Electronic probe micro-discharge detection system and detection method

Abstract

The invention discloses an electronic probe micro-discharge detection system and method, and the system comprises a signal source, a modulation unit, a microwave power amplifier, a bi-directional coupler, a vacuum tank and a coupler which are sequentially arranged. The coupler is connected with a high-power matching load and a first spectrum analyzer. For whether the electronic probe micro-discharge detection system can sensitively detect electronic changes, rated electrons can be generated by controlling the wavelength and energy distribution of a UV light source, controlling hardware use through an aperture, irradiating the UV light source to a metal plate through a silica optical fiber and setting the voltage and the aperture of the light source; the current calibration test system is used for testing rated electrons in advance; the method for confirming the optimal detection current position of the electronic probe is provided, different tested pieces adopt different testing positions, and the technical problem that in the prior art, local testing cannot be carried out, and the current change generated when part local micro-discharge is generated cannot be reflected is solved.

Description

Technical Field

[0001] This invention belongs to the field of micro-discharge and relates to a micro-discharge detection method, specifically an electron probe micro-discharge detection system and detection method. Background Technology

[0002] Micro-discharge is a vacuum resonant discharge phenomenon that occurs between two metal surfaces or on a single dielectric surface. It is typically excited by a radio frequency (RF) electric field transmitted within a component. Electrons, accelerated and gaining energy in the RF field, collide with the surface to generate secondary electrons. The conditions for its occurrence vary depending on the type of micro-discharge. For micro-discharges between metal surfaces, the conditions are: the mean free path of the electrons must be greater than the gap between the two metal surfaces, and the average transit time of the electrons between the two surfaces must be an odd multiple of the half-cycle of the RF electric field. For micro-discharges occurring on a single dielectric surface, the DC electric field generated by the surface charge must be sufficient to accelerate the electrons back to the dielectric surface, thereby generating secondary electrons.

[0003] The micro-discharge effect is caused by secondary electron emission from the device surface. Its occurrence may be influenced by factors such as the primary electrons, the magnitude of the input power, the distance between the two surfaces, the gap impedance, the frequency, and the surface latent potential.

[0004] The complex geometry, non-uniform field distribution, influence of space charge, presence of residual gas molecules, and characteristics and quality of the electrode surface make the characteristics of this resonance phenomenon more complex, thus making the sensitivity analysis of the electron double multiplication effect of the structure more complicated.

[0005] With the ever-increasing power demands of space payloads, micro-discharges have become a crucial factor determining the normal operation of the entire satellite. There are various methods for detecting micro-discharges, categorized into global and local detection methods. Global detection is widely used and is currently the primary means of detecting micro-discharges in prototype products. Local methods, on the other hand, can clearly measure the actual current changes and location of the discharge, effectively complementing the global method.

[0006] The global detection methods for micro-discharge typically include the following: (1) Zero-adjustment detection method: the most commonly used method, using a zero-adjustment system composed of analog devices; (2) Forward and reverse power method: monitoring the incident power and reflected power of the device under test; (3) Output spectrum method: monitoring the spectral characteristics of the output of the device under test (cannot monitor the output spectrum of radiating devices, limited by the characteristics of the device under test itself); (4) Amplitude modulation detection method, near-carrier noise detection, etc. The global detection method is currently the main method for detecting micro-discharge. Among them, the Xi'an Branch mainly uses the zero-adjustment detection method and the forward and reverse power detection method. The characteristic of the global detection method is that it can conveniently and reliably detect micro-discharge phenomena. It is currently an effective method for testing products. At present, it has micro-discharge detection systems in multiple frequency bands and conducts more than 2,000 high-power tests every year. The advantages of the global detection method are that it has a wide range of applications, covers many frequency bands, and is technically mature. The local method has a deeper detection and understanding of the details of the discharge and is an effective supplement.

[0007] In recent years, with the continuous increase in power capacity of some models and the development of various micro-discharge research projects, there is a need to more accurately locate the local phenomena of micro-discharge. The global method has also shown certain limitations. In terms of technical breakthroughs and process verification, the global method cannot accurately determine the details of discharge and the situation of partial discharge. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide an electron probe micro-discharge detection system and method to solve the technical problem that existing technologies cannot locally test and reflect the current changes when local micro-discharges occur in components.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] An electron probe micro-discharge detection system includes a signal source, a modulation unit, a microwave power amplifier, a dual directional coupler, a vacuum tank, and a coupler arranged in sequence. A power meter is connected to the microwave power amplifier, and a high-power matching load and a spectrum analyzer are connected to the coupler.

[0011] It also includes a zeroing unit connected to the forward and reverse ends of the dual directional coupler, and the zeroing unit is respectively connected to a second spectrum analyzer, a second power meter, and a third power meter;

[0012] The vacuum chamber contains the test piece and an electronic probe. One end of the electronic probe passes through the vacuum chamber and is connected to a picoammeter. The probe tip at the other end of the electronic probe is suspended above the test piece.

[0013] This invention also includes the following technical features:

[0014] The electron probe comprises, from the outside in, a shielding layer, an outer conductor, an insulating layer, and an inner conductor arranged sequentially.

[0015] The coupler is a harmonic coupler or a directional coupler.

[0016] An electron probe micro-discharge detection method includes setting up a UV light source to irradiate the test piece, specifically comprising the following steps:

[0017] S1, Calibration;

[0018] S1.1, set the power and aperture size of the UV light source. When the UV light source is not turned on, the current displayed on the picoammeter is I1;

[0019] S1.2, turn on the UV light source, the test current value of the picoammeter is I2, and the current converted to the UV light source by the detection system built into the UV light source is I3;

[0020] S1.3, turn off the built-in detection system of the UV light source, and use the electron probe micro-discharge detection system to test and obtain the current of the UV light source as I4;

[0021] S1.4, determine whether the current I3 converted from the UV light source obtained in S1.2 is equal to the current I4 of the UV light source obtained in S1.3. If yes, the electron probe micro-discharge detection system can detect a constant electron current and proceed to S2. If no, end.

[0022] S2, Adjust the position of the electron probe and perform micro-discharge testing using the electron probe micro-discharge detection system.

[0023] The adjustment of the position of the electron probe shall be carried out using either Scheme 1 or Scheme 2;

[0024] Option 1: For the test piece with an exhaust port, place the electron probe 5mm above the exhaust port;

[0025] Option 2 involves placing electron probes at different locations on open-type devices.

[0026] Place the electronic probe close to the sensitive point of the product circuit without making contact, or place the electronic probe 1.5cm above the vent hole and parallel to the outer wall of the product being tested.

[0027] Compared with the prior art, the beneficial technical effects of this invention are:

[0028] This invention addresses the issue of whether an electron probe micro-discharge detection system can sensitively detect electron changes. It proposes a system that controls the wavelength and energy distribution of a UV light source, uses an aperture control mechanism, and directs the UV light source onto a metal plate via a quartz optical fiber. By setting the voltage and aperture of the light source on the product surface, rated electrons can be generated. A calibration test system is then established to pre-test the rated electron current. Furthermore, a method for confirming the optimal detection current position of the electron probe is proposed, allowing different test positions to be used for different test devices. This solves the technical problem of existing technologies being unable to locally test and reflect current changes during localized micro-discharges in components. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the electron probe micro-discharge detection system of the present invention.

[0030] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0031] It should be noted that, unless otherwise specified, all components in this invention are those known in the art.

[0032] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0033] This invention provides an electron probe micro-discharge detection system, comprising a signal source, a modulation unit, a microwave power amplifier, a dual directional coupler, a vacuum tank, and a coupler arranged in sequence. A power meter is connected to the microwave power amplifier, and a high-power matching load and a spectrum analyzer are connected to the coupler.

[0034] It also includes a zeroing unit connected to the forward and reverse ends of the dual directional coupler, and a second spectrum analyzer, a second power meter, and a third power meter are respectively connected to the zeroing unit;

[0035] The vacuum chamber contains the test piece and an electronic probe. One end of the electronic probe passes through the vacuum chamber and is connected to a picoammeter, while the other end of the electronic probe is suspended above the test piece.

[0036] In the above technical solution, the signal output from the signal source is modulated by a modulation unit to output a radio frequency pulse modulated signal. This radio frequency pulse modulated signal is amplified by a microwave power amplifier to output a high-power signal. This high-power signal is then sent to the device under test (DUT) in the vacuum chamber via a dual-directional coupler. The output signal of the DUT is connected to a high-power load. The power value of the signal input to the DUT can be detected on power meters 1 and 2 via the dual-directional coupler and power divider. An electronic probe is placed inside the vacuum chamber. For enclosed products such as filters and waveguides, the electronic probe needs to be inserted into the vent of the DUT; for open products such as antennas, the electronic probe is placed near the antenna. The electronic probe is fixed via a coaxial connector, semi-rigid cable, and vacuum interface, and connected to a picoammeter outside the vacuum chamber via a vacuum flange.

[0037] An electron probe consists of a shielding layer, an outer conductor, an insulating layer, and an inner conductor arranged sequentially.

[0038] In the above technical solution, the inner conductor is made of metal, and the diameter of the metal tip processed at the probe end is less than 1 μm. It can penetrate deep into the interior of the test piece through the vent hole or be placed near the vent hole of the test piece. A voltage difference is formed between the inner conductor and the shielding layer, and the intermediate insulating layer is made of polytetrafluoroethylene or Teflon to prevent short circuits between the inner and outer conductors. The inner conductor acts as an electron collecting part. When a suitable positive bias voltage is applied, the current formed by the collected electrons when a micro-discharge occurs can be detected on a picoammeter.

[0039] The outer conductor is made of metal, mainly for grounding. The inner and outer conductors are isolated by a dielectric insulating material. Because the electron probe needs to be used in a vacuum environment, the probe is connected to a cable and led out to the outside of the vacuum tank. It is then connected to a picoammeter outside the vacuum tank through a vacuum flange.

[0040] The coupler can be a harmonic coupler or a directional coupler.

[0041] This invention also provides a method for detecting micro-discharge using an electron probe, which involves setting up a UV light source to irradiate the test piece, specifically including the following steps:

[0042] S1, Calibration;

[0043] S1.1, set the power and aperture size of the UV light source. When the UV light source is not turned on, the current displayed on the picoammeter is I1;

[0044] S1.2, turn on the UV light source, the test current value of the picoammeter is I2, and the current converted to the UV light source by the detection system built into the UV light source is I3;

[0045] S1.3, turn off the built-in detection system of the UV light source, and use the electron probe micro-discharge detection system to test and obtain the current of the UV light source as I4;

[0046] S1.4, determine whether the current I3 converted from the UV light source obtained in S1.2 is equal to the current I4 of the UV light source obtained in S1.3. If so, the electron probe micro-discharge detection system can detect a constant electron current and proceed to S2. If not, end.

[0047] S2, Adjust the position of the electron probe and use the electron probe micro-discharge detection system to perform micro-discharge testing.

[0048] In the above technical solution, if the power of the UV light source is set to 200W and the aperture size is 99, the current displayed by the picoammeter when the UV light source is not turned on is 0.01nA (I1); when the UV light source is turned on, the test current value of the picoammeter is 0.25pA (I2), and the current converted by the UV light source using the built-in detection system is 0.25pA (I3); when the built-in detection system of the UV light source is turned off, the current of the UV light source is measured to be 0.25pA (I4) using the electron probe micro-discharge detection system; then the current I3 converted by the UV light source is equal to the current I4 of the UV light source obtained in S1.3, and the electron probe micro-discharge detection system can detect a constant electron current.

[0049] To address the question of whether an electron probe micro-discharge detection system can sensitively detect electron changes, a calibration test system is proposed. This system controls the wavelength and energy distribution of a UV light source, uses an aperture control mechanism, and directs the UV light source onto a metal plate via a quartz optical fiber. By setting the voltage and aperture of the light source on the product surface, rated electrons can be generated. The system also includes a method for confirming the optimal detection current position of the electron probe. Different test positions are used for different test devices, thus solving the technical problem that existing technologies cannot locally test and reflect the current changes during the generation of local micro-discharges in components.

[0050] When a micro-discharge occurs, the number of secondary electrons increases dramatically, a phenomenon known as the secondary electron avalanche effect. These secondary electrons are absorbed through the inner walls of components. If a positively charged probe is placed near these secondary electrons, they will be attracted to the probe. By introducing the probe through a vent or small hole in the component and applying a positive voltage to it, the secondary electrons generated by the micro-discharge will be attracted to the positively charged probe. During a micro-discharge, secondary electrons are continuously generated, and these electrons are attracted to the probe, forming positive and negative discharge currents. The current value can be detected on a picoammeter connected to the other end of the probe, allowing for sensitive detection of the micro-discharge.

[0051] S2, Adjust the position of the electron probe and use the electron probe micro-discharge detection system to perform micro-discharge testing.

[0052] The position of the electron probe can be adjusted using either Option 1 or Option 2.

[0053] Option 1: For the test piece with an exhaust port, place the electron probe 5mm above the exhaust port;

[0054] Option 2 involves placing electron probes at different locations on open-type devices.

[0055] Place the electronic probe close to the sensitive point of the product circuit without making contact, or place the electronic probe 1.5cm above the vent hole and parallel to the outer wall of the product being tested.

[0056] In the above technical solutions, different solutions are selected according to the different structures of the tested parts.

[0057] In Option 1, the farther the electron probe is placed from the exhaust port, the lower the test sensitivity and the smaller the change in current detected by the probe. The recommended distance for the final test is 5mm above the exhaust port, which can ensure the detection sensitivity without damaging the test piece.

[0058] In Option 2, when the electron probe is placed close to the sensitive point of the product circuit without contact, the detected current change is 0.75 nA. When the electron probe is placed 1.5 cm above the vent and parallel to the outer wall of the test piece, the probe current change is 0.50 nA. The farther the probe is from the sensitive point of the discharge product circuit, the lower the test sensitivity and the smaller the current change detected by the probe. The final recommended distance for testing is one where both positions provide sensitive detection. For open test pieces, placing the probe near a location that facilitates discharge is sufficient.

Claims

1. An electron probe micro-discharge detection system, characterized in that, The system includes a signal source, a modulation unit, a microwave power amplifier, a dual directional coupler, a vacuum tank, and a coupler arranged in sequence. A power meter is connected to the microwave power amplifier, and a high-power matching load and a spectrum analyzer are connected to the coupler. It also includes a zeroing unit connected to the forward and reverse ends of the dual directional coupler, and the zeroing unit is respectively connected to a second spectrum analyzer, a second power meter, and a third power meter; The vacuum chamber contains the test piece and an electronic probe. One end of the electronic probe passes through the vacuum chamber and is connected to a picoammeter. The probe tip at the other end of the electronic probe is suspended above the test piece.

2. The electron probe micro-discharge detection system as described in claim 1, characterized in that, The electron probe comprises, from the outside in, a shielding layer, an outer conductor, an insulating layer, and an inner conductor arranged sequentially.

3. The electron probe micro-discharge detection system as described in claim 1, characterized in that, The coupler is a harmonic coupler or a directional coupler.

4. A method for detecting micro-discharge using an electron probe, comprising setting up a UV light source to irradiate the test piece, characterized in that, Specifically, the following steps are included: S1, Calibration; S1.1, set the power and aperture size of the UV light source. When the UV light source is not turned on, the current displayed on the picoammeter is I1; S1.2, turn on the UV light source, the test current value of the picoammeter is I2, and the current converted to the UV light source by the detection system built into the UV light source is I3; S1.3, turn off the built-in detection system of the UV light source, and use the electron probe micro-discharge detection system according to any one of claims 1 to 3 to test and obtain the current of the UV light source as I4; S1.4, determine whether the current I3 converted from the UV light source obtained in S1.2 is equal to the current I4 of the UV light source obtained in S1.

3. If yes, the electron probe micro-discharge detection system according to any one of claims 1 to 3 can detect a constant electron current and proceed to S2. If no, end. S2, Adjust the position of the electron probe and perform micro-discharge testing using the electron probe micro-discharge detection system according to any one of claims 1 to 3.

5. The electron probe micro-discharge detection method as described in claim 4, characterized in that, The adjustment of the position of the electron probe shall be carried out using either Scheme 1 or Scheme 2; Option 1: For the test piece with an exhaust port, place the electron probe 5mm above the exhaust port; Option 2 involves placing electron probes at different locations on open-type devices. Place the electronic probe close to the sensitive point of the product circuit without making contact, or place the electronic probe 1.5cm above the vent hole and parallel to the outer wall of the product being tested.

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