer and further second piezoelectric transformers that are arranged parallel to one another and form a single row, wherein the first group of piezoelectric transformers and the second group of piezoelectric transformers are arranged opposite one another, and wherein the drive circuit is configured to apply the input voltages to each of the piezoelectric transformers of a row in such a way that the input voltages at immediately adjacent piezoelectric transformers are each phase-shifted by 90° with respect to one another, and that the input voltages at piezoelectric transformers that are opposite one another are each phase-shifted by 90° with respect to one another.

9. The apparatus according to claim 1 , wherein a first group of piezoelectric transformers comprises the first piezoelectric transformer and further first piezoelectric transformers that are arranged parallel to one another and form an array with at least two columns and at least two rows, wherein a second group of piezoelectric transformers comprises the second piezoelectric transformer and further second piezoelectric transformers that are arranged parallel to one another and form an array with at least two columns and at least two rows, wherein the first group of piezoelectric transformers and the second group of piezoelectric transformers are arranged opposite one another, and wherein the drive circuit is configured to apply the input voltages to each of the piezoelectric transformers in such a way that input voltages at immediately adjacent piezoelectric transformers are each phase-shifted by 90° with respect to one another, that the input voltages at the piezoelectric transformers that are arranged on one and the same diagonal of the array are each phase-shifted through 0° with respect to one another, and that the input voltages at piezoelectric transformers that are opposite one another are each phase-shifted through 90° with respect to one another.

10. The apparatus according to claim 1 , wherein the first piezoelectric transformer and the second piezoelectric transformer are spaced apart by a gap.

11. A method for generating a non-thermal atmospheric-pressure plasma, the method comprising:

applying a first input voltage to at least one first piezoelectric transformer; and

applying a second input voltage to a second piezoelectric transformer,

wherein the first input voltage is phase-shifted by 90° with respect to the second input voltage, and

wherein a frequency resulting from a mean value of resonant frequencies of the first and second piezoelectric transformers is chosen for a drive circuit driving the first and second piezoelectric transformers.

12. An apparatus for generating a non-thermal atmospheric-pressure plasma comprising:

a first piezoelectric transformer;

a second piezoelectric transformer; and

a drive circuit configured to apply an input voltage to each of the piezoelectric transformers,

wherein the input voltage applied to the first piezoelectric transformer is phase-shifted by 90° in relation to the input voltage applied to the second piezoelectric transformer, and

wherein the first and the second piezoelectric transformers are arranged in such a way that their output-side front faces are opposite one another,

wherein the first piezoelectric transformer and the second piezoelectric transformer are spaced apart by a gap and the gap is present between the output-side front faces of the two transformers.

13. The apparatus according to claim 12 , wherein the first and the second piezoelectric transformers are arranged at a distance of less than 5 cm from one another.

14. The apparatus according to claim 12 , wherein the drive circuit is configured in such a way that both input voltages have the same frequency.

15. The apparatus according to claim 12 , wherein the apparatus comprises more than two piezoelectric transformers, and wherein the drive circuit is configured to apply input voltages to the piezoelectric transformers in such a way that the input voltages of immediately adjacent piezoelectric transformers are each phase-shifted by 90° with respect to one another.

16. The apparatus according to claim 15 , wherein the piezoelectric transformers are arranged parallel to one another and form a single row.

17. The apparatus according to claim 15 , wherein the piezoelectric transformers are arranged parallel to one another and form an array with at least two rows and at least two columns, and wherein the drive circuit is configured to apply the input voltages to the piezoelectric transformers in such a way that the input voltages at the piezoelectric transformers that are arranged on one and the same diagonal of the array are each phase-shifted by 0° with respect to one another.

18. The apparatus according to claim 12 , wherein a first group of piezoelectric transformers comprises the first piezoelectric transformer and further first piezoelectric transformers that are arranged parallel to one another and form a single row, wherein a second group of piezoelectric transformers comprises the second piezoelectric transformer and further second piezoelectric transformers that are arranged parallel to one another and form a single row, wherein the first group of piezoelectric transformers and the second group of piezoelectric transformers are arranged opposite one another, and wherein the drive circuit is configured to apply the input voltages to each of the piezoelectric transformers of a row in such a way that the input voltages at immediately adjacent piezoelectric transformers are each phase-shifted by 90° with respect to one another, and that the input voltages at piezoelectric transformers that are opposite one another are each phase-shifted by 90° with respect to one another.

19. The apparatus according to claim 12 , wherein a first group of piezoelectric transformers comprises the first piezoelectric transformer and further first piezoelectric transformers that are arranged parallel to one another and form an array with at least two columns and at least two rows, wherein a second group of piezoelectric transformers comprises the second piezoelectric transformer and further second piezoelectric transformers that are arranged parallel to one another and form an array with at least two columns and at least two rows, wherein the first group of piezoelectric transformers and the second group of piezoelectric transformers are arranged opposite one another, and wherein the drive circuit is configured to apply the input voltages to each of the piezoelectric transformers in such a way that input voltages at immediately adjacent piezoelectric transformers are each phase-shifted by 90° with respect to one another, that the input voltages at the piezoelectric transformers that are arranged on one and the same diagonal of the array are each phase-shifted through 0° with respect to one another, and that the input voltages at piezoelectric transformers that are opposite one another are each phase-shifted through 90° with respect to one another.

20. The apparatus according to claim 12 ,

wherein the apparatus is configured to treat an object by the non-thermal atmospheric-pressure plasma when passing through the gap, and

wherein two mutually opposite surfaces of the object are subjected simultaneously to plasma generated by the apparatus.

21. The apparatus according to claim 20 , wherein the object is a foil.

22. A method for generating a non-thermal atmospheric-pressure plasma, the method comprising:

applying a first input voltage to at least one first piezoelectric transformer; and

applying a second input voltage to a second piezoelectric transformer,

wherein the first input voltage is phase-shifted by 90° with respect to the second input voltage, and

wherein the first piezoelectric transformer and the second piezoelectric transformer are spaced apart by a gap and the gap is formed between an output-side front face of the first piezoelectric transformer and an output-side front face of the second piezoelectric transformer; and

passing an object through the gap; and

simultaneously subjecting two mutually opposite surfaces of the object to plasma.

23. The method according to claim 22 , wherein the object is a foil.