APPARATUS AND METHOD FOR PRODUCING A PLASMA, AND USE OF SUCH AN APPARATUS

Abstract

The invention relates to an apparatus (1) for producing a plasma, having at least one first electrode (3), at least one second electrode (5), which is arranged at a distance from the first electrode (3), a voltage source (7), which is connected to at least one electrode (3,59) selected from the first electrode (3) and the second electrode (5) such that a potential difference between the at least one first electrode (3) and the at least one second electrode (5) can be produced by the voltage source (7), wherein the at least one first electrode (3) and the at least one second electrode (5) define at least one discharge path (9) for an electrical discharge in a discharge region (11) between the at least one first electrode (3) and the at least one second electrode (5). In this case, a magnetic field arrangement (15) is provided that is set up and arranged relative to the at least one first electrode (3) and the at least one second electrode (5), to provide a magnetic field in the discharge region (11), so that a magnetic field vector (B) of the magnetic field is oriented at an angle to the discharge path (9).

Claims

1. An apparatus for producing a plasma, comprising at least one first electrode, at least one second electrode located at a distance from the first electrode, a voltage source, which is connected in such a manner with at least one electrode selected from the first electrode and the second electrode that a potential difference between the at least one first electrode and the at least one second electrode can be produced by the voltage source, and the at least one first electrode and the at least one second electrode define at least one discharge path for an electrical discharge in a discharge zone between the at least one first electrode and the at least one second electrode, and a magnetic field arrangement, that is set up and located relative to the at least one first electrode and the at least one second electrode in order to provide a magnetic field in the discharge region, so that a magnetic field vector of the magnetic field is oriented at an angle to the discharge path.

2. The apparatus according to claim 1, wherein the voltage source is embodied as a direct current voltage source.

3. The apparatus according to claim 1, wherein: a) the at least one first electrode is embodied as a rod or wire-shaped electrode, and the at least one second electrode is embodied as a ring-shaped electrode thatseen from the direction of the circumferenceencompasses the at least one first electrode; and/or b) the at least one first electrode and the at least one second electrode are embodied as rod- or wire-shaped electrodes, and/or c) the at least one second electrode is embodied as a flat electrode with a plurality of openings.

4. The apparatus according to claim 1, wherein a distance between the at least one first electrode and the at least one second electrode, along the extension of at least one of the electrodes, a) is constant, or b) divergent, or c) is constant in a first segment and divergent in a second segment.

5. The apparatus according to claim 1, wherein the magnetic field arrangement has at least one permanent magnet and/or at least one electromagnet.

6. The apparatus according to claim 1, wherein the magnetic field arrangement a) has at least one ring magnet or at least one coil, and/or b) has a plurality of bar magnets or coils, which are located along at least one electrode, selected from the first electrode and the second electrode, and/or c) has at least one strip magnet, which is located along at least one electrode, selected from the at least one first electrode and the at least one second electrode.

7. The apparatus according to claim 1, wherein the apparatus has a tube segment that is in fluid contact with the discharge region, so that a fluid can be conveyed along the tube segment through the discharge region.

8. A method for producing a plasma, particularly by means of an apparatus according to claim 1, wherein at least one discharge filament is produced along a discharge path in a discharge region between at least two electrodes, and a magnetic field is provided, which permeates the discharge region at an angle to the discharge path, and the discharge filament is driven by the magnetic field into a propagating movement within the discharge region.

9. The method according to claim 8, wherein a fluid is conveyed through the discharge region, and the propagating movement of the discharge filament and a flow velocity of the fluid through the discharge region are preferably tuned to each other in such a way that every volume element of the fluid moving through the discharge region is swept at least once by the discharge filament.

10. The method according to claim 8, wherein atmospheric pressure predominates in the discharge region.

11. The method according to claim 8, wherein air, nitrogen, a noble gas, particularly argon, carbon dioxide, a gas mixture, or a mixture of at least one gas and at least one liquid, particularly water vapor, is used as a fluid.

12. The method according to claim 8, wherein the fluid moving through the discharge region is cleaned a) of odors, b) of allergens c) of microorganisms, and/or d) of particles.

13. The use of an apparatus according to claim 1, a) as an air purification device in a dwelling, a kitchen, particularly of a gastronomic establishment, a stable or a meat production facility, a chemical facility an office, a factory, a sewage treatment plant, a landfill, or a medical facility, and/or b) for the purification of a fluid of odors, allergens, microorganisms, and/or particles.

Description

[0060] The invention is explained below in more detail with reference to the drawing. Thereby are shown in:

[0061] FIG. 1 A schematic illustration of a first exemplary embodiment of an apparatus;

[0062] FIG. 2 A schematic illustration of a second exemplary embodiment of the apparatus;

[0063] FIG. 3 A schematic illustration of a third exemplary embodiment of the apparatus;

[0064] FIG. 4 A schematic illustration of a fourth exemplary embodiment of the apparatus;

[0065] FIG. 5 A schematic illustration of a fifth exemplary embodiment of the apparatus; [0066] and

[0067] FIG. 6 A schematic illustration of a sixth exemplary embodiment of the apparatus.

[0068] FIG. 1 shows a schematic illustration of a first exemplary embodiment of an apparatus 1 for producing a plasma. Thereby, in FIG. 1a), an apparatus 1 is illustrated that has one first electrode 3 and one second electrode 5; here, the first electrode 3 is embodied as a rod- or wire-shaped electrode, and the second electrode 5 is embodied as a ring-shaped electrode, which, seen from the direction of the circumference, encompasses the first electrode 3. Thereby, an axial direction extends perpendicular to the image plane of FIG. 1a); a radial direction is oriented perpendicular to the axial direction and located in the image plane, and a circumferential direction extends concentrically around the axial direction. The first electrode 3 and the second electrode 5 are located at a distance from each other.

[0069] In particular, the second electrode 5 is embodied here as an annular ring, and the first electrode 3 is located in the center of the circle defined by the second electrode 5. A voltage source 7 is schematically indicated as part of the apparatus 1, and which is connected with the first electrode 3 and the second electrode 5 in such a manner that a potential difference between the first electrode 3 and the second electrode 5 is capable of being produced by the voltage source 7. The first electrode 3 and the second electrode 5 define a discharge path 9 for a discharge in a discharge region 11 between the first electrode 3 and the second electrode 5. Thereby, it can be seen, on the basis of the cylindrically symmetrical setup of the arrangement of the first electrode 3 and the second electrode 5, a entire family of discharge paths 9 are defined here, whichparticularly in a radial directionextend along the circumference of the annular ring-shaped discharge region 11, and because of the constant distance between the first electrode 3 and the second electrode 5, it cannot be predicted with certainty at which point a discharge will actually initially occur, and thus which discharge path 9 from the family of possible discharge paths will be initially realized.

[0070] The voltage source 7 is preferably embodied as a direct current voltage source; it is particularly set up to produce a potential difference between the first electrode 3 and the second electrode 5 of at least 0.5 kV up to a maximum of 9 kV; preferably of at least 1 kV up to a maximum of 6 kV, and the voltage source is further preferably set up to deliver a current strength of at least 0.5 mA up to a maximum of 20 mA.

[0071] In FIG. 1a), a magnetic field arrangement is not yet illustrated, in order to explain in more detail, in steps, the mode of operation of the apparatus 1. If a discharge between the first electrode 3 and the second electrode 5 is initiated without the influence of a magnetic fieldfor example, with a magnetic field arrangement that has been switched off or removeda schematically indicated discharge filament 13 develops here, that extendsexcept for possible interferences through air or gas movements, for examplein a radial direction within the discharge region 11. Thereby, this discharge filament 13, without the influence of a magnetic field, is stationary, in the sense that the discharge path 9, once developed, remains constant over time.

[0072] FIG. 1b) shows the apparatus 1 supplemented with a magnetic field arrangement 15 that is set up and located relative to the first electrode 3 and the second electrode 5 in such a way that it provides a magnetic field within the discharge region 11, so that a magnetic field vector B of the magnetic field is oriented at an angle, and preferably vertical, to the discharge path 9. It can be seen here that the magnetic field vector B is perpendicular to the image plane of FIG. 1. In the exemplary embodiment of the apparatus 1 concretely illustrated here, the magnetic field arrangement 15 is preferably embodied as a permanent magnet, and particularly as a ring magnet, whichseen from the direction of the circumferenceencompasses the second electrode 5 and the first electrode 3. Alternatively, however, it is possible that the magnetic field arrangement 15 has a correspondingly located electromagnet, and in particular an electrical coil.

[0073] For reasons of a simplified illustration, the voltage source 7 is not shown in FIG. 1b); it is nevertheless, however, present.

[0074] If a discharge between the first electrode 3 and the second electrode 5 is now initiated, a Lorentz force has an effect on the discharge filament 13, so that the discharge filament 13 is set into rotation and propagates with a specific rotational frequency along the annular ring-shaped discharge region 11; the rotational frequency is in particular dependent on the field strength of the magnetic field. The discharge filament 13 thus sweeps across the entire discharge region 11 and forms within thisand particularly as seen in an average over timea type of plasma sheet, and the entire discharge region 11 is impinged on by plasma.

[0075] FIG. 2 shows a schematic illustration of a second exemplary embodiment of the apparatus 1. The same and functionally same elements are provided with the same reference numerals, so that in this respect, reference is made to the previous description. The magnetic field arrangement 15 includes in this exemplary embodiment a plurality of bar magnets 17, whichpreferably with the same angular distances, thus symmetricallyare located, seen from the direction of the circumference, around the first electrode 3 and the second electrode 5. The bar magnets 17 are thereby oriented so that here too, the magnetic field vector B is oriented perpendicular to the image plane of FIG. 2. Alternatively to the bar magnets 17, it is also possible that the magnetic field arrangement 15 has a plurality of electromagnets, and in particular coils, which are correspondingly located around the arrangement of the electrodes 3, 5. It is particularly preferred that the apparatus 1, and particularly the magnetic field arrangement 15, has six bar magnets 17.

[0076] It is possible that an arrangement of bar magnets 17 or an arrangement of spatially distributed coils can be more simply and more economically manufactured than a magnetic field arrangement 15 with a larger ring magnet or a correspondingly larger coil that encompasses the arrangement of electrodes 3, 5, as is illustrated in FIG. 1b).

[0077] The resulting physical effect, in consideration of the rotation of the discharge filament 13 along the discharge region 11, however, is the same in the first exemplary embodiment according to FIG. 1b) and the second exemplary embodiment according to FIG. 2. It must only be considered that typically, the magnetic field that is created by a plurality of bar magnets 17 or a plurality of coils is less homogeneous than the magnetic field created by a ring-shaped magnet or a single coil, as in the case of the first exemplary embodiment. Because of this, it is possible that in the case of the second exemplary embodiment according to FIG. 2, the discharge filament 13 exhibits varying rotational velocities along a circumferential line in the discharge region 11, because the Lorentz force also varies locally.

[0078] FIG. 3 shows a schematic illustration of a third exemplary embodiment of the apparatus 1. The same and functionally same elements are provided with the same reference numerals, so that in this respect, reference is made to the previous description. In this exemplary embodiment, the first electrode 3 and the second electrode 5 are both embodied as rod- or particularly as wire-shaped electrodes, and have a diverging distance to each other. The magnetic field arrangement 15, which preferentially here has a permanent magnet, and in particular a ring or bar magnet, is arranged here adjacent to the arrangement of the electrodes 3, 5, and namely in such a manner that here, too, the magnetic field vector B is oriented perpendicular to the image plane of FIG. 3. Alternatively, it is possible that the magnetic field arrangement 15 has an electromagnet or at least one coil. If a potential difference is applied to the electrodes 3, 5, a discharge filament 13 results, particularly at the location of the shortest distance between the electrodes 3, 5, and, by means of the magnetic field, a Lorentz force has an effect on the discharge filament 13, so that it travels along the extension of the electrodes 3, 5here, toward the rightand sweeps the discharge region 11, until the distance between the electrodes 3, 5 becomes too great in a termination region 19, so that the voltage source 7 can no longer drive the discharge. The concrete position of the termination region 19 is particularly dependent on the voltage, and hence the potential difference, between the electrodes 3, 5. After collapse of the discharge, this starts anew at the location of the smallest distance between the electrodes 3, 5, and the previously described process repeats itself in cyclical manner. This too leadsparticularly in an average over timeto an embodiment, so to speak, of a plasma sheet in the discharge region 11, that is cyclically swept by the discharge filament 13 with a specific frequency. Thereby, this frequency is particularly dependent on the field strength of the magnetic field and the length of the electrodes 3, 5 between the origination point of the discharge filament 13 and the termination region 19.

[0079] The distance between the electrodes 3, 5 is preferably between at least 1 mm and at most 30 mm in the discharge region 11.

[0080] The distance between the electrodes 3, 5 in the termination region 19 can be, for example, 3 cm.

[0081] FIG. 4 shows a schematic illustration of a fourth exemplary embodiment of the apparatus 1. The same and functionally same elements are provided with the same reference numerals, so that in this respect, reference is made to the previous description. In this exemplary embodiment as well, the electrodes 3, 5 are embodied as rod- or particularly wire-shaped electrodes; a distance between the electrodes 3, 5 in one segment is constant and in one segment is divergent; namely, it is constant in a first segment 20 and diverges in a second segment 22. Thereby, a defined location 24 is provided, at which the electrodes 3, 5 have the shortest distance from each other and where a discharge filament 13 is initially produced.

[0082] The magnetic field arrangement 15 has a strip magnet here, which extends along the arrangement of the electrodes 3, 5. Here, too, the magnetic field vector B is oriented perpendicular to the image plane of FIG. 4. The mode of operation of this exemplary embodiment of the apparatus 1 is essentially identical to the previously described mode of operation of the third exemplary embodiment according to FIG. 3; however, the result is the relatively elongated homogeneous region between the electrodes 3, 5, with a constant distance, to which the second segment with diverging electrodes 3, 5 ultimately connects, and where ultimately the termination region 19 is embodied. The first segment, in which the electrodes 3,5 have a constant distance from each other, can preferably have a length of up to 100 cm, particularly because strip magnets are currently available which, in any case, can have such a length when strung together. Thereby, the length of the region that can be realized in such a manner is particularly dependent on the length of the available strip magnets; several strip magnets can also be sequentially strung together. In this manner, there are principally no fundamental limits set for the overall length of the discharge region 11. Practical limits result, on the one hand, on the basis of sensible dimensions of the apparatus 1, and on the other hand, on the basis of desirable frequencies with which the discharge filament 13 sweeps the discharge region 11; these frequencies depend particularly on the magnetic field strength of the strip magnet and, on the other hand, on the length of the electrodes 3, 5 from the origination point 24 of the discharge filament 13 to the termination region 19. Instead of a strip magnet, it is also possible that a plurality of bar magnets are arranged next to one another, or that electromagnets, and particularly coils, are arranged in a corresponding manner next to one another, along the extension of the electrodes 3, 5.

[0083] FIG. 5 shows a schematic illustration of a fifth exemplary embodiment of the apparatus 1. The same and functionally same elements are provided with the same reference numerals, so that in this respect, reference is made to the previous description. The second electrode 5 is embodied in this exemplary embodiment as a flat electrode with a plurality of openings 21. The openings 21 are embodied here with a circular form. However, there are other openings possible, with regular or also irregular boundaries, in particular rectangular openings, or openings that have predefined irregular edge characteristics; for example, in accordance with the type of orientation of the electrodes 3, 5 in the exemplary embodiments according to FIGS. 3 and 4.

[0084] The first electrode 3 is not illustrated here. In the concretely illustrated exemplary embodiment, it is preferably provided that in each opening 21, a wire- or rod-shaped electrode is centrally oriented, and the majority of such electrodes are preferably electrically connected with each other and can be connected to a common potential that differs from the potential of the second electrode 5. In the case of other embodiments, it is also possible that the first electrode 3 extends at least in a range along at least one edge of at least one opening 21, and particularly parallel to a surface of the flat electrode 5. In this case too, it is possible that the first electrode 3 is embodied as a wire- or rod-shaped electrode.

[0085] Here, the magnetic field arrangement 15 has a plurality of bar magnets 17, of which, in order to provide better clarity, only one has been provided with the reference numeral 17. The bar magnets 17 are arranged around the openings 21, and produce preferably a magnetic field, of which the magnetic field vector is oriented vertically to a surface of the second electrode 5. The discharge filaments produced in the openings 21 then propagate in the openings 21 in a manner as was explained in connection with the FIGS. 1 through 4. In the exemplary embodiment concretely illustrated here, a behavior would particularly result as in the exemplary embodiment according to FIG. 2.

[0086] Instead of bar magnets 17, electromagnets, and particularly coils, can also be provided, or both electromagnets as well as bar magnets 17 can be provided. Alternatively, it is also possible that each opening 21, or in any case a plurality of openings 21particularly in each caseis encompassed by a ring magnet. A common ring magnet or a common coil for a plurality of openings 21 is also possible.

[0087] Differing, adjacent magnets and/or coils can, incidentally, have magnetic fields that are oriented in parallel or antiparallel.

[0088] During operation of the apparatus 1, a fluid is preferably passed through the openings 21, and it is then treated with the plasma produced in the openings 21.

[0089] The discharge zones 11 of the other exemplary embodiments of the apparatus 1, according to FIGS. 1 through 4, preferably also have a fluid passed through them during operation, which is treated in the discharge zones 11.

[0090] Ifas illustrated in FIG. 5openings 21 with circular boundaries are selected, it is fundamentally possible to establish a 1:1 relationship from a total area of the openings 21 to a total area without openings of the second electrode 5. If openings with rectangularly shaped boundaries or openings with substantially rectangularly shaped boundaries are selected, which are then preferably combined with strip magnets, a 9:1 relationship between a total area of the openings 21 and a total area without opening of the second electrode 5 can be provided, so that, advantageously, a significantly reduced flow resistance for a fluid permeating the second electrode 5 is produced.

[0091] FIG. 6 shows a schematic illustration of a sixth exemplary embodiment of the apparatus 1. The same and functionally same elements are provided with the same reference numerals, so that in this respect, reference is made to the previous description. Apparatus 1 is embodied here as a flow tube, in which the first electrode 3 is located centrally, and preferably centered, as a rod-shaped electrode; the second electrode 5 is embodied as a ring-shaped electrode, here as a hollow, cylindrically-shaped electrode, and particularly as a cylindrical tubular element. Thereby, the second electrode 5 serves at the same time as a flow or conductive tube for a fluid, which, during operation of the apparatus 1, permeates the discharge region 11. In this respect, the apparatus 1 has a tube segment 23 that is in fluid contact with the discharge region 11, so that a fluid can be conveyed along the tube segment 23 through the discharge region 11. Thereby, the tube segment 23 is in fluid contact with a fluid inlet 25 and a fluid outlet 27, and the fluid inlet 25 and the fluid outlet 27 are particularly connecting elements to further fluid lines that are not illustrated here, such as threaded connectors for the connection of flexible tubing.

[0092] The magnetic field arrangement 15 is embodied here as a ring magnet that encompasses the arrangement of the electrodes 3, 5 in the discharge region 11.

[0093] Thereby, the mode of operation of the sixth exemplary embodiment according to FIG. 6 is identical to the mode of operation that was explained with respect to the first exemplary embodiment according to FIG. 1b), whereby a discharge propagating along the annular ring-shaped discharge region 11 is produced. The magnetic field vector B is preferably chosen parallel to the longitudinal extension of the first electrode 3, and is thus directed in an axial direction, and particularly in the longitudinal direction of the apparatus 1.

[0094] The propagating movement of the discharge filament 13 along the discharge path 11 and a flow velocity of the fluid through the discharge region 11 are preferably tuned to each other in such a way that every volume element of the fluid flowing through the discharge region 11 is swept at least once by the discharge filament 13, so that, from the viewpoint of the moving fluid, it appears, so to speak, that a discharge sheet, and particularly a plasma sheet, is embodied, through which the fluid moves and with which the fluid is treated. Thereby, the fluid is preferably cleaned of odors, of allergen, of microorganisms, and particularly of microbes, bacteria, spores, fungi, and/or of viruses, or of particles, and particularly nanoparticles, and preferably of filth or dust.

[0095] The fluid is preferably conveyed through the discharge region 11 in such a manner that, within the discharge region 11, atmospheric pressure or a pressure approximating atmospheric pressure, and preferably no coarse vacuum, and especially no medium or high vacuum, and also no high pressure, predominates.

[0096] As a fluid, preferably air, nitrogen, a noble gas such as argon, carbon dioxide, a gas mixture, or a mixture of at least one gas and at least one liquid, such as water vapor, is used.

[0097] The apparatus 1 can be used in an advantageous manner as an air purifying device, particularly for air purifying in a dwelling, in a kitchen, particularly in a commercial kitchen such as a kitchen in a gastronomic establishment, in a stable or a meat production facility, in a chemical facility, in an office, in a factory, in a sewage treatment plant, in a landfill, or in any other facility in which there is a necessity for purifying air of at least one of the previously noted materials or other materials. Under this, for example, a medical facility, such as a medical clinic or a hospital, can obviously also be included.

[0098] Altogether, it can be seen that with the apparatus 1, with the help of the method and by means of the use of apparatus 1, an effective purification of a fluid is possible with little effort and at low cost.