Method for igniting and supplying power to laser or plasma, and plasma or laser system

Abstract

A method for improved ignition and supply of electrical power to a laser or processing plasma in a discharge chamber (30) comprises: a. Providing power to the discharge chamber (30) from an output terminal (24) of an amplifier (12), where the amplifier (12) comprises at least two amplifier paths (14, 16) respectively providing a signal to a combiner (22), where the combiner (22) is configured to supply a signal to the discharge chamber (30) from an output terminal (24) of the amplifier (12); wherein the combiner (22) has an output terminal (24) and an isolation terminal (26) and is configured such that it combines the signals and provides power to the output terminal (24) and / or the isolation terminal (26) according to an amplitude relationship and / or a phase relationship of the signals; b. Actuating an impedance switching component (27, 27a, 27b) connected to the isolation connection (26) and to the ground in accordance with a first actuation mode in order to carry out an ignition of the laser or the processing plasma; c. Actuating an impedance switching component (27, 27a, 27b) connected to the isolation terminal (26) according to a second actuation mode in order to operate the laser or in order to maintain the processing plasma in the discharge chamber (30).

Description

Technical Field

[0001] The invention relates to a method for improved ignition and power supply of a gas laser or plasma in a discharge chamber. Furthermore, the invention relates to a plasma or laser system comprising a discharge chamber and an amplifier. Background Art

[0002] Plasma is used for workpiece processing, i.e., for example, in industrial plasma equipment for etching or coating workpieces, and it is usually excited using high-frequency energy. It is known that for the ignition of plasma, the full operating power needs to be put into the plasma equipment under increasing voltage to achieve the fastest ignition of the plasma. In such systems, so-called balanced amplifiers are usually used. Such a balanced amplifier usually has two amplifier paths, which respectively provide signals to a combiner (also called a coupler), wherein the combiner has an output terminal and an isolation terminal and is configured so that it combines the signals according to the amplitude relationship and / or phase relationship of the signals and provides power to the output terminal and / or the isolation terminal. For this purpose, the amplifier paths are usually operated with a phase offset of 90° from each other. For example, the following publications also describe such balanced amplifiers and their characteristics: “Analysis of high power LDMOS amplifiers for industrial applications under mismatch conditions” by Alexander Alt et al., published in 2014 IEEE Topical Conference on Power Amplifiers for Wireless and Radio Applications (PAWR), Electronic ISBN: 978-1-4799-2778-4. An alternative to "balanced amplifier" is the term "balanced amplifier".

[0003] For a balanced amplifier designed for operation at a laser or plasma, the output power in the complex load plane is substantially flat, i.e. substantially constant. Power maximums (peaks) can only be produced with difficulty. Pseudo-peaks can only be achieved by selecting a higher DC supply voltage. Due to the temporarily higher DC supply voltage, higher powers can be produced for ignition. However, generating a higher DC supply voltage for the power maximum (power peak) is very costly.

[0004] For unbalanced amplifiers, especially those without couplers, the impedance that produces the maximum power for ignition can be selected by appropriate cable length between the amplifier and the plasma chamber or discharge chamber. Unbalanced amplifiers have many other disadvantages, so they are used less and less in operation on plasmas or lasers.

[0005] For example, DE 102022108631.3, filed on April 8, 2022, entitled "Method for supplying power to a laser or plasma and plasma or laser system", describes a scheme for igniting such a plasma or laser system with a balanced amplifier. An alternative to "balanced amplifier" is the term "balanced amplifier". For ignition and operation, the phase relationship between the amplifier paths in ignition operation changes compared to the phase relationship in plasma processing or laser excitation operation. The method described therein works well in many systems, but not in all systems with satisfactory reliability. Summary of the invention

[0006] The object of the present invention is to provide a method and a device by means of which a reliable ignition of a laser or a plasma can be achieved.

[0007] According to the invention, this object is achieved by a method for improved ignition and supply of a laser or a processing plasma with electrical power in a discharge chamber, wherein the method comprises:

[0008] a. Providing power to the discharge chamber from an output terminal of an amplifier, wherein the amplifier comprises at least two amplifier paths, the at least two amplifier paths respectively providing signals to a combiner, wherein the combiner has an output terminal and an isolation terminal and is configured such that it combines the signals according to an amplitude relationship and / or a phase relationship of the signals and provides power to the output terminal and / or the isolation terminal;

[0009] b. controlling an impedance switching component connected to the isolation terminal and the ground terminal according to a first control mode to perform ignition of a laser or a processing plasma;

[0010] c. Operating the impedance switching component connected to the isolation terminal according to the second operating mode to operate the laser or to maintain a processing plasma in the discharge chamber.

[0011] Therefore, it is proposed according to the invention to use an impedance switching component at the isolation terminal of the combiner. The impedance switching component replaces the conventional absorption resistor known from the prior art. Here, the impedance switching component can be designed so that: in the second control mode, the design and function of the impedance switching component are like a conventional absorption resistor. Conventional absorption resistors usually have the impedance of the coupler, which is usually 50Ohm. In some designs, the resistance value can also be an integer divisor or integer multiple of 50Ohm, that is, for example, 25Ohm or 100Ohm. By controlling the impedance switching component, it can be ensured that an overvoltage is generated at the output terminal of the combiner and a power maximum (power peak) is generated in connection therewith, which is suitable for ignition of a laser or a processing plasma.

[0012] In this case, ground refers to the electrical connection of the reference potential of the amplifier, which is also referred to as “Ground” and is often abbreviated to “GND”.

[0013] The impedance switching component here refers to a component suitable for switching back and forth between different impedances. It should be appreciated that the impedance is not continuously changed in a similar manner, but jumps between two values ​​or more values. For this purpose, a switching element can preferably be used. Such a switching element can be, for example, a transistor, in particular an IGBT or a MOSFET. However, it is also conceivable to be an electromechanical switching element or a PIN diode. Obviously, such a switching element also has a transition time for switching, that is, they cannot switch infinitely quickly, but in order to achieve reliable and rapid ignition, this switching time should be as short as possible. The connection mode of the switching element can short-circuit the impedance for it. Alternatively, the connection mode of the switching element can disconnect the impedance for it. Two or more switching elements can also be provided. The connection mode of these switching elements can cause the impedance to be short-circuited and the impedance to be disconnected.

[0014] In the case of an unignited laser or plasma, multiple reflections sufficient for ignition usually do not occur between the amplifier (its output terminal) and the unignited load, since most of the energy is absorbed in the impedance connected to the isolation terminal (usually a so-called absorption resistor). According to the invention, this impedance is now switched for the first control mode so that it absorbs no energy or only little energy. This can lead to multiple reflections of power between the amplifier and the unignited load. This can generate a sufficiently high power or voltage to ignite the plasma or laser. In particular, it has been shown that switching has advantages over a regulated or controlled continuous change of the impedance of the absorption resistor. This is because a faster and more reliable ignition can be achieved in this way.

[0015] According to the method of the invention, the ignition of a plasma or a laser can be carried out quickly and reliably. In particular, the method can be used when the phase relationship or amplitude relationship of the signals combined in the combiner is not adjustable. This may be the case when the signals to be combined themselves come from the combiner, in particular a 3dB coupler.

[0016] The signals to be coupled in the combiner may have a frequency in the range of 1 to 100 MHz. Furthermore, they may have a power in the range of 0.5 to 6 kW. The signals to be coupled in the combiner may have a phase shift of 90°.

[0017] The impedance switching component can be controlled so that the impedance between the isolation terminal and the ground terminal is approximately 0 Ohm. To this end, the impedance switching component can have a switching element, which is arranged in parallel with the absorption resistor, wherein the impedance switching component is arranged between the isolation terminal and the ground terminal, and the absorption resistor is designed and functions like a conventional absorption resistor known from the prior art. By turning on the switching element, the absorption resistor can be short-circuited, so that no energy is absorbed into the impedance switching component, especially the absorption resistor.

[0018] Alternatively, the impedance switching component can be manipulated so that the impedance between the isolation terminal and the ground terminal is approximately infinite. To this end, the switching element can be arranged in series with the absorption resistor between the isolation terminal and the ground terminal, wherein the design and mode of action of the absorption resistor can be the same as the conventional absorption resistor known from the prior art. By disconnecting the switching element, the absorption resistor can be disconnected from the isolation terminal or the ground terminal, so that no energy is absorbed into the impedance switching component, especially the absorption resistor.

[0019] In order to ignite the laser or the processing plasma, the impedance switching component can be controlled in the first control mode for a predetermined time, in particular in the range of 0.1 to 10,000 μs, preferably in the range of 1 to 1,000 μs. The time can be predetermined in this case so that a sufficiently large power peak is generated at the output terminal of the combiner so that the ignition of the laser or the processing plasma is reliable.

[0020] Alternatively or additionally, in order to ignite the laser or the processing plasma, the impedance switching component can be operated in a first control mode until the ignition of the laser or the plasma is detected. The ignition of the plasma can be monitored, for example, optically. However, it is also possible to detect signals such as current, voltage and power between the combiner and the discharge chamber and to deduce the ignition of the laser or the plasma therefrom, for example by determining a reflection factor from the detected signals.

[0021] A 3dB coupler, in particular a 90° hybrid coupler, can be used as a combiner. With a 3dB coupler, two input signals that are phase-shifted by 90° can be combined so that the combined power is output at the output terminal, while no power is output at the isolation terminal. Here, the amplifier paths that generate the signals can be decoupled so that they do not affect each other. Ideally, the 3dB coupler itself can be lossless. This means that the power of the two amplifier paths can be fully supplied to the load (plasma or laser) connected to the output terminal.

[0022] In order to maintain the plasma or laser, a 90° phase shift can be set between the signals. Especially in combination with a 3dB coupler, this allows the maximum power to be delivered to the plasma or laser.

[0023] The present invention also relates to a plasma or laser system, comprising:

[0024] a.Discharge chamber;

[0025] b. an amplifier connected to the discharge chamber, the amplifier comprising a combiner and at least two amplifier paths, the at least two amplifier paths respectively providing signals to the combiner, wherein the combiner has an output terminal and an isolation terminal and is configured to combine the signals according to an amplitude relationship and / or a phase relationship of the signals and provide power to the output terminal and / or the isolation terminal;

[0026] c. an impedance switching component connected between the isolation terminal and the ground terminal and comprising an impedance and at least one switching element;

[0027] d. A control device configured to operate the impedance switching assembly to ignite a laser or a processing plasma in the discharge chamber.

[0028] It is therefore possible with such a system to ignite a plasma or a laser even when using a balanced amplifier.

[0029] The switching element can be connected in series or in parallel with the impedance. Preferably, the switching element is arranged in parallel with the impedance. It is also conceivable to provide a switching element in series with the impedance and a switching element in parallel with the impedance. This allows greater flexibility in setting the impedance at the isolation terminal to ignite the plasma or laser. The switching element can be designed as a MOSFET.

[0030] An impedance matching device can be arranged between the plasma chamber or discharge chamber and the balanced amplifier, wherein the impedance matching device is connected to the output terminal via a pipeline having a specially selected electrical length depending on the wavelength, dielectric and magnetic properties of the connection. This measure can assist in achieving rapid ignition of the laser or plasma.

[0031] The combiner can be designed as a 3dB coupler, in particular as a 90° hybrid coupler. Such a combiner can operate in particular with low losses and combine a plurality of input signals into an output signal whose power is greater than that of each individual input signal.

[0032] In particular, the amplifier can provide a signal with a frequency of 13.56 and / or 27 MHz. The amplifier paths can each have a class F inverter. The class F inverter can have an LDMOS transistor.

[0033] Further features and advantages of the invention are apparent from the following detailed description of exemplary embodiments of the invention with the aid of drawings showing essential details of the invention, and from the claims. In variants of the invention, individual features can be realized both individually and in any combination of multiple features.

[0034] In particular, the above method can be combined with the method described in DE 102022108631.3. The two methods can be used simultaneously, successively in different orders or overlapped. For this purpose, the entire content of DE 102022108631.3 is incorporated into the present application by reference. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Exemplary embodiments of the invention are illustrated in the schematic drawings and are explained in the following description.

[0036] In the attached picture:

[0037] Figure 1 A schematic diagram showing a plasma system or a laser system;

[0038] Figure 2 A first design of an impedance switching component is shown;

[0039] Figure 3 A second design of the impedance switching component is shown;

[0040] Figure 4a shows the output characteristics of the amplifier on the load plane when the isolation terminal is separated by impedance;

[0041] Figure 4b a graph showing the variation of power with the value of the reflection factor when the isolated terminals of the combiner of the amplifier are blocked by an impedance;

[0042] Figure 4c a graph showing the variation of power with the angle of the reflection factor when the isolated terminals of the combiner of the amplifier are blocked by an impedance;

[0043] Figure 5a shows the output characteristics of the amplifier on a load plane when the impedance at the isolated terminals of the amplifier's combiner is short-circuited;

[0044] Figure 5b a graph showing the variation of power with the value of the reflection factor when the impedance at the isolation terminals of the combiner of the amplifier is short-circuited;

[0045] Figure 5c a graph showing the variation of power with the angle of the reflection factor when the impedance at the isolated terminals of the combiner of the amplifier is short-circuited;

[0046] Figure 6a shows the output characteristics of the amplifier on the load plane when the isolated terminals of the amplifier's combiner are operating at no load;

[0047] Figure 6b a graph showing the variation of power with the value of the reflection factor when the isolated terminals of the combiner of the amplifier are operated at no load;

[0048] Figure 6c A graph showing the variation of power with the angle of the reflection factor when the isolated terminals of the amplifier's combiner are operating at no load. DETAILED DESCRIPTION

[0049] The plasma or laser system described here is also described, for example, in WO 2015 / 091468 A1 or WO 2020 / 025547 A1, DE 10 2016 110141 A1. The entire contents of these three publications are incorporated into the present application by reference. Here, the plasma or laser system described in the citation is further improved by an impedance switching component. Advantageously, the method described here and the device described here can also be used and / or incorporated into the method and device as described in the citation.

[0050] For example, the component referred to herein as a “combiner” may be designed in the same manner as the phase shifting coupler unit in WO 2015 / 091468 A1 or the “phase shifting coupler” in WO 2020 / 025547 A1.

[0051] In this document, the isolation terminal of the combiner usually refers to the output terminal of the combiner, where no power is provided during normal operation without reflection. In other public documents, it is also called the compensation terminal. An absorption resistor is usually connected to it, for example as in the documents cited above. Such an absorption resistor is also usually called an absorption resistor, a compensation resistor or a terminal resistor.

[0052] Figure 1 A plasma or laser system 10 is shown. The plasma or laser system 10 comprises an especially balanced amplifier 12 having a first amplifier path 14 and a second amplifier path 16. The output signals of the first and second amplifier paths 14, 16 are provided to input terminals 18, 20 of a combiner 22. Thus, the first and second amplifier paths 14, 16 are connected to the input terminals 18, 20 of the combiner 22. The combiner 22 has an output terminal 24 and an isolation terminal 26, to which is connected an impedance switching component 27. The impedance switching component 27 is connected between the isolation terminal 26 and a ground terminal 39.

[0053] The output connection 24 is connected to a discharge chamber 30 via a line 28. An impedance matching device 32 is arranged adjacent to the discharge chamber 30. In the exemplary embodiment shown, the discharge chamber 30 is therefore connected to the amplifier 12 via the line 28 and the impedance matching device 32.

[0054] The combiner 22 is configured to couple the signals input at the input terminals 18, 20 to each other according to their phase relationship and / or amplitude relationship and provide them to the output terminal 24 and / or the isolation terminal 26. The input signals of the combiner have a phase relationship and / or amplitude relationship, which causes the signals to be coupled by the combiner 22 so that maximum power is output at the output terminal 24 and ideally no output power is output at the isolation terminal 26.

[0055] The impedance switching component 27 is controlled by the control device 34. In particular, one or more switching elements of the impedance switching component 27 are controlled thereby. Different configurations of the impedance switching component 27 will also be described.

[0056] It is conceivable that there are further amplifier paths 14, 16 which are connected to the combiner 22. In the exemplary embodiment shown, the amplifier path 14 itself again has amplifier paths 36, 38, the output signals of which are combined by the combiner 40. The output signal of the combiner 40 corresponds to the output signal of the amplifier path 14.

[0057] Each of the amplifier paths 16, 36, 38 can therefore be constructed similarly to the amplifier path 14. It is also possible for only some of the amplifier paths to be constructed in the same manner as the amplifier path 14.

[0058] The input signals for the amplifier paths 14, 16 may come from a splitter. The splitter may be constructed similarly to the combiner 22.

[0059] exist Figure 2 In the embodiment of the present invention, the first design of the impedance switching component 27 is denoted by reference numeral 27a. The impedance switching component 27a has an impedance 36 designed as an absorption resistor, and a switching element 38 is connected in parallel with the impedance. The switching element 38 is controlled by a control device 34.

[0060] When the switching element 38 is controlled by the control device 34 in the first control mode so that the switching element 38 is conductive, the impedance 36 configured as an absorption resistor is short-circuited, so that no energy is absorbed at the isolation terminal 26. If the laser or plasma has not yet been ignited in the discharge chamber 30, the power is reflected at the discharge chamber 30. Now, this power is not absorbed in the impedance 36, so that power reflection also occurs at the combiner 22. Therefore, a power peak occurs at the output end 24, which causes the laser or plasma to be ignited in the discharge chamber 30.

[0061] After a predetermined time or when ignition of the laser or plasma is detected, the switching element 38 can be disconnected in the second control mode and the ignited laser or the ignited plasma can be supplied with power during normal operation. If the impedance of the plasma changes due to the dynamics of the plasma and an associated mismatch occurs, the power reflected at the discharge chamber 30 can be absorbed in the impedance 36 designed as an absorption resistor.

[0062] exist Figure 3 In the embodiment of the present invention, the second design of the impedance switching component 27 is denoted by reference numeral 27 b. The impedance switching component 27 b has an impedance 36 designed as an absorption resistor, and a switching element 38 is connected in series with the impedance. The switching element 38 is controlled by the control device 34 .

[0063] When the switching element 38 is controlled by the control device 34 in the first control mode so that the switching element 38 is opened, the connection between the isolation terminal 26 and the ground terminal 39 is disconnected, so that no energy is absorbed at the isolation terminal 26. If the laser or plasma has not yet been ignited in the discharge chamber 30, the power is reflected at the discharge chamber 30. Now, this power is not absorbed in the impedance 36, so that power reflection also occurs at the combiner 22. Therefore, a power peak occurs at the output end 24, which causes the laser or plasma to be ignited in the discharge chamber 30.

[0064] After a predetermined time or when ignition of the laser or plasma is detected, the switching element 38 can be closed in the second control mode and the ignited laser or the ignited plasma can be supplied with power during normal operation. If the impedance of the plasma changes due to the dynamics of the plasma and an associated mismatch occurs, the power reflected at the discharge chamber 30 can be absorbed in the impedance 36.

[0065] Figure 4a The load plane 50 is shown in the form of a Smith chart. The real part of the reflection factor is plotted on the x-axis and the imaginary part of the reflection factor is plotted on the y-axis. The output power is shown on the z-axis. It can be seen that the output power at the output terminal 24 is almost constant for all reflection factors. Therefore, this produces a flat output power characteristic on the load plane 50. In particular, no power maximum is seen. The illustrated figure is produced by a balanced amplifier, which has a 3dB coupler as a combiner and in the case of this balanced amplifier, the impedance 36 designed as an absorption resistor is neither short-circuited nor disconnected from the connection of the isolation terminal 26 to the ground terminal 39. For the case of no load impedance, there is a power peak suitable for ignition of a plasma or a laser.

[0066] Figure 4b Shown with Figure 4a , which shows the output power provided by the amplifier 12 as a function of the value of the reflection factor. It can be seen that the power is substantially constant and is insufficient to ignite a plasma or a laser.

[0067] Figure 4c Shown with Figure 4a , Figure 4b , which shows the output power provided by the amplifier 12 as a function of the phase angle of the reflection factor changes.

[0068] Figure 5a , Figure 5b , Figure 5c Shown with Figures 4a to 4cCorresponding diagram, in which the switching element 38 of the impedance switching component 27 a is actuated according to the first actuation mode in order to short-circuit the impedance 36 .

[0069] from Figure 5a It can be seen from the figure that a substantially flat power distribution is not achieved, but a power maximum or peak occurs in region 52. Figure 5b and Figure 5c It can be seen that Figures 4a to 4c Compared to the case of , the power generated in the case of a reflection factor value greater than 0.7 and a reflection factor angle of 0° is significantly higher, which is suitable for ignition of plasma or laser.

[0070] Figure 6a , Figure 6b , Figure 6c Shown with Figures 4a to 4c Corresponding diagram, in which the switching element 38 of the impedance switching component 27 b is actuated according to the first actuation mode in order to disconnect the isolating terminal 26 from the ground terminal 39 .

[0071] from Figure 6a It can be seen from the figure that a substantially flat power distribution is not achieved, but a power maximum or peak occurs in region 54. Figure 6b and Figure 6c It can be seen that Figures 4a to 4c Compared to the case of , the power generated is significantly higher in the case of reflection factor values ​​greater than 0.7 and reflection factor angles of approximately +180° and −180°, which is suitable for ignition of plasma or laser.

Claims

1. A method for improved ignition and supply of a laser or a processing plasma with electrical power in a discharge chamber (30), wherein: The method comprises: a. supplying power to the discharge chamber (30) from an output terminal (24) of an amplifier (12), wherein the amplifier (12) comprises at least two amplifier paths (14, 16), and the at least two amplifier paths respectively supply signals to a combiner (22), wherein the combiner (22) has an output terminal (24) and an isolation terminal (26) and is configured such that the combiner combines the signals according to an amplitude relationship and / or a phase relationship of the signals and supplies power to the output terminal (24) and / or the isolation terminal (26); b. controlling an impedance switching component (27, 27a, 27b) connected to the isolation terminal (26) and the ground terminal (39) according to a first control mode so as to perform ignition of the laser or the processing plasma; c. operating the impedance switching component (27, 27a, 27b) connected to the isolation terminal (26) according to a second operating mode to operate the laser or to maintain the processing plasma in the discharge chamber (30).

2. The method according to claim 1, characterized in that The step 1.a. comprises: operating the impedance switching component (27, 27a) in such a way that the impedance between the isolation terminal (26) and the ground terminal (39) is approximately equal to zero ohm or approximately infinite.

3. The method according to any one of the preceding claims, characterized in that In order to ignite the laser or the processing plasma, the impedance switching component (27, 27a, 27b) is controlled in the first control mode for a predetermined time, in particular for a time in the range of 0.1 μs to 10000 μs, preferably in the range of 1 μs to 1000 μs.

4. The method according to any one of the preceding claims 1 to 3, characterized in that To ignite the laser or the processing plasma, the impedance switching component (27, 27a, 27b) is operated in the first operation mode until ignition of the laser or plasma is detected.

5. The method according to any one of the preceding claims, characterized in that A 3 dB coupler, in particular a 90° hybrid coupler, is used as the combiner (22).

6. An amplifier (12), which can be connected to a discharge chamber (30), and has: a. A combiner (22) having an output terminal (24) and an isolation terminal (26) and two input terminals (18, 20), wherein: The combiner (22) is configured such that the combiner provides the signal to the output terminal (24) and / or the isolation terminal (26) according to the amplitude relationship and / or phase relationship of the signals at the input terminals (18, 20); b. at least two amplifier paths (14, 16), wherein the two amplifier paths (14, 16) are configured to provide signals to input terminals (18, 20) of the combiner (22), respectively; c. an impedance switching component (27, 27a, 27b), the impedance switching component being connected between the isolation terminal (26) and the ground terminal (39) and comprising an impedance (36) and at least one switching element (38); and d. A control device (34) configured to operate the impedance switching assembly (27, 27a, 27b) to ignite a laser or a processing plasma in the discharge chamber (30).

7. A plasma or laser system (10), comprising: a. a discharge chamber (30); b. an amplifier (12) connected to the discharge chamber (30), the amplifier comprising a combiner (22) and at least two amplifier paths (14, 16), the at least two amplifier paths respectively providing signals to the combiner (22), wherein the combiner (22) has an output terminal (24) and an isolation terminal (26) and is configured to combine the signals according to an amplitude relationship and / or a phase relationship of the signals and provide power to the output terminal (24) and / or the isolation terminal (26); c. an impedance switching component (27, 27a, 27b), the impedance switching component being connected between the isolation terminal (26) and the ground terminal (39) and comprising an impedance (36) and at least one switching element (38); d. A control device (34) configured to operate the impedance switching assembly (27, 27a, 27b) to ignite a laser or a processing plasma in the discharge chamber (30).

8. The plasma system according to claim 7, characterized in that: The switching element (38) is connected in series or in parallel with the impedance (36).

9. The plasma system according to any one of the preceding claims 7 or 8, characterized in that An impedance matching device (32) is arranged between the plasma chamber (30) and the balanced amplifier (12), wherein the impedance matching device (32) is connected to the output terminal (24) via a pipeline (28), the pipeline having an electrical length specifically selected depending on the magnetic properties, wavelength and dielectric of the connection.

10. The plasma system according to any one of the preceding claims 8 or 9, characterized in that The combiner (22) is designed as a 3dB coupler, in particular a 90° hybrid coupler.

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