Device and method for plasma generation in a wide pressure range, and system and method for optical gas analysis / detecting using such a device

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a device and a method for plasma generation. Furthermore, the invention relates to a system for optical gas analysis and / or gas detection, for example, a measuring device for determining a gas composition or for detecting a specific gas, using such a device, and a method for operating the system.

[0002] The present invention belongs to the technical field of plasma generation, the ionization and excitation of molecules and ions to generate plasma light, and further the measurement and evaluation of information about the gas composition of the generated plasma. BACKGROUND OF THE INVENTION

[0003] Optical emission spectrometry (OES) is frequently used for the quantitative and qualitative analysis of gaseous samples. This method is based on the fact that excited atoms emit electromagnetic radiation characteristic of the chemical element, thus providing information about the composition of the sample. The atoms are excited, for example, by converting the sample into a plasma state. Common instruments for optical emission spectrometry each use a specific plasma source, in which plasma generation functions consistently and stably within a defined pressure range. However, many applications involve a very wide pressure range, where the gas composition plays a crucial role and therefore needs to be measured, controlled, or monitored.Therefore, a large number of plasma-generating instruments are required, resulting in high expenditures in terms of electronics, software, space, energy, and costs. Thus, multiple measuring devices such as spectrometers and multiple flange ports are required on the system where the gas is to be analyzed over a wide pressure range. Known systems for optical emission spectrometry are mentioned in US 2010 / 224322 A1, EP 3 702 760 A1, and WO 2021 / 052600 A1.

[0004] There is therefore a need to develop instruments that enable stable generation of a plasma and its emission light in or over a large pressure range, e.g. from 10 -8 < Torr (high vacuum) to 1500 Torr (> normal pressure), with minimal spatial requirements and the lowest possible expenditure on electronics, software, energy and costs. SUMMARY OF THE INVENTION

[0005] An object of the present invention is to provide a device for plasma generation in (or across) a wide pressure range, which can be connected to a system (or a system) from which a gas is to be analyzed and / or detected in the most space-saving manner possible, and which is less complex and more cost-effective than known plasma generation devices. This object is achieved according to the invention by the device according to claim 1.

[0006] Furthermore, it is an object of the present invention to provide a system for optical gas analysis or gas detection that includes such an advantageous device for plasma generation. This object is achieved by the system according to claim 16.

[0007] It is also an object of the present invention to propose a corresponding method for plasma generation in (or over) a large pressure range. Such a method is specified in claim 17.

[0008] Furthermore, it is an object of the present invention to propose a corresponding method for optical gas analysis or gas detection. Such a method is specified in claim 20.

[0009] Specific embodiments of the invention are specified in the dependent claims.

[0010] A device according to the invention for generating plasma in a wide pressure range comprises: a first plasma source, wherein the first plasma source is arranged in a first discharge chamber and is designed to generate a first plasma in a low-pressure region, wherein the low-pressure region extends in particular to a high vacuum, e.g. up to 10 -8 < Torr; a second plasma source, wherein the second plasma source is arranged in a second discharge chamber and is designed to generate a second plasma in a high-pressure region, wherein the high-pressure region extends in particular to above normal pressure, e.g. up to 1500 Torr; a first coupling element, in particular with a flange, for coupling the device to a system (in particular a gas source), wherein the coupling element is designed to lead gas out of the system; a second coupling element for coupling the device to an optical sensor, such as a photodiode or a spectrometer, for optical gas analysis orGas detection (or gas pressure measurement), . wherein the first discharge chamber has a first optical connection with at least one optical lens to the second coupling element and the second discharge chamber has a second optical connection with at least one optical lens to the second coupling element (wherein the optical lens can be a common optical lens of the first and second optical connections).

[0011] The device according to the invention is therefore characterized in that it can generate at least two different discharge forms, i.e. it has two or more plasma sources which are (together) integrated in this (single) device. Furthermore, the device has only one (connecting) flange with which it can be connected to the system with the gas to be analyzed, and it also has only one coupling to a (single) optical sensor, such as a spectrometer, in order to carry out the optical gas analysis over the entire pressure range, e.g. from 10 -8 < Torr to 1500 Torr. The (two) discharge chambers of the (two) plasma sources can be arranged parallel to one another or in series (one after the other), and the gas to be analyzed or detected can be supplied to the individual discharge chambers in parallel or passed from one discharge chamber to the next.A combination of discharge chambers arranged in parallel / side by side and in series / series with plasma sources that are fluidically connected to each other or decoupled in a gas-tight manner is also conceivable.

[0012] The light emitted by the respective plasma is guided via an optical connection from the respective discharge chamber to the second coupling element (in front of the optical sensor). Each optical connection has an optical lens; for example, two optical connections can also share a common optical lens. In addition to one or more optical lenses, the optical connections can also include suitable light guides (elements) such as fibers, tubes, or rods.

[0013] In one embodiment of the device, the low-pressure region and the high-pressure region together extend over a pressure range of at least 10 decades, in particular over 12 decades (e.g. in Torr).

[0014] In a further embodiment of the device, the low pressure range and the high pressure range overlap, in particular over a pressure range of one decade, e.g. from 0.35 Torr to 3.5 Torr.

[0015] In a further embodiment of the device, the first and second plasma sources are different plasma sources, e.g. one each from the group consisting of a glow discharge source (cold cathode source), a silent discharge source (dielectric barrier discharge or dielectrically hindered discharge, DBE; dielectric barrier discharge, DBD), a radio frequency plasma source (RF plasma source), a microwave plasma source (-> normal / atmospheric pressure plasma) and an inductively coupled plasma source (ICP source).

[0016] In a further embodiment of the device, the first discharge chamber is fluidically coupled to the second discharge chamber (in particular, the same or almost the same pressure prevails in both discharge chambers).

[0017] In a further embodiment of the device, the first discharge chamber is decoupled from the second discharge chamber in a gas-tight manner.

[0018] In a further embodiment of the device, gas can be fed from the first coupling element into the first discharge chamber and from the first into the second discharge chamber.

[0019] In a further embodiment of the device, gas can be supplied separately from the first coupling element into the first discharge chamber and into the second discharge chamber.

[0020] In a further embodiment of the device, an optical lens is arranged between the first discharge chamber and the second discharge chamber, which is part of the first optical connection.

[0021] In a further embodiment of the device, the second coupling element comprises an optical lens which is part of the first and / or the second optical connection.

[0022] In a further embodiment of the device, the second optical connection is part of the first optical connection, ie the two optical connections overlap partially or in sections.

[0023] In a further embodiment, the device further comprises a pressure sensor. The pressure sensor can, for example, be one of the following: Pirani thermal conduction vacuum gauges (for a measuring range from approximately 10 -3 < Torr to 1 Torr); Penning cold cathode ionization vacuum gauges (for a measuring range from approximately 10 -7 < Torr to 10 -3 < Torr); Bayard-Alpert hot cathode ionization vacuum gauges (for a measuring range from approximately 10 -12 < Torr to 10 -3 < Torr); capacitance diaphragm (vacuum) gauges (CDG; for a measuring range from approximately 10 -5 < Torr to 10 3 < Torr).

[0024] In order to cover a large pressure range, e.g. from 10 -8< Torr to 1500 Torr, the device can also have several pressure sensors.

[0025] In a further embodiment, the device further comprises a controller which is designed to control the first and / or the second plasma source, in particular to switch the first and / or the second plasma source on or off, depending on the pressure (or pressures) determined with the aid of the pressure sensor (or pressure sensors).

[0026] In a further embodiment of the device, the first discharge chamber and the second discharge chamber are cylindrical and arranged one behind the other (in series) coaxially (on a common cylinder axis), wherein the first coupling element is arranged on the first discharge chamber and the second coupling element is arranged on the second discharge chamber, wherein the first plasma source is in particular a glow discharge source (cold cathode source) and wherein the second plasma source is in particular a silent discharge source (for dielectric barrier discharge).

[0027] In a further embodiment of the device, an anode of the first plasma source is glazed in a vacuum-tight manner in a feedthrough through the optical lens in the second coupling element, and in particular also (e.g. vacuum-tight) in a feedthrough through the optical lens which is arranged between the first discharge chamber and the second discharge chamber, and the two feedthroughs are arranged in particular centrally in the two optical lenses, and the anode extends coaxially (on the common cylinder axis of the two discharge chambers) through the second discharge chamber into the first discharge chamber.

[0028] In a further embodiment of the device, the second plasma source has a high-voltage electrode and a ground electrode, wherein the high-voltage electrode is embedded in a dielectric which forms at least part of an inner wall of the second discharge chamber, and the ground electrode is arranged concentrically to the high-voltage electrode within the second discharge chamber and along the inner wall, at a distance of less than 1 mm, in particular between 0.05 mm and 0.5 mm, from the high-voltage electrode, in particular on a hollow cylinder, e.g. made of ceramic, wherein there is a gap between the inner wall and the ground electrode, in which gap a discharge zone with a plasma (namely the second plasma) forms when an alternating voltage is applied between the high-voltage electrode and the ground electrode, e.g. with a voltage in the range of ±1 to ±10 kV and a frequency in the range of 1 to 10 kHz.For example, the voltage curve can change from -5 kV to +5 kV and back again over one period of the alternating voltage, i.e. a voltage of 10 kV pp (peak-to-peak) can be applied. The voltage curve can, for example, correspond to a sine wave. A rectangular voltage is also possible. It is advantageous to vary the voltage from positive to negative relative to ground potential. In this way, a significantly more stable plasma is obtained than, for example, by varying between zero (GND) and positive voltage or between zero (GND) and negative voltage. The high-voltage electrode and the ground electrode can, for example, both be designed as thin-walled hollow cylinders. These two electrodes can also be segmented, i.e. made up of conductive strips that lie next to each other on a cylindrical surface.

[0029] In a further embodiment of the device, the high-voltage electrode is connectable to ground (e.g. switchable / controlled) for operation of the first plasma source and is connectable to a high-voltage alternating current source (e.g. switchable / controlled) for operation of the second plasma source, and / or the anode is connectable (e.g. switchable or controlled) for operation of the first plasma source to a high-voltage direct current source (e.g. 3.3 kV DC voltage) and is connectable to ground (e.g. switchable / controlled) for operation of the second plasma source.

[0030] In a further embodiment of the device, a coaxial arrangement of the anode (in particular) within the first discharge chamber, wherein the discharge chamber serves as the cathode, and a radial arrangement of the high-voltage electrode and the ground electrode (on the inner wall of the second discharge chamber) result in a first plasma generated by the first plasma source forming on the cylinder axis of the first discharge chamber and first light emitted by the first plasma propagating in particular axially towards the second coupling element, and in a second plasma generated by the second plasma source forming on the inner wall of the second discharge chamber and second light emitted by the second plasma propagating in particular obliquely to the cylinder axis of the second discharge chamber towards the second coupling element, so that the first light and the second light strike the optical lens in the second coupling element from different directions.

[0031] In another variant of the device, the anode is made of molybdenum.

[0032] In another variant of the device, the first discharge chamber is made of titanium.

[0033] In another version of the device, the high-voltage electrode is made of platinum.

[0034] In another embodiment of the device, the dielectric is made of sapphire (Al 2 O 3 ).

[0035] In another variant of the device, the ground electrode is made of molybdenum.

[0036] In a further embodiment of the device, the optical lens or lenses are made of sapphire (Al 2 O 3 ).

[0037] According to a further aspect of the present invention, a system for optical gas analysis or gas detection (or gas pressure measurement) comprises: a device for plasma generation according to one of the above-specified embodiments; a gas source, wherein the device for plasma generation is coupled to the gas source by a first coupling element, in particular by a flange; an optical sensor, such as a photodiode or a spectrometer for optical gas analysis or gas detection (or gas pressure measurement), wherein the device for plasma generation is coupled to the optical sensor by a second coupling element.

[0038] According to a further aspect of the present invention, a method for generating plasma in a large pressure range by means of the device for generating plasma according to one of the above-mentioned embodiments comprises the following steps: Feeding a gas from a system via a first coupling element into a first discharge chamber with a first plasma source and / or into a second discharge chamber with a second plasma source; generating a first plasma by the first plasma source in a low-pressure region in the first discharge chamber, wherein the low-pressure region extends in particular to high vacuum, ie for example to 10 -8< Torr, and / or generating a second plasma by the second plasma source in a high-pressure region in the second discharge chamber, wherein the high-pressure region extends in particular to above normal pressure, iefor example up to 1500 Torr; guiding light emitted by the first plasma from the first discharge chamber via a first optical connection with at least one optical lens and / or light emitted by the second plasma from the second discharge chamber via a second optical connection with at least one optical lens to a second coupling element for coupling the device to an optical sensor, such as a photodiode or a spectrometer; coupling out at least part of the light emitted by the first and / or the second plasma through the second coupling element.

[0039] In one embodiment of the method, the second plasma source is a silent discharge source with a high-voltage electrode and a ground electrode, wherein an alternating voltage is applied between the high-voltage electrode and the ground electrode to generate the second plasma, e.g. with a voltage in the range of ±1 to ±10 kV and a frequency in the range of 1 to 10 kHz.

[0040] In a further embodiment of the method, the first and / or the second plasma source is controlled depending on the pressure determined with the aid of a pressure sensor, in particular the first and / or the second plasma source is switched on or off.

[0041] In a further embodiment of the method, in a pressure range in which the low-pressure range and the high-pressure range overlap, e.g. in a pressure range from 0.35 Torr to 3.5 Torr, the first and second plasma sources simultaneously generate a first and a second plasma.

[0042] According to a further aspect of the present invention, a method for optical gas analysis or gas detection (or gas pressure measurement) comprises carrying out the steps according to one of the above-mentioned embodiments of the method for plasma generation and further the following steps: Directing the outcoupled light to an optical sensor, such as a photodiode or a spectrometer; determining a gas or components of a gas or detecting a specific gas or components of a gas (or determining a pressure of a gas) based on the outcoupled light, in particular an intensity and / or a spectral distribution of the outcoupled light.

[0043] If the first and second plasma sources simultaneously generate a first and a second plasma in a pressure range where the low-pressure and high-pressure ranges overlap, for example, in a pressure range from 0.35 Torr to 3.5 Torr, this leads to increased sensitivity in optical gas analysis or gas detection due to the higher (e.g. twice) intensity of the light from both plasmas. This can be useful, for example, for trace gas detection. Such simultaneous plasma generation by the first and second plasma sources can also be helpful in identifying or determining the partial proportion of a trace gas (partial pressure / concentration), since the fractionation of the gas by the two plasmas is different. Furthermore, it is possible to use the analysis result of the light from the first (or second) plasma to correct or compare the analysis result of the light from the second (or first) plasma.to use one to calibrate the other.

[0044] It should be noted that combinations of the above-mentioned embodiments are possible, which in turn lead to more specific embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Non-limiting embodiments of the present invention are explained in more detail below with reference to the figures. They show: Fig. 1 is a schematic representation of an embodiment of a device according to the invention for plasma generation in a large pressure range; Fig. 2 is a longitudinal section through an embodiment of a device according to the invention for plasma generation in a large pressure range with dimensions; Fig. 3 is an alternative representation of the longitudinal section through the embodiment according to Fig. 2 with plasma areas marked Fig. 4 a variant of the device; and Fig. 5 a further variant of the device.

[0046] In the figures, the same reference symbols represent the same elements. DETAILED DESCRIPTION OF THE INVENTION

[0047] Fig. 1 shows a schematic representation of an embodiment of a device according to the invention for plasma generation in a large pressure range. The device comprises a first plasma source 1, e.g. a glow discharge source (GD, cold cathode source), which is arranged in a first discharge chamber 2, and a second plasma source 3, e.g. a silent discharge source (DBD source), which is arranged in a second discharge chamber 4, wherein the two discharge chambers 2, 4 are arranged one behind the other (in series), adjacent to one another. The device further comprises a first coupling element 5, e.g. with a flange, for coupling the device to a system (not shown) in which a gas is located. The gas is led from the system into the first discharge chamber 2 via the coupling element 5. The gas can flow from the first discharge chamber 2 into the second discharge chamber 4.For this purpose, for example, several (e.g. 6 to 12) ventilation holes, each with a diameter of at least 1 mm, are located between the two discharge chambers 2, 4. Furthermore, the device comprises a second coupling element 6 for coupling the device to an optical sensor, such as a photodiode or a spectrometer, for optical gas analysis or gas detection (or also for gas pressure measurement).

[0048] The first plasma source 1 is suitable for generating a plasma in a low-pressure range, e.g., from 10-8< Torr to approximately 3.5 Torr, and the second plasma source 2 is suitable for generating a plasma in a high-pressure range, e.g., from approximately 0.35 Torr to 1500 Torr. Depending on the pressure of the gas, the first (at low pressure -> high vacuum) or the second (at atmospheric pressure) plasma source 1, 3 will ignite the gas and thereby generate a first or second plasma 14, 15, which emits different light depending on the type or composition of the gas. In the pressure overlap range of the two plasma sources 1, 3, e.g., from 0.35 Torr to 3.5 Torr, both plasma sources 1, 3 can be active at the same time and thus generate a first and a second plasma 14, 15 simultaneously. This parallel operation of both plasma sources 1, 3 is particularly possible because of the low power of both discharges.

[0049] The light emitted by the first plasma 14 in the first discharge chamber 2 is guided through an optical lens 7, which is located between the two discharge chambers 2, 4. The light is then guided through the second discharge chamber 4 and passes through a second optical lens 8, which is located in the second coupling element 6, to an optical sensor 12, with the aid of which an optical gas analysis or gas detection (or also a gas pressure measurement) can be carried out. The optical sensor 12 is sensitive in the wavelength range that can be transmitted through the two optical lenses 7, 8. The optical sensor 12 can be a simple radiation sensor, e.g. a light sensor such as a photodiode, but it can also be a more complex optical sensor, e.g. a spectrometer.

[0050] The anode 9 of the first plasma source 1 is guided from the second coupling element 6 through the second optical lens 8 in the second coupling element 6, through the second discharge chamber 4, through the first optical lens 7 between the two discharge chambers 2, 4, and into the first discharge chamber 2. The anode 9 is, in particular, glazed in a vacuum-tight manner in a feedthrough through the optical lens 8 in the second coupling element 6. The anode 9 can also be glazed in a feedthrough through the optical lens 7 between the two discharge chambers 2, 4. The feedthrough through the optical lens 7 can also be vacuum-tight, although this is not absolutely necessary. The two feedthroughs are, in particular, arranged centrally in the two optical lenses 7, 8, such that the anode 9 extends coaxially through the second discharge chamber 4 into the first discharge chamber 2.

[0051] The cathode of the first plasma source 1 is located at the edge of the first discharge chamber 2, spaced from the anode 9. The inner wall of the first discharge chamber 2 can form the cathode. The cathode is made of titanium, for example. To generate a glow discharge of the gas, a high direct voltage (HV DC), for example, of 3.3 kV, is applied between the anode 9 and the cathode. This high voltage accelerates electrons from the cathode material toward the anode 9. By applying an external magnetic field using (permanent) magnets 13, the electrons are guided onto circular or spiral paths. This increases the probability of collision with an atom / molecule of the gas. These collisions lead to the excitation or ionization of the atom / molecule. The ions migrate toward the cathode, thus generating an ion current. Photons are generated, on the one hand, by relaxation of the excited atoms, molecules, or ions, and, on the other hand, by recombination of these ions.The emitted photons radiate throughout the room and, among other things, strike the first optical lens 7 between the two discharge chambers 2, 4. Here, the incoming photons are refracted and guided to the second optical lens 8 in the second coupling element 6. The optical lenses 7, 8 can be made of one or more materials, e.g., sapphire, and can have an aspherical shape to counteract spherical or chromatic aberration.

[0052] The optical wavelength range includes electromagnetic radiation with wavelengths from 100 nm to 1 mm, i.e. in particular the ranges of visible light, ultraviolet radiation and infrared radiation.

[0053] Details regarding the second plasma source 3, i.e., the device for generating a silent plasma discharge, can be found in the Swiss patent application entitled "Vacuum feedthrough, electrode arrangement, and device for generating a silent plasma discharge," filed on the same day as the present patent application by the same applicant as the present patent application. The second plasma source 3 has a high-voltage electrode 10 and a ground electrode 11, wherein the high-voltage electrode 10 is embedded in a dielectric that forms at least part of an inner wall of the second discharge chamber 4. The ground electrode 11 is arranged concentrically to the high-voltage electrode 10 on the inner wall of the second discharge chamber 4, in particular on a hollow cylinder, e.g., made of ceramic.The ground electrode 11 is located at a distance of less than 1 mm from the high-voltage electrode 10, with a gap between the inner wall and the ground electrode 11, in which a discharge zone containing the (second) plasma 15 forms when a high alternating voltage (HV AC) is applied between the high-voltage electrode 10 and the ground electrode 11. The inventors have recognized that with this expansion of the gap, a dielectric barrier discharge (alternatively known as a dielectric barrier discharge, DBE; English: dielectric barrier discharge, DBD) with a high alternating voltage in the range ±1 to ±10 kV and a frequency in the range of 1 to 10 kHz can be stably generated over a large pressure range of approximately 0.35 Torr to 1500 Torr.

[0054] In Fig. 2 A longitudinal section through an embodiment of a device according to the invention for plasma generation in a large pressure range is shown, along with dimensions. In this embodiment, the first discharge chamber 2 and the second discharge chamber 4 are cylindrical and arranged coaxially one behind the other (so to speak, "connected in series"). As shown in Fig. 1 The first coupling element 5 is arranged on the right side of the first discharge chamber 2, and the second coupling element 6 is arranged on the left side of the second discharge chamber 4. The total length of the device in this example is only approximately 60 mm, and the total diameter is only approximately 25 mm. As this shows, the present invention enables a very compact design, which is consequently very space-saving.

[0055] Fig. 3 shows an alternative representation of the longitudinal section through the embodiment according to Fig. 2 . In Fig. 3 The plasmas 14, 15 in the two discharge chambers 2, 4 are also shown, as well as the two optical connections L1, L2. The areas in which the plasmas 14, 15 are generated are outlined with dashed lines.

[0056] Fig. 4 shows a longitudinal section through an embodiment which is largely identical to that shown in Fig. 1 shown embodiment. In addition, this variant has at least one further electrode 16, which is guided radially outside the high-voltage electrode 10 of the second plasma source and insulated from it from the vacuum side to the outside. This further electrode is guided, for example, between a molten glass ring and a cylinder made of insulating material. The cylinder made of insulating material can, for example, protrude beyond the molten glass ring on both sides in order to form a continuous support surface for the electrode. A plurality of such further electrodes is possible, wherein the electrodes can, for example, be strip-shaped with a longitudinal direction parallel to the longitudinal axis of the device. Several such further electrodes can be distributed in the azimuthal direction and arranged insulated from one another, so that most of them would not be visible in this longitudinal sectional view.are not visible. One or more such electrodes enable the connection of additional sensors on the vacuum side or alternative ways of connecting the previously discussed anodes and cathodes of the first and second plasma sources.

[0057] Fig. 5 shows a different embodiment from Fig. 4 further with an alternative connection 17 to the anode of the first plasma source. The feedthrough from the outside to the plasma side is designed as in connection with Fig. 4 for the further electrode 16 and is located 180 degrees opposite the further electrode 16 visible in the longitudinal section in the illustrated case with respect to the longitudinal axis of the device. The alternative connection 17 is guided through a bore into the first discharge chamber 2 and contacts the central anode pin. This allows the Fig. 4The electrical connection routed centrally through the second discharge chamber 4 and the associated passage through the first 7 and second 8 optical lenses are eliminated. This has the effect that a larger portion of the electromagnetic radiation from the first or second plasma reaches the outside. Electrodes can, for example, be covered with an insulating layer over their entire length.

[0058] This has the advantage of avoiding undesirable exposed potentials, which could affect charged particles in electron / ion optics. For example, a glass ring overlying the electrodes can be extended further axially, or individual conductor tracks can be realized with a thin glass layer overlapping the respective conductor track.

[0059] Advantages of the present invention are that multiple plasma sources are integrated into a single device, which also has only a single connection for introducing the gas to be analyzed and only a single connection for coupling the device to an optical sensor. With the device according to the invention, a stable plasma can be generated over a pressure range of more than approximately 12 decades (in Torr), from high vacuum (10 -8 < Torr) to above normal pressure (> atmospheric pressure, e.g., 1500 Torr). The invention also provides for selecting and controlling the respective optimal plasma source depending on the pressure range by means of an internal pressure measurement within the device. LIST OF REFERENCE SYMBOLS

[0060] 1First plasma source 2First discharge chamber 3Second plasma source 4Second discharge chamber 5First coupling element 6Second coupling element 7First optical lens (between the two discharge chambers) 8Second optical lens (in the second coupling element) 9Anode of the first plasma source 10High-voltage electrode of the second plasma source 11Ground electrode of the second plasma source 12Optical sensor (e.g. photodiode or spectrometer) 13(Permanent) magnet 14First plasma 15Second plasma 16Further electrode 17Alternative connection to the anode of the first plasma source L1First optical connection L2Second optical connection

Claims

1. Device for plasma generation in a wide pressure range comprising: - a first plasma source (1), wherein the first plasma source (1) is arranged in a first discharge chamber (2) and is adapted to generate a first plasma (14) in a low-pressure range, wherein the low-pressure range extends in particular up to high vacuum, i.e., for example up to 10-8 Torr; - a second plasma source (3), wherein the second plasma source (3) is arranged in a second discharge chamber (4) and is adapted to generate a second plasma (15) in a high-pressure range, wherein the high-pressure range extends in particular to above normal pressure, i.e., for example to 1500 Torr; - a first coupling element (5), in particular having a flange, for coupling the device to a system, wherein the coupling element (5) is designed to lead gas out of the system; - a second coupling element (6) for coupling the device to an optical sensor, such as a photodiode or spectrometer, for optical gas analysis or gas detection, wherein the first discharge chamber (2) has a first optical connection (L1) having at least one optical lens (7, 8) to the second coupling element (6), and the second discharge chamber (4) has a second optical connection (L2) having at least one optical lens (8) to the second coupling element (6).

2. Device according to claim 1, wherein the low-pressure range and the high-pressure range together extend over a pressure range of at least 10 decades, in particular over 12 decades.

3. Device according to claim 1 or 2, wherein the low-pressure range and the high-pressure range overlap, in particular over a pressure range of one decade, e.g., from 0.35 Torr to 3.5 Torr.

4. Device according to one of claims 1 to 3, wherein the first and second plasma sources (1, 3) are different plasma sources, e.g., one each from the group consisting of a glow discharge source, a silent discharge source, a radio frequency plasma source, a microwave plasma source, and an inductively coupled plasma source.

5. Device according to one of claims 1 to 4, wherein the first discharge chamber (2) is fluidically coupled to the second discharge chamber (4).

6. Device according to one of claims 1 to 5, wherein gas can be supplied from the first coupling element (5) into the first discharge chamber (2) and can be supplied from the first discharge chamber (2) into the second discharge chamber (4).

7. Device according to one of claims 1 to 6, wherein an optical lens (7), which is part of the first optical connection (L1), is arranged between the first discharge chamber (2) and the second discharge chamber (4).

8. Device according to one of claims 1 to 7, wherein the second coupling element (6) comprises an optical lens (8) which is part of the first and / or the second optical connection (L1, L2).

9. Device according to one of claims 1 to 8, wherein the second optical connection (L2) is part of the first optical connection (L1).

10. Device according to one of claims 1 to 9, wherein the device further comprises a pressure sensor.

11. Device according to claim 10, wherein the device further comprises a controller which is designed to control the first and / or the second plasma source (1, 3), in particular to switch the first and / or the second plasma source (1, 3) on or off, as a function of the pressure determined by means of the pressure sensor.

12. Device according to one of claims 1 to 11, wherein the first discharge chamber (2) and the second discharge chamber (4) are of cylindrical design and are arranged coaxially one behind the other, wherein the first coupling element (5) is arranged on the first discharge chamber (2) and the second coupling element (6) is arranged on the second discharge chamber (4), wherein the first plasma source (1) is in particular a glow discharge source and wherein the second plasma source (3) is in particular a silent discharge source.

13. Device according to claim 12, wherein an anode (9) of the first plasma source (1) is glazed in a vacuum-tight manner in a feedthrough through the optical lens (8) in the second coupling element (6), and in particular also in a feedthrough through the optical lens (7), which is arranged between the first discharge chamber (2) and the second discharge chamber (4), and the two feedthroughs are arranged in particular centrally in the two optical lenses (7, 8), and the anode (9) extends coaxially through the second discharge chamber (4) into the first discharge chamber (2).

14. Device according to claim 12 or 13, wherein the second plasma source (3) has a high-voltage electrode (10) and a ground electrode (11), wherein the high-voltage electrode (10) is embedded in a dielectric which forms at least part of an inner wall of the second discharge chamber (4), and the ground electrode (11) is arranged concentrically to the high-voltage electrode (10) within the second discharge chamber (4) and along the inner wall, at a distance of less than 1 mm, in particular between 0.05 mm and 0.5 mm, from the high-voltage electrode (10), in particular on a hollow cylinder, e.g., of ceramic, wherein a gap is located between the inner wall and the ground electrode (11), in which gap a discharge zone with a plasma is formed when an alternating voltage is applied between the high-voltage electrode (10) and the ground electrode (11), e.g., with a voltage in the range from ±1 to ±10 kV and a frequency in the range from 1 to 10 kHz.

15. Device according to one of claims 12 to 14, wherein the high-voltage electrode (10) is connectable to ground (GND) for operation of the first plasma source (1) and is connectable to a high-voltage alternating current source for operation of the second plasma source (3), and / or wherein the anode (9) is connectable to a high-voltage direct current source for operation of the first plasma source (1) and is connectable to ground (GND) for operation of the second plasma source (3).

16. System for optical gas analysis or gas detection comprising: - a device for plasma generation according to one of claims 1 to 15; - a gas source, wherein the device for plasma generation is coupled to the gas source with a first coupling element, in particular with a flange; - an optical sensor, such as a photodiode or a spectrometer for optical gas analysis or gas detection, wherein the plasma generation device is coupled to the optical sensor by a second coupling element.

17. Method for plasma generation in a wide pressure range by means of the device according to one of claims 1 to 15, comprising the steps of: - feeding a gas from a system via a first coupling element (5) into a first discharge chamber (2) having a first plasma source (1) and / or into a second discharge chamber (4) having a second plasma source (3); - generating a first plasma (14) by the first plasma source (1) in a low-pressure range in the first discharge chamber (2), wherein the low-pressure range extends in particular to high vacuum, i.e., for example to 10-8 Torr, and / or generating a second plasma (15) by the second plasma source (3) in a high-pressure range in the second discharge chamber (4), wherein the high-pressure range extends to above normal pressure, i.e., for example, to 1500 Torr; - guiding light which is emitted from the first plasma (14) from the first discharge chamber (2) via a first optical connection (L1) having at least one optical lens (7, 8) and / or light emitted from the second plasma (15) from the second discharge chamber (4) via a second optical connection (L2) having at least one optical lens (8) to a second coupling element (6) for coupling the device to an optical sensor, such as a photodiode or a spectrometer; - coupling out at least a portion of the light, which is emitted by the first and / or the second plasma (14, 15), by the second coupling element (6).

18. Method according to claim 17, wherein the first and / or the second plasma source (1, 3) is controlled as a function of the pressure determined with the aid of a pressure sensor, in particular the first and / or the second plasma source (1, 3) is switched on or off.

19. Method according to claim 18, wherein in a pressure range in which the low-pressure range and the high-pressure range overlap, e.g., in a pressure range of 0.35 Torr to 3.5 Torr, the first and second plasma sources (1, 3) simultaneously generate a first and a second plasma (14, 15).

20. Method for optical gas analysis or gas detection, comprising carrying out the steps according to one of claims 17 to 19 and further comprising the steps of: - directing the decoupled light to an optical sensor, such as a photodiode or spectrometer; - determining a gas or components of a gas or detecting a specific gas or specific components of a gas or determining a pressure of the gas based on the decoupled light, in particular an intensity and / or a spectral distribution of the decoupled light.