Equipment for generating nonthermal atmospheric pressure plasma

Abstract

The present invention relates to an apparatus for generating non-thermal atmospheric pressure plasma, the apparatus comprising: a piezoelectric transformer (1) configured to ignite non-thermal atmospheric pressure plasma in a process medium; and a control circuit (11) configured to apply an input voltage to the piezoelectric transformer (1), wherein the control circuit (11) is configured to modulate the input voltage such that the piezoelectric transformer (1) generates an acoustic signal due to the modulation.

Description

[0001] This invention application is a divisional application of the invention patent application filed on March 14, 2018, with application number "201880018509.5" and invention title "Apparatus for Generating Non-thermal Atmospheric Pressure Plasma". Technical Field

[0002] This invention relates to an apparatus for generating non-thermal atmospheric pressure plasma. The apparatus particularly includes a piezoelectric transformer. The apparatus is further configured to generate acoustic signals. Background Technology

[0003] By utilizing devices capable of generating non-thermal atmospheric pressure plasma and acoustic signals, the synergistic effect between plasma and acoustic signals can be leveraged in various applications. For example, non-thermal atmospheric pressure plasma and acoustic signals within the ultrasonic frequency range can be used for cleaning and disinfection. If plasma and ultrasound are now generated using the aforementioned device, both can be used simultaneously for cleaning and disinfection, thereby achieving highly efficient cleaning and disinfection.

[0004] It is also possible to apply devices in which the acoustic signal is used only for the intended purpose. For example, an acoustic signal can be generated by producing plasma in a plasma loudspeaker. A plasma loudspeaker is characterized by linear frequency characteristics over a wide frequency range. These linear frequency characteristics exist within a frequency range in which the power of the generated acoustic signal does not vary significantly with respect to different frequencies within that range, for example, by less than 5 dB, given a preset input power. Summary of the Invention

[0005] The purpose of this invention is to provide a device capable of generating acoustic signals and non-thermal atmospheric pressure plasma.

[0006] The objective is achieved by the device according to the invention.

[0007] An apparatus for generating non-thermal atmospheric pressure plasma is proposed, the apparatus comprising: a first piezoelectric transformer configured to ignite the non-thermal atmospheric pressure plasma in a process medium; and a control circuit configured to apply an input voltage to the first piezoelectric transformer, wherein the control circuit is configured to modulate the input voltage such that the first piezoelectric transformer generates an acoustic signal due to the modulation.

[0008] This invention therefore relates to an apparatus in which a piezoelectric transformer, capable of igniting plasma at its output end, can generate not only plasma but also acoustic signals. If the input voltage applied to the piezoelectric transformer is modulated, the high voltage generated within the output range of the piezoelectric transformer is modulated. Therefore, the power of the high voltage, and thus the amplitude of the non-thermal atmospheric pressure plasma generated by the piezoelectric transformer, fluctuates according to the modulation of the input voltage. An acoustic signal is then generated due to the fluctuation in the amplitude of the generated plasma. Here, the process medium surrounding the piezoelectric transformer can oscillate. A pressure difference in the process medium caused by the change in the volume of the generated plasma flame is sensed as an acoustic signal. The pressure fluctuation caused by the modulation of the generated plasma can thus induce oscillation of the process medium, through which an acoustic signal is generated.

[0009] Several advantages can be achieved by using a piezoelectric transformer to generate plasma whose amplitude is modulated to produce sound waves.

[0010] The device can be constructed to a very small size because no transmission components are needed for transmitting sound signals. Furthermore, the system can be without mechanical inertia because mechanical diaphragms are not required when generating sound waves using plasma; instead, the oscillation of the process medium can be directly induced. Correspondingly, sound signals can be generated over a very wide frequency range. In contrast, in mechanical systems used to generate sound, the achievable upper frequency limit is usually limited by the system's inertia. If the sound signal is generated using a piezoelectric transformer, the upper frequency limit is limited by the transformer's geometry, allowing for very high upper frequency limits. Moreover, in a piezoelectric transformer, the upper frequency limit is also determined by the transformer's material and its piezoelectric and mechanical properties.

[0011] If PZT ceramic is used as the piezoelectric material in a piezoelectric transformer, the upper frequency limit is 130kHz for a component length of 30mm. For a piezoelectric transformer using lead-free ceramic as the piezoelectric material, the upper frequency limit is also approximately 130kHz when the transformer length is 50mm. The upper frequency limit can be further increased by reducing the transformer length.

[0012] Compared to systems that use coil transformers to generate plasma and sound waves, devices that generate plasma using piezoelectric transformers also have significant advantages. Because a high-voltage transformer is not required in the device according to the invention, the device can be manufactured in a small size. Correspondingly, the device can be easily integrated into a loudspeaker or loudspeaker system. Furthermore, the energy requirements of piezoelectric transformers are low. Consequently, the device can operate using a battery. This demonstrates a safety advantage compared to systems that require mains voltage to generate high power.

[0013] In the device, sufficient shielding of the piezoelectric transformer from the main electromagnetic waves is possible. However, shielding of other components of the device can be omitted. This also allows for a smaller structural size of the device.

[0014] The small size of the device, its low voltage and power requirements, and the insensitivity of the piezoelectric transformer to damage allow for a wide range of applications. For example, its application in dentistry can be considered. Here, teeth and / or gums can be cleaned and disinfected using acoustic signals and plasma within the ultrasonic frequency range. Systems requiring mains voltage to generate plasma are unsuitable for this application or can only be used with particular caution and associated additional costs, as there are safety hazards due to mains voltage. Furthermore, systems requiring mains voltage to generate plasma are generally unsuitable for dental applications due to their excessively large component size.

[0015] The medium in which the plasma is ignited can be referred to as the process medium. The process medium can be, for example, the ambient air of a piezoelectric transformer. The process medium can also be any substance that exists in the gaseous state at the applied temperature and applied pressure, all conceivable mixtures of substances that exist in the gaseous state at the applied temperature and applied pressure, aerosols containing liquid and / or solid particles suspended in a gas, liquids, or biological tissue. The applied pressure and applied temperature refer to the pressures or temperatures at which the apparatus is typically used to generate non-thermal atmospheric pressure plasma. The applied pressure is particularly atmospheric pressure. The applied pressure can be between 0.2 bar and 1.5 bar, preferably between 0.8 bar and 1.2 bar. The applied temperature is particularly room temperature. The applied temperature can be in the range of -50°C and +155°C, preferably between 0°C and 45°C.

[0016] If the process medium is a gaseous substance, this is, for example, a pure gas such as pure He, pure Ar, pure N2, pure O2, pure CO2, pure H2, or pure Cl2. Furthermore, the process medium H2O can be in the supercritical range. The process medium can be a supercritical, i.e., a pure substance that is not condensable at the applied temperature and pressure.

[0017] The process medium can be one or more of the above-mentioned pure gases or mixtures of the following gases: air, protective gas, and mixed gas. Here, the process medium is selected such that the gas state remains constant at the application temperature and application pressure.

[0018] The process medium can be a liquid aerosol in a gas or gas mixture. For example, it can be air above the dew point, saturated vapor, or a gasoline / diesel-air mixture. The process medium can also be a solid aerosol in a gas or gas mixture. For example, it can be carbon black in exhaust gas or fine dust in the air. Particularly good results can be achieved when using aerosols as a process medium for medical and technical applications. Aerosols can be, in particular, small water droplets in the air. Furthermore, the aerosol can be small droplets of H2O2 or formaldehyde. OH radicals can be generated by treating the small water droplets with the aid of plasma. In addition, the small water droplets can be used to recombine generated irritating gases, such as ozone or nitrogen oxides, thereby reducing the environmental impact caused by these gases and improving safety. The recombination of irritating gases can be further enhanced by irritating gases, particularly those used for disinfection, such as ozone dissolved in the small water droplets. The device can also be used for particulate deposition in exhaust gas streams. The equipment can also be used in steam circulation loops or in bathrooms and their ventilation circulation loops, where aerosols can also form process media.

[0019] The device can be housed within a generating unit for producing plasma and sound waves. This generating unit can be, for example, a loudspeaker, medical device, a pest control device, or a piping system. The generating unit may have an outer housing in which the device is housed. However, the device can also be used independently, i.e., without the need for a generating unit with an outer housing.

[0020] If sound waves are generated by modulation during plasma generation in a piezoelectric transformer, a subsequent interference mechanism may arise that can cause noise: the piezoelectric transformer is excited to oscillate. This oscillation can be transmitted to the transformer's mounting portion and / or the housing where the transformer is located, thereby generating an acoustic signal whose frequency substantially corresponds to the excitation frequency, by which the piezoelectric transformer operates. To prevent the resulting noise within the acoustically perceptible range, the transformer's excitation frequency is preferably chosen to be sufficiently large. For example, the excitation frequency can be greater than 100 kHz, preferably greater than 130 kHz. In this case, the vibration caused by the oscillation of the piezoelectric transformer does not generate an audible sound signal.

[0021] The generated plasma may also exhibit noise. This noise can be caused by regularly stopping plasma ignition. This interference mechanism, and the possibilities for reducing plasma noise, are then described in more detail.

[0022] Modulation can be amplitude modulation. Here, the control circuit can be configured to apply an AC voltage with a carrier frequency as input voltage to the piezoelectric transformer, and modulate the amplitude of the applied input voltage using a modulation frequency, where the modulation frequency is less than the carrier frequency. For example, the modulation frequency can be at most one-tenth of the carrier frequency. The modulation frequency here corresponds to the desired audio frequency of the sound signal to be generated. The carrier frequency can be determined by the geometry and material of the piezoelectric transformer. Its resonant frequency is determined by the component length, i.e., the distance between the input end and the output end of the piezoelectric transformer. The carrier frequency should be very close to the resonant frequency; that is, the carrier frequency should differ from the resonant frequency by only a few hertz, for example, no more than 50 Hz.

[0023] Sound signals may have frequencies within the audible frequency range and / or within the ultrasonic frequency range. For example, sound signals may have frequencies between 0 Hz and 10 Hz. 2 The frequency range is kHz. Frequency ranges between 16 Hz and 20 kHz are considered audible. The ultrasonic frequency range can range from 20 kHz to 1.6 GHz. Frequency ranges within the ultrasonic frequency range are inaudible to humans because they are too high a frequency.

[0024] The device may have a housing in which a piezoelectric transformer is disposed. The housing may be a resonant volume. The housing may be configured to eliminate ozone generated during plasma generation. Alternatively or additionally, the housing may also be configured to eliminate other irritating gases generated during plasma generation.

[0025] The housing can, for example, be a catalytically active wire braid. The wire braid can surround the transformer. Alternatively, the housing can be flared and made, for example, of copper or other metals. The housing can be a Faraday cage. The housing can be coated with MnO2 (pyrolusite). The embodiments of the housing mentioned herein respectively enable the elimination of ozone and irritating gases generated during plasma production. Accordingly, pollution by means of ozone, which can be harmful to health, can be prevented. In many applications, such as when the device is used in a loudspeaker, plasma is merely a byproduct of the desired sound wave generation. The housing provides an effective means of avoiding ozone pollution for such applications.

[0026] The housing, designed as a wire mesh or in a horn shape, can eliminate the generated ozone in a manner that does not damage or attenuate the acoustic signal generated by the transformer. The acoustic signal can exit unimpeded through openings in the wire mesh or horn shape.

[0027] The transformer can be a Rosen-type transformer. Specifically, the transformer can have an input region and an output region, to which an input voltage can be applied, wherein when the input voltage is applied, a high voltage is generated on the output side of the output region, opposite to the input region. The input voltage here is low and can, for example, originate from a battery. Plasma can be generated by means of the high voltage generated on the output side.

[0028] The transformer can have an output region where a high voltage can be generated, sufficient to ignite a non-thermal atmospheric pressure plasma in the process medium without a separate corresponding electrode. The resulting output voltage can be large enough to ionize the atoms and molecules of the process medium.

[0029] Alternatively, the device may also have a corresponding electrode, wherein the device is configured to ignite the plasma by means of a voltage generated between the output region of the piezoelectric transformer and the corresponding electrode.

[0030] Abandoning the corresponding electrode allows for a further reduction in the device's structural form. Using the corresponding electrode allows for the shaping of the generated plasma beam in a desired manner. Furthermore, by igniting the plasma near the corresponding electrode, acoustic noise that might be caused by the plasma beam can be suppressed to a great extent, or even completely, resulting in a significant quality improvement, especially for devices configured as high-frequency speakers in the audio range.

[0031] The equipment can be configured and is suitable for enabling, accelerating, or catalyzing chemical reactions. In particular, the equipment can be configured and is suitable for eliminating or reducing harmful substances such as nitrogen oxides, carbon monoxide, and / or fine dust.

[0032] The equipment can be configured for and suitable for activating or disinfecting surfaces.

[0033] The plasma noise mentioned above can be generated through the following mechanism: each time the input voltage applied to the transformer crosses zero or each half-wave, it does not actually cause plasma ignition. If the corresponding electrode is discarded, then a short circuit occurs, for example, every third to fourth zero-crossing, i.e., an interruption in plasma ignition. Therefore, plasma ignition can be superimposed on the short circuit at the frequency of the control signal, which occurs at a frequency, for example, one-quarter of the control frequency. If, for example, the control frequency is 50 kHz, then the short circuit can occur at a frequency of approximately 15 kHz. Accordingly, the short circuit can occur at frequencies within the audible range. Due to the interruption in plasma ignition, acoustically perceptible noise can thus be generated. If the plasma is now ignited near the corresponding electrode, then the interruption in plasma ignition occurs less frequently. This allows the noise frequency to be shifted into the ultrasonic range. This is particularly important when using the device in a plasma loudspeaker.

[0034] Alternatively or supplementarily, plasma noise can also be shifted into the ultrasonic range by controlling the piezoelectric transformer at a significantly higher control frequency. This is predicated on an interruption at the same frequency as plasma ignition; in this case, the noise frequency also shifts into the ultrasonic range. To avoid plasma noise in the audible spectrum, the control frequency can, for example, be greater than 100 kHz, preferably greater than 130 kHz. In this case, regularly interrupting plasma ignition only causes noise whose frequency is outside the audible range.

[0035] The process medium can be exhaust gas. In particular, it can be exhaust gas from an internal combustion engine.

[0036] In another embodiment, a dielectric barrier can be provided directly against the output side of the first piezoelectric transformer. The device is configured to capacitively couple the high voltage generated at the output side into an ignition chamber containing a process medium, thereby igniting a non-thermal atmospheric pressure plasma within the process medium. Correspondingly, in this embodiment, the plasma is not ignited directly at the output side of the transformer, but rather in an ignition chamber spatially separated from the output side by a dielectric barrier.

[0037] The dielectric resistance barrier can be, for example, a layer having glass, SiO2, or Al2O3.

[0038] Dielectric resistance can be formed by the cladding of the transformer. The cladding can completely cover the piezoelectric transformer, with the outer electrodes remaining unclad, or the cladding can cover only the output area of ​​the piezoelectric transformer.

[0039] Alternatively, the transformer can be housed within a cavity that surrounds the output region of the piezoelectric transformer. The cavity may have sidewalls that form dielectric resistance barriers. Here, the sidewalls are made of a dielectric material. The transformer can be pushed into the cavity. The cavity can also be formed by a cover that serves to secure it to a device.

[0040] Ignition of the plasma in an ignition chamber spatially separate from the piezoelectric transformer can be advantageous for certain applications. If the process medium is not gaseous but liquid or biological tissue, then ignition of the plasma in an ignition chamber spatially separate from the piezoelectric transformer is preferred to avoid direct contact between the transformer and the process medium. Liquids could otherwise damage the transformer. Biological tissue could also be damaged through direct contact with the piezoelectric transformer. If the device used to generate non-thermal atmospheric pressure plasma is used, for example, in medical devices such as endoscopes, a dielectric resistance barrier is preferably provided at the output end of the first piezoelectric transformer to prevent direct contact between the biological tissue and the transformer. This improves safety when operating medical devices.

[0041] If a tissue or liquid is used as the process medium, then the process medium can attenuate the transformer's oscillations. However, by separating the transformer and the process medium through a dielectric resistance level, it can be ensured that the process medium does not attenuate the transformer's oscillations.

[0042] In applications where plasma needs to be ignited under high pressure or high temperature, it is also advantageous to ignite the plasma in an ignition chamber separate from the transformer space. This avoids subjecting the transformer to high pressure and / or high temperature. Otherwise, high pressure and / or high temperature could damage the transformer and reduce its service life.

[0043] If the device for igniting plasma is used in a corrosive medium, at high temperature, or under high pressure, then the device is preferably configured such that only the portion of the piezoelectric transformer surrounded by the dielectric barrier is in contact with the process medium. In this case, the dielectric barrier is preferably an inert dielectric, such as glass. The rest of the device can be encapsulated by the process medium.

[0044] Alternatively, the high voltage generated by the piezoelectric transformer can be coupled into the ignition chamber via a correspondingly configured target device. For example, the target device can have a glass tube through which the piezoelectric transformer can be guided. The target device can be configured for mechanical coupling with the ignition chamber. For example, the target device can be connected to other tubes, such as part of an air conditioning system or a steam generator, through which plasma is coupled into the air conditioning system or steam generator in the aforementioned manner. Accordingly, the generated plasma can be directed to the desired application location via the target device.

[0045] Furthermore, in applications where the process medium is conductive, it is advantageous that the transformer is isolated from the process medium by a dielectric resistance level. This could be, for example, the structural metal of an air conditioning unit or a tool in which such equipment is mounted.

[0046] Furthermore, a dielectric resistance setting can also be advantageous in applications where plasma is used to generate, accelerate, or catalyze chemical reactions. For such applications, it is equally advantageous to bring a transformer into contact with the process medium without a dielectric resistance setting and to ignite the plasma directly therein.

[0047] Furthermore, the device may include a second piezoelectric transformer, wherein the control circuitry may be configured to apply an input voltage to the second piezoelectric transformer, thereby generating a non-thermal atmospheric pressure plasma through a voltage difference between the two piezoelectric transformers, wherein the first and second piezoelectric transformers are controlled with a 180° phase offset from each other. Accordingly, the plasma may be ignited, in particular, between the two transformers. The input voltage applied to the two transformers is amplitude modulated separately.

[0048] Noise can be suppressed by igniting plasma between two transformers, in a manner similar to igniting plasma between a transformer and its corresponding electrode. If the plasma is ignited between two transformers operating in opposite phases, interruptions in plasma ignition occur at a lower frequency and / or less frequently compared to ignition at adjacent corresponding electrodes. Correspondingly, the noise frequency shifts further into the ultrasonic range, making the noise acoustically imperceptible. For the sake of noise suppression, the quality of the resulting acoustic signal can be significantly improved.

[0049] The two transformers ignited between the plasma can be identical to each other. Alternatively, the transformers can differ from each other in length and / or material.

[0050] Furthermore, the device may have at least one additional piezoelectric transformer having a length different from that of the first piezoelectric transformer and / or made of a different material. The control circuitry may also be configured to modulate the input voltage applied to the additional transformer, such that the additional piezoelectric transformer also generates an acoustic signal due to the modulation.

[0051] Transformers can be operated at different frequencies. Transformers can be operated in parallel with each other. Parallel operation here means that the transformers are arranged side by side and the plasma is not ignited between the transformers. By using multiple transformers whose lengths are different and whose resonant frequencies are different from each other, the acoustic quality of the generated sound signal can be improved.

[0052] The device can be a handheld device. In particular, the handheld device can be a portable device suitable for mobile applications in different locations.

[0053] The present invention also relates to a loudspeaker having the aforementioned device. Here, the linear frequency characteristics, particularly over a very wide frequency range of the acoustic signal generated by the device, contribute significantly to the high quality of the loudspeaker. This plasma loudspeaker is theoretically very close to an ideal tweeter because it uses a process medium as a diaphragm, which can operate as ungrounded as possible and is unlikely to experience partial oscillations that would otherwise cause tone distortion in the normal diaphragm material.

[0054] The present invention also relates to an exhaust device having the aforementioned apparatus. The apparatus is particularly useful for eliminating or reducing harmful substances such as nitrogen oxides, carbon monoxide, and / or fine dust. Alternatively, the apparatus may also be used for analytical purposes, for example.

[0055] The present invention also relates to a medical device having the aforementioned apparatus. In this device, acoustic signals, particularly acoustic signals in the ultrasonic frequency range, and plasma are used for disinfection and cleaning, for example. Here, synergistic effects can be achieved through cleaning using two different signals. In the medical device, especially in non-thermal atmospheric pressure plasma, the groups contained therein or generated therefrom, as well as other generated reactive substances, particularly O3 and NO, are utilized. x It plays an important role in relevant applications, such as dental caries treatment, wound care, or surface disinfection. Plasma can be used to enhance cleaning and disinfection effects through additional combination with the generated acoustic signals. Medical devices can include, for example, probes or endoscopes.

[0056] Furthermore, the present invention relates to a device for repelling pests, the device having the aforementioned features. For example, large rats, small mice, weasels, but also dogs or children can be kept away from ultrasound. Plasma can also promote a synergistic effect in repelling pests. The device for repelling pests can be used, for example, in cars, gardens, storage rooms, or plumbing systems, such as air conditioning systems.

[0057] According to another aspect, the present invention relates to an analytical apparatus for particle analysis, the analytical apparatus having means configured and arranged to ionize particles for analytical purposes and / or for cleaning exhaust gas flow and / or for reducing associated particles.

[0058] According to another aspect, the present invention relates to a piping system having the aforementioned device, or a loudspeaker having the aforementioned device, or an exhaust device having such a device, or a medical device having such a device, or a device for pest control having such a device, or an analytical device for particle analysis having such a device. Attached Figure Description

[0059] The present invention will now be described in detail with reference to the accompanying drawings.

[0060] Figure 1 A three-dimensional view of a piezoelectric transformer is shown.

[0061] Figure 2 A schematic diagram of an apparatus for generating plasma and acoustic signals according to a first embodiment is shown.

[0062] Figure 3 A schematic diagram of a device according to a second embodiment is shown.

[0063] Figure 4 A schematic diagram of a device according to a third embodiment is shown.

[0064] Figure 5 An apparatus according to a fourth embodiment is shown, the apparatus having two transformers connected in parallel with each other.

[0065] Figure 6 A cross-section of the device according to the fifth embodiment is shown, wherein plasma ignition is performed downstream of the dielectric resistance setting.

[0066] Figure 7 A cross-section of a device according to a variant of the fifth embodiment is shown.

[0067] Figure 8 Shown in Figure 7 The image shows a three-dimensional view of the device.

[0068] Figure 9 and Figure 10 A device according to a sixth embodiment is shown.

[0069] Figure 11 The first variant of the sixth embodiment is shown.

[0070] Figure 12 A second variant of the sixth embodiment is shown.

[0071] Figure 13 and Figure 14 The third variant of the sixth embodiment is shown. Detailed Implementation

[0072] Figure 1 A perspective view of piezoelectric transformer 1 is shown. Piezoelectric transformer 1 can be used in plasma generators, particularly for producing non-thermal atmospheric pressure plasma.

[0073] The piezoelectric transformer 1 is a structural form of a resonant transformer, which is based on piezoelectricity and, unlike conventional magnetic transformers, is an electromechanical system. The piezoelectric transformer 1 is, for example, a Rosen-type transformer.

[0074] The piezoelectric transformer 1 has an input region 2 and an output region 3, wherein the output region 3 is connected to the input region 2 along the longitudinal direction z. In the input region 2, the piezoelectric transformer 1 has an electrode 4 to which an AC voltage can be applied. The electrode 4 extends along the longitudinal direction z of the piezoelectric transformer 1. The electrode 4 is alternately stacked with piezoelectric material 5 in a stacking direction x perpendicular to the longitudinal direction z. The piezoelectric material 5 is polarized along the stacking direction x.

[0075] Electrode 4 is disposed inside the piezoelectric transformer 1 and is also referred to as the internal electrode. The piezoelectric transformer 1 has a first side 6 and a second side 7, the second side being opposite to the first side 6. A first external electrode 8 is disposed on the first side 6. A second external electrode (not shown) is disposed on the second side 7. The internal electrode 4 is alternately in electrical contact with either the first external electrode 8 or the second external electrode along the stacking direction x.

[0076] Input region 2 can be controlled by a small AC voltage applied between electrodes 4. Due to the piezoelectric effect, the AC voltage applied to the input side is first converted into mechanical oscillations. The frequency of these mechanical oscillations is primarily related to the geometry and mechanical construction of the piezoelectric transformer 1.

[0077] Output region 3 has a piezoelectric material 9 and no internal electrodes. The piezoelectric material 9 in output region 3 is polarized along the longitudinal direction x. The piezoelectric material 9 in output region 3 can be the same material as the piezoelectric material 5 in input region 2, wherein piezoelectric materials 5 and 9 can differ in their polarization directions. In output region 3, the piezoelectric material 9 is formed as a single monolayer, which is completely polarized along the longitudinal direction z. Here, the piezoelectric material 9 in output region 3 has only one polarization direction.

[0078] If an alternating current is applied to electrode 4 in input region 2, a mechanical wave is formed within the piezoelectric materials 5 and 9. This mechanical wave generates an output voltage through the piezoelectric effect in output region 3. Output region 3 has an output-side end 10. A voltage is thus generated between end 10 and the end of electrode 4 in input region 2 within output region 3. A high voltage is generated at end 10 on the output side. Here, a high potential difference is also generated between the output-side end and the environment of the piezoelectric transformer, sufficient to generate a strong electric field that ionizes the process medium.

[0079] In this manner, the piezoelectric transformer 1 generates a high electric field capable of ionizing a gas or liquid through electrical excitation. Here, the molecules or atoms of the corresponding gas or liquid are ionized and plasma is formed. Ionization always occurs if the electric field strength on the surface of the piezoelectric transformer 1 exceeds the ignition field strength of the plasma. The ignition field strength of the plasma is here defined as the field strength required for the ionization of atoms or molecules.

[0080] exist Figure 1 The piezoelectric transformer shown can be used to generate acoustic signals in addition to producing non-thermal atmospheric pressure plasma. Figure 2 An apparatus for generating plasma and acoustic signals is shown. In addition to the piezoelectric transformer 1, the apparatus includes a control circuit 11 configured to apply an input voltage to the transformer 1. The input voltage is an alternating current voltage as described above, applied to the electrode 4 of the input region 2. The frequency of the input voltage is also referred to hereinafter as the carrier frequency. The frequency of the input voltage is equal to or at least approximately approximates the resonant frequency of the piezoelectric transformer 1, so that the piezoelectric transformer operates under a first harmonic.

[0081] The control circuit 11 is now configured to modulate the amplitude of the power applied to the piezoelectric transformer 1. Here, the amplitude of the input voltage applied to the piezoelectric transformer 1 is modulated using a modulation frequency. The modulation frequency is less than the carrier frequency. Based on the modulation of the input voltage amplitude, the high voltage generated in the output region 3 of the piezoelectric transformer 1 is also modulated. The power of the plasma generated by the piezoelectric transformer 1 fluctuates at the modulation frequency. Due to the fluctuations in the power of the generated plasma, an acoustic signal is generated, the frequency of which coincides with the modulation frequency.

[0082] The generated acoustic signal has a frequency range of 0 Hz to 10 Hz. 2 Linear frequency response within a frequency range of Hz. Linear frequency response here means that the amplitude of the generated acoustic signal is independent of the frequency of the signal within the given frequency range, or at least differs by less than 5 dB within the given frequency range, assuming that the input power remains constant.

[0083] The equipment also has a housing 12. The housing 12 surrounds the piezoelectric transformer 1. Figure 2 In the embodiment shown, the control circuit 11 is also disposed within the housing 12. Alternatively, the control circuit 11 may be disposed outside the housing 12.

[0084] The housing 12 may be a catalytically active wire braid. The housing 12 is configured such that acoustic signals generated by the transformer 1 can exit from the housing 12. The housing 12 is configured to absorb plasma generated by the piezoelectric transformer 1. In particular, the housing should absorb ozone (O3), which is generated during plasma generation. The housing 12 is preferably configured as a grounded and potentially catalytically active wire braid.

[0085] Alternatively, the piezoelectric transformer 1 may be partially housed within the housing 12. In another embodiment, the housing 12 surrounding the piezoelectric transformer is not provided.

[0086] Alternatively or supplementally to housing 12, the device may have an outer housing in which all other components of the device are housed. Figure 2 In the embodiment shown, the input voltage applied to the piezoelectric transformer 1 is strong enough to generate an alternating voltage in the output region 3 of the transformer 1, which ignites the plasma without a separate corresponding electrode.

[0087] Figure 3 The device according to the second embodiment is shown, wherein a corresponding electrode 13 is provided. In the second embodiment, the control circuit 11 is also configured to perform amplitude modulation on the input voltage applied to the piezoelectric transformer 1, the amplitude modulation causing the generation of an acoustic signal.

[0088] The corresponding electrode 13 is disposed upstream of the output side 10 of the piezoelectric transformer 1. The corresponding electrode 13 is connected to a defined potential, particularly a ground potential. The voltage between the output side 10 of the piezoelectric transformer 1 and the corresponding electrode 13 is used to ignite the plasma. The corresponding electrode 13 can be used as if... Figure 3 As shown in the diagram, it is disposed separately near the output area 3 of the piezoelectric transformer 1, or also corresponding to the housing 12 of the device. Alternatively, an additional external housing may be provided.

[0089] By igniting the plasma near the corresponding electrode 13, acoustic noise caused by the plasma can be suppressed to a great extent or even completely, which results in a corresponding quality improvement, especially for applications as high-frequency loudspeakers in the audio field.

[0090] Figure 4 A third embodiment of a device for generating non-thermal atmospheric pressure plasma and acoustic signals is shown. The device has two piezoelectric transformers 1 and 14. Transformers 1 and 14 are operated by a control circuit 11 with a 180° phase offset. The plasma is ignited between the two transformers 1 and 14. The control circuit 11 is further configured to modulate the amplitude of the input voltage applied to the two piezoelectric transformers 1 and 14.

[0091] The control circuit 11 can be constructed on two separate printed circuit boards, each of which is connected to a transformer 1, 14, as shown in Figure 4 As shown in the schematic diagram. Alternatively, the control circuit 11 can be configured on a single printed circuit board connected to the two transformers 1 and 14.

[0092] Igniting plasma between two piezoelectric transformers 1 and 14, which operate in phase-shifted manner, also causes a very large or complete suppression of acoustic white noise, which is induced by the plasma.

[0093] Furthermore, the device may have multiple piezoelectric transformers 1 arranged side by side, which respectively generate plasma and acoustic signals to, for example, increase acoustic power. The piezoelectric transformers 1 may differ from each other in their geometry, and thus in their respective resonant frequencies. In this case, the control circuit 11 is configured to control the piezoelectric transformers by means of different carrier frequencies.

[0094] Figure 5 The device according to the fourth embodiment is shown. The device also has two piezoelectric transformers 1 and 14. These two piezoelectric transformers 1 and 14 are arranged in parallel with each other. Correspondingly, the output ends 10 of the two piezoelectric transformers 1 and 14 face the same direction. The two piezoelectric transformers 1 and 14 have different lengths. Correspondingly, the corresponding resonant frequencies of the two piezoelectric transformers 1 and 14 are also different.

[0095] Two piezoelectric transformers 1 and 14 are connected to a control circuit 11. The control circuit 11 is configured to apply an AC voltage as an input voltage to each of the two transformers 1 and 14, wherein the frequency of the AC voltage corresponds to the resonant frequency of the respective transformer 1 or 14. The control circuit 11 is further configured to modulate the amplitude of the input voltage, wherein each of the two transformers 1 and 14 generates an acoustic signal through modulation.

[0096] The acoustic signal is thus generated through multiple piezoelectric transformers 1 and 14, the resonant frequencies of which are thus different from the frequencies of the input voltages applied to the transformers 1 and 14 by the control circuit 11. The quality of the resulting acoustic signal can therefore be improved compared to a signal generated by only a single transformer 1.

[0097] Figure 6 An apparatus according to a fifth embodiment is shown. The apparatus has a piezoelectric transformer 1 and a dielectric resistance gate 15. The dielectric resistance gate 15 is disposed directly upstream of the output end 10 of the piezoelectric transformer 1. A gap 16 is disposed between the piezoelectric transformer 1 and the dielectric resistance gate 15.

[0098] Plasma ignition takes place in ignition chamber 17, which is separated from piezoelectric transformer 1 by dielectric resistance plate 15. The process medium is located in ignition chamber 17. Correspondingly, piezoelectric transformer 1 is not in direct contact with the process medium.

[0099] Especially in applications using high-pressure and / or high-temperature and / or corrosive or aggressive process media in the ignition chamber 17, plasma generation in the ignition chamber 17, separated from the piezoelectric transformer 1 by the dielectric resistance barrier 15, is advantageous. In this case, damage to the piezoelectric transformer 1 due to high pressure, high temperature, or the process media can be avoided. It is also advantageous in applications where the process media is liquid or biological tissue, that plasma is generated in the ignition chamber 17, which is separated from the piezoelectric transformer 1 by the dielectric resistance barrier 15. Such applications could be, for example, endoscopes having a piezoelectric transformer 1 for generating non-thermal atmospheric pressure plasma.

[0100] Another advantage of plasma ignition in the ignition chamber 17, which is separated from the piezoelectric transformer 1 by the dielectric resistance barrier 15, is that the process medium does not dampen the oscillation of the piezoelectric transformer 1. This is particularly significant in the case of liquid or solid process media.

[0101] In order to achieve plasma ignition of the adjacent conductive material without damaging the piezoelectric transformer 1, plasma ignition downstream of the dielectric resistance range 15 can be advantageous.

[0102] The dielectric resistance barrier 15 can be a thin wall made of any dielectric material, such as glass, SiO2, or Al2O3. The dielectric resistance barrier 15 is configured to capacitively couple the power generated on the output side 10 of the piezoelectric transformer 1 into the ignition chamber 17, thereby triggering plasma ignition in the ignition chamber 17.

[0103] In an alternative embodiment, dielectric barrier 15 is formed by the cladding of transformer 1. In this case, the cladding may be made of a dielectric material, such as glass, SiO2, or Al2O3.

[0104] The dielectric resistance barrier 15 can be formed by a cover disposed on the piezoelectric transformer 1. The cover can be configured to deliver the process medium to the output side 10 of the piezoelectric transformer 1. The cover can be a nozzle cover.

[0105] Figure 7 A cross-section of a device according to a variant of the fifth embodiment is shown. Figure 8 A perspective view of the device is shown.

[0106] The dielectric resistance barrier 15 is not formed by a planar wall, but rather constitutes a cavity that partially extends beyond the sidewall of the piezoelectric transformer 1 in the output region 3. The piezoelectric transformer 1 can be pushed into the cavity formed by the dielectric resistance barrier 15. The cavity can, for example, cover the piezoelectric transformer 1 for one-quarter of its length. In this case, a gap 16 can be left between the piezoelectric transformer 1 and the dielectric resistance barrier 15. The plasma is ignited in an ignition chamber 17, which is separated from the piezoelectric transformer 1 by the dielectric resistance barrier 15.

[0107] Figure 9 and Figure 10 A device according to a sixth embodiment is shown.

[0108] Ignition chamber 17 is formed here via conduit 18. Conduit 18 has walls, which are made of, for example, steel. Process media can flow in any direction through conduit 18 or remain statically within conduit 18.

[0109] The equipment has multiple, for example three, piezoelectric transformers 1, 14, and 19, which are separated from the ignition chamber 17 by planar dielectric resistance barriers 15. Transformers 1, 14, and 19 are arranged along pipe 18. If the process medium flows along pipe 18, it passes sequentially through piezoelectric transformers 1, 14, and 19.

[0110] Transformers 1, 14, and 19 are installed on the outer side 20 of pipe 18. Dielectric resistance barriers 15 are installed on the inner side 21 of pipe 18. Here, the dielectric resistance barriers 15 are installed directly upstream of piezoelectric transformers 1, 14, and 19 and are separated from them only by a wall.

[0111] Each transformer 1, 14, 19 can generate a high voltage on its output end 10, which is coupled into the interior of the pipe 18 via a dielectric resistance barrier 15, i.e., coupled into the ignition chamber, where it triggers plasma ignition. A control circuit connected to each piezoelectric transformer 1, 14, 19 is configured to control each piezoelectric transformer 1, 14, 19 by means of a modulated input voltage, thereby generating an acoustic signal in the ignition chamber 17.

[0112] Figure 11 A variation of the sixth embodiment is shown. Figure 11 In the embodiment shown, the dielectric resistance barrier 15 is configured as a cavity, for example, also... Figure 7 and 8 As shown in the diagram, the wall of the conduit 18 forming the ignition chamber has a recess 22 into which a dielectric resistance barrier 15 is introduced. A piezoelectric transformer 1 is also disposed within the cavity.

[0113] Figure 12 A second variation of the described embodiment is shown. Figure 12The variant shown in the figure is the same as that in Figure 10 The difference in the embodiment shown is that only the dielectric resistance barrier 15 is provided on the inner side 21 of the pipe 18, and the piezoelectric transformer 1 is provided on the outer side 22 of the pipe 18. The number of transformer 1 and dielectric resistance barrier 15 can be arbitrarily large.

[0114] Figure 13 and 14 A third variation of the sixth embodiment is shown, in which a plurality of piezoelectric transformers 1, 14, and 19 are provided. The wall of the pipe 18 has a plurality of recesses 22, in which dielectric resistance barriers 15 are respectively provided, the dielectric resistance barriers forming cavities. A piezoelectric transformer 1, 14, or 19 is provided in each of the cavities, the piezoelectric transformers being able to generate plasma ignition inside the pipe 18.

[0115] In each of the embodiments shown here, where plasma ignition takes place in an ignition chamber 17 separate from the piezoelectric transformer 1 by a dielectric resistance plate 15, a control circuit 11 is connected to the piezoelectric transformer 1. This control circuit is configured to apply an input voltage to the transformer 1 and modulate the input voltage. An acoustic signal is generated due to this modulation. Accordingly, the acoustic signal is always generated in the ignition chamber 17 in these embodiments.

[0116] According to embodiments of this disclosure, the following notes are also disclosed:

[0117] 1. An apparatus for generating non-thermal atmospheric pressure plasma, said apparatus comprising:

[0118] A first piezoelectric transformer (1), configured to ignite a non-thermal atmospheric pressure plasma in a process medium, and

[0119] The control circuit (11) is configured to apply an input voltage to the first piezoelectric transformer (1).

[0120] The control circuit (11) is configured to modulate the input voltage so that the first piezoelectric transformer (1) generates an acoustic signal due to the modulation.

[0121] 2. The equipment described in the preceding appendix,

[0122] The modulation mentioned therein is amplitude modulation.

[0123] 3. The equipment according to any one of the foregoing notes,

[0124] The control circuit (11) is configured to apply an AC voltage having a carrier frequency as an input voltage to the first piezoelectric transformer (1) and modulate the amplitude of the applied input voltage by means of a modulation frequency, wherein the modulation frequency is less than the carrier frequency.

[0125] 4. The equipment according to any one of the foregoing notes,

[0126] The acoustic signal has a frequency in the audible frequency range and / or in the ultrasonic frequency range.

[0127] 5. The equipment according to any one of the foregoing notes,

[0128] The device has a housing (12) in which the first piezoelectric transformer (1) is disposed.

[0129] 6. The equipment described in the preceding appendix,

[0130] The housing (12) therein is a resonant volume.

[0131] 7. The equipment according to any one of the foregoing notes,

[0132] The shell (12) therein has a catalytically active metal wire braid.

[0133] 8. The equipment according to any one of Annexes 5 to 7,

[0134] The housing (12) is horn-shaped.

[0135] 9. The equipment according to any one of Annexes 5 to 8,

[0136] The housing (12) is configured to eliminate ozone generated when the plasma is ignited.

[0137] 10. The device according to any one of the foregoing notes,

[0138] The piezoelectric transformer (1) mentioned therein is a Rosen type transformer.

[0139] 11. The device according to any one of the foregoing appendices,

[0140] The first piezoelectric transformer (1) has an output region (3) where a high voltage can be generated, which is sufficient to ignite the non-thermal atmospheric pressure plasma in the process medium without a separate corresponding electrode.

[0141] 12. The equipment according to any one of Annexes 1 to 10,

[0142] The device also has a corresponding electrode (13), and the device is configured to ignite the plasma by means of a voltage generated between the output region (3) of the first piezoelectric transformer (1) and the corresponding electrode (13).

[0143] 13. The equipment according to any one of the foregoing notes,

[0144] The device is used to realize, accelerate or catalyze chemical reactions.

[0145] 14. The equipment described in the preceding appendix,

[0146] The device is used to eliminate or reduce harmful substances such as nitrogen oxides, carbon monoxide, and / or fine dust.

[0147] 15. The equipment according to any one of the foregoing notes,

[0148] The device is configured to activate or disinfect a surface.

[0149] 16. The equipment according to any one of the foregoing notes,

[0150] The process medium is a gaseous medium, a substance that exists in the gaseous state at the applied temperature and applied pressure, a mixture of substances that exist in the gaseous state at the applied temperature and applied pressure, an aerosol, liquid and / or solid particles suspended in a gas, a liquid or biological tissue.

[0151] 17. The device according to any one of the preceding appendices,

[0152] The process medium is waste gas.

[0153] 18. The equipment described in the preceding appendix,

[0154] The exhaust gas mentioned above is the exhaust gas from an internal combustion engine.

[0155] 19. The equipment according to any one of the foregoing notes,

[0156] A dielectric barrier (1) is provided upstream of the output side (10) of the first piezoelectric transformer (1), and the device is configured to capacitively couple the high voltage generated on the output side (10) into an ignition chamber (17) containing the process medium, such that a non-thermal atmospheric pressure plasma is ignited in the process medium in the ignition chamber (17).

[0157] 20. The device according to any one of the foregoing notes,

[0158] The device has a second piezoelectric transformer (14) disposed opposite to the first piezoelectric transformer (1), wherein the control circuit (11) is configured to apply an input voltage to the second piezoelectric transformer (14) such that the non-thermal atmospheric pressure plasma is generated by the voltage between the two piezoelectric transformers (1, 14), wherein the two piezoelectric transformers (1, 14) are controlled to be phase-shifted by 180° to each other.

[0159] 21. The equipment according to any one of the preceding appendices,

[0160] The device has at least one additional piezoelectric transformer (14) connected in parallel with the first piezoelectric transformer (1) and the additional piezoelectric transformer has a different length than the first piezoelectric transformer (1), wherein the control circuit (11) is configured to modulate the input voltage applied to the additional transformer (14) such that the additional piezoelectric transformer (14) generates an acoustic signal due to the modulation.

[0161] 22. The equipment according to any one of the foregoing notes,

[0162] The device in question is a handheld device.

[0163] 23. A loudspeaker having the device according to any one of the preceding appendices.

[0164] 24. An exhaust device having the equipment according to any one of Appendix 1 to 22.

[0165] 25. A medical device having the device according to any one of Annexes 1 to 22.

[0166] 26. A device for resisting pests, said device having the device according to any one of Appendix 1 to 22.

[0167] 27. An apparatus for particle analysis, the apparatus having the device according to any one of Appendices 1 to 22, wherein the apparatus is configured and constructed to ionize particles for analytical purposes and / or for cleaning exhaust gas flow and / or for reducing the associated particles.

[0168] 28. A piping system having a device according to any one of Appendix 1 to 22, or a loudspeaker according to Appendix 23, or an exhaust device according to Appendix 24, or a medical device according to Appendix 25, or a device for pest control according to Appendix 26, or a device for particle analysis according to Appendix 27.

[0169] List of reference numerals in the attached diagram:

[0170] 1. Piezoelectric Transformer

[0171] 2 Input Area

[0172] 3 Output Area

[0173] 4 electrodes

[0174] 5. Piezoelectric materials

[0175] 6 First side view

[0176] 7 Second side view

[0177] 8 First external electrode

[0178] 9. Piezoelectric materials

[0179] 10 Output side terminal

[0180] 11 Control Circuit

[0181] 12. Shell

[0182] 13 Corresponding electrodes

[0183] 14. Piezoelectric Transformer

[0184] 15 Dielectric Resistance Range

[0185] 16 gaps

[0186] 17 Ignition Room

[0187] 18 pipes

[0188] 19. Piezoelectric Transformer

[0189] 20 Outer side

[0190] 21 Inner side

[0191] 22 recess

[0192] x Stacking direction

[0193] z Longitudinal direction

Claims

1. An apparatus for generating non-thermal atmospheric pressure plasma, said apparatus comprising: A first piezoelectric transformer (1) is configured to ignite a non-thermal atmospheric pressure plasma in a process medium, and Control circuit (11), configured to apply an input voltage to the first piezoelectric transformer (1), The control circuit (11) is configured to modulate the input voltage so that the first piezoelectric transformer (1) generates an acoustic signal due to the modulation.

2. The device according to claim 1, The modulation mentioned therein is amplitude modulation.

3. The device according to claim 1 or 2, The control circuit (11) is configured to apply an AC voltage having a carrier frequency as an input voltage to the first piezoelectric transformer (1) and modulate the amplitude of the applied input voltage by means of a modulation frequency, wherein the modulation frequency is less than the carrier frequency.

4. The device according to claim 1 or 2, The acoustic signal has a frequency in the audible frequency range and / or in the ultrasonic frequency range.

5. The device according to claim 1 or 2, The device has a housing (12) in which the first piezoelectric transformer (1) is disposed.

6. The device according to claim 5, The housing (12) therein is a resonant volume.

7. The device according to claim 6, The shell (12) therein has a catalytically active metal wire braid.

8. The device according to claim 5, The housing (12) is flared.

9. The device according to claim 5, The housing (12) is configured to eliminate ozone generated when the plasma is ignited.

10. The device according to claim 1 or 2, The first piezoelectric transformer (1) is a Rosen type transformer.

11. The device according to claim 1 or 2, The first piezoelectric transformer (1) has an output region (3) where a high voltage can be generated, which is sufficient to ignite the non-thermal atmospheric pressure plasma in the process medium without a separate corresponding electrode.

12. The device according to claim 1 or 2, The device also has a corresponding electrode (13), and the device is configured to ignite the plasma by means of a voltage generated between the output region (3) of the first piezoelectric transformer (1) and the corresponding electrode (13).

13. The device according to claim 1 or 2, The device is used to realize, accelerate or catalyze chemical reactions.

14. The device according to claim 13, The device is used to eliminate or reduce harmful substances.

15. The device according to claim 14, The hazardous substances mentioned are nitrogen oxides, carbon monoxide, and / or fine dust.

16. The device according to claim 1 or 2, The device is configured to activate or disinfect a surface.

17. The device according to claim 1 or 2, The process medium is a gaseous medium, a substance that exists in the gaseous state at the applied temperature and applied pressure, a mixture of substances that exist in the gaseous state at the applied temperature and applied pressure, an aerosol, liquid and / or solid particles suspended in a gas, a liquid or biological tissue.

18. The device according to claim 1 or 2, The process medium is waste gas.

19. The device according to claim 18, The exhaust gas mentioned above is the exhaust gas from an internal combustion engine.

20. The device according to claim 1 or 2, A dielectric barrier is provided upstream of the output side (10) of the first piezoelectric transformer (1), and the device is configured to capacitively couple the high voltage generated on the output side (10) into the ignition chamber (17), in which the process medium is present, so that a non-thermal atmospheric pressure plasma is ignited in the process medium in the ignition chamber (17).

21. The device according to claim 1 or 2, The device has a second piezoelectric transformer (14) disposed opposite to the first piezoelectric transformer (1), wherein the control circuit (11) is configured to apply an input voltage to the second piezoelectric transformer (14) such that the non-thermal atmospheric pressure plasma is generated by the voltage between the first piezoelectric transformer (1) and the second piezoelectric transformer (14), wherein the first piezoelectric transformer (1) and the second piezoelectric transformer (14) are controlled with a phase offset of 180° from each other.

22. The device according to claim 1 or 2, The device has at least one additional piezoelectric transformer connected in parallel with the first piezoelectric transformer (1) and the additional piezoelectric transformer has a different length than the first piezoelectric transformer (1), wherein the control circuit (11) is configured to modulate the input voltage applied to the additional transformer, such that the additional piezoelectric transformer generates an acoustic signal due to the modulation.

23. The device according to claim 1 or 2, The device in question is a handheld device.

24. The device according to claim 1 or 2, The amplitude of the non-thermal atmospheric pressure plasma generated by the first piezoelectric transformer (1) fluctuates according to the modulation of the input voltage.

25. The device according to claim 1 or 2, The power of the non-thermal atmospheric pressure plasma generated by the first piezoelectric transformer (1) fluctuates at the modulated frequency.

26. The device according to claim 1 or 2, The acoustic signal is generated due to the power fluctuations in the non-thermal atmospheric pressure plasma, and its frequency is consistent with the modulation frequency.

27. The device according to claim 1 or 2, The device described herein is configured for use in dentistry.

28. The device according to claim 1 or 2, The device is configured to clean and disinfect teeth and / or gums by means of plasma and acoustic signals in the ultrasonic frequency range.

29. The device according to claim 1, The first piezoelectric transformer, which can ignite plasma at its output end, can generate not only plasma but also acoustic signals.

30. A loudspeaker having the device according to any one of claims 1 to 29.

31. An exhaust device having the equipment according to any one of claims 1 to 29.

32. A medical device having the device according to any one of claims 1 to 29.

33. The medical device according to claim 32, The medical device described herein is designed for the treatment of dental caries or for the treatment of wounds.

34. The medical device according to claim 32 or claim 33, The medical device mentioned is a probe or endoscope.

35. A device for resisting pests, the device having the means according to any one of claims 1 to 29.

36. An apparatus for particle analysis, the apparatus having the apparatus according to any one of claims 1 to 29, wherein the apparatus is configured and constructed to ionize particles for analytical purposes and / or for cleaning exhaust gas flow and / or for reducing associated particles.

37. A piping system having the device according to any one of claims 1 to 29, or the loudspeaker according to claim 30, or the exhaust device according to claim 31, or the medical device according to claim 32, or the device for pest control according to claim 35, or the device for particle analysis according to claim 36.

38. An apparatus for generating non-thermal atmospheric pressure plasma, the apparatus comprising: A first piezoelectric transformer (1) is configured to ignite a non-thermal atmospheric pressure plasma in a process medium, and Control circuit (11), configured to apply an input voltage to the first piezoelectric transformer (1), The control circuit (11) is configured to modulate the input voltage such that the first piezoelectric transformer (1) generates an acoustic signal due to the modulation. The power of the non-thermal atmospheric pressure plasma generated by the first piezoelectric transformer (1) fluctuates at the modulated frequency, and The acoustic signal is generated by the power fluctuations in the non-thermal atmospheric pressure plasma, and its frequency is consistent with the modulation frequency.

39. An apparatus for generating non-thermal atmospheric pressure plasma, said apparatus comprising: A first piezoelectric transformer (1) is configured to ignite a non-thermal atmospheric pressure plasma in a process medium, and Control circuit (11), configured to apply an input voltage to the first piezoelectric transformer (1), The control circuit (11) is configured to modulate the input voltage such that the first piezoelectric transformer (1) generates an acoustic signal due to the modulation. The amplitude of the non-thermal atmospheric pressure plasma generated by the first piezoelectric transformer fluctuates according to the modulation of the input voltage, thereby causing a change in the volume of the generated plasma flame. This change creates a pressure difference in the process medium, which is perceived as an acoustic signal.

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