Linear power amplifier for Langmuir probe diagnosis and working method thereof

Abstract

The invention discloses a linear power amplifier for Langmuir probe diagnosis and a working method thereof. The linear power amplifier comprises a high-potential power amplifier and a low-potential power amplifier, each of the high-potential power amplifier and the low-potential power amplifier comprises an NPN triode and a PNP triode; base electrodes of two triodes in the high-potential power amplifier are connected to the high-potential driving circuit; base electrodes of two triodes in the low-potential power amplifier are connected to the low-potential driving circuit; the collector electrode of the NPN triode in the high-potential power amplifier and the collector electrode of the NPN triode in the low-potential power amplifier are both connected to a positive power supply, and the collector electrode of the PNP triode in the high-potential power amplifier and the collector electrode of the PNP triode in the low-potential power amplifier are both connected to a negative power supply. The emitting electrodes of the two triodes in the high-potential power amplifier are both connected with the high-potential output end, and the emitting electrodes of the two triodes in the low-potential power amplifier are both connected with the low-potential output end.

Description

Technical Field

[0001] This application relates to the technical field of fusion device probe diagnosis, and specifically relates to a linear power amplifier for Langmuir probe diagnosis and its working method. Background Art

[0002] In a fusion Tokamak device, measuring the required parameters by the interaction between a probe and a plasma is one of the basic means of plasma diagnosis. In addition to the single probe, the existing main probe theoretical models also include double probes, triple probes, etc. Currently, most of the probes used in the probe diagnosis system of the fusion Tokamak device work in the current DC output mode, and the power supply that provides drive for the probe is often a power supply mainly based on a switching power supply or a simple inverter structure. This kind of inverter is a switching power converter based on PWM control technology, with a simple structure and high efficiency. However, its output waveform is essentially a discrete pulse square wave, and a filter needs to be added to filter out the rich harmonic content to obtain a waveform with performance meeting the requirements, such as a single-frequency sine wave or a triangular wave. Moreover, the high-frequency switching process of its semiconductor switching devices will bring electromagnetic interference. For a probe diagnosis system with a wide current range, spanning from a few milliamperes to several amperes, especially under low scanning voltage and weak current conditions, these high-frequency noises are difficult to control, resulting in very unsatisfactory overall performance.

[0003] Using a linear power amplifier with low external interference can avoid the above problems. Although the mature linear power supply products on the market can work under high-frequency conditions and also have advantages such as high precision, high linearity, and small ripple, it is difficult to output both high frequency and high voltage at the same time, and there are problems such as large loss, low efficiency, and large volume, such as class-A power amplifiers, class-AB power amplifiers, etc. For the probe diagnosis system of a fusion device, the backend power supply system is a large system, and the floor area near the fusion device is very tight. This kind of power supply with large power consumption and large volume cannot meet the requirements of the probe diagnosis system cabinet for the power supply size. In addition, in the double-probe mode, it is required that the power supply output is floating ground, which is also not satisfied by ordinary class-AB power amplifiers on the market. The conventional method is to connect an isolation transformer at the output end of an ordinary class-AB power amplifier, increasing the system complexity. Summary of the Invention

[0004] In order to meet the requirements of the fusion device probe diagnosis system for power consumption, volume, etc., this application proposes a linear power amplifier for Langmuir probe diagnosis and its working method. By adopting a high-potential power amplifier and a low-potential power amplifier, this application can reduce the amplitude of the power supply voltage required for a single power triode under the condition of outputting the same voltage, thereby reducing the power consumption of the power device and the difficulty of component selection.

[0005] In the first aspect, this application is realized through the following technical solutions:

[0006] A linear power amplifier for Langmuir probe diagnosis, the linear power amplifier comprising: a high-potential power amplifier, a low-potential power amplifier, a high-potential drive circuit, and a low-potential drive circuit;

[0007] Both the high-potential power amplifier and the low-potential power amplifier include an NPN triode and a PNP triode;

[0008] Wherein, the bases of the two triodes in the high-potential power amplifier are both connected to the high-potential drive circuit, and the high-potential drive circuit is used to realize the base drive of the triodes in the high-potential power amplifier;

[0009] The bases of the two triodes in the low-potential power amplifier are both connected to the low-potential drive circuit, and the low-potential drive circuit is used to realize the base drive of the triodes in the low-potential power amplifier;

[0010] The collectors of the NPN triode in the high-potential power amplifier and the NPN triode in the low-potential power amplifier are both connected to the positive power supply, and the collectors of the PNP triode in the high-potential power amplifier and the PNP triode in the low-potential power amplifier are both connected to the negative power supply;

[0011] The emitters of the two triodes in the high-potential power amplifier are both connected to the high-potential output terminal of the linear power amplifier, and the emitters of the two triodes in the low-potential power amplifier are both connected to the low-potential output terminal of the linear power amplifier.

[0012] In some embodiments, the linear power amplifier further comprises: a high-potential feedback circuit and a low-potential feedback circuit;

[0013] The high-potential feedback circuit receives the external drive signal after passing through the non-inverting amplifier, and at the same time receives the voltage signal output from the high-potential output terminal of the linear power amplifier. The high-potential feedback circuit outputs a signal to the high-potential drive circuit to realize the feedback control of the high-potential power amplifier;

[0014] The low-potential feedback circuit receives the external drive signal after passing through the inverting amplifier, and at the same time receives the voltage signal output from the low-potential output terminal of the linear power amplifier. The low-potential feedback circuit outputs a signal to the low-potential drive circuit to realize the feedback control of the low-potential power amplifier.

[0015] In some embodiments, the voltage amplitudes of the positive power supply and the negative power supply are equal.

[0016] In some embodiments, the high-potential output terminal and the low-potential output terminal of the linear power amplifier supply power to the load.

[0017] In some embodiments, the output voltage of the linear power amplifier is equal to the voltage output from the high-potential output terminal of the linear power amplifier minus the voltage output from the low-potential output terminal of the linear power amplifier.

[0018] In a second aspect, the present application proposes a working method for the above linear power amplifier, and the working method includes:

[0019] When the external drive signal is positive, the base voltages of the two triodes in the high-potential power amplifier are positive, and the base voltages of the two triodes in the low-potential power amplifier are negative. Then, the NPN triode in the high-potential power amplifier and the PNP triode in the low-potential power amplifier are turned on, while the PNP triode in the high-potential power amplifier and the NPN triode in the low-potential power amplifier are turned off. Ignoring the triode voltage drop, the output voltage of the high-potential output terminal of the linear power amplifier follows the base voltage of the NPN triode in the high-potential power amplifier, the output voltage of the low-potential output terminal of the linear power amplifier follows the base voltage of the PNP triode in the low-potential power amplifier, and the amplitude of the output voltage of the linear power amplifier is twice the amplitude of the external drive signal voltage.

[0020] In some embodiments, the working method further includes:

[0021] When the external drive signal is negative, the base voltages of the two triodes in the high-potential power amplifier are negative, and the base voltages of the two triodes in the low-potential power amplifier are positive. Then, the NPN triode in the high-potential power amplifier and the PNP triode in the low-potential power amplifier are turned off, while the PNP triode in the high-potential power amplifier and the NPN triode in the low-potential power amplifier are turned on. Ignoring the triode voltage drop, the output voltage of the high-potential output terminal of the linear power amplifier follows the base voltage of the PNP triode in the high-potential power amplifier, the output voltage of the low-potential output terminal of the linear power amplifier follows the base voltage of the NPN triode in the low-potential power amplifier, and the amplitude of the output voltage of the linear power amplifier is twice the amplitude of the external drive signal voltage.

[0022] In some embodiments, the amplitude of the output voltage of the linear power amplifier is twice the amplitude of the voltage of the triode power supply.

[0023] In some embodiments, the external drive signal is a sine wave signal or a triangular wave signal.

[0024] In a third aspect, the present application proposes a Langmuir probe diagnostic system, and the Langmuir probe diagnostic system employs the above linear power amplifier.

[0025] A linear power amplifier for Langmuir probe diagnosis and its working method proposed in this application adopt a symmetric structure of a high-potential power amplifier and a low-potential power amplifier, which can reduce the amplitude of the power supply voltage of a single power device under the condition of outputting the same voltage, thereby reducing the power consumption of the power device and the difficulty of component selection; in addition, with the reduction of the power consumption of the power device, the heat dissipation difficulty is also reduced, the volume of the power amplifier can be reduced, and the problem of the tight floor area near the fusion device can be greatly alleviated.

[0026] A linear power amplifier for Langmuir probe diagnosis and its working method proposed in this application, the output voltage of the linear power amplifier is the voltage difference between the high-potential output terminal and the low-potential output terminal, which is not related to the internal or external GND of the power amplifier, so that the output potential can be absolutely floating, simplifying the system complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the embodiments of the present application, and constitute a part of the present application, without limiting the embodiments of the present application. In the drawings:

[0028] Figure 1 is the principle block diagram of the linear power amplifier proposed in the embodiment of the present application;

[0029] Figure 2 is the structural schematic diagram of the linear power amplifier proposed in the embodiment of the present application;

[0030] Figure 3 is the output waveform diagram of the two output terminals of the linear power amplifier proposed in the embodiment of the present application in the positive half cycle of the external drive signal;

[0031] Figure 4 is the output waveform diagram of the two output terminals of the linear power amplifier proposed in the embodiment of the present application in the negative half cycle of the external drive signal;

[0032] Figure 5 is the output waveform diagram of the linear power amplifier proposed in the embodiment of the present application;

[0033] Reference numerals and corresponding component names:

[0034] 1 - low-potential power amplifier, 2 - high-potential power amplifier. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] Hereinafter, the term "comprising" or "may comprise" which may be used in various embodiments of the present application indicates the presence of the invented functions, operations, or elements, and does not limit the addition of one or more functions, operations, or elements. Further, as used in various embodiments of the present application, the terms "comprising", "having" and their cognates are only intended to represent a specific feature, number, step, operation, element, component, or combination of the foregoing items, and should not be construed as precluding the existence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing items first.

[0036] In various embodiments of the present application, the expression "or" or "at least one of A or / and B" includes any combination or all combinations of the recited words. For example, the expression "A or B" or "at least one of A or / and B" may include A, may include B, or may include both A and B.

[0037] Expressions (such as "first", "second", etc.) used in various embodiments of the present application may modify various constituent elements in the various embodiments, but do not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only for the purpose of distinguishing one element from other elements. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, without departing from the scope of the various embodiments of the present application, the first element may be referred to as the second element, and similarly, the second element may also be referred to as the first element.

[0038] It should be noted that: if it is described that one constituent element is "connected" to another constituent element, the first constituent element may be directly connected to the second constituent element, and a third constituent element may be "connected" between the first constituent element and the second constituent element. Conversely, when one constituent element is "directly connected" to another constituent element, it can be understood that there is no third constituent element between the first constituent element and the second constituent element.

[0039] The terms used in various embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the various embodiments of the present application. As used herein, the singular form is also intended to include the plural form unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the present application belong. The terms (such as those defined in a commonly used dictionary) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or being overly formal unless clearly defined in the various embodiments of the present application.

[0040] To make the objectives, technical solutions, and advantages of this application more clear and understandable, the following further details this application in combination with embodiments and drawings. The illustrative embodiments of this application and their descriptions are only used to explain this application and do not limit this application.

[0041] Embodiment 1:

[0042] Existing mature linear power supply products on the market have problems such as large losses, low efficiency, and large volume, and are not suitable for the probe diagnostic system of the fusion device. In response to this, this embodiment proposes a linear power amplifier for Langmuir probe diagnosis and its working method.

[0043] As Figure 1 shown, the linear power amplifier proposed in this embodiment includes:

[0044] A high-potential power amplifier, a low-potential power amplifier, a non-inverting amplifier, an inverting amplifier, a high-potential feedback circuit, a low-potential feedback circuit, a high-potential drive circuit, and a low-potential drive circuit.

[0045] Among them, the high-potential drive circuit is used to realize the base drive of the power triode in the high-potential power amplifier; the low-potential drive circuit is used to realize the base drive of the power triode in the low-potential power amplifier; the non-inverting amplifier is used to realize the non-inverting amplification of the external drive signal; the inverting amplifier is used to realize the inverting amplification of the external drive signal; both the high-potential power amplifier and the low-potential power amplifier are composed of an NPN triode and a PNP triode. The bases of the two triodes in the high-potential power amplifier are connected to the high-potential drive circuit, and the bases of the two triodes in the low-potential power amplifier are connected to the low-potential drive circuit. The collectors of the NPN triode in the high-potential power amplifier and the NPN triode in the low-potential power amplifier are connected to the positive power supply, and the collectors of the PNP triode in the high-potential power amplifier and the PNP triode in the low-potential power amplifier are connected to the negative power supply. The emitters of the NPN triode and the PNP triode in the high-potential power amplifier are connected to the high-potential output terminal of this linear power amplifier, and the emitters of the NPN triode and the PNP triode in the low-potential power amplifier are output-connected to the low-potential output terminal of this linear power amplifier.

[0046] The external drive signal is input to the high-potential feedback circuit after passing through the non-inverting amplifier. At the same time, the voltage output from the high-potential output terminal of the linear power amplifier is fed back to the high-potential feedback circuit to achieve the feedback control of the high-potential power amplifier. The external drive signal is input to the low-potential feedback circuit after passing through the inverting amplifier. At the same time, the voltage output from the low-potential output terminal of the linear power amplifier is fed back to the low-potential feedback circuit to achieve the feedback control of the low-potential power amplifier. It should be noted that the feedback control method can adopt existing feedback control technologies, such as PID control technology, etc., which will not be elaborated here too much.

[0047] Further, the output voltage of the linear power amplifier is equal to the voltage output from the high-potential output terminal of the linear power amplifier minus the voltage output from the low-potential output terminal of the linear power amplifier. In practical applications, the load is connected between the high-potential output terminal and the low-potential output terminal of the linear power amplifier to supply power to the load.

[0048] This embodiment uses Figure 2 the shown structure to further illustrate the above linear power amplifier. As can be seen from Figure 2 this, the linear power amplifier includes a low-potential power amplifier 1 and a high-potential power amplifier 2.

[0049] Among them, the low-potential power amplifier 1 includes an NPN transistor Q1 and a PNP transistor Q2. The bases of the NPN transistor Q1 and the PNP transistor Q2 are both connected to the low-potential drive circuit. The high-potential power amplifier 2 includes an NPN transistor Q3 and a PNP transistor Q4. The bases of the NPN transistor Q3 and the PNP transistor Q4 are both connected to the high-potential drive circuit. The collectors of the NPN transistor Q1 and the NPN transistor Q3 are both connected to the power supply +VCC, and the collectors of the PNP transistor Q2 and the PNP transistor Q4 are both connected to the power supply -VCC. The emitters of the NPN transistor Q1 and the PNP transistor Q2 are both connected to the COM terminal (i.e., the low-potential output terminal of the linear power amplifier). The voltage output from the low-potential output terminal of the linear power amplifier is the voltage between the COM terminal and GND. In addition, the voltage output from the low-potential output terminal of the linear power amplifier is also fed back to the low-potential feedback circuit to achieve the feedback control of the low-potential power amplifier. The emitters of the NPN transistor Q3 and the PNP transistor Q4 are both connected to the OUTPUT terminal (i.e., the high-potential output terminal of the linear power amplifier). The voltage output from the high-potential output terminal of the linear power amplifier is the voltage between the OUTPUT terminal and GND. In addition, the voltage output from the high-potential output terminal of the linear power amplifier is also fed back to the high-potential feedback circuit to achieve the feedback control of the high-potential power amplifier. The high-potential output terminal and the low-potential output terminal of the linear power amplifier supply power to the load.

[0050] The working principle of the linear power amplifier is as follows:

[0051] When the external drive signal is positive, the base voltages of Q3 and Q4 are positive, so Q4 is cut off and Q3 is turned on. The emitter voltage of Q3 follows the output of its base voltage. Ignoring the voltage drop of the triode, the voltage of the OUTPUT terminal relative to GND is the base voltage VQ3E of Q3. At the same time, the base voltages of Q1 and Q2 are negative, so Q1 is cut off and Q2 is turned on. The emitter voltage of Q2 follows the output of its base voltage. Ignoring the voltage drop of the triode, the voltage of the COM terminal relative to GND is the base voltage VQ2E of Q2. Thus, the output voltage of this linear power amplifier is VQ3E - VQ2E, and its voltage amplitude is 20 times that of the external drive signal voltage amplitude, which can be up to 2 times the supply voltage VCC (ignoring the voltage drop of the triode, the voltage of the OUTPUT terminal relative to GND can be up to VCC, and the voltage of the COM terminal relative to GND can be up to -VCC. Therefore, the output voltage of this linear power amplifier can be up to 2VCC).

[0052] When the external drive signal is negative, the base voltages of Q3 and Q4 are negative, so Q3 is cut off and Q4 is turned on. The emitter voltage of Q4 follows the output of its base voltage. Ignoring the voltage drop of the triode, the voltage of the OUTPUT terminal relative to GND is the base voltage VQ4E of Q4. At the same time, the base voltages of Q1 and Q2 are positive, so Q2 is cut off and Q1 is turned on. The emitter voltage of Q1 follows the output of its base voltage. Ignoring the voltage drop of the triode, the voltage of the COM terminal relative to GND is VQ1E. Thus, the output voltage of this linear power amplifier is VQ4E - VQ1E, and its voltage amplitude is 20 times that of the external drive signal voltage amplitude, which can be up to 2 times the external supply voltage VCC (ignoring the voltage drop of the triode, the voltage of the OUTPUT terminal relative to GND can be up to -VCC, and the voltage of the COM terminal relative to GND can be up to VCC. Therefore, the output voltage of this linear power amplifier can be up to -2VCC).

[0053] From the above working principle, it can be seen that the linear power amplifier proposed in this embodiment adopts a symmetrical structure of a high-potential power amplifier and a low-potential power amplifier, which can reduce the amplitudes of the supply voltages +VCC and -VCC by half under the condition of outputting the same voltage, reducing the power consumption of the power devices and the difficulty of device selection. With the reduction of the power consumption of the power devices, the heat dissipation difficulty is also reduced, so the volume of the power amplifier can be reduced, greatly alleviating the problem of the tight floor area near the fusion device.

[0054] In addition, the output voltage of the linear power amplifier proposed in this embodiment is the voltage difference between the OUTPUT terminal and the COM terminal, which has nothing to do with the internal or external GND of the amplifier, so that the output potential can be absolutely floating, simplifying the system complexity.

[0055] Embodiment 2:

[0056] In this embodiment, the linear power amplifier proposed in the above embodiment is simulated and tested, taking a sine wave as an example.

[0057] When the external drive signal is positive, the output of the high-potential drive circuit is positive, and the output of the low-potential drive circuit is negative. At this time, Q1 and Q4 are cut off, and Q2 and Q3 are turned on. Ignoring the voltage drop of the triode, the OUTPUT terminal follows the base voltage of Q3, that is, the output waveform at the OUTPUT terminal is the positive half-cycle waveform of the sine wave, and the COM terminal follows the base voltage of Q2, that is, the output waveform at the COM terminal is the negative half-cycle waveform of the sine wave. Specifically, as Figure 3 shown, the red is the output waveform at the OUTPUT terminal, and the blue is the output waveform at the COM terminal.

[0058] When the external drive signal is negative, the output of the high-potential drive circuit is negative, and the output of the low-potential drive circuit is positive. At this time, Q2 and Q3 are cut off, and Q1 and Q4 are turned on. Ignoring the voltage drop of the triode, the OUTPUT terminal follows the base voltage of Q4, that is, the output waveform at the OUTPUT terminal is the negative half-cycle waveform of the sine wave, and the COM terminal follows the base voltage of Q1, that is, the output waveform at the COM terminal is the positive half-cycle waveform of the sine wave. Specifically, as Figure 4 shown, the red is the output waveform at the OUTPUT terminal, and the blue is the output waveform at the COM terminal. It should be noted that for easy display and viewing, Figure 3 and Figure 4 the waveforms in are set with offsets.

[0059] When the external drive signal is a complete sine wave, that is, the positive and negative half-cycles work alternately, the output voltage of this linear power amplifier, that is, the voltage between the OUTPUT terminal and the COM terminal, is 20 times that of the external drive signal, and can be as high as 2 times VCC. Specifically, as Figure 5 shown, the red is the waveform of the external drive signal, and the blue is the voltage waveform between the OUTPUT terminal and the COM terminal. It should be noted that for easy display and viewing, Figure 5 in, the range of the red waveform is 5V / div, and the range of the blue waveform is 50V / div.

[0060] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of this application. It should be understood that the above are only specific embodiments of this application and are not used to limit the protection scope of this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims

1. A linear power amplifier for Langmuir probe diagnosis, characterized in that: The linear power amplifier comprises: a high potential power amplifier, a low potential power amplifier, a high potential driving circuit and a low potential driving circuit; The high potential power amplifier and the low potential power amplifier each include an NPN transistor and a PNP transistor; Wherein, the bases of the two transistors in the high potential power amplifier are connected to the high potential driving circuit, and the high potential driving circuit is used to realize the base driving of the transistors in the high potential power amplifier; The bases of the two transistors in the low potential power amplifier are both connected to the low potential driving circuit, and the low potential driving circuit is used to realize the base driving of the transistors in the low potential power amplifier; The collectors of the NPN transistor in the high potential power amplifier and the NPN transistor in the low potential power amplifier are both connected to a positive power supply, and the collectors of the PNP transistor in the high potential power amplifier and the PNP transistor in the low potential power amplifier are both connected to a negative power supply; The emitters of the two transistors in the high potential power amplifier are both connected to the high potential output end of the linear power amplifier, and the emitters of the two transistors in the low potential power amplifier are both connected to the low potential output end of the linear power amplifier.

2. A linear power amplifier for Langmuir probe diagnosis according to claim 1, characterized in that: The linear power amplifier further comprises: a high potential feedback circuit and a low potential feedback circuit; The high potential feedback circuit receives the external driving signal after passing through the in-phase amplifier, and simultaneously receives the voltage signal outputted from the high potential output terminal of the linear power amplifier, and the high potential feedback circuit outputs the signal to the high potential driving circuit to realize feedback control of the high potential power amplifier; The low potential feedback circuit receives an external driving signal after passing through an inverting amplifier, and simultaneously receives a voltage signal output from a low potential output terminal of the linear power amplifier. The low potential feedback circuit outputs a signal to the low potential driving circuit to implement feedback control of the low potential power amplifier.

3. A linear power amplifier for Langmuir probe diagnosis according to claim 1, characterized in that: The voltage amplitudes of the positive power supply and the negative power supply are equal.

4. A linear power amplifier for Langmuir probe diagnosis according to any one of claims 1 to 3, characterized in that: The high potential output terminal and the low potential output terminal of the linear power amplifier supply power to the load.

5. A linear power amplifier for Langmuir probe diagnosis according to claim 4, characterized in that: The output voltage of the linear power amplifier is equal to the voltage output from the high potential output terminal of the linear power amplifier minus the voltage output from the low potential output terminal of the linear power amplifier.

6. A method for operating a linear power amplifier for Langmuir probe diagnosis according to any one of claims 1 to 5, characterized in that: The working method comprises: When the external driving signal is positive, the base voltages of the two transistors in the high-potential power amplifier are positive, and the base voltages of the two transistors in the low-potential power amplifier are negative, then the NPN transistor in the high-potential power amplifier and the PNP transistor in the low-potential power amplifier are turned on, while the PNP transistor in the high-potential power amplifier and the NPN transistor in the low-potential power amplifier are cut off, and when the transistor voltage drop is ignored, the output voltage of the high-potential output end of the linear power amplifier follows the base voltage of the NPN transistor in the high-potential power amplifier, and the output voltage of the low-potential output end of the linear power amplifier follows the base voltage of the PNP transistor in the low-potential power amplifier, and the output voltage amplitude of the linear power amplifier is twice the voltage amplitude of the external driving signal.

7. The working method according to claim 6, characterized in that: The working method also includes: When the external driving signal is negative, the base voltages of the two transistors in the high-potential power amplifier are negative, and the base voltages of the two transistors in the low-potential power amplifier are positive, then the NPN transistor in the high-potential power amplifier and the PNP transistor in the low-potential power amplifier are cut off, while the PNP transistor in the high-potential power amplifier and the NPN transistor in the low-potential power amplifier are turned on, and when the transistor voltage drop is ignored, the output voltage of the high-potential output end of the linear power amplifier follows the base voltage of the PNP transistor in the high-potential power amplifier, and the output voltage of the low-potential output end of the linear power amplifier follows the base voltage of the NPN transistor in the low-potential power amplifier, and the output voltage amplitude of the linear power amplifier is twice the voltage amplitude of the external driving signal.

8. The working method according to claim 6 or 7, characterized in that: The output voltage amplitude of the linear power amplifier is twice the voltage amplitude of the transistor power supply.

9. The working method according to claim 6 or 7, characterized in that: The external driving signal is a sine wave signal or a triangle wave signal.

10. A Langmuir probe diagnostic system, characterized in that: The Langmuir probe diagnostic system adopts the linear power amplifier described in any one of claims 1-5.

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