Plasma measurement device

Abstract

The present invention relates to a plasma measurement device, comprising: a probe assembly for collecting electron and ion currents of plasma; a high-voltage scanning power supply module for generating a voltage waveform and applying it to the probe assembly; a signal conditioning module for switching the working mode of the probe assembly and conditioning the voltage and current signals fed back by the probe assembly; a data acquisition module for collecting the conditioned voltage and current signals under different working modes, and obtaining plasma parameters after processing the voltage and current signals; the working modes include scanning single probe, DC biased single probe, scanning double probe and DC biased triple probe. Therefore, the present invention can realize a wide range of plasma density and temperature measurement by switching four probe working modes, meet the measurement of steady-state and transient plasma parameters, and greatly improve the measurement accuracy and efficiency of plasma parameters.

Description

Technical Field

[0001] The invention relates to a plasma measuring device. Background Art

[0002] The electrostatic probe is one of the most commonly used plasma parameter measurement devices, also known as the Langmuir probe, with a simple structure and good spatial resolution. The electrostatic probe measurement device consists of a controller and a sensor. The sensor is a conductive metal needle inserted into the plasma, usually made of sputtering-resistant and high-temperature resistant materials such as tungsten wire; the controller usually includes a high-voltage scanning power module system, a signal conditioning system, and a data acquisition system. The working mode of the electrostatic probe is to apply a set voltage waveform to the needle tip through the probe high-voltage scanning power module system, and at the same time obtain the weak current collected by the needle tip and the voltage applied by the probe through the signal conditioning system and the data acquisition system, and then calculate the plasma parameters through a special algorithm of the obtained voltage-current curve.

[0003] Due to the different ways of generating plasma and application scenarios, the span of the measured plasma parameters is large and the stability is poor, which greatly increases the difficulty of measuring the parameters of plasma with electrostatic probes. Therefore, the Langmuir probe must have a large dynamic range measurement capability for plasma densities spanning multiple orders of magnitude, and must have a certain time resolution. There are two main solutions in the prior art. One is to replace the probe tip and use cylindrical probes of various sizes or large-sized spherical probes for measurement. When this method is used, in order to simply obtain a higher probe current signal, the aspect ratio of the probe is too small to meet the theoretical assumptions of plasma calculations, or a large-sized spherical probe is used to cause serious interference to the plasma, making it impossible to accurately obtain the parameters of the plasma. At the same time, a large number of preliminary tests are required for measurement, and the optimal probe size is determined based on experience, and the measurement process is cumbersome. Another method is to develop single-probe, double-probe, triple-probe and other electrostatic probe measurement devices with different working modes for different plasma measurement conditions. However, due to the changes in the plasma environment and the similarity of electrostatic probes in different modes, the equipment is redundant and wasted. Each working mode of the probe is an independent system. The probe systems of different measurement modes are designed and used independently. A single system cannot cover the plasma density measurement range and cannot be adjusted in real time according to the measurement conditions, which brings great inconvenience to the measurement process. At present, there is a lack of a high-precision test method and test equipment for Langmuir probes for dynamic plasma parameters in a large density range.

[0004] There are many ways to generate plasma, and the characteristic parameters of plasma, such as density and temperature, have a wide range, making accurate measurement difficult. For different types of discharge plasma, traditional electrostatic probe measurement devices need to adjust the probe size or use electrostatic probes with different working modes for measurement according to the state and characteristics of the measured plasma. Therefore, there is a need for an electrostatic probe measurement device that can simultaneously measure different plasma states with high precision.

[0005] For example, patent CN101650230A discloses a measurement system that can take into account single-probe, dual-probe, and triple-probe measurement at the same time. By controlling the action of the relay, the three different probe modes can be switched. It can be applied to a variety of plasma diagnosis without being restricted by the discharge form. It integrates the traditional single-probe, dual-probe, and triple-probe to achieve the combination of different functions, but it cannot improve the measurement accuracy, and it is impossible to compare and calibrate between different modes. In addition, the probe working modes in this patent are relatively few, and it cannot cover the measurement of plasmas with a large span of characteristic parameters. In transient plasma testing, it can only be measured by a single mode of three probes, and the measurement error is large. Summary of the invention

[0006] The object of the present invention is to solve the above-mentioned problem and provide a plasma measuring device.

[0007] To achieve the above-mentioned object of the invention, the present invention provides a plasma measuring device, comprising:

[0008] a probe assembly for collecting electron and ion currents from the plasma;

[0009] A high-voltage scanning power supply module, used for generating a voltage waveform and applying it to the probe assembly;

[0010] A signal conditioning module, used for switching the working mode of the probe assembly and conditioning the voltage and current signals fed back by the probe assembly;

[0011] A data acquisition module, used for acquiring the conditioned voltage and current signals under different working modes, and obtaining plasma parameters after processing the voltage and current signals;

[0012] The working modes include scanning single probe, DC biasing single probe, scanning double probe and DC biasing triple probe.

[0013] According to one aspect of the present invention, the probe assembly includes first, second and third probes which are cylindrical or spherical.

[0014] According to one aspect of the present invention, the signal conditioning module includes a channel control module, a voltage measurement module and a current measurement module, and the data acquisition module includes a data acquisition card and a host computer.

[0015] According to one aspect of the present invention, in the scanning single-probe mode and the scanning dual-probe mode, an optocoupler is used to transmit signals between the signal conditioning module and the data acquisition module. The bandwidth of the optocoupler module can meet the signal undistorted acquisition when the scanning voltage frequency of the high-voltage scanning power supply module is not less than 250kHz, and the measurement response time can reach the μs level.

[0016] According to one aspect of the present invention, the voltage waveform generated by the high-voltage scanning power supply module includes a DC bias mode and a fast scanning mode.

[0017] According to one aspect of the present invention, the high voltage scanning power supply module comprises:

[0018] A signal generator, used for generating a triangular wave input signal with high frequency and low amplitude and adjustable amplitude and frequency;

[0019] A first operational amplifier, used to amplify an input signal;

[0020] Voltage converter for signal isolation;

[0021] A linear isolator, used for converting the input signal amplified by the first operational amplifier into a DC bias signal and isolating the signal;

[0022] A relay, used for switching the on and off states of the voltage converter and the linear isolator;

[0023] The second operational amplifier is used to amplify the signal output by the relay.

[0024] According to one aspect of the present invention, in the single-probe working mode, the positive terminal of the high-voltage scanning power supply module is connected to the second probe, and the negative terminal is connected to the safety ground;

[0025] The voltage measurement module collects the voltage between the second probe and the safety ground, and the current measurement module collects the current of the second probe loop.

[0026] According to one aspect of the present invention, in the dual-probe working mode, the positive end of the high-voltage scanning power supply module is connected to the second probe, and the negative end is connected to the first probe;

[0027] The voltage measurement module collects the voltage applied to the first probe or the second probe, and the current measurement module collects the current of the loop formed by the first probe and the second probe.

[0028] According to one aspect of the present invention, in the three-probe working mode, the high-voltage scanning power supply module is connected to the second probe, and the negative end is connected to the first probe; the third probe is in a suspended state;

[0029] The voltage measurement module collects the voltage between the second probe and the third probe, and the current measurement module collects the current signal of the second probe loop.

[0030] According to one aspect of the present invention, it further comprises a chassis, wherein the high-voltage scanning power supply module, the signal conditioning module and the data acquisition module are all located in the chassis;

[0031] The high-voltage scanning power supply module and the data acquisition module are respectively connected to the signal conditioning module, and the signal conditioning module is connected to the probe assembly via a coaxial cable.

[0032] According to the concept of the present invention, the present invention can switch the working modes of various electrostatic probes, realize a wide range of plasma density and temperature measurements, meet the measurement of steady-state and transient plasma parameters, and greatly improve the measurement accuracy and efficiency of plasma parameters.

[0033] According to one solution of the present invention, three forms of single probe, double probe and triple probe are used to realize four different measurement functions, thereby minimizing the number of probes arranged in the plasma environment to reduce the interference caused by the probe support rod and the probe tip to the measured plasma. The plasma parameters obtained by different measurement modes can also be verified and compared with each other, thereby improving the measurement accuracy.

[0034] According to a scheme of the present invention, a switch matrix is ​​formed by using multiple relays to realize the probe scanning power supply output mode and the on-off of the probe assembly, so as to realize the sharing of a set of probe assemblies. Since the three-probe mode is specifically used for transient plasma measurement, because the response time of the traditional single probe and double probe depends on the speed of the scanning voltage, too fast will increase the error, so generally transient measurement cannot be performed. Therefore, the scanning power supply used is a high-frequency scanning voltage with a frequency of not less than 250kHz, and combined with a method of reducing displacement current such as a high-speed optical coupler plus a coaxial cable, transient measurement and biased three-probe transient measurement results can be compared and calibrated in the scanning single probe mode and the scanning double probe mode, thereby improving the measurement accuracy. Each module adopts a modular design, which can realize the array design of the probe assembly and realize the spatial distribution measurement of plasma parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram showing the structure of a plasma measuring device according to an embodiment of the present invention;

[0036] Figure 2 A schematic diagram showing a structure of a high voltage power supply scanning module in a plasma measuring device according to an embodiment of the present invention;

[0037] Figure 3The figure schematically shows the operation of a signal conditioning module in a plasma measurement device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0040] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0041] See also Figure 1 The plasma measuring device of the present invention is based on an electrostatic probe for measurement and has multiple measurement functions, and can be used to measure the parameters of complex plasmas. The device includes a probe assembly 1, a high-voltage scanning power supply module 2, a signal conditioning module 3, and a data acquisition module 4. Among them, the probe assembly 1 is used to support the needle tip of the probe to receive the electron and ion current of the plasma; the high-voltage scanning power supply module 2 can generate different voltage waveforms and apply them to the probe needle tip of the probe assembly 1; the signal conditioning module 3 is used to switch the working mode of the probe assembly 1, and condition the voltage and current signals fed back by the probe assembly 1; the data acquisition module 4 is composed of a data acquisition card and a host computer, which is used to collect the conditioned voltage and current signals under different working modes, and obtain various parameters of the plasma after processing them according to the corresponding theoretical algorithm.

[0042] Continue to see Figure 1, the plasma measurement device of the present invention also includes a chassis 5 with a shielding function, so as to reduce interference and improve test accuracy. The above-mentioned high-voltage scanning power supply module 2, signal conditioning module 3 and data acquisition module 4 are all located in the chassis 5, and the high-voltage scanning power supply module 2 and the data acquisition module 4 are respectively connected to the signal conditioning module 3 by cables. The signal conditioning module 3 is connected to the probe assembly 1 through a coaxial cable 6 to collect voltage and current. The present invention uses a coaxial cable 6 to connect the probe and the chassis here because the displacement current of the coaxial cable 6 is small, so the interference generated is also less. Of course, other cables can also selectively use coaxial cables as needed to complete the integration and connection of the above modules. It can be seen that the probe control box (chassis 5 and internal modules) and the probe assembly 1 of the present invention adopt a modular design, which is convenient for expansion design. The probe assembly 1 forms a probe array, and spatial distribution measurement can be achieved by adjusting the spacing and layout of the probe assembly.

[0043] According to the concept of the present invention, the working modes of the probe assembly 1 include four types, namely scanning single probe, DC bias single probe, scanning double probe and DC bias three probe. Therefore, the device can achieve a wide range of plasma density and temperature measurements by switching the working modes of multiple electrostatic probes, thereby meeting the measurement of steady-state and transient plasma parameters, and greatly improving the measurement accuracy and efficiency of plasma parameters. The design of these four working modes covers almost all the modes required for plasma probe measurement, so compared with traditional measurement devices with a single working mode, the measurement range of the present invention is larger.

[0044] See also Figure 2 The voltage waveform generated by the high-voltage scanning power supply module 2 is divided into a DC bias mode and a fast scanning mode, and its circuit core is a high-power amplifier. Specifically, the high-voltage scanning power supply module 2 includes a signal generator 21, a first operational amplifier 22, a voltage converter 23, a linear isolator 24, a relay 25, and a second operational amplifier 26. Figure 2As shown, the signal generator 21 is used to generate a high-frequency, low-amplitude, and adjustable-amplitude and frequency triangle wave signal as an input signal. The first operational amplifier 22 can perform preliminary operational amplification on the input signal. The function of the voltage converter 23 is to achieve signal isolation. The linear isolator 24 is used to convert the input signal amplified by the first operational amplifier 22 into a bias signal and isolate it. It can be seen that the voltage converter 23 and the linear isolator 24 of the present invention can realize two voltage waveform modes of two high-voltage scanning power supply modules 2, and these two modes are switched by the relay 25. Specifically, the relay 25 completes the switching work of the scanning mode and the bias mode by switching the on and off states of the voltage converter 23 and the linear isolator 24. The second operational amplifier 26 can output the signal output by the relay 25 after high-voltage amplification, thereby providing the probe assembly 1 with a bias / scanning signal that has been amplified twice. In the present invention, the scanning signal is a triangle wave signal in the range of ±10V, and the bias signal is a DC adjustable signal.

[0045] That is, in the two working modes of DC bias single probe and DC bias three probe, the high-voltage scanning power supply module 2 adopts the DC bias output mode. At this time, by switching the relay 25, the input signal is converted into a DC signal after passing through the first operational amplifier 22 and the linear isolator 24 for high-voltage amplification and loaded onto the probe. The output of this mode is a DC adjustable voltage. In the two measurement modes of scanning single probe and scanning double probe, the high-voltage scanning power supply module 2 adopts a fast scanning output mode. At this time, by switching the relay 25, the input signal is converted into a triangle wave in the range of ±10V after passing through the first operational amplifier 22 and the voltage converter 23 for high-voltage amplification and loaded onto the probe. The output of this mode is a high-speed scanning voltage.

[0046] See also Figure 3 The probe assembly 1 includes three identical probes, namely, the first, second, and third probes 11, 12, and 13, which are all cylindrical or spherical. The above working modes can be switched by switching the three metal wires. In the single-probe mode, one metal wire is connected, in the double-probe mode, two metal wires are connected, and in the triple-probe mode, three metal wires are connected.

[0047] Among them, the probe assembly 1 of the electrostatic single probe is a metal wire, on which a scanning voltage from negative to positive is applied, and the current between the loop formed by the needle tip and the wall where the plasma annihilates and the voltage to the ground are measured, so as to obtain various key plasma parameters such as plasma density, temperature, space potential, suspension potential, electron energy distribution, etc. The measured parameter range is the widest, and it is necessary to assume that the plasma space potential remains unchanged during the measurement process.

[0048] The probe assembly 1 of the electrostatic double probe is two completely identical metal wires, on which a scanning voltage from negative to positive is applied, and the current and needle tip voltage values ​​in the loop formed by the two needle tips and the plasma are measured, so that the plasma density and temperature can be obtained. There is no need to provide a wall as a reference electrode, and the measurement result is independent of the plasma space potential and is not affected by the space potential fluctuation. The probe collects a small current and has little interference with the plasma.

[0049] The probe assembly 1 of the electrostatic three-probe is three completely identical metal wires, composed of a single probe and a double probe. The single probe is in a suspended state. By applying a fixed bias voltage to the double probe, the plasma density and temperature can be measured, thereby realizing the measurement of transient plasma parameters.

[0050] In this way, the number of probes arranged in the plasma environment can be reduced to the greatest extent, the interference of the probe support rod and the probe tip on the measured plasma can be reduced, and the plasma parameters obtained by different measurement modes can be verified and compared with each other, thereby improving the measurement accuracy. In addition, the probe assembly 1 of the present invention can adapt to different plasma density conditions by changing the shape of the probe. For example, if the density of the plasma is low, the probe needs a larger size to obtain more current, so as to achieve higher measurement accuracy, and the probe shape should be spherical (i.e., a ball probe); if the plasma density is high, the probe size needs to be small, so as to obtain less current, so as to improve the measurement accuracy, and therefore the probe shape should be cylindrical. Furthermore, this method of array designing the probe assembly 1 can also realize the spatial distribution measurement of plasma parameters by adjusting the spacing and layout of the probe assembly 1.

[0051] As can be seen from the above, in the single-probe mode, the scanning mode and the bias mode can be realized respectively, the dual-probe mode is the scanning mode, and the triple-probe mode is the bias mode, thus forming the working modes of the four probe assemblies 1 of the present invention. In this way, the plasma measurement device of the present invention highly integrates three different electrostatic probes to realize four different measurement functions, and adopts a scanning voltage frequency of not less than 250kHz. Both the single electrostatic probe and the triple-probe can realize transient measurement, and the measurement results can be compared and calibrated. Compared with the traditional electrostatic probe working in a single mode, and the method of simply integrating the three probes, the present invention maximizes the system integration and measurement accuracy, and can meet the high-precision measurement of plasma parameters under various discharge conditions.

[0052] like Figure 3It can be seen that the signal conditioning module 3 is mainly composed of a channel control module, a voltage measurement module, and a current measurement module, so as to complete the hardware circuit switching of the electrostatic probe in four working modes: scanning single probe, DC bias single probe, scanning double probe, and DC bias three probe. Among them, the voltage measurement module and the current measurement module can also be understood as a circuit for signal conditioning of voltage and current. The input of the circuit is a probe connected by a coaxial cable, and the output is to the data acquisition system. It can also be seen that the signal conditioning module 3 of the present invention itself can be regarded as a switch matrix (or relay), which has four sampling resistors 31 with different resistance values, thereby realizing the switching of different current values.

[0053] Specifically, in the single-probe working mode, the scanning / bias signal outputted from the positive terminal of the high-voltage scanning power module 2 is loaded onto the second probe 12 (i.e., point b), and the negative terminal of the high-voltage scanning power module 2 is connected to the safety ground (i.e., point e) through a relay switch. The voltage measurement module switches to collect the voltage V between the second probe 12 and the safety ground through a relay (a relay in the signal conditioning module). be The current measurement module collects the current signal I of the second probe 12 loop b In addition, in the (scanning) single-probe mode of the present invention, a high-speed optical coupler is used to transmit signals between the signal conditioning module 3 and the data acquisition module 4, and the scanning voltage frequency of the high-voltage scanning power supply module 2 is not less than 250kHz (the same as the scanning double-probe mode), and the plasma measurement response time reaches the μs level, which can meet the transient measurement requirements in the single-probe mode and can be compared and calibrated with the results of the electrostatic three-probe transient measurement mode.

[0054] In the dual-probe working mode, the scanning signal outputted from the positive terminal of the high-voltage scanning power module 2 is loaded onto the second probe 12 (i.e., point b), and the negative terminal of the high-voltage scanning power module 2 is switched to the first probe 11 (i.e., point c) through the relay 25. The voltage measurement module is switched to collect the voltage V applied to the first probe 11 or the second probe 12 through the relay. bc The current measurement module collects the current signal I formed by the first probe 11 and the second probe 12. b .

[0055] In the three-probe working mode, the bias signal output from the positive end of the high-voltage scanning power module 2 is loaded onto the second probe 12 (i.e., point b), and the negative end of the high-voltage scanning power module 2 is switched to the first probe 11 (i.e., point c) through a relay, and the third probe 13 is in a suspended state. It can be seen that the power signal application method of the three-probe mode is the same as that of the high-voltage scanning power module in the dual-probe mode. The voltage measurement module is switched to collect the voltage V between the second probe 12 and the third probe 13 through a relay. ac The current measurement module collects the current signal I of the second probe 12 loopb .

[0056] It can be seen that the present invention adopts a plurality of relays to form a matrix switch, and by switching the matrix switch, the switching of the output mode of the high-voltage scanning power supply module under the four working modes of scanning a single probe, a DC bias single probe, scanning a double probe, and a DC bias three probes, the switching of the probe voltage and current signal acquisition circuit, and the switching of the probe output voltage path (i.e., the on-off of the probe assembly 1) are realized, and a set of probe assemblies are shared. Compared with the traditional complex plasma environment, each working mode uses an independent probe control system, which cleverly utilizes the common characteristics between different measurement modes, and realizes the switching of four measurement functions by a high-voltage scanning power supply module and a switch matrix joint mode, significantly reducing the development cost, reducing the requirements of the plasma chamber probe measurement interface, and improving the measurement efficiency. In addition, by switching the probe assembly and the matrix switch, the comparison and self-calibration of the measurement results under different modes can be completed during the measurement process. In combination with the above-mentioned modular design and the form of the array setting of multiple groups of probes, the spatial distribution measurement of transient and steady-state plasma parameters under a large range can be realized. By reasonably setting the spacing between the three probes in the probe assembly and the spacing between different groups, the spatial distribution measurement of variable spatial resolution (the spatial distribution measurement of plasma parameters) can also be realized.

[0057] In summary, the plasma measurement device of the present invention adopts a single-probe, dual-probe, and triple-probe matching coupling method, and can realize four different measurement functions in the same device. In the same test scenario, it can be switched according to the test requirements, and is compatible with the multi-parameter measurement characteristics of a scanning single probe, the high-precision probe current measurement characteristics of a biased single probe, the suspended anti-interference characteristics of a scanning dual probe, and the transient measurement characteristics of a triple probe. By matching probe components of different sizes and switching functions, it can be used in 10 12 m -3 -10 18 m -3 In a large density span, the non-steady-state plasma core parameters can be accurately obtained, and the self-calibration function can be achieved by comparing different modes. In a single measurement process, the advantages of various probe measurements can be combined, and the measurement results can be self-calibrated. Compared with the traditional measurement method of changing the probe size, the multifunctional measuring device broadens the measurement range, improves the measurement accuracy and measurement automation level, and can be used as a multifunctional plasma probe measuring device for measuring dynamic plasma parameters in a large density range. Therefore, the present invention can meet the needs of most plasma applications. 12 m -3 -10 18 m -3At the same time, due to the integration of four different measurement modes under three structures of single probe, double probe and triple probe, it can also be widely used in the measurement of transient plasma parameters in high enthalpy shock wind tunnels, shock tubes, etc.

[0058] In summary, the device of the present invention has a simple structure, a high degree of automation, and rich testing functions. It can be widely used in various low-temperature and high-enthalpy plasma environments such as reactive ion etching, plasma enhanced chemical vapor deposition and other chip manufacturing processes. It has broad application prospects in space missions and general plasma applications, and can be converted into mass production and sales of products to generate significant economic and social benefits.

[0059] The above is only one embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A plasma measuring device, comprising: A probe assembly (1) for collecting electron and ion currents of the plasma; A high-voltage scanning power supply module (2), used for generating a voltage waveform and applying the voltage waveform to the probe assembly (1); A signal conditioning module (3) is used to switch the working mode of the probe assembly (1) and to condition the voltage and current signals fed back by the probe assembly (1); A data acquisition module (4) is used to acquire the conditioned voltage and current signals under different working modes, and obtain plasma parameters after processing the voltage and current signals; It is characterized in that The working modes include scanning single probe, DC biasing single probe, scanning double probe and DC biasing triple probe; An optical coupler is used to transmit signals between the signal conditioning module (3) and the data acquisition module (4), and the scanning voltage frequency of the high-voltage scanning power supply module (2) is not less than 250 kHz; The high-voltage scanning power supply module (2) and the data acquisition module (4) are respectively connected to the signal conditioning module (3), and the signal conditioning module (3) is connected to the probe assembly (1) via a coaxial cable (6); The high-voltage scanning power supply module (2) comprises: A signal generator (21) is used to generate a triangular wave input signal with high frequency, low amplitude and adjustable amplitude and frequency; A first operational amplifier (22), used for amplifying an input signal; A voltage converter (23) for signal isolation; A linear isolator (24), used for converting the input signal amplified by the first operational amplifier (22) into a DC bias signal and isolating the signal; A relay (25) for switching the on and off states of the voltage converter (23) and the linear isolator (24); The second operational amplifier (26) is used to amplify the signal output by the relay (25).

2. The plasma measuring device according to claim 1, characterized in that: The probe assembly (1) comprises first, second and third probes (11, 12, 13) which are cylindrical or spherical.

3. The plasma measuring device according to claim 1, characterized in that: The signal conditioning module (3) comprises a channel control module, a voltage measurement module and a current measurement module, and the data acquisition module (4) comprises a data acquisition card and a host computer.

4. The plasma measuring device according to claim 1, characterized in that: The voltage waveform generated by the high-voltage scanning power supply module (2) includes a direct current bias mode and a fast scanning mode.

5. The plasma measuring device according to claim 3, characterized in that: In the single-probe working mode, the positive end of the high-voltage scanning power supply module (2) is connected to the second probe (12), and the negative end is connected to the safety ground; The voltage measurement module collects the voltage between the second probe (12) and the safety ground, and the current measurement module collects the current of the second probe (12) loop.

6. The plasma measuring device according to claim 3, characterized in that: In the dual-probe working mode, the positive end of the high-voltage scanning power supply module (2) is connected to the second probe (12), and the negative end is connected to the first probe (11); The voltage measurement module collects the voltage applied to the first probe (11) or the second probe (12), and the current measurement module collects the current of the loop formed by the first probe (11) and the second probe (12).

7. The plasma measuring device according to claim 3, characterized in that: In the three-probe working mode, the high-voltage scanning power supply module (2) is connected to the second probe (12), and the negative end is connected to the first probe (11); the third probe (13) is in a suspended state; The voltage measurement module collects the voltage between the second probe (12) and the third probe (13), and the current measurement module collects the current signal of the second probe (12) loop.

8. The plasma measuring device according to claim 1, characterized in that: It also comprises a chassis (5), wherein the high-voltage scanning power supply module (2), the signal conditioning module (3) and the data acquisition module (4) are all located in the chassis (5).

Images