Method for igniting and powering a laser or plasma, and a plasma system or laser system

Abstract

An improved ignition and power supply method for a laser or processing plasma in a discharge chamber 30 includes: a. supplying power from an output port 24 of an amplifier 12 to the discharge chamber 30, where the amplifier 12 includes at least two amplifier path portions 14, 16 each supplying a signal to a coupler 22, the coupler 22 having an output port 24 and an isolation port 26 and being configured to combine signals depending on an amplitude relationship and / or a phase relationship and supply power to the output port 24 and / or the isolation port 26; b. controlling impedance switching units 27, 27a, 27b connected to the isolation port 26 and a ground 39 according to a first control mode to ignite the laser or processing plasma; and c. controlling impedance switching units 27, 27a, 27b connected to the isolation port 26 according to a second control mode to operate the laser or maintain the processing plasma in the discharge chamber 30.

Description

Technical Field

[0001] The present invention relates to an improved method for igniting and powering a gas laser or plasma in a discharge chamber. Further, the present invention relates to a plasma system or a laser system comprising a discharge chamber and an amplifier.

Background Art

[0002] Plasma for processing workpieces, i.e., for example, plasma for etching or coating workpieces in industrial plasma devices, is often excited using high-frequency energy. To ignite the plasma, it is known to apply a full operating power at a voltage higher than normal to the plasma device to ignite the plasma as quickly as possible. In such a system, a so-called balanced amplifier is often used. Such a balanced amplifier usually has two amplifier path sections, each supplying a signal to a coupler (also called a capacitor). At this time, the coupler has an output port and an isolation port, and is configured to combine signals depending on the amplitude relationship (Amplitudenbeziehung) and / or phase relationship (Phasenbeziehung) of the signals and supply power to the output port and / or the isolation port. For this purpose, the amplifier path sections usually operate at a mutual phase difference of 90°. Such a balanced amplifier and its characteristics are also described in, for example, Non-Patent Document 1. In that document, the term "balanced amplifier" is used as an alternative to the term "balancierter Verstaerker".

[0003] In a properly balanced amplifier designed for operation in lasers or plasmas, the output power is essentially flat, or essentially constant, across the entire complex load plane. Creating power peaks (peaking) is difficult. Pseudo-peaking can only be achieved by selecting a higher DC supply voltage. A short burst of high DC supply voltage can generate high power for ignition. However, generating high DC supply voltages for power peaking is very costly.

[0004] In the case of unbalanced amplifiers, especially when there is no coupler, the appropriate cable length between the amplifier and the plasma chamber or discharge chamber can be used to select the ignition impedance at which the power peak occurs. Unbalanced amplifiers have many other drawbacks and are therefore rarely used in plasma or laser operations.

[0005] One method for igniting such a plasma or laser system using a balanced amplifier is described, for example, in Patent Document 1, filed August 4, 2022, entitled "Method for supplying power to a laser or plasma, and a plasma system or laser system." In that document, the term "balanced amplifier" is used as a substitute for the term "balancierter Verstaerker." During ignition and operation, the phase relationship between the amplifier paths in the ignition operation differs from the phase relationship in the plasma processing or laser excitation operation. While the method described in that document is very effective in many systems, it does not guarantee satisfactory reliability in all systems. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] German Patent Application Publication No. 102022108631.3 Specification [Patent Document 2] International Publication No. 2015 / 091468A1 Pamphlet [Patent Document 3] International Publication No. 2020 / 025547A1 brochure [Patent Document 4] German Patent Application Publication No. 102016110141A1 Specification [Non-patent literature]

[0007] [Non-Patent Document 1] Alexander Alt et al.: “Analysis of high power LDMOS amplifiers for industrial applications under mismatch conditions”, published in 2014 IEEE Topical Conference on Power Amplifiers for Wireless and Radio Applications (PAWR), Electronic ISBN:978-1-4799-2778-4. [Overview of the project] [Problems that the invention aims to solve]

[0008] The object of the present invention is to provide a method and apparatus that can achieve reliable ignition of a laser or plasma. [Means for solving the problem]

[0009] This problem is solved by an improved ignition and power supply method for the laser or processing plasma in the discharge chamber. This method is a. The step of supplying power from the output port of an amplifier to a discharge chamber, wherein the amplifier includes at least two amplifier paths, each supplying a signal to a coupler, the coupler having an output port and an isolation port, and configured to couple signals depending on the amplitude relationship and / or phase relationship of the signals, and to supply power to the output port and / or isolation port. b. A step of controlling an impedance switching unit connected to an isolated port and ground in accordance with a first control mode in order to ignite a laser or processing plasma, c. Controlling an impedance switching unit connected to an isolation port according to a second control mode in order to operate the laser or to maintain the processing plasma in the discharge chamber.

[0010] The present invention provides the use of an impedance switching section in the isolation port of a coupler. This impedance switching section replaces a well-known absorption resistor known in the prior art. In this case, the impedance switching section can be configured to be configured and operate like a conventional absorption resistor in a second control mode. Conventional absorption resistors typically have the impedance of the coupler, usually an impedance of 50 ohms. In a given form, the resistance value can also be an integer multiple or fraction of 50 ohms, for example, 25 ohms or 100 ohms. Control of the impedance switching section ensures that an overvoltage is generated at the output port of the coupler, and consequently, that a power peak suitable for ignition of a laser or processing plasma is generated.

[0011] In this specification, "ground" refers to the electrical connection to the reference potential of the amplifier, and is often abbreviated as "GND".

[0012] In this specification, “impedance switching section” means a configuration suitable for switching between different impedances. This involves switching between two or more values, rather than intentionally changing the impedance continuously in an analog manner. For this purpose, a switching element can preferably be used. Such a switching element may be, for example, a transistor, particularly an IGBT or MOSFET. However, electromechanical switching elements or PIN diodes are also possible. Such switching elements have a transition time for switching and cannot achieve infinitely fast switching, but it is clear that the switching time must be as short as possible to achieve reliable and fast ignition. The switching element can be connected to short-circuit the impedance element. Alternatively, the switching element can be connected to isolate the impedance element. Two or more switching elements may also be provided. These switching elements can short-circuit the impedance element and also isolate the impedance element.

[0013] When a laser or plasma does not ignite, typically, not enough reflections to ignite occur between the amplifier (its output port) and the unignited load. This is because most of the energy is absorbed by an impedance element, often called an absorption resistor, connected to an isolated port. According to the present invention, this impedance element is appropriately switched for a first control mode, absorbing little to no energy. This can cause multiple reflections of power between the amplifier and the unignited load, thereby generating a power or voltage high enough to ignite the plasma or laser. In particular, switching has been shown to be superior to controlled or managed continuous changes in the impedance of the absorption resistor. This means that faster and more reliable ignition is possible.

[0014] According to the method of the present invention, a plasma or laser can be ignited quickly and reliably. This method can be used in particular when the phase relationship or amplitude relationship of the signals to be coupled in the coupler cannot be adjusted. This may be the case when the coupled signals themselves originate from the coupler, especially a 3dB coupler.

[0015] The signals coupled by the coupler can have frequencies in the range of 1 MHz to 100 MHz. Furthermore, they can have powers in the range of 0.5 kW to 6 kW. The signals coupled in the coupler can have a phase offset of 90°.

[0016] The impedance switching section can be controlled so that the impedance between the isolated port and ground is approximately zero ohms. For this purpose, the impedance switching section may have a switching element positioned in parallel with an absorption resistor. In this case, the impedance switching section is positioned between the isolated port and ground, and the absorption resistor is configured and functions like a conventional absorption resistor known in the art. By switching the conduction of the switching element, the absorption resistor can be short-circuited, thereby preventing energy absorption within the impedance switching section, particularly in the absorption resistor.

[0017] Alternatively, the impedance switching section can be controlled so that the impedance between the isolated port and ground is nearly infinite. To achieve this, a switching element can be placed in series with an absorption resistor between the isolated port and ground, in which case the absorption resistor can be configured and function like a conventional absorption resistor known from the prior art. By opening the switching element, the absorption resistor can be disconnected from the isolated port or ground, so that no energy is absorbed within the impedance switching section, particularly in the absorption resistor.

[0018] For the ignition of a laser or a processing plasma, the impedance switching unit can be controlled in a first control mode for a predetermined time, particularly in the range of 0.1 μs to 10,000 μs, preferably in the range of 1 μs to 1,000 μs. At that time, this time can be set so as to ensure that a sufficiently large power peak is generated at the output port of the coupler to reliably ignite the laser or the processing plasma.

[0019] Alternatively or additionally, for the ignition of a laser or a processing plasma, the impedance switching unit can be controlled in the first control mode until the ignition of the laser or the plasma is detected. The ignition of the plasma can be monitored optically, for example. However, between the coupler and the discharge chamber, signals such as current, voltage, and power can be detected, and the ignition of the laser or the plasma can also be derived, for example, by determining the reflection coefficient from the detected signals.

[0020] As the coupler, a 3dB coupler, particularly a 90° hybrid coupler, can be used. The 3dB coupler combines two input signals with a 90° phase shift, whereby the combined power is output at the output port and no power is output at the isolation port. At that time, the amplification path parts for generating signals are separated and do not affect each other. The 3dB coupler itself can be ideally lossless. This means that the power of the two amplification path parts can be completely supplied to the load (plasma or laser) connected to the output port.

[0021] To maintain the plasma or the laser, a 90° phase relationship can be set between the signals. Particularly in relation to the 3dB coupler, the maximum power can be supplied to the plasma or the laser.

[0022] The present invention further relates to a plasma system or a laser system, and the plasma system or the laser system a. a discharge chamber, and b. An amplifier connected to a discharge chamber, having a combiner and at least two amplifier path sections respectively supplying signals to the combiner, wherein the combiner has an output port and an isolation port, is configured to combine signals depending on their amplitude relationship and / or phase relationship, and supply power to the output port and / or the isolation port. c. An impedance switching section connected between the isolation port and the ground, including an impedance element and at least one switch element. d. A controller configured to control the impedance switching section for ignition of a laser or processing plasma in the discharge chamber.

[0023] With such a system, it becomes possible to ignite a plasma or a laser even when using a balanced amplifier.

[0024] The switch element can be connected in series or in parallel with respect to the impedance element. The switch element is preferably arranged in parallel with respect to the impedance element. Also, it is conceivable to provide the switch element in series and in parallel with respect to the impedance element. This increases the flexibility regarding the setting of the impedance at the isolation port for igniting a plasma or a laser. The switch element can be formed as a MOSFET.

[0025] An impedance matching device can be arranged between the plasma chamber or the discharge chamber and the balanced amplifier. In that case, the impedance matching device can be connected to the output port via a wiring, and the wiring has a specially selected electrical length that can depend on the wavelength of the connection and the dielectric and magnetic characteristics. This measure enables high-speed ignition of a laser or a plasma.

[0026] The combiner can be formed as a 3dB coupler, particularly as a 90° hybrid coupler. Such a combiner operates particularly with low loss and can combine a plurality of input signals into one output signal having higher power than the individual input signals.

[0027] The amplifier can supply signals at frequencies of 13.56 MHz and / or 27 MHz. Each amplifier path may have a Class F inverter, which may have an LDMOS transistor.

[0028] Further features and advantages of the present invention will become apparent from the following detailed description of embodiments of the invention with reference to the drawings, and also from the claims. Various features can be realized individually or in any combination in modifications of the present invention.

[0029] In particular, the above method can be combined with the method described in Patent Document 1. Both methods can be used simultaneously, sequentially in different orders, or overlappingly. Patent Document 1 is incorporated fully into this application by reference for this purpose.

[0030] An embodiment of the present invention is shown in the schematic diagram and will be explained in the following description. [Brief explanation of the drawing]

[0031] [Figure 1] This is a schematic diagram illustrating a plasma system or laser system. [Figure 2] This is a diagram showing the first embodiment of the impedance switching unit. [Figure 3] This figure shows a second embodiment of the impedance switching section. [Figure 4a] This figure shows the output characteristics of an amplifier across the load plane when the isolated port is terminated by an impedance element. [Figure 4b] This graph shows the power dependent on the magnitude of the reflection coefficient when the isolated port of an amplifier coupler is terminated by an impedance element. [Figure 4c]This is a graph of the angle-dependent power of the reflection coefficient when the isolated port of an amplifier coupler is terminated by an impedance element. [Figure 5a] This figure shows the output characteristics of the amplifier across the load plane when the impedance element at the isolation port of the amplifier's coupling section is short-circuited. [Figure 5b] This graph shows the power dependent on the magnitude of the reflection coefficient when the impedance element at the isolation port of the amplifier coupler is short-circuited. [Figure 5c] This graph shows the power dependent on the angle of the reflection coefficient when the impedance element at the isolation port of the amplifier coupler is short-circuited. [Figure 6a] This figure shows the output characteristics of the amplifier across the load plane when the isolation port of the amplifier coupler is open. [Figure 6b] This graph shows the power dependent on the magnitude of the reflection coefficient when the insulating port of the amplifier coupler is open. [Figure 6c] This is a graph of the power, which depends on the angle of the reflection coefficient when the insulating port of the amplifier coupler is open. [Modes for carrying out the invention]

[0032] The plasma system or laser system described in this embodiment is also described, for example, in Patent Document 2, Patent Document 3, and Patent Document 4. These three publications are fully incorporated into this application by reference. The plasma system or laser system described in these referenced documents is further developed in this embodiment by an impedance switching unit. The methods and apparatus described in this embodiment can also be advantageously used and / or incorporated in the methods and apparatus described in these referenced documents.

[0033] In this specification, the component referred to as a "coupler" can be configured, for example, as the phase-shift coupler unit in Patent Document 2 or the "phase-shift coupler" in Patent Document 3.

[0034] In this specification, the isolation port of a coupler typically refers to the output port of the coupler that is not normally supplied with power during operation without reflection. In other publications, it is also called a compensating port. An absorption resistor is conventionally connected to the isolation port, for example, as in the publication cited above. This absorption resistor is often also called a compensating resistor or termination resistor.

[0035] Figure 1 shows a plasma system or laser system 10. The plasma system or laser system 10 includes, in particular, a balanced amplifier 12, which has a first amplifier path section 14 and a second amplifier path section 16. The output signals of the first and second amplifier paths 14 and 16 are applied to the input ports 18 and 20 of a coupler 22. Therefore, the first and second amplifier paths 14 and 16 are connected to the input ports 18 and 20 of the coupler 22. The coupler 22 has an output port 24 and an isolated port 26 to which an impedance switching unit 27 is connected. The impedance switching unit 27 is connected between the isolated port 26 and ground 39.

[0036] The discharge chamber 30 is connected to the output port 24 via wiring 28. An impedance matching device 32 is positioned directly in the discharge chamber 30. The discharge chamber 30 is therefore connected to the amplifier 12 via wiring 28 and the impedance matching device 32 in the illustrated embodiment.

[0037] The coupler 22 is configured to couple the signals input to input ports 18 and 20 to each other depending on their phase relationship and / or amplitude relationship, and output them to output port 24 and / or isolated port 26. The input signals to the coupler 22 have a phase relationship and / or amplitude relationship, and the input signals are guided so that the signals are coupled by the coupler 22, the maximum power is output at output port 24, and ideally, no power is output at isolated port 26.

[0038] The impedance switching unit 27 is controlled by the controller 34. In particular, this controls one or more switching elements of the impedance switching unit 27. Different configurations of the impedance switching unit 27 will be described.

[0039] The existence of further amplifier paths 14 and 16 connected to the coupler 22 is also conceivable. In the illustrated embodiment, the amplifier path 14 itself further has amplifier paths 36 and 38, and their output signals are coupled by the coupler 40. The output signal of the coupler 40 corresponds to the output signal of the amplifier path 14.

[0040] Each amplifier path section 16, 36, and 38 can be configured in the same way as amplifier path section 14. Alternatively, only a portion of the amplifier path section can be configured in the same way as amplifier path section 14.

[0041] The input signals for amplifier paths 14 and 16 can come from a splitter. The splitter can be configured similarly to the coupler 22.

[0042] A first embodiment of the impedance switching unit 27 is indicated by reference numeral 27a in Figure 2. The impedance switching unit 27a has an impedance element 36 in the form of an absorption resistor, with a switch element 38 connected in parallel thereto. The switch element 38 is controlled by a controller 34.

[0043] When the switch element 38 is controlled by the controller 34 in the first control mode and the switch element 38 becomes conductive, the impedance element 36 configured as an absorption resistor is short-circuited, and as a result, energy cannot be absorbed in the insulating port 26. If the laser or plasma has not yet been ignited in the discharge chamber 30, the power is reflected in the discharge chamber 30. Since this cannot be absorbed by the impedance element 36, power reflection also occurs in the coupler 22. In the output unit 24, a power peak is generated that leads to the ignition of the laser or plasma in the discharge chamber 30.

[0044] After a predetermined time has elapsed, or when ignition of the laser or plasma is detected, the switch element 38 is opened in a second control mode, allowing power to be supplied to the ignited laser or plasma in normal operation. If the plasma dynamics cause a change in the plasma impedance and a related mismatch occurs, the power reflected in the discharge chamber 30 can be absorbed by the impedance element 36 configured as an absorption resistor.

[0045] A second embodiment of the impedance switching unit 27 is indicated by reference numeral 27b in Figure 3. The impedance switching unit 27b has an impedance element 36 in the form of an absorption resistor, with a switch element 38 connected in series therewith. The switch element 38 is controlled by a controller 34.

[0046] When the controller 34 controls the switch element 38 in the first control mode so that the switch element 38 is in an open state, the connection between the isolation port 26 and ground 39 is disconnected, and as a result, energy cannot be absorbed at the isolation port 26. If the laser or plasma has not yet been ignited in the discharge chamber 30, the power is reflected in the discharge chamber 30. Since this cannot be absorbed by the impedance element 36, power reflection also occurs in the coupler 22. In the output unit 24, this becomes a power peak, leading to the ignition of the laser or plasma in the discharge chamber 30.

[0047] After a predetermined time has elapsed, or when ignition of the laser or plasma is detected, the switch element 38 is closed in the second control mode, allowing power to be supplied to the ignited laser or plasma in normal operation. If the plasma dynamics cause a change in the plasma impedance and a related mismatch occurs, the power reflected in the discharge chamber 30 can be absorbed by the impedance element 36.

[0048] Figure 4a shows the load plane 50 in the form of a Smith chart. The real part of the reflection coefficient is plotted on the x-axis, and the imaginary part of the reflection coefficient is plotted on the y-axis. The output power is shown on the z-axis. Here, it can be seen that the output power at output port 24 is almost constant for all reflection coefficients. As a result, the output power characteristics across the load plane 50 are flat. In particular, no power peaks are observed. The figure shown was generated by a balanced amplifier with a 3dB coupler as the coupler, in which the impedance element 36 formed as an absorption resistor is neither short-circuited nor disconnected from the ground 39 of the isolated port 26. No power peaks occur for load impedances suitable for plasma or laser ignition.

[0049] Figure 4b is a graph corresponding to the situation in Figure 4a, in which the output power supplied by amplifier 12 is shown as depending on the magnitude of the reflection coefficient. It can be seen that the power is basically constant and insufficient to ignite the plasma or laser.

[0050] Figure 4c is a graph corresponding to the situations in Figures 4a and 4b, in which the output power supplied by amplifier 12 is shown as dependent on the phase angle φ of the reflection coefficient.

[0051] Figures 5a, 5b, and 5c show graphs corresponding to Figures 4a to 4c, in which case the switch element 38 of the impedance switching unit 27a is controlled according to the first control mode to short-circuit the impedance element 36.

[0052] From Figure 5a, it can be seen that a basically flat power distribution is not achieved, and power peaks, or peaking, occur in range 52. From the related Figures 5b and 5c, it can be seen that when the magnitude of the reflection coefficient is greater than 0.7 and the angle of the reflection coefficient is 0°, a considerably higher power is generated, which is suitable for igniting plasma or lasers, compared to the cases in Figures 4a-4c.

[0053] Figures 6a, 6b, and 6c show graphs corresponding to Figures 4a to 4c, in which the switch element 38 of the impedance switching unit 27b is controlled according to the first control mode to disconnect the isolated port 26 from the ground 39.

[0054] From Figure 6a, it can be seen that a basically flat power distribution is not achieved, and power peaks, or peaking, occur in region 54. From the related Figures 6b and 6c, it can be seen that when the magnitude of the reflection coefficient is greater than 0.7 and the angle of the reflection coefficient is approximately +180° and approximately -180°, a considerably higher power is generated, which is suitable for igniting plasma or lasers, compared to the situation in Figures 4a-4c. [Explanation of symbols]

[0055] 10 Plasma system or laser system 12 Amplifiers 14, 16 Amplifier Path Section 22 Combiner 24 output ports 26 isolated ports 27, 27a, 27b Impedance switching section 28 Wiring 30 Discharge Chamber 32 Impedance matching device 34 controllers 36 Impedance elements 38 Switching elements 39 Grand

Claims

1. An improved method for igniting and power supplying a machining plasma in a discharge chamber (30), a. The step of supplying power to the discharge chamber (30) from the output port (24) of the amplifier (12), wherein the amplifier (12) includes at least two amplifier path sections (14, 16) each supplying a signal to a coupler (22), the coupler (22) having an output port (24) and an isolation port (26), and is configured to couple the signals depending on the amplitude relationship and / or phase relationship of the signals and to supply power to the output port (24) and / or the isolation port (26), b. A step of controlling the impedance switching units (27, 27a, 27b) connected to the insulated port (26) and ground (39) according to a first control mode in order to ignite the processing plasma, c. The process includes the step of controlling the impedance switching units (27, 27a, 27b) connected to the insulating port (26) according to a second control mode in order to maintain the processing plasma in the discharge chamber (30), The impedance switching section (27, 27a, 27b) has an impedance element (36) and at least one switch element (38), In the first control mode, the method involves switching the connection so that the switch element (38) short-circuits or disconnects the impedance element (36) to generate a power peak at the output port (24).

2. The method according to claim 1, characterized in that step a. includes controlling the impedance switching unit (27, 27a) such that the impedance between the insulated port (26) and the ground (39) is approximately zero ohms or approximately infinite.

3. The method according to claim 1 or 2, characterized in that the impedance switching units (27, 27a, 27b) are controlled in the first control mode in the range of 0.1 μs to 10,000 μs for ignition of the processing plasma.

4. The method according to claim 3, characterized in that the impedance switching units (27, 27a, 27b) are controlled in the first control mode in the range of 1 μs to 1,000 μs for ignition of the processing plasma.

5. The method according to claim 1 or 2, characterized in that the impedance switching unit (27, 27a, 27b) is controlled in the first control mode until plasma ignition is detected in order to ignite the processing plasma.

6. The method according to claim 1 or 2, characterized in that a 3 dB coupler is used as the coupling device (22).

7. The method according to claim 6, characterized in that a 90° hybrid coupler is used as the coupler (22).

8. An amplifier (12) that can be connected to a discharge chamber (30), a. A coupler (22) having an output port (24), an isolation port (26), and two input terminals (18, 20), wherein the coupler (22) is configured to supply the signals at the input terminals (18, 20) to the output port (24) and / or the isolation port (26) depending on their amplitude relationship and / or phase relationship. b. At least two amplification paths (14, 16) configured to supply signals to the input terminals (18, 20) of the coupler (22), c. An impedance switching section (27, 27a, 27b) connected between the insulated port (26) and ground (39), including an impedance element (36) and at least one switching element (38), d. A controller (34) configured to control the impedance switching units (27, 27a, 27b) for igniting the processing plasma in the discharge chamber (30), The controller (34) is an amplifier (12) that generates a power peak at the output port (24) by switching the connection of the switch element (38) to short-circuit or disconnect the impedance element (36) in order to ignite the processing plasma.

9. Plasma system (10), a. Discharge chamber (30) and b. An amplifier (12) connected to the discharge chamber (30) having a coupler (22) and at least two amplifier paths (14, 16) that each supply signals to the coupler (22), wherein the coupler (22) has an output port (24) and an isolation port (26), and is configured to couple signals depending on their amplitude relationship and / or phase relationship, and to supply power to the output port (24) and / or the isolation port (26), c. An impedance switching section (27, 27a, 27b) connected between the insulated port (26) and ground (39), including an impedance element (36) and at least one switching element (38), d. A controller (34) configured to control the impedance switching units (27, 27a, 27b) for igniting the processing plasma in the discharge chamber (30), The plasma system (10) includes a controller (34) that switches the connection of the switch element (38) to short-circuit or disconnect the impedance element (36) in order to ignite the processing plasma, thereby generating a power peak at the output port (24).

10. The plasma system according to claim 9, characterized in that the switch element (38) is connected in series or in parallel with the impedance element (36).

11. An impedance matching device (32) is placed between the discharge chamber (30) and the amplifier (12). The plasma system according to claim 9 or 10, characterized in that the impedance matching device (32) is connected to the output port (24) via wiring (28) having a specially selected electrical length depending on the wavelength, dielectric properties, and magnetic properties of the connection.

12. The plasma system according to claim 9 or 10, characterized in that the coupling device (22) is formed as a 3 dB coupler.

13. The plasma system according to claim 12, characterized in that the coupler (22) is formed as a 90° hybrid coupler.

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