DEVICE FOR ATMOSPHERIC BARRIER DISCHARGE, USE OF THE SAME FOR PLUG-IN MOUNTING AND METHOD FOR OPERATING THE SAME

Description

Field of invention

[0001] The invention relates to a device for atmospheric barrier discharge and, in particular, an electrode arrangement for generating a non-thermal plasma based on a dielectric barrier discharge (DBD), in the form of a plasma actuator, especially for treating surfaces in a closed system (e.g., a disinfection chamber). Furthermore, the invention relates to a plug-in mounting method for an atmospheric barrier discharge device and a method for operating an atmospheric barrier discharge device. Background of the invention

[0002] A dielectric barrier discharge (DBD) is a type of non-thermal plasma generated by applying an alternating voltage to electrodes separated by an insulating layer (e.g., a dielectric material).

[0003] It is known that a DBD can be used for the removal of pollutants from gases and aqueous media, for the treatment of wounds, for the treatment of surfaces, or in plasma actuators.

[0004] The invention relates to a device for a dielectrically hindered barrier discharge for the simultaneous and separate generation of reactive nitrogen species (RNS) and reactive oxygen species (ROS), and in particular a plasma actuator that can continuously release RNS and ROS without a blower, for example in a disinfection chamber.

[0005] Conventional plasma or ionization devices typically feature a dielectric material made of glass, ceramic, or polymers, with an inner electrode on its surface. This electrode can be made of electrically conductive films / layers, metal cores, fabrics, or stainless steel wool, for example. An outer electrode, made of a fabric, knitted material, or expanded metal mesh, is located on the outer surface of the dielectric and is grounded (e.g., connected to a ground potential).

[0006] Applying an alternating voltage to the inner electrode creates a dielectric barrier discharge (DBD), which generates reactive species.

[0007] It has been found that the most frequently identified species include ozone (O 3 ), nitrous oxide (N 2 O), nitric acid (HNO 3 ), nitrous acid (HNO 2 ) and nitrogen dioxide, with ozone being associated with lower power discharges and nitrogen dioxide being associated with higher power discharges.

[0008] Under special conditions, ozone, nitrous oxide, nitrous pentoxide (N2O5) and nitric acid are produced in an afterglow region after discharge.

[0009] It was also found that plasma operated in a high-frequency, low-voltage state has the same antimicrobial activity as plasma operated in a low-frequency, high-voltage state when the discharge power density is the same.

[0010] The gaseous concentrations of ozone (O 3 ) and nitrogen oxides (NO and NO 2 or NO X ) are quantified in the generally established "regimes" for the chemistry of a barrier discharge: an ozone-dominated low-power mode; a nitrogen oxide-dominated high-power mode; and an intermediate, unstable transition region.

[0011] It has been found that bacterial decontamination of surfaces, especially tissues, is most effective in "NOx mode" (i.e., nitric oxide mode), less effective in "ozone mode", and has the weakest antibacterial effects in the transition range.

[0012] A representative publication from 2018 ("Antimicrobial Applications of Ambient-Air Plasmas", University of California, Berkeley by Matthew John Pavlovich, dissertation) makes the following findings [1]: Both nitrogen oxide and nitrogen dioxide increase with increasing power at the discharge surface, but only above a certain power density threshold, approximately 0.10 W / cm²< for NO and 0.20 W / cm²< for NO₂. In contrast, ozone is only observed below a power density threshold of approximately 0.50 W / cm²< at the discharge surface.

[0013] The discharge area is defined as the area on the outer electrode where a closed discharge occurs. This area can be identified by a typical plasma glow under atmospheric conditions.

[0014] From DE 10 2019 006 536 B3, a device for skin and, in particular, wound treatment using an atmospheric pressure plasma is known, which has a plasma generator comprising at least one electrode, at least one dielectric, an electrical supply unit, and a control unit, and is configured to generate the atmospheric pressure plasma by means of a dielectric barrier discharge, characterized in that the control unit is configured to operate the plasma generator in different operating modes such that, in a first operating mode (M1), the at least one electrode is supplied with a first excitation energy sufficient to generate a nitric oxide (NO)-containing plasma, and in a second operating mode (M2), with a second excitation energy sufficient to generate an ozone (O3)-containing plasma, wherein the first excitation energy is greater than the second excitation energy.wherein the nitrogen monoxide-containing plasma generated in the first operating mode is essentially free of ozone and contains, at most, traces of this compound that are practically undetectable analytically, and wherein the ozone-containing plasma generated in the second operating mode is essentially free of nitrogen monoxide and contains, at most, practically undetectable traces. In this publication, the discharge is performed as a surface microdischarge (SMD).

[0015] A plasma source for hand disinfection is known from WO 2022 / 063446 A1. In a preferred embodiment, the invention relates to a device for disinfecting body areas comprising a fan for generating an airflow and a plasma generator, wherein the plasma generator is located in the airflow, characterized in that the plasma generator has at least one plasma rod, which has a dielectric tube with an electrically conductive core inside the dielectric tube, wherein the dielectric tube has on an outer surface a wire wound in turns, wherein the electrically conductive core forms an electrode pair with the wire wound on the outer surface, which generates a plasma when a voltage is applied.

[0016] The dielectric tube has a wire on its outer surface. This wire is wound into turns along this outer surface. The electrically conductive core inside and the wound wire outside the dielectric tube form an electrode pair. The dielectric tube with the electrode pair is also referred to as a plasma rod in accordance with WO 2022 / 063446 A1. Applying a voltage, preferably an alternating voltage, generates the dielectric barrier discharge and thus the plasma, and consequently the reactive species, along the surface of the dielectric tube. Preferably, the wire on the outside of the dielectric tube is wound twice in opposite directions. This compensates for any inductance that this winding might have. The double winding achieves a structure similar to a coaxial cable, which does not emit electromagnetic radiation.Instead, the current-carrying windings can effectively serve to generate the plasma. The airflow around the dielectric tube is forced in a transverse direction by the fan.

[0017] From US 5,581,152 A "Dielectric barrier discharge lamp", a dielectric barrier discharge lamp is known, which is used, for example, as an ultraviolet light source for a photochemical reaction and in which light is emitted by "excimer" molecules formed by a dielectric barrier discharge.

[0018] Plasma actuators generally function by generating a plasma field that produces an ionized gas cloud which acts on the flow of gases or liquids. The plasma field is generated by applying a high voltage between two electrodes located in a dielectric.

[0019] When a high voltage is applied, electrons are repelled from the electrode and accelerated through the gas. These electrons then collide with the atoms and molecules in the gas, ionizing them. This leads to the formation of positively charged ions and negatively charged electrons.

[0020] The ionized gas cloud, known as plasma, then generates electrical forces and electromagnetic fields that cause a flow. By controlling the high voltage, the shape and intensity of the plasma, and thus its effect on the flow, can be controlled.

[0021] Plasma actuators can also be used to generate ozone. When a plasma actuator is applied to air or oxygen, the plasma creates an ionized gas cloud that produces reactive oxygen species, including ozone (O3).

[0022] JP2009242172A describes an ozone-generating device based on a plasma actuator. Using a pair of electrodes on the back and on the surface electrodes, and an alternating voltage applied to both electrodes, a surface plasma is generated at the edge of the surface electrode.

[0023] A representative study from 2022 (Wang Xi et al. "Mode transition of air surface micro-discharge and its effect on the water activation and antibacterial activity", 2022 Plasma Sources Sci. Technol.) found that the concentrations of H⁺, H₂O₂, NO₂⁻, NO₃⁻, and ONOO⁻ for the nitrogen oxide mode are about 2–3 times higher than those for the ozone mode, while the O₃⁻ concentration for the ozone mode is more than 28 times higher than in the nitrogen oxide mode. It was also found that the effect of ambient temperature on the mode transition is consistent with the discharge power. [3]

[0024] A plasma coil for air disinfection using plasma is known from US 2015 / 351212 A1.

[0025] From KR 101 003 729 B1 a plasma device for the ionization of oxygen in the air is known.

[0026] A 2022 study (Zifeng Wang et al. "Combination of NOX mode and O3 mode air discharges for water activation to produce a potent disinfectant", 2022 Plasma Sources Sci. Technol.) found that N₂O₅ is produced effectively and stably by separately generating and then mixing NOₓ-mode and O₃-mode plasmas. NOₓ-mode air plasma was generated by a sliding arc discharge, and O₃-mode air plasma was generated by a dielectric barrier discharge. High concentrations of N₂O₅ were achieved after mixing the two gases. This combination resulted in a germ reduction of almost 6 log units. [2]

[0027] However, previous investigations show that it would be desirable to have a device, a use thereof, and a method for operating it for germ reduction on surfaces that can simultaneously generate a plasma in nitrogen oxide and ozone mode. (e.g. The object of the invention is therefore to provide such a device, such a use, and such a method. Brief description of the characters

[0028] The invention is described in detail below with reference to the drawings. Fig. 1 schematically illustrates the attachment of an external electrode to a hollow cylindrical dielectric and a ground wire from a top view according to one embodiment. Fig. 2schematically represents a device for atmospheric barrier discharge according to one embodiment (right: top view; left: side view). Fig. 3 presents a rectangular mesh fabric (e.g. a schematic side view of a dielectric (outer electrode) according to one embodiment. Fig. 4 schematically represents the geometry of an external electrode with slopes according to one embodiment. Fig. 5 schematically represents a modular arrangement of the outer electrode on the dielectric as a side view according to one embodiment (top: spiral winding; bottom: wound in segments in modules). Fig. 6 schematically represents an embodiment with an internal electrode made of an elastomer as a perspective view. Fig. 7 schematically represents an embodiment with an internal electrode made of mesh fabric as a perspective view. Fig. 8 The compression of the inner electrode is shown. Fig. 7According to one embodiment, it is shown schematically as a top view. Fig. 9 schematically represents a reaction chamber according to one embodiment. Explanation of the invention

[0029] According to the first aspect of the invention, a device for atmospheric barrier discharge (e.g., in the form of a plasma actuator) is provided, wherein the device comprises: at least one hollow cylindrical dielectric having an inner surface and an outer surface and having a dielectric constant greater than 4; a plug-in device (e.g., a mounting plate) having at least one (e.g., integrally formed, e.g., in one piece, e.g., monolithically formed) holding means on which at least one inner electrode and at least one outer electrode are arranged (e.g., by insertion, e.g., by sliding on) and on which the hollow cylindrical dielectric is arranged (e.g., by insertion, e.g., by sliding on).The device consists of an inner electrode, which is arranged within the hollow cylindrical dielectric and (e.g., with an outer surface thereof) rests against the inner surface of the dielectric, and an outer electrode, which has a rectangular mesh fabric (i.e., a mesh fabric whose meshes are rectangular but not square) and which (e.g., with an inner surface thereof) rests against the outer surface of the dielectric (e.g., closely rests against / is in contact with it). The outer electrode is formed as a hollow cylinder (e.g., which has an outer electrode-cylinder longitudinal axis) and has transverse wires (which extend, for example, circumferentially around the outer electrode-cylinder longitudinal axis) as well as longitudinal wires (which extend, for example, parallel to the outer electrode-cylinder longitudinal axis). The transverse wires (also referred to as a chain) are made of a conductive material (e.g.,formed with a wire diameter of 0.25 mm to 0.35 mm, preferably 0.315 mm), and the longitudinal wires (also referred to as weft) are formed from a conductive material (e.g. stainless steel) with a wire diameter that is 10% to 15% thinner (preferably 12.5% ​​thinner) than the wire diameter of the transverse wires.

[0030] The plug-in device may also have a permanent magnet (e.g. a permanent ring magnet) which is arranged coaxially to the inner electrode (e.g. in the hollow cylindrical dielectric, e.g. in the hollow cylindrical dielectric at one end facing away from the plug-in device) (e.g. so that magnetic field lines of the permanent magnet pass through discharge zones between the outer electrode and the dielectric).

[0031] The plug-in device can have a plate-shaped base on which at least one holding element (e.g. integral, e.g. one-piece, e.g. monolithic) is formed.

[0032] The plate-shaped base may also have mounting elements (e.g. tabs, e.g. mounting holes) (e.g. with which the plug-in device can be mounted on pipes), which are optionally arranged on an edge of the plate-shaped base.

[0033] The plate-shaped base can have a photodiode holding element which projects from a first surface of the plate-shaped base, and the plug-in device can further have a photodiode for monitoring the atmospheric barrier discharge which is arranged on (e.g. in) the photodiode holding element and which is exposed to the outside (i.e. (in operation of the device) towards the plasma).

[0034] The plate-shaped base can have a UV-C emitting device retaining element which projects from a first surface of the plate-shaped base, and the plug-in device can further have a UV-C emitting device (e.g. a UV-C light-emitting diode) which is arranged on (e.g. in) the UV-C emitting device retaining element and which is exposed to the outside (i.e. (in operation of the device) towards the plasma).

[0035] The at least one holding means can have a first holding element which projects from the first surface of the plate-shaped base (e.g. and is integrally formed thereon, e.g. formed in one piece thereon, e.g. formed monolithically thereon), and the first holding means can be configured to press (e.g. press) the inner electrode against the hollow cylindrical dielectric with a contact pressure between 10 N / cm 2< and 50 N / cm 2<.

[0036] The first retaining element can be a tension pin.

[0037] The inner electrode can be made of a temperature-resistant conductive elastomer (e.g., which has a specific through-resistance of 0.2 Ohm*cm to 0.004 Ohm*cm, preferably 0.008 Ohm*cm).

[0038] The inner electrode can be pressed (e.g., pressed) against the inner surface of the casing by means of the first holding element (e.g., across a flat surface and with uniform pressure, e.g., across the entire surface).

[0039] The inner electrode can be formed from a mesh fabric made of a paramagnetic material. For example, the paramagnetic material can be an aluminum alloy (AlMg5). The mesh fabric can have a mesh size w of 0.050 mm to 0.150 mm and a wire diameter d of 0.05 mm to 0.14 mm, preferably a mesh size w of 0.075 mm and a wire diameter d of 0.052 mm.

[0040] The spring pin can have a longitudinal slot (e.g. in a direction orthogonal to the plate-shaped base), the inner electrode can be wound around the spring pin (e.g. in a circumferential direction thereof) to rest against an outer surface of the spring pin, two opposite end sections of the inner electrode can be inserted (e.g. inserted) into the longitudinal slot, and the hollow cylindrical dielectric can be arranged around the spring pin in such a way that it presses the inner electrode against the outer surface of the spring pin.

[0041] The first retaining element may have a through-hole (e.g., which penetrates the first retaining element and the plate-shaped base), the device may have an AC connection lead which is electrically connected to the inner electrode, and the AC connection lead may be guided through the through-hole of the first retaining element (e.g., to the outside, e.g., outwards in relation to the device).

[0042] The device can have a ground connection lead which is electrically connected to the external electrode (e.g. at a connection section), the at least one holding means can have a second holding element which projects from the first surface of the plate-shaped base (e.g. and which has a U-shaped cross-section; e.g. and is integrally formed thereon, e.g. formed in one piece thereon, e.g. formed monolithically thereon), and the second holding means can be configured to mechanically guide the ground connection lead (e.g. to fix a position of the external electrode at least radially outwards and / or in the circumferential direction).

[0043] The transverse wires and the longitudinal wires can form the rectangular mesh fabric, and the distance between adjacent (e.g., immediately adjacent, e.g., immediately, without any further transverse wires in between) transverse wires can be 4 to 6 times (preferably 5 times) the diameter of the longitudinal wires.

[0044] This results in the longitudinal and transverse wires in the rectangular mesh fabric having different angles to the dielectric. The larger the spacing (mesh size) of the transverse wires, the smaller the angles of the longitudinal wires to the dielectric. Thus, a first plasma actuator is generated at the longitudinal wires, which can be detected by a stripe-shaped discharge. It is generally known that in a plasma actuator, the electrode edges or wires form no or only a very small angle to the dielectric. Therefore, the spacing of the transverse wires is preferably 4 to 6 times, and preferably 5 times, the diameter of the longitudinal wire. This enables the device to function as a plasma actuator.

[0045] The distance from an outermost (e.g., the last) transverse wire, which is arranged longitudinally in an edge section of the rectangular mesh fabric, to each free end of the longitudinal wires (e.g., extending beyond the outermost (e.g., the last) transverse wire in the edge section) in the edge section can be 0.8 to 1.5 times (particularly advantageously 1.0 times) the distance between adjacent (e.g., immediately adjacent) transverse wires of the rectangular mesh fabric. This creates a second plasma actuator at each free end of the longitudinal wires in the edge section.

[0046] This geometry advantageously ensures simultaneous discharge in nitrogen oxide mode (i.e., nitrogen-dominated mode) and ozone mode (i.e., ozone-dominated mode). Section edges (i.e., the free ends in the boundary section, e.g., electrode edges) of the outer electrode form a non-thermal surface micro discharge (SMD ozone mode), while a volume dielectric barrier discharge (VDBD nitrogen oxide mode) forms below the outer electrode.

[0047] With regard to dielectric barrier discharge (DBE) in nitrogen oxide mode, it has been found that there are certain advantages of rectangular mesh fabrics (i.e., mesh fabrics whose meshes are rectangular but not square) over square mesh fabrics.

[0048] One of the further advantages of rectangular mesh fabrics lies in the fabric structure. Compared to square mesh fabrics, a rectangular mesh fabric has a higher wire density, which activates a larger proportion of the electrode surface. This leads to higher plasma power and a higher efficiency of the DBE (Direct Electrode Beam Energy).

[0049] Another advantage of rectangular mesh fabrics is the ability to change the orientation of the wires to control the direction of the electric field. This helps to distribute the plasma more evenly and avoid hotspots that can lead to undesirable effects, such as the formation of excessively high ozone concentrations.

[0050] According to the second aspect of the invention, a use of a device described above for plug-in assembly (e.g., for plug-in assembly as a single unit, e.g., for plug-in assembly as a single unit without disassembling the device) of the device by means of the plug-in device in a predefined opening on a reactor (e.g., a germicidal cabinet) is provided.

[0051] According to the third aspect of the invention, a method for operating an atmospheric barrier discharge device described above is provided, wherein the plug-in device has a plate-shaped base on which the at least one holding element (e.g., integral, one-piece, monolithic) is formed, the plate-shaped base having a photodiode holding element projecting from a first surface of the plate-shaped base, and the plug-in device further comprising a photodiode for monitoring the atmospheric barrier discharge, which is arranged on (e.g., in) the photodiode holding element and which is exposed to the outside (i.e., towards the plasma during operation of the device), the method comprising: applying an alternating voltage with a voltage value (e.g., a voltage amplitude) and a frequency between the inner electrode and the outer electrode to generate an atmospheric barrier discharge (e.g.,of a plasma) at the outer electrode; measuring the UV intensity of the generated atmospheric barrier discharge using the photodiode; controlling the voltage value and frequency based on the measured UV intensity so that the atmospheric barrier discharge device is operated in the region of an electrical resonance state (e.g., an electrical resonance state of the atmospheric barrier discharge device).

[0052] The method can further include: controlling the voltage value and frequency, so that an ozone-dominated plasma and a nitrogen oxide-dominated plasma are generated simultaneously and spatially separately in the atmospheric barrier discharge device.

[0053] The method may further comprise: operating the atmospheric barrier discharge device on a reactor (e.g., a disinfection cabinet); supplying filtered (e.g., dust-free) air from outside the reactor (e.g., from the atmosphere) through the atmospheric barrier discharge device; plasma-treating the supplied air by means of the atmospheric barrier discharge device; supplying the plasma-treated air into the reactor. Detailed description

[0054] The following description of various embodiments of the invention is not intended to limit the invention to any of these embodiments or corresponding details. The same reference numerals are used across the drawings for the same components. Terms such as "first," "second," etc., are intended merely to name / designate a corresponding component without defining a specific sequence or number of components, so that a component designated as a first component may also be a second component and vice versa.

[0055] Exemplary embodiments are described below with reference to the figures.

[0056] For example, in Fig. 2 , Fig. 6 , Fig. 7 , Fig. 8 and Fig. 1As shown, one embodiment provides a device 10 for atmospheric barrier discharge, which comprises: at least one hollow cylindrical dielectric 2 having an inner surface 2a and an outer surface 2b and having a dielectric constant greater than 4; a plug-in device 3 having at least one holding means 3a, 3b, 3c on which at least one inner electrode 4, 4a, 4b and at least one outer electrode 1 are arranged and on which the hollow cylindrical dielectric 2 is arranged in order to be held on the plug-in device 3; the inner electrode 4, 4a, 4b, which is arranged inside the hollow cylindrical dielectric 2 and bears against the inner surface 2a of the hollow cylindrical dielectric 2; and an outer electrode 1, which has a rectangular mesh fabric 21 and bears against the outer surface 2b of the hollow cylindrical dielectric. 2 is attached.

[0057] For example, it may be preferred that the length of the inner electrode 4, 4a, 4b (e.g. in a longitudinal / axial direction of the device) is at least twice as long as the length of the outer electrode 1 (e.g. in the longitudinal / axial direction of the device).

[0058] The plug-in device 3 can be designed so that it can be easily attached to existing (e.g., external to the invention) pipelines or various (e.g., external to the invention) reactor components (e.g., reactors).

[0059] The device can be used for disinfection and / or odor neutralization of equipment, clothing, especially shoes (boots), technical or medical products and objects, food, animals, especially beehives, and for mite removal in a closed system.

[0060] The device may also include an electrical supply unit (e.g. for supplying voltage to the inner electrode 4, 4a, 4b and to the outer electrode 1) and a control unit (e.g. for controlling the device 10 and / or for controlling the voltage supply to the device 10).

[0061] The control unit can be configured to operate the device 10 (i.e., the plasma generator) via the light intensity of the plasma with an optimal excitation energy such that (simultaneously) at least one region of the outer electrode 1 is in a nitrogen oxide mode (VDPE) and at least two regions of the outer electrode 1 are in an ozone mode (SMD, e.g. SMD mode) can be operated (e.g., operated).

[0062] For example, in Fig. 2 (left side) shown, the plugging device 3 can further have a permanent magnet 8 which is arranged coaxially to the inner electrode 4, 4a, 4b.

[0063] In this context, it was surprisingly found that the ozone concentration can be increased or decreased using a permanent magnet 8, depending on the arrangement of the poles (south or north pole relative to the inner electrode 4, 4a, 4b). It was also found that the discharges in a magnetic field are more homogeneous. This is explained by the fact that the filaments in a DBD are not uniformly distributed over the dielectric 2, but are formed from numerous microfilaments. When a magnetic field is applied, the vector of magnetic induction is perpendicular to the filaments. Consequently, a Lorentz force occurs, which influences the dimensions, uniformity, and orientation of the filaments and thus alters the ozone and nitrogen oxide concentrations. In this way, the use of a magnetic field according to one embodiment contributes to a reduction of undesirable effects. Preferably, the ionization tube (i.e.,the plasma tube) generates a magnetic field which leads from the north pole of the permanent magnet 8 through the inner electrode 4, 4a, 4b and outer electrode 1.

[0064] A further advantage arises from the fact that the plasma head (i.e. the plasma tube, e.g. the device 10) can be attached / fixed to a magnetizable material without any further fastening elements.

[0065] For example, in Fig. 2 , Fig. 6 , Fig. 7 , Fig. 8 and Fig. 1 As shown, the plugging device 3 can have a plate-shaped base 11 on which at least one holding means 3a, 3b, 3c is formed.

[0066] For example, in Fig. 2(right side) shown, the plate-shaped base 11 can further have mounting elements 3d (e.g. tabs, e.g. mounting holes) (e.g. with which the plug-in device 3 can be mounted on pipes), which are optionally arranged on an edge of the plate-shaped base 11.

[0067] For example, in Fig. 2 (left side) and Fig. 7 As shown, the plate-shaped base 11 can have a photodiode holding element 12 which projects from a first surface 13 of the plate-shaped base 11, and the plug-in device 3 can further have a photodiode 9 for monitoring the atmospheric barrier discharge, which is arranged on the photodiode holding element 12 and which is exposed to the outside.

[0068] Photodiode 9 can convert incident UV-C light into an electric current. Due to this photoelectric effect, the device 10 (e.g., the plasma actuator) can be controlled / regulated via the voltage supplied (e.g., by the control unit). Thus, the plasma intensity, which depends strongly on the humidity and temperature in addition to the excitation frequency, excitation voltage, and excitation current, can be continuously measured and controlled. Surprisingly, under atmospheric conditions, the ozone and negative ion concentrations can also be approximately determined and controlled / regulated using photodiode 9.

[0069] Alternatively, the plate-shaped base 11 can have a UV-C emitting device retaining element 12, which projects from the first surface 13 of the plate-shaped base 11, and the plug-in device 3 can further have a UV-C emitting device (e.g. a UV-C light-emitting diode, e.g. a UV-C light-emitting diode emitting in the wavelength range of 254 nm to 280 nm) 9, which is arranged on the UV-C emitting device retaining element 12 and which is exposed to the outside (e.g. (in operation of the device 10) towards the plasma).

[0070] In this context, they show Fig. 2 and Fig. 7Examples of different positions where the photodiode mounting element 12 or the UV-C emitting device mounting element 12 can be arranged are shown. The position can be chosen depending, among other things, on the desired airflow. The photodiode mounting element 12 or the UV-C emitting device mounting element 12 can advantageously contribute to air turbulence (and thus generate and / or influence an airflow).

[0071] Generally, when a dielectric barrier discharge (DBD) is irradiated with a UV-C lamp (e.g., a UV-C emitting device 9) under atmospheric conditions with a spectrum from 254 nm to 280 nm, various chemical reactions occur. These reactions are part of a complex process known as plasma chemistry. Among other things, it is known that UV-C radiation excites oxygen molecules and forms reactive oxygen species, such as singlet oxygen (O₂*) or hydroperoxyl radicals (HO₂*). According to the embodiment, all components of a dielectric barrier discharge device 10 are integrated onto (e.g., on) a connector 3 (e.g., integrally, in one piece, or monolithically).This results in the advantageous effect that the use of the plug-in device 3 makes it possible to use thinner material for the inner electrode 4, 4a, 4b compared to the prior art, and that at the same time the device 10 of the embodiment can be produced quickly and cost-effectively. The use of the plug-in device 3 also enables the inner electrode 4, 4a, 4b to be pressed against the dielectric 2 over a uniform surface by means of a first holding element 3a, 3b (e.g., a spring pin).

[0072] For example, in Fig. 6 , Fig. 7 and Fig. 8As shown, the at least one holding means 3a, 3b, 3c can have a first holding element 3a, 3b which projects from the first surface 13 of the plate-shaped base 11 (e.g., and is integrally formed thereon, e.g., formed in one piece thereon, e.g., formed monolithically thereon), and the first holding means 3a, 3b can be configured to press the inner electrode 4, 4a, 4b against the hollow cylindrical dielectric 2 with a contact pressure between 10 N / cm² and 50 N / cm². The first holding element 3a, 3b can be a spring pin.

[0073] For example, in Fig. 6As shown, the inner electrode 4, 4a can be formed from a temperature-resistant conductive elastomer (e.g., from a round hollow profile of a temperature-resistant conductive elastomer). The inner electrode 4, 4a can, for example, be a silicone-based conductive elastomer with a temperature resistance of at least 125 °C and a specific volume resistivity of 0.2 Ω*cm to 0.004 Ω*cm, particularly preferably 0.008 Ω*cm. In an assembled state, the inner electrode 4, 4a can be pressed against the inner surface 2a by means of the first retaining element 3a (e.g., across its entire surface). For example, the outer diameter of the elastomer (i.e., the inner electrode 4, 4a) before assembly (i.e., clamping) is 5% to 10%, particularly preferably 5% to 6%, smaller than the inner diameter of the cylindrical dielectric 2. Homogeneically distributed, conductive solid particles in the elastomer (i.e.,The inner electrode 4, 4a) can contain silver-coated spheres made of nickel, copper, aluminum, or glass, preferably copper. The conductive elastomer can be produced, for example, by extrusion; in this process, the conductive solid particles are aligned in a web-like manner in the axial direction, which has a positive effect on the elongation of the filaments in the SMD area.

[0074] For example, in Fig. 7 and Fig. 8As shown, the inner electrode 4, 4b can alternatively be formed from a mesh made of a paramagnetic material. For example, the inner electrode 4, 4b can have a finely structured wire mesh made of a paramagnetic material, which can be an aluminum alloy (AlMg5). A mesh size w of 0.098 mm to 0.150 mm and a wire diameter d of 0.05 mm to 0.14 mm are preferred, for example; a mesh size of 0.075 mm and a wire diameter of 0.052 mm are particularly preferred. It is true that the electron temperature of the generated plasma with an aluminum inner electrode 4, 4b can be lower than with other electrodes using silver, copper, or stainless steel due to the uniform electrical discharge (laminar ionization).It was found that when using Al internal electrodes 4, 4a, the reactive species are generated in higher concentrations—in terms of intensities, types of ions, and number of ions—than when using Ag internal electrodes, Cu internal electrodes, and stainless steel internal electrodes. With this electrode configuration of rectangular mesh fabric 21 and aluminum mesh electrode, a ratio of negative ions to positive ions of 0.9 to 1.1 is preferably achieved.

[0075] The clamping pin 3b can have a longitudinal slot 14, (in this case) the inner electrode 4, 4b can be wound around the clamping pin 3b to bear against an outer surface 15 of the clamping pin 3b, (in this case) two opposite end sections 16, 17 of the inner electrode 4, 4b can be inserted into the longitudinal slot 14, and (in this case) the hollow cylindrical dielectric 2 can be arranged around the clamping pin 3b in such a way that it presses the inner electrode 4, 4b against the outer surface 15 of the clamping pin 3b.

[0076] As in Fig. 6 and Fig. 7 As shown, the first retaining element 3a, 3b can have a through-hole 18. The through-hole can penetrate the first retaining element 3a, 3b along a longitudinal direction. Furthermore, the through-hole 18 can penetrate the plug-in device 3 as well as the plate-shaped base 11.

[0077] Furthermore, the device 10 can have an AC voltage connection line 6 which is electrically connected to the internal electrode 4, 4a, 4b. The AC voltage connection line 6 can be connected to an external power supply to supply an AC voltage to the internal electrode 4, 4a, 4b.

[0078] The AC voltage connection line 6 can be routed through the through-hole 18 of the first retaining element 3a, 3b. This allows the inner electrode 4, 4a, 4b to be supplied with a voltage from the outside (e.g., from the electrical supply unit and controlled by the control unit).

[0079] As in Fig. 6 , Fig. 7 , Fig. 2 and Fig. 1As shown, the device 10 can have a ground connection 5 which is electrically connected to the external electrode 1. For this purpose, the ground connection 5 can be crimped to and fixed to a connection section 7 of the external electrode 1 with a clamping force of 150 N / cm² to 250 N / cm², particularly preferably with 200 N / cm². The ground connection 5 can be grounded and / or connected to an earth potential.

[0080] The at least one retaining element 3a, 3b, 3c can have a second retaining element 3c, which projects from the first surface 13 of the plate-shaped base 11. The second retaining element 3c can be configured to mechanically guide the ground connection 5. The second retaining element 3c can have a U-shaped cross-section, which is open, for example, in the direction of the first retaining element 3a, 3b. This allows the second retaining element 3c, when the ground connection 5 is inserted (e.g., inserted) into the second retaining element 3c, to fix a position of the outer electrode 1 at least radially outwards and / or circumferentially.As with the photodiode holding element 12 or the UV-C emitting device holding element 12, additional air turbulence can be caused by means of the second holding element 3c, which can enhance the corresponding effects by means of the photodiode holding element 12 or the UV-C emitting device holding element 12.

[0081] As in Fig. 1 , Fig. 2 , Fig. 6 and Fig. 7 As shown, the outer electrode 1 is formed as a hollow cylinder (made of) and has transverse wires 1b and longitudinal wires 1a (cf. Fig. 3 ). The cross wires 1b are made of a conductive material.

[0082] The longitudinal wires 1a are made of a conductive material with a wire diameter that is 10% to 15% thinner than the wire diameter of the transverse wires 1b.

[0083] As in Fig. 3As shown, the transverse wires 1b (i.e., wires extending in the transverse direction) and the longitudinal wires 1a (i.e., wires extending in the longitudinal direction) can form the rectangular mesh fabric 21. The distance between adjacent transverse wires 1b can be 4 to 6 times the wire diameter of the longitudinal wires 1a.

[0084] As further in Fig. 3As shown, the distance from an outermost (e.g., last) transverse wire 19, which is arranged in a border section 20 of the rectangular mesh fabric 21 in the longitudinal direction of the rectangular mesh fabric 21, to a respective free end 30 of the longitudinal wires 1a (e.g., which extends beyond the outermost (e.g., last) transverse wire 19 in the border section 20) in the border section 20 can be 0.8 to 1.5 times (particularly advantageously 1.0 times) the distance between adjacent (e.g., immediately adjacent) transverse wires 1b of the rectangular mesh fabric 21. The respective free ends 30 can have a knife-edged or needle-like section edge (e.g., electrode edge). The configuration shown for one end of the rectangular mesh fabric 21 applies equally to the opposite end of the rectangular mesh fabric 21 (in Fig. 3(not highlighted, but shown in the result). This results in a first plasma actuator 11a at the end of the longitudinal wires 1a.

[0085] As in Fig. 9 As shown, one aspect of the invention provides for the use of a device 10 described in this application for plug-in mounting of the device 10 by means of the plug-in device 3 in a predefined opening on a reactor.

[0086] Furthermore, an aspect of the invention comprises a method according to claim 16, wherein the method comprises: applying an alternating voltage with a voltage value and frequency between the inner electrode 4, 4a, 4b (e.g., by means of the AC voltage connection line 6) and the outer electrode 1 (e.g., by means of the ground connection line 5) to generate an atmospheric barrier discharge at the outer electrode 1; measuring a UV intensity of the generated atmospheric barrier discharge (i.e., the generated plasma) by means of the photodiode 9; controlling the voltage value and the frequency based on the measured UV intensity, such that the atmospheric barrier discharge device 10 is operated in the region of an electrical resonance state (e.g., an electrical resonance state of the atmospheric barrier discharge device 10).

[0087] Furthermore, the method can include: controlling the voltage value and the frequency, so that an ozone-dominated plasma and a nitrogen-dominated plasma are generated simultaneously and spatially separated from each other in the device 10 for atmospheric barrier discharge.

[0088] Furthermore, the method can include: operating the atmospheric barrier discharge device 10 at a reactor (e.g., a disinfection cabinet); supplying filtered air from outside the reactor through the atmospheric barrier discharge device 10; plasma-treating the supplied air by means of the atmospheric barrier discharge device 10; supplying the plasma-treated air into the reactor.

[0089] In general, a dielectric barrier discharge (DBD) emits a broad range of electromagnetic radiation, including ultraviolet (UV) radiation. There are two types of UV radiation that can be emitted by a DBD: UV-C (wavelength 100 nm - 280 nm) and UV vacuum (wavelength 10 nm - 200 nm).

[0090] It was found that, with a constant gas composition, constant pressure and constant discharge geometry, the UVC radiation of an SMD plasma increases linearly with the discharge power until saturation is reached.

[0091] The UVC emission of an SMD plasma is primarily determined by the discharge power. As the discharge power increases, the UVC emission initially rises linearly. This is because higher discharge powers generate more electrons and ions in the plasma, resulting in a greater number of UVC photons.

[0092] However, there is also a saturation limit beyond which further increases in discharge power no longer lead to a significant increase in UVC emission. This can occur due to various factors, such as self-absorption of UVC radiation in the plasma or saturation of the precursor species that contribute to the generation of UVC photons.

[0093] Changes in environmental conditions, particularly humidity and temperature, alter the discharge power and thus the generation of UVC photons. By measuring the UVC radiation via photodiode 9, the plasma can be easily regulated and controlled; in particular, the power density of the SMD area can be controlled to between 0.1 W / cm² and 0.2 W / cm².

[0094] In view of the chemical properties and electrostatic physics of plasma, a core idea of ​​the present embodiment / invention is to provide a device for atmospheric barrier discharge. (e.g. a plasma module) for simultaneous operation with at least two different operating modes, which can be manufactured cheaply and without welds and chemically hazardous adhesives and can be easily integrated into existing reactors.

[0095] The excitation energies for the formation of at least two different operating modes are designed such that they lead to the formation of at least two different chemically composed plasmas. Preferably, the outer electrode 1 is / is divided into at least two segments, an inner region of the outer electrode 1 and an outer region of the outer electrode 1.

[0096] An inner area of ​​the outer electrode 1 can be made of a rectangular mesh fabric 21 with at least two different wire thicknesses (the longitudinal wires 1a and the transverse wires 1b), which forms the nitrogen oxide mode, preferably produces RNS, and the generation of the RNS is largely achieved by means of a " volume dielectric barrier discharge" (VDBD) is being carried out, be educated.

[0097] An outer area is formed by the electrode edges of the outer electrode 1, which, due to their sharp edges, leads to improved corona discharge, a more frequent occurrence of microdischarges, and a higher temperature in the discharge area. The electrode edges, which operate in ozone mode, result in a significant increase in the energy densities and effective discharge lengths of the dielectric surface discharge. This discharge at the section edges / electrode edges is generally referred to as "surface discharge." micro discharge" (SMD) is the designation.

[0098] The higher the number of filaments per unit area and time, the greater the power flux absorbed by dielectric materials, and the hotter they become. Temperature also affects ion production and ion loss. At temperatures around 100 °C, negative and positive ions can no longer be measured at sharp (e.g., sharp-edged) section edges (e.g., electrode edges).

[0099] Negative ions are also considered to have disinfectant properties. Experiments have shown that when using the device according to the invention / embodiment, the temperature at the section edges must be limited to a maximum of 80 °C, preferably below 50 °C, to ensure ideal disinfection conditions. Surprisingly, it was found that a correlation exists in that the intensity of the emitted UV-C radiation is higher at higher electrode temperatures. This intensity can be determined, for example, using a photodiode 9, and the temperature can thereby be adjusted to achieve a favorable intensity.

[0100] A complete transition from O 3 to NO X in electrical discharge currents occurs at an electrode temperature of about 90 °C.

[0101] It is known that the ozone mode requires a higher ignition voltage than the nitrogen oxide mode.

[0102] However, the micro-discharges occurring at the (e.g., sharp-edged) section edges and the effective discharge lengths at these edges reduce the required ignition voltage and enable the ozone mode. Due to the micro-discharges at the dielectric 2, the temperature at the section edges is approximately 20% higher than in the VDBD region, which further reduces the ignition voltage.

[0103] This grid-like outer electrode 1 is inherently thin and features a knife-edged or needle-like section edge at its axially oriented ends (e.g., the ends in their longitudinal direction). This results in high field strengths at the ends, where discharges occur in an atmospheric gas, such as air. This generates a creep discharge-like discharge associated with a multitude of microplasmas. This SMD area at the section edges is advantageously optimized to maximize the ozone content and minimize the nitrogen oxide content.

[0104] The maximum ozone content of the plasma generated in ozone mode (SMD range) is generally lower than the hygienic limits for ozone, which are 0.1 ppm as the threshold and 0.3 ppm as the maximum limit.

[0105] A disadvantage of using a sieve cylinder as an external electrode (e.g., a mesh external electrode) is that the warp and weft of the fabric have the same wire diameter and mesh size. Dirt, especially ammonium nitrite and ammonium nitrate, accumulates in the pores of the fabric as a white deposit. These are byproducts that primarily result from a reaction of ammonia and ozone, which are present in low concentrations in the gas being treated, particularly ambient air.

[0106] These issues are particularly noticeable in the pores of the fabric, where warp and weft wire diameters are the same. The reason lies in the fact that dead zones exist within the pores, preventing sufficient flow and thus inadequate cleaning. Using thinner wire diameters, and therefore smaller dead zones, in the discharge zone cannot eliminate this disadvantage. This is because, in the documents cited in this application, which utilize small plasma tubes, a minimum wire diameter is required under optimal operating conditions to generate gas vortices in the discharge zone.

[0107] This problem can be solved by forming the transverse wires 1b (chain) from a conductive wire with a wire diameter of 0.25 to 0.35 mm, preferably 0.315 mm, and the longitudinal wires 1a (weft) from a conductive material, preferably stainless steel, with a wire diameter 10% to 15% thinner, particularly preferably 12.5% ​​thinner than the wire diameter of the transverse wires 1b (chain).

[0108] Furthermore, the spacing between the longitudinal wires 1a (mesh size) can be between 0.30 mm and 0.5 mm, particularly preferably 0.45 mm. The spacing between the transverse wires 1b can be 3 to 4 times, particularly preferably 3.2 times, the spacing between the longitudinal wires 1a.

[0109] According to the embodiment, the wires that are 10% to 15% thinner are longitudinal wires 1a in the longitudinal direction. Longitudinal direction means that the thinner wires are parallel to the axis. (e.g. longitudinal axis, e.g.The cylinder axis) of the hollow cylindrical dielectric 2 is arranged. Thus, up to 3 times the number of thinner wires (i.e., transverse wires 1b) compared to the number of wires (i.e., longitudinal wires 1a) in the radial direction can be arranged in the axial direction.

[0110] The cross wires 1b are understood to be those wires in the rectangular mesh fabric 21 which are / will be guided tangentially around the hollow cylindrical dielectric 2. (e.g. and perpendicular to the longitudinal wires 1a).

[0111] The electrode arrangement (i.e. An arrangement of inner electrode 4, 4a, 4b and outer electrode 1) can be designed such that the dielectric barrier discharge can be induced simultaneously with two different operating modes. (e.g.is caused). The rectangular mesh fabric 21 can be designed such that the supplied excitation energy is sufficient to generate a nitrogen species (RNS)-containing plasma and simultaneously generate an oxygen species (ROS / ozone)-containing plasma.

[0112] A rectangular mesh fabric 21 can be a fabric formed from parallel longitudinal wires 1a and transverse wires 1b, interwoven at right angles to each other. The size of the meshes is usually specified in mesh size, which is the distance between the parallel wires in the longitudinal direction. (i.e. the longitudinal wires 1a) and transverse direction (i.e. the cross wires 1b) of the fabric. The mesh size can also be defined by the number of meshes per square centimeter or by the weight of the fabric per square meter.

[0113] This can be achieved with two different wire diameters of the rectangular fabric 21 of the outer electrode 1 (i.e. by having different wire diameters for the longitudinal wires 1a of the rectangular mesh fabric 21 and different wire diameters for the transverse wires 1b of the rectangular mesh fabric 21. The longitudinal wires 1a with the smaller wire diameter, which are guided axially along the hollow cylindrical dielectric 2, result in a higher electric field strength at the section edges above the hollow cylindrical dielectric 2, leading to higher power and thus to the ozone mode.

[0114] The field strength is selected based on the electrode geometry such that the length of the micro-discharges preferably between 1.0 mm and 3 mm, particularly preferably between 1.8 mm and 2.0 mm, results in / discharges on the surface of the hollow cylindrical dielectric 2 in the SMD area.

[0115] The field strength is lower on the thicker wires in the VDBD region, and therefore the excitation energy is lower than on the thinner wires of the cylindrical outer electrode 1, and the excitation energy is sufficient to produce a nitrogen-containing gas.

[0116] The rectangular mesh fabric 21 can be used as an electrode in the DBD to enlarge the discharge zone and / or increase the gas discharge efficiency. Combining different wire diameters can help to produce a more uniform discharge in the rectangular mesh fabric 21 and to modify the electric field to achieve a more effective discharge.

[0117] The device 10 according to the embodiment / invention can enable the simultaneous generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS), while avoiding the generation of ozone concentrations above 0.3 ppm.

[0118] The electrodes (i.e., the inner electrode 4, 4a, 4b and the outer electrode 1) can be designed such that the device 10 for atmospheric barrier discharge (i.e., the plasma head) functions as a plasma actuator, which generates a flow containing plasma gas by generating a plasma field.

[0119] This allows operation without forced ventilation, i.e., operation without the use of a (e.g., separate) fan. Operation with forced ventilation is also possible and enhances the mixing of the plasma gases, which are generated simultaneously in nitrogen oxide and ozone modes. This mixing effectively and stably generates highly reactive RNAs and ROS, especially N₂O₅. N₂O₅ is highly water-soluble, which enhances the germination reaction on surfaces. Surfaces, especially fabrics, have a baseline moisture level due to an ambient humidity of 20% to 60%, in which N₂O₅ is readily absorbed and effectively contributes to disinfection.

[0120] The device 10 according to the embodiment / invention can be designed to be modular and segmented. The plug-in device 3 is configured to be arranged in parallel or, particularly preferably, in series (i.e., that several plug-in devices 3 can be arranged in parallel or in series). With an increasing number of modules in series (i.e., for example, with an increasing number of separate external electrodes 1 or, for example, with an increasing number of segmented external electrodes 1) arranged on at least one dielectric 2, the total discharge power can be adapted to an airflow.

[0121] With an increasing number of segmented electrodes (e.g., outer electrode 1), the edge effect (i.e., the effect that discharges occur preferentially at (sharp) segment edges) becomes more pronounced, and many current pulses with lower amplitude can be generated / observed. The significant increase in microdischarges means that more discharge channels are generated. The main cause of this is the locally enhanced corona discharge caused by the segment edge of the electrode (e.g., outer electrode 1).

[0122] The device according to the embodiment / invention is intended for disinfection and / or odor neutralization of equipment, clothing, in particular shoes (boots), technical or medical products and objects, food, animals, in particular beehives, for mite removal in a closed system.

[0123] The plasma actuator can generate an airflow containing reactive oxygen and nitrogen species, which can be located, for example, in a closed system (reaction chamber) with a volume of max. 5 m³.

[0124] For a given plasma actuator geometry and a given resonant frequency, the excitation energy depends on the dielectric barrier voltage. According to the embodiment / invention, this voltage is adjusted so that typical filamentary microdischarges occur, starting at the sharp-edged section edges.

[0125] With a further increase in voltage, a discharge forms on the thinner wires of the rectangular mesh fabric 21 in the VDBD range. From a current of approximately 1 mA per cm² of the rectangular mesh fabric 21, a discharge begins on the thicker wires, resulting in a simultaneous discharge in both ozone and nitrogen oxide modes. After a warm-up phase of approximately 5 minutes, the optimal temperatures in the plasma actuator are established. These optimal temperatures are preferably from 20 °C to 60 °C, more preferably from 25 °C to 60 °C, and particularly preferably from 40 °C to 50 °C in the nitrogen oxide mode (VDBD range), and from 40 °C to 70 °C, and particularly preferably from 45 °C to 60 °C, and particularly preferably from 45 °C to 50 °C in the ozone mode (SMD range).

[0126] It was shown that ozone concentrations below 0.3 ppm can form at the section edges from a temperature of 50 °C.

[0127] It is also understood that the performance of a plasma unit with dielectric barrier discharge depends on the number of segments / modules.

[0128] The device 10 according to the embodiment / invention can have a ratio of the diameter of the hollow cylindrical dielectric 2 to the electrode length of the outer electrode 1 of 1 to 2, preferably of 1 to 1.8, particularly preferably of 1.2 to 1.3.

[0129] The device 10 according to the embodiment / invention can have a ratio of the length of the outer electrode 1 to the discharge width in the SMD area preferably of 3 to 10, particularly preferably of 4 to 8, most preferably of 4.4 to 4.6. This means that, with a given electrode configuration and an embodiment of the dielectric 2 according to the embodiment / invention, with a dielectric constant of 4.6 and a wall thickness s of 0.8 m, a discharge width of 1.8 mm to 2 mm can be observed at the section edges.

[0130] When using larger diameters of the dielectric 2, according to one embodiment the outer electrode 1 can be wound spirally on the dielectric 2 (see Fig. 5 above) and / or arranged in segments in modules (see Fig. 5 below) be / become.

[0131] With reference to Fig. 4It is shown that, according to one embodiment, the wires (e.g., the longitudinal wires 1a and the transverse wires 1b) in the rectangular mesh fabric 21 have different slopes 12a, 12b to the dielectric 2. The larger the spacing (mesh size) of the transverse wires 1b to each other, the smaller the angles 12a of the longitudinal wires 1a to the dielectric 2. Thus, a second plasma actuator can be generated on the longitudinal wires 1a, which is caused by a stripe-shaped discharge 11b (see Fig. 3 ) can be determined. It is generally known that in a plasma actuator, the electrode edges or wires form no or only a very small angle with respect to the dielectric 2. Therefore, the spacing of the transverse wires 1b can preferably be 4 to 6 times, and particularly preferably 5 times, the diameter of the longitudinal wire 1a. Thus, the plasma head functions as a plasma actuator.

[0132] The length of the plasma in a surface microdischarge (SMD) device at the cut edges influences ozone production and is affected by the dielectric constant. The dielectric constant is a measure of how easily a material allows electric field lines to penetrate. In an SMD, an electric field is generated between two electrodes separated by a thin layer of dielectric. The dielectric influences the distribution of the electric field and thus also the length of the plasma from the cut edges.

[0133] A higher value of the dielectric constant of the dielectric generally leads to a greater attenuation of the electric field and thus to a shorter plasma length. Conversely, a lower value of the dielectric constant leads to a lesser attenuation of the electric field and thus to a longer plasma length. For the device according to the embodiment / invention, a dielectric material with high dielectric strength and low power loss is preferably used in order to ensure effective insulation between the electrodes (i.e., the inner electrode 4, 4a, 4b and the outer electrode 1) and to achieve a high power density.

[0134] Preferably a material with a dielectric loss factor (tan φ) of 10*10 -4< to 30*10 -4< is used.

[0135] Preferably, the glass tube (i.e., the hollow cylindrical dielectric 2) can be made of borosilicate glass. The use of borosilicate glass with a wall thickness of 0.8 mm, whose dielectric constant ε is approximately between 4.3 and 5.5, preferably ε = 4.9, contributes to a discharge in which the temperature development and the duration of the discharges are particularly advantageous in the ozone mode (SMD range). In the device according to the embodiment / invention, a dielectric constant of ε = 4.9 and a dielectric loss factor (tan φ) of 22 × 10⁻⁴ are particularly preferred.

[0136] Preferably, the total power density of 0.5 W / cm² to 2.2 W / cm², particularly preferably 1.5 W / cm², can be at the entire discharge area of ​​the outer electrode 1. This results in a power density of 0.1 W / cm² to 0.2 W / cm² in ozone mode (SMD range).

[0137] Generally, a high minimum electron density is required to achieve an ignition voltage in a dielectric barrier discharge. This required minimum electron density is achieved in a dielectric barrier discharge (DBE) through charge carrier deposition on the dielectric 2 and residual conductivity of the ionized air in the gas space of the outer electrode 1. This characteristic of the DBE is also known as the memory effect. The higher the applied frequency, the more pronounced the memory effect. A high dielectric constant in combination with a frequency in the kHz range leads to increased filament formation and a weak development of the SMD area due to the memory effect.

[0138] The IM 806 ionometer from Umweltanalytik Holbach GmbH in D-66687 Wadem, for example, can be used to continuously measure the atmospheric ion concentration of positively and negatively charged oxygen ions. The measuring range is 0 to 40 million ions / cm³. In this particular configuration, a negative ion concentration of 1.1 million negative ions per cm³ is detected – under atmospheric conditions such as 47.30% relative humidity, 942 hPa, and 20 °C – at a distance of 30 cm from the plasma head.

[0139] Generally, plasma generated / operated in a high-frequency, low-voltage state exhibits the same antimicrobial activity as plasma generated / operated in a low-frequency, high-voltage state, provided the discharge power density is the same. The device 10 according to the embodiment / invention can be operated at a frequency outside the range of human hearing, specifically at its resonant frequency. Frequencies of, for example, 17 kHz to 50 kHz are preferred, depending on the capacity of the device according to the embodiment / invention. Frequencies of, for example, 20 kHz to 35 kHz are particularly preferred. At these frequencies, micro-discharges in the range of preferably 1.8 mm to 2.0 mm can be generated / detected due to the memory effect.

[0140] It was found that the dielectrics (e.g., the hollow cylindrical dielectric 2) and their properties play a crucial role in plasma formation. One of these properties is the type of dielectric material, the second is the thickness of the dielectric barrier, and the third is the surface roughness of the dielectric barrier.

[0141] Surface roughness has a significant impact on plasma generation. The rougher the dielectric surface, the more electrons it can hold and the more seed electrons it can provide for the next AC half-cycle discharge of the DBD. The surface roughness of the dielectric material reduces the electric breakdown field due to its uneven surface.

[0142] A surface roughness of Ra 1.5 µm to 10 µm is preferred, more preferably 2 µm to 8 µm, and most preferably 3 µm to 5 µm. This refers exclusively to the roughness under the outer electrode 1. For example, the surfaces in the SMD area should be smooth to increase the length of the microdischarges. For example, the roughness is preferably produced by sandblasting.

[0143] For example, the device 10 according to the embodiment / invention can be operated with a 12 V low-voltage supply. The required amount of energy can then be generated from sunlight and daylight. This is particularly advantageous when small mobile systems are operated outdoors and no (stationary) power grid is available. The 12 V low voltage is then generated via an electronic voltage regulator ranging from 600 Vrms to 1.3 kVrms.

[0144] Preferably, when using the device 10 according to the embodiment / invention, the energy input can be less than 1 watt per m³ (W / m³) in closed treatment volumes, preferably less than about 0.8 W / m³. This energy input is calculated by dividing the energy expenditure measured for the ionization of the air by the volume of the reactor system into which the air is introduced.

[0145] Preferably, the degree of ionization of the air can be less than 90 vol.%, more preferably less than 80 vol.%, in particular less than 70 vol.%, even more preferably less than 60 vol.%, even more preferably less than 50 vol.%, more preferably less than 40 vol.%, in particular less than 30 vol.%, and most preferably less than 20 vol.%. According to one embodiment, the degree of ionization as stated herein refers not to the total amount of oxygen present, but to the ozone threshold.

[0146] Within the scope of the invention, it was found that at operating temperatures of the plasma head (e.g., the device 10), after at least five minutes of operation, the degree of ionization is linearly proportional to the power density at the outer electrode 1. However, this can only be observed at operating temperatures below 60 °C and is therefore, under atmospheric conditions such as those found in the reaction chamber, a measure of the plasma intensity. According to ATEX guidelines, atmospheric conditions are generally understood to mean ambient temperatures from -20 °C to 60 °C and a pressure range between 0.8 bar and 1.1 bar.

[0147] In the course of the invention, it was unexpectedly discovered that, according to one embodiment, it is advantageous to select a low degree of air ionization and, if necessary, to carry out a longer treatment time of the volume to be treated with the weakly ionized air in order to avoid strongly oxidizing conditions in the medium. The operating temperature should also be selected accordingly.

[0148] For example, the treatment of the air volume can additionally be preferably carried out with the plasma actuator 10 in a closed system 40 in a continuous process. The generated plasma gas, which contains RNS and ROS, is then directed / guided onto the objects (e.g., items) 25 to be treated (see Fig. 9 ).

[0149] Continuous air circulation 21 can be achieved, for example, with a fan 22. Preferably, the air in the continuous circulation is treated, whereby the airflow is not necessarily directed directly onto the plasma actuator 10. Due to its electrode geometry, the device 10 according to the embodiment / invention allows for an independent airflow. For example, filtered air is particularly preferably directed from outside the reactor to the plasma actuator 10 via a flow 24. This reduces potential contamination of the plasma actuator (e.g., the device 10) by dust and dirt particles in the circulation. Dust filters 23 of ISO classes G1 to G3 are particularly preferably used for air filtration.

[0150] According to a preferred embodiment, the continuous treatment time for disinfection is between 1 minute and 120 minutes, more preferably between 20 minutes and 60 minutes, and particularly preferably between 25 minutes and 35 minutes.

[0151] The treatment of the recirculated air enriched with RNA and ROS can be carried out such that the concentrations of microorganisms and viruses on the surfaces to be treated are inactivated (log-reduced) by at least log 3, more preferably by log 4, even more preferably by log 5, and most preferably by log 6. The microbial count of the "untreated" surface, i.e., before treatment with ROS and RNA, is measured. This provides the baseline value. This baseline value is then compared with the final value measured after the plasma treatment has ended.

[0152] For example, it may be additionally preferred that in the process according to the embodiment only plasma gas, but no additional oxidizing agents, such as chlorine and chlorine gas, hydrogen peroxide or the like, are used. Quotes

[0153] [1] MJ Pavlovich, "Antimicrobial Applications of Ambient-Air Plasmas," dissertation, University of California, Berkeley, 2014. [2] WX e. al, "Mode transition of air surface micro-discharge and its effect on the water activation and antibacterial activity," Plasma Sources Science and Technology, Vol. Volume 29, No. 5, 2022. [3] ZW e. al, "Combination of NOx mode and O3 mode air discharges for water activation to produce a potent disinfectant," Plasma Sources Science and Technology, Vol. Volume 31, No. 5, 2022.

Claims

1. Device (10) for atmospheric barrier discharge, comprising: at least one hollow cylindrical dielectric (2), which has an inner jacket surface (2a) as well as an outer jacket surface (2b), and which has a dielectric constant greater than 4, a plug-in device (3) which comprises at least one holder (3a, 3b, 3c), on which at least one inner electrode (4, 4a, 4b) and at least one outer electrode (1) are arranged, and on which the hollow cylindrical dielectric (2) is arranged in order to be held on the plug-in device (3), the inner electrode (4, 4a, 4b), which is arranged inside the hollow cylindrical dielectric (2) and abuts against the inner jacket surface (2a), and an outer electrode (1) which comprises a rectangular mesh fabric (21) and which abuts against the outer jacket surface (2b) of the dielectric (2), wherein the outer electrode (1) is formed as a hollow cylinder and comprises transverse wires (1b) and longitudinal wires (1a), the transverse wires (1b) are formed from a conductive material, and characterized in that the longitudinal wires (1a) are formed from a conductive material with a wire diameter that is 10% to 15% thinner than a wire diameter of the transverse wires (1b).

2. Device (10) according to claim 1, wherein the plug-in device (3) further comprises a permanent magnet (8) which is arranged coaxially with the inner electrode (4, 4a, 4b).

3. Device (10) according to claim 1 or 2, wherein the plug-in device (3) comprises a plate-shaped base (11) on which the at least one holder (3a, 3b, 3c) is formed, wherein, optionally, the plate-shaped base (11) further comprises mounting elements (3d) which are optionally arranged at an edge of the plate-shaped base (11).

4. Device (10) according to claim 3, wherein the plate-shaped base (11) comprises a photodiode holding element (12) which protrudes from a first surface (13) of the plate-shaped base (11), and the plug-in device (3) further comprises a photodiode (9) for monitoring the atmospheric barrier discharge, which is arranged on the photodiode holding element (12) and which is exposed to the outside.

5. Device (10) according to claim 3, wherein the plate-shaped base (11) comprises a UV-C-emitting device holding element (12) which protrudes from a first surface (13) of the plate-shaped base (11), and the plug-in device (3) further comprises a UV-C-emitting device (9) which is arranged on the UV-C-emitting device holding element (12) and which is exposed to the outside.

6. Device (10) according to any of claims 3 to 5, wherein the at least one holder (3a, 3b, 3c) comprises a first holding element (3a, 3b) which protrudes from the first surface (13) of the plate-shaped base (11), and the first holder (3a, 3b) is configured to push the inner electrode (4, 4a, 4b) against the hollow cylindrical dielectric (2) with a contact pressure between 10 N / cm2 and 50 N / cm2.

7. Device (10) according to claim 6, wherein the first holding element (3a, 3b) is a spring pin.

8. Device (10) according to any one of claims 1 to 7, wherein the inner electrode (4, 4a) is formed from a temperature-resistant conductive elastomer.

9. Device (10) according to claim 8 provided that in combination with claim 6 or claim 7, wherein the inner electrode (4, 4a) is pushed against the inner jacket surface (2a) by means of the first holding element (3a).

10. Device (10) according to any one of claims 1 to 7, wherein the inner electrode (4, 4b) is formed from a mesh fabric made of a paramagnetic material.

11. Device (10) according to claim 10 provided that in combination with claim 7, wherein the spring pin (3b) comprises a longitudinal slit (14), the inner electrode (4, 4b) is wound around the spring pin (3b) so as to abut against an outer jacket surface (15) of the spring pin (3b), two opposite end portions (16, 17) of the inner electrode (4, 4b) are inserted into the longitudinal slit (14), and the hollow cylindrical dielectric (2) is arranged around the spring pin (3b) such that it pushes the inner electrode (4, 4b) against the outer jacket surface (15) of the spring pin (3b).

12. Device (10) according to any one of claims 6 to 11, wherein the first holding element (3a, 3b) has a through hole (18), the device (10) has an alternating voltage connection line (6) which is electrically connected to the inner electrode (4, 4a, 4b), and the alternating voltage connection line (6) is guided through the through hole (18) of the first holding element (3a, 3b).

13. Device (10) according to any of claims 3 to 12, wherein the device (10) comprises a ground connection line (5) which is electrically connected to the outer electrode (1), the at least one holder (3a, 3b, 3c) comprises a second holding element (3c) which projects from the first surface (13) of the plate-shaped base (11), and the second holder (3c) is configured to mechanically guide the ground connection line (5).

14. Device (10) according to claim 1, wherein the transverse wires (1b) and the longitudinal wires (1a) form the rectangular mesh fabric (21), and a distance of adjacent transverse wires (1b) is 4 to 6 times the wire diameter of the longitudinal wires (1a), wherein, optionally, a distance from an outermost transverse wire (19), which is arranged in an edge portion (20) of the rectangular mesh fabric (21) in the longitudinal direction of the rectangular mesh fabric (21), to a respective free end (30) of the longitudinal wires (1a) in the edge portion (20) is 0.8 to 1.5 times the distance of adjacent transverse wires (1b) of the rectangular mesh fabric (21).

15. Use of a device (10) according to any one of the previous claims for plug-in mounting of the device (10) by means of the plug-in device (3) in a predefined opening on a reactor.

16. Method for operating a device (10) for atmospheric barrier discharge according to any one of claims 1 to 14 provided that in combination with claim 4, wherein the method comprises: applying an alternating voltage with a voltage value and a frequency between the inner electrode (4, 4a, 4b) and the outer electrode (1) for generating an atmospheric barrier discharge at the outer electrode (1); measuring a UV intensity of the generated atmospheric barrier discharge by means of the photodiode (9); controlling the voltage value and the frequency based on the measured UV intensity so that the device (10) for atmospheric barrier discharge is operated in the region of an electrical resonance state.

17. Method according to claim 16, which further comprises: controlling the voltage value and the frequency so that, in the device (10) for atmospheric barrier discharge, an ozone-dominated plasma and a nitrogen-dominated plasma are generated simultaneously and spatially separated from each other.

18. Method according to claim 16 or 17, which further comprises: operating the device (10) for atmospheric barrier discharge on a reactor (e.g., a disinfection cabinet); supplying filtered air from outside the reactor through the device (10) for atmospheric barrier discharge; plasma treating the supplied air by means of the device (10) for atmospheric barrier discharge; supplying the plasma-treated air into the reactor.