A high voltage electrode device and method for measuring spatial charge distribution of thick samples

Abstract

The present invention relates to a high-voltage electrode device and method for measuring the spatial charge distribution of a thick sample, belonging to the technical field of spatial charge measurement. The outer flat electrode, the insulating tube and the inner flat electrode constitute an upper flat electrode, which is equivalent to dividing a circular area on the upper flat electrode by the insulating tube. The inner flat electrode applies a first DC high voltage and a pulse voltage, and the outer flat electrode applies a second DC high voltage with the same amplitude as the first DC high voltage. The insulating tube separates the pulse application area from the overall electrode area to prevent the increase of equivalent load capacitance due to excessive electrode area, thereby realizing the measurement of the spatial charge distribution of the thick sample.

Description

Technical Field

[0001] The invention relates to the technical field of space charge measurement, and in particular to a high voltage electrode device and method for measuring space charge distribution of thick samples. Background Art

[0002] Space charge is an important parameter to characterize the electrical properties of dielectric materials, and the measurement of space charge is of great significance for the study of dielectric properties of dielectrics. There are a large number of traps in polymers. Under the action of the electric field, the traps will capture carriers and form space charges inside the dielectric. Space charge will cause serious distortion to the internal electric field of the insulating material. Among them, the same polarity space charge reduces the electric field strength in the accumulation area, while the opposite polarity space charge will increase the electric field strength in the accumulation area, thereby affecting the charge injection of the electrode, the mobility of the carriers and the breakdown strength of the insulating material. Therefore, by measuring the space charge distribution of the material, we can not only understand the establishment and decay process of the space charge in the insulating material, but also have a deeper understanding of the electrical breakdown and electrical aging process of the dielectric material. This is of great significance for the analysis and optimization of insulating materials.

[0003] There are many methods for measuring space charge. The most commonly used method is the Pulsed Electro-Acoustic (PEA) method. The traditional PEA device measures the space charge distribution by applying a pulse voltage to a thin sample through an electrode. The voltage required to be applied is relatively small, and the area of ​​the electrode used is also relatively small. However, when measuring the space charge distribution of thick samples, a higher voltage needs to be applied to ensure that the electric field meets the measurement requirements. The increase in voltage will increase the probability of flashover, so the area of ​​the sample needs to be increased. In order to ensure that the electric field in the sample is uniform, the electrode area must also be increased accordingly. However, if a pulse voltage is applied to an electrode with a larger area, the equivalent load capacitance of the electrode will increase, making it difficult to apply a narrow pulse signal to the sample. Therefore, it is difficult for traditional PEA devices to measure the space charge distribution of thick samples. Summary of the invention

[0004] The purpose of the present invention is to provide a high voltage electrode device and method for measuring the spatial charge distribution of a thick sample, so as to realize the measurement of the spatial charge distribution of a thick sample.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A high-voltage electrode device for measuring the spatial charge distribution of a thick sample, the high-voltage electrode device comprising: a pressurizing device, an insulating tube, an inner flat electrode and an outer flat electrode;

[0007] The insulating tube is a hollow cylindrical structure, and the inner flat electrode is embedded in the hollow part of the insulating tube; a cylindrical through hole matching the insulating tube is opened on the outer flat electrode, and the insulating tube and the inner flat electrode are both arranged in the cylindrical through hole; the outer flat electrode, the insulating tube and the inner flat electrode constitute an upper flat electrode;

[0008] The upper surface of the inner flat electrode in the upper flat electrode is connected to the pressurizing device; the thickness test sample to be measured is arranged between the lower flat electrode and the lower surface of the upper flat electrode;

[0009] The pressurizing device is used to pass a first DC high voltage and a pulse voltage to the inner flat electrode and apply them to the sample to be measured; the outer flat electrode is used to pass a second DC high voltage and apply it to the sample to be measured; the amplitudes of the first DC high voltage and the second DC high voltage are equal.

[0010] Optionally, the inner and outer flat electrodes on the upper surface of the upper flat electrode have the same height; the insulating tube on the upper surface of the upper flat electrode is higher than the inner and outer flat electrodes to form an annular raised structure; the annular raised structure is used to increase the insulation distance to prevent the influence of surface discharge caused by applying high voltage when measuring a thick sample to be measured.

[0011] Optionally, the pressurizing device includes: a pressure equalizing ball, a high-pressure guide rod and a DC isolation circuit;

[0012] One end of the high-voltage guide rod is threadedly connected to the pressure-equalizing ball, and the other end of the high-voltage guide rod is connected to the inner flat electrode; the pressure-equalizing ball is used to access high-voltage direct current and pass into the inner flat electrode through the high-voltage guide rod;

[0013] The DC isolation circuit is connected to the high-voltage conductor; the DC isolation circuit is used to access the pulse voltage and pass it into the inner flat electrode through the high-voltage conductor.

[0014] Optionally, the DC isolation circuit includes: a DC isolation capacitor and a BNC connector;

[0015] One pin of the DC blocking capacitor is connected to the high-voltage guide rod, and the other pin of the DC blocking capacitor is connected to the BNC connector; the DC blocking capacitor is used to isolate the DC high voltage from the pulse voltage; the BNC connector is used to access the pulse voltage and introduce it into the high-voltage guide rod after passing through the DC blocking capacitor.

[0016] Optionally, the pressurizing device further comprises: a metal shielding shell and an epoxy resin insulating layer;

[0017] The metal shielding shell is a sleeve structure; the metal shielding shell is sleeved on the high-voltage guide rod, the high-voltage guide rod is located at the axial position of the metal shielding shell, and the high-voltage guide rod does not contact the metal shielding shell; an epoxy resin insulation layer is filled between the metal shielding shell and the high-voltage guide rod;

[0018] The DC blocking capacitor is arranged in the epoxy resin insulating layer, and the BNC connector is arranged on the metal shielding shell;

[0019] The metal shielding shell is grounded and used for shielding external interference signals; the epoxy resin insulation layer is used for preventing insulation breakdown between the high-voltage guide rod and the metal shielding shell.

[0020] Optionally, when the thickness sample to be measured is a solid sample, a semiconductive layer is provided in the hollow part of the insulating tube, the inner flat electrode contacts the solid sample through the semiconductive layer, and the semiconductive layer, the insulating tube and the outer flat electrode are all in close contact with the solid sample without air gaps;

[0021] When the thickness sample to be measured is a liquid sample, a chamfered structure is provided at the hollow part of the insulating tube, the inner flat electrode is in direct contact with the liquid sample, and the insulating tube and the outer flat electrode are in close contact with the liquid sample without air gap.

[0022] Optionally, the area of ​​the upper flat electrode is smaller than that of the lower flat electrode.

[0023] Optionally, the inner flat electrode, the outer flat electrode and the lower flat electrode are all metal electrodes;

[0024] The materials of the high-voltage guide rod and the metal shielding shell are both metal aluminum.

[0025] A method for measuring the spatial charge distribution of a thick sample based on the above-mentioned high-voltage electrode device, the method comprising:

[0026] The thickness sample to be measured is placed between the lower flat electrode and the upper flat electrode;

[0027] Connecting a pressurizing device to the inner flat electrode in the upper flat electrode;

[0028] A first DC high voltage is supplied to the pressurizing device, and a second DC high voltage is supplied to the outer plate electrode in the upper plate electrode; the amplitudes of the first DC high voltage and the second DC high voltage are equal;

[0029] The pressurizing device is supplied with a pulse voltage;

[0030] The spatial charge distribution of the thick sample to be measured is measured at the lower flat electrode.

[0031] Optionally, the step of placing the thickness sample to be measured between the lower flat electrode and the upper flat electrode specifically includes:

[0032] When the thickness sample to be measured is a solid sample, place the thickness sample to be measured on the lower flat electrode;

[0033] After silicone oil is dripped onto the upper surface of the thick sample to be measured, a semi-conductive layer is placed, and silicone oil is applied on the surface of the semi-conductive layer;

[0034] Align and clamp the semi-conductive layer to the hollow part of the insulating tube of the upper flat electrode, so that the insulating tube, the outer flat electrode and the semi-conductive layer are in close contact with the thick sample to be measured without air gap;

[0035] When the thick sample to be measured is a liquid sample, immerse the lower flat electrode in the liquid sample;

[0036] The upper plate electrode is immersed in the liquid sample and vacuumed in a vacuum drying oven so that there are no bubbles between the liquid thick sample to be tested and the upper plate electrode.

[0037] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0038] The present invention discloses a high-voltage electrode device and method for measuring the spatial charge distribution of thick samples. The outer flat electrode, the insulating tube and the inner flat electrode constitute an upper flat electrode, which is equivalent to dividing a circular area on the upper flat electrode by the insulating tube. The inner flat electrode applies a first DC high voltage and a pulse voltage, and the outer flat electrode applies a second DC high voltage with the same amplitude as the first DC high voltage. The insulating tube separates the pulse application area from the overall electrode area to prevent the increase of equivalent load capacitance due to the excessively large electrode area, thereby realizing the measurement of the spatial charge distribution of the thick sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] 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 will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0040] Figure 1 A schematic structural diagram of a high voltage electrode device for measuring spatial charge distribution of thick samples provided by the present invention;

[0041] Figure 2 This is a structural diagram of the upper plate electrode provided by the present invention.

[0042] Explanation of symbols: 1-voltage equalizing ball, 2-high voltage guide rod, 3-metal shielding shell, 4-DC isolation circuit, 41-DC isolation capacitor, 42-BNC connector, 5-epoxy resin insulation layer, 6-insulating tube, 7-inner flat electrode, 8-outer flat electrode, 9-semi-conductive layer, 10-thick sample to be measured, 11-lower flat electrode. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] The purpose of the present invention is to provide a high voltage electrode device and method for measuring the spatial charge distribution of a thick sample, so as to realize the measurement of the spatial charge distribution of a thick sample.

[0045] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] In order to overcome the problem that the PEA measuring device in the prior art is difficult to measure the spatial charge distribution of thick samples, the present invention provides a high-voltage electrode device for measuring the spatial charge distribution of thick samples, such as Figure 1 As shown, the high-voltage electrode device includes: a pressurizing device, an insulating tube 6, an inner flat electrode 7 and an outer flat electrode 8.

[0047] The insulating tube 6 is a hollow cylindrical structure, and the inner flat electrode 7 is nested in the hollow part of the insulating tube 6; a cylindrical through hole matching the insulating tube 6 is opened on the outer flat electrode 8, and the insulating tube 6 and the inner flat electrode 7 are both arranged in the cylindrical through hole; the outer flat electrode 8, the insulating tube 6 and the inner flat electrode 7 constitute an upper flat electrode. The upper surface of the inner flat electrode 7 in the upper flat electrode is connected to the pressure device; the thickness sample 10 to be measured is arranged between the lower flat electrode 11 and the lower surface of the upper flat electrode. The pressure device is used to pass the first DC high voltage and pulse voltage to the inner flat electrode 7, and apply them to the thickness sample 10 to be measured; the outer flat electrode 8 is used to pass the second DC high voltage and apply it to the thickness sample 10 to be measured; the amplitudes of the first DC high voltage and the second DC high voltage are equal. After applying the first DC high voltage, the second DC high voltage and the pulse voltage to the thickness sample 10 to be measured, the spatial charge distribution of the thickness sample 10 to be measured is measured at the lower flat electrode 11.

[0048] Preferably, the insulating tube 6 and the outer plate electrode 8 are connected together in a nested manner, and the connection is tightened by pressure. The insulating tube 6, the inner plate electrode 7, and the outer plate electrode 8 are in close contact without gaps, and the radius of the insulating tube 6 is much smaller than the width of the upper plate electrode.

[0049] A circular area is divided in the center of the flat electrode by an insulating tube 6 made of polytetrafluoroethylene. A DC voltage is applied to the entire rectangular electrode, and in the circular area divided by the insulating tube 6 in the center of the rectangular electrode, a pulse voltage is applied in addition to the DC voltage, thereby achieving the measurement of space charge and space electric field. The insulating tube 6 in the center area separates the pulse application area from the entire electrode area to prevent the equivalent load capacitance from increasing due to the large electrode area, which affects the measurement effect.

[0050] For example, refer to Figure 2 The inner plate electrode 7 and the outer plate electrode 8 on the upper surface of the upper plate electrode are at the same height; the insulating tube 6 on the upper surface of the upper plate electrode is higher than the inner plate electrode 7 and the outer plate electrode 8, forming an annular convex structure; the annular convex structure is used to increase the insulation distance and prevent the influence of surface discharge caused by applying high voltage when measuring the thick sample 10 to be measured. The convex structure of the insulating tube 6 on the upper surface of the plate electrode effectively increases the insulation distance of the pulse voltage application area on the upper surface of the electrode to reduce the influence of the pulse voltage surface discharge.

[0051] Exemplarily, the pressurizing device includes: a pressure equalizing ball 1, a high-voltage guide rod 2 and a direct current isolation circuit 4. One end of the high-voltage guide rod 2 is threadedly connected to the pressure equalizing ball 1, and the other end of the high-voltage guide rod 2 is connected to the inner plate electrode 7; the pressure equalizing ball 1 is used to connect the high-voltage direct current and pass it into the inner plate electrode 7 through the high-voltage guide rod 2. The direct current isolation circuit 4 is connected to the high-voltage guide rod 2; the direct current isolation circuit 4 is used to connect the pulse voltage and pass it into the inner plate electrode 7 through the high-voltage guide rod 2. The diameter of the high-voltage guide rod 2 is smaller than the diameter of the inner plate electrode 7.

[0052] The top of the high-voltage guide rod 2 is connected to the equalizing ball 1 through a threaded structure, and the bottom end is tightly connected to the inner flat electrode 7 of the upper flat electrode. The equalizing ball 1 is a smooth spherical structure. Compared with the direct connection, the high-voltage direct current is connected to the equalizing ball 1, and there are fewer metal burrs. When the applied DC voltage is high, it can effectively reduce the impact of local discharge. The pressure-applying device is inserted into the center of the annular raised structure of the insulating tube 6 through the high-voltage guide rod 2, and is pressed against the inner flat electrode 7 of the upper flat electrode by pressure. The insulating tube 6 fixes the position of the high-voltage guide rod 2 so that it does not move, so that the electrode forms a whole.

[0053] Exemplarily, the DC isolation circuit 4 includes: a DC isolation capacitor 41 and a BNC connector 42. One pin of the DC isolation capacitor 41 is connected to the high-voltage guide rod 2, and the other pin of the DC isolation capacitor 41 is connected to the BNC connector 42; the DC isolation capacitor 41 is used to isolate the DC high voltage from the pulse voltage; the BNC connector 42 is used to connect the pulse voltage and introduce it into the high-voltage guide rod 2 after passing through the DC isolation capacitor 41. The structure and working principle of the DC isolation circuit 4 are as follows: the DC isolation capacitor 41 has two pins. In order to prevent local discharge at the pin connection, the original pin of the capacitor is thickened with a metal sleeve, and one end of the thickened pin is welded to the middle high-voltage guide rod 2, and the other end is welded to the metal core of the BNC connector 42 on the metal shielding shell 3. The DC isolation capacitor 41 plays the role of isolating the DC high voltage from the pulse power supply, and the BNC connector 42 is connected to the pulse power supply on the outside of the metal shielding shell 3 to form a complete DC isolation circuit 4.

[0054] Exemplarily, the pressurizing device also includes: a metal shielding shell 3 and an epoxy resin insulation layer 5. The metal shielding shell 3 is a sleeve structure; the metal shielding shell 3 is sleeved on the high-voltage conductor 2, the high-voltage conductor 2 is located at the axial position of the metal shielding shell 3, and the high-voltage conductor 2 does not contact the metal shielding shell 3; the epoxy resin insulation layer 5 is filled between the metal shielding shell 3 and the high-voltage conductor 2. The DC blocking capacitor 41 is arranged in the epoxy resin insulation layer, and the BNC connector 42 is arranged on the metal shielding shell 3. The metal shielding shell 3 is grounded, and the metal shielding shell 3 is used to shield external interference signals; the epoxy resin insulation layer 5 is used to prevent insulation breakdown between the high-voltage conductor 2 and the metal shielding shell 3. The epoxy resin insulation layer 5 plays a role in improving the insulation strength. This pressurizing device can apply a voltage of up to 30kV.

[0055] Exemplarily, on the side where the electrode contacts the sample, the bottom end of the inner flat electrode 7 is slightly higher than the plane where the bottom ends of the insulating tube 6 and the outer flat electrode 8 are located. When the thickness sample 10 to be measured is a solid sample, a semiconductive layer 9 is provided in the hollow part of the insulating tube 6, and the inner flat electrode 7 contacts the solid sample through the semiconductive layer 9, and the semiconductive layer 9, the insulating tube 6 and the outer flat electrode 8 are all in close contact with the solid sample without air gaps. When the thickness sample 10 to be measured is a liquid sample, a chamfered structure is provided in the hollow part of the insulating tube 6, and the inner flat electrode 7 directly contacts the liquid sample, and the insulating tube 6 and the outer flat electrode 8 are all in close contact with the liquid sample without air gaps.

[0056] That is, the upper plate electrode structure needs to be fine-tuned to measure solid and liquid samples. When measuring solid samples, the inner plate electrode 7 does not need to be chamfered on the side of the contact surface between the inner plate electrode 7 and the insulating tube 6 close to the sample, but the inner plate electrode 7 is raised to prevent the generation of air gaps and facilitate the placement of the semi-conductive layer 9. The semi-conductive layer 9 serves as a transition layer to ensure acoustic impedance matching. When measuring liquid samples, the inner plate electrode 7 does not need to be raised. The structure is changed to add a chamfer on the side of the contact surface between the inner plate electrode 7 and the insulating tube 6 close to the sample to improve the discharge generated by the inner plate electrode 7 and the outer plate electrode 8 on the insulating tube 6 and reduce the size of the electric field.

[0057] Exemplarily, the area of ​​the upper plate electrode is smaller than that of the lower plate electrode 11. This structure increases the creepage distance between the upper plate electrode and the lower plate electrode 11.

[0058] Exemplarily, the inner plate electrode 7, the outer plate electrode 8 and the lower plate electrode 11 are all metal electrodes. The high voltage conducting rod 2 and the metal shielding shell 3 are both made of metal aluminum.

[0059] The high-voltage conductor 2 is inserted into the annular area defined by the insulating tube 6, and is closely connected to the inner flat electrode 7, and pulse voltage and DC high voltage are applied to the circular area in the center of the insulating tube 6. The outer flat electrode 8 applies DC high voltage to the sample to be tested by directly connecting to a DC power supply, and the amplitude is consistent with the DC high voltage applied by the high-voltage conductor 2. The insulating tube 6 is used to isolate the area where the pulse voltage is applied and reduce the load capacitance of the upper flat electrode during the measurement process. The upper flat electrode does not contact the side of the sample, and the raised part of the insulating tube 6 is used to increase the insulation distance to prevent the influence of surface discharge caused by applying a large DC voltage when measuring thick samples. When the thick sample to be measured is a solid sample, the end area of ​​the inner flat electrode 7 on the side of the upper flat electrode in contact with the sample is slightly higher than the plane where the electrode contacts the sample. In actual measurement, a semi-conductive layer 9 with a height slightly greater than the height difference between the inner flat electrode 7 and the lower plane of the upper flat electrode is placed in this area and compacted to ensure that the lower surface of the semi-conductive layer 9, the insulating tube 6 and the outer flat electrode 8 are in close contact with the sample to be tested without air gaps. When the thick sample to be measured is a liquid sample, the bottom end of the insulating tube is in a chamfered shape, and the upper plate electrode is immersed in the liquid sample, so that there are no bubbles between the liquid sample and the upper plate electrode. The width of the upper plate electrode is slightly lower than the lower plate electrode 11. In practical applications, this structure can increase the creepage distance from the upper plate electrode to the lower plate electrode 11.

[0060] During measurement, a DC high voltage is applied to the voltage-equalizing ball 1, and a pulse voltage is applied through the DC isolation circuit 4 to meet the requirements of applying a uniform DC electric field and a pulse voltage to the sample to be tested when measuring space charge. A DC high voltage is directly applied to the outer flat electrode 8, and the amplitude is consistent with the DC voltage on the voltage-equalizing ball 1, thereby achieving the requirement of applying high voltage to measure the space charge of thick samples.

[0061] The advantages of the high voltage electrode device of the present invention are as follows:

[0062] (1) The flat electrode is divided into two areas by an insulating tube. The inner metal electrode is applied with pulse voltage and DC high voltage, and the outer metal electrode is applied with DC high voltage of the same amplitude as the central circular area. The division of the insulating tube reduces the electrode area in the pulse voltage application area, thereby reducing the equivalent load capacitance of the pulse power supply during the space charge measurement process. The electrode area for applying DC voltage is larger, which ensures the uniformity of the electric field when applying high voltage to measure thick samples.

[0063] (2) The raised structure of the insulating tube effectively increases the insulation distance of surface discharge and prevents the occurrence of surface discharge. When the thick sample to be measured is a solid sample, the bottom end of the inner metal electrode is slightly higher than the lower surface of the upper plate electrode, which is convenient for inserting the semi-conductive layer during measurement. The height of the semi-conductive layer is greater than the height difference between the bottom end of the inner metal electrode and the lower surface of the upper plate electrode, ensuring close contact with the sample during measurement. When the thick sample to be measured is a liquid sample, the shape of the bottom end of the insulating tube is set to a chamfered structure, and there is no need to insert a semi-conductive layer.

[0064] (3) The voltage-equalizing ball structure can effectively prevent the influence of partial discharge signals that may be generated when DC high voltage is applied on the test.

[0065] (4) The external signal interference is effectively reduced by grounding the metal shielding shell, and the insulation strength of the signal shielding area is improved by using the epoxy resin insulation layer.

[0066] Based on the above-mentioned high voltage electrode device, the present invention also provides a method for measuring the spatial charge distribution of a thick sample, the method comprising the following steps:

[0067] Step 1: Place the thickness sample to be measured between the lower flat electrode and the upper flat electrode.

[0068] Exemplarily, the specific implementation process of step 1 is:

[0069] When the thickness sample to be measured is a solid sample, the thickness sample to be measured is placed on the lower flat electrode; after silicone oil is dripped on the upper surface of the thickness sample to be measured, a semi-conductive layer is placed, and silicone oil is smeared on the surface of the semi-conductive layer; the semi-conductive layer is aligned and clamped on the hollow part of the insulating tube of the upper flat electrode, so that the insulating tube, the outer flat electrode and the semi-conductive layer are in close contact with the thickness sample to be measured without air gap;

[0070] When the thick sample to be measured is a liquid sample, the lower plate electrode is immersed in the liquid sample; the upper plate electrode is immersed in the liquid sample, and vacuum is evacuated through a vacuum drying oven so that there are no bubbles between the thick liquid sample to be measured and the upper plate electrode.

[0071] Step 2, connecting the pressurizing device to the inner flat electrode in the upper flat electrode.

[0072] Step 3, pass a first DC high voltage to the pressure device, and pass a second DC high voltage to the outer flat electrode in the upper flat electrode; the amplitudes of the first DC high voltage and the second DC high voltage are equal.

[0073] Step 4: A pulse voltage is applied to the pressure applying device.

[0074] Step 5: measuring the spatial charge distribution of the thick sample to be measured at the lower flat electrode.

[0075] The method of analyzing the charge transport process in nano-medium using a high-voltage electrode device with an insulating paper sample as the thick sample to be measured is as follows:

[0076] Step 1: Place the sample. Place the treated insulating paper sample to be tested on the upper surface of the lower electrode. After applying silicone oil on the upper and lower surfaces of the insulating paper, place a cylindrical semi-conductive layer on top of the insulating paper. The radius of the semi-conductive layer is slightly larger than the radius of the inner metal electrode, and the height of the semi-conductive layer is slightly larger than the height difference between the bottom end of the inner metal electrode and the lower surface of the upper flat electrode. After applying silicone oil on the upper surface of the semi-conductive layer, align the center area of ​​the upper flat electrode with the semi-conductive layer and place it on the sample to be tested. Press the upper flat electrode and the lower electrode to ensure that no bubbles appear on the contact surface of the electrode, the sample to be tested and the semi-conductive layer.

[0077] Step 2: Align the high-voltage guide rod with the annular area of ​​the insulating tube and insert it so that it is tightly connected to the inner metal electrode, thereby integrating the entire high-voltage electrode device.

[0078] Step 3: Apply DC voltage. After completing step 2, directly connect the DC high-voltage power supply to the voltage-equalizing ball to apply DC voltage through the high-voltage guide rod and the inner metal electrode, and apply the DC high voltage to the outer metal electrode at the same time. The amplitude of the applied DC high voltage is the same as that of the voltage-equalizing ball to apply DC voltage to the entire upper plate electrode. The way to apply DC high voltage to the outer metal electrode is as follows: the DC high-voltage power supply applies high-voltage DC to the outer metal electrode through the structure of voltage-equalizing ball + guide rod. The voltage-equalizing ball and guide rod used here are not the same as the voltage-equalizing ball and guide rod used to pressurize the inner metal electrode.

[0079] Step 4: Apply pulse voltage. Connect the BNC connector on the side wall of the metal shielding shell to the pulse power supply, and apply pulse voltage to the center area of ​​the insulating tube through the DC isolation circuit and the high-voltage guide rod.

[0080] Step 5: After steps 1 to 4 are completed, the space charge of the thick sample is measured by the measuring device of the lower electrode.

[0081] The present invention improves the electrode structure in the existing PEA measuring device so that it can simultaneously measure the space electric field and space charge of a large-size sample. The central area of ​​the flat electrode is divided into a circular area by an insulating tube made of polytetrafluoroethylene. A DC voltage is applied to the entire rectangular electrode, and in the circular area divided by the insulating tube in the center of the rectangular electrode, a pulse voltage is applied in addition to the DC voltage, thereby realizing the measurement of space charge and space electric field.

[0082] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0083] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A high voltage electrode device for measuring the spatial charge distribution of thick samples, characterized in that: The high-voltage electrode device comprises: a pressurizing device, an insulating tube, an inner flat electrode and an outer flat electrode; The insulating tube is a hollow cylindrical structure, and the inner flat electrode is embedded in the hollow part of the insulating tube; a cylindrical through hole matching the insulating tube is opened on the outer flat electrode, and the insulating tube and the inner flat electrode are both arranged in the cylindrical through hole; the outer flat electrode, the insulating tube and the inner flat electrode constitute an upper flat electrode; The upper surface of the inner flat electrode in the upper flat electrode is connected to the pressurizing device; the thickness test sample to be measured is arranged between the lower flat electrode and the lower surface of the upper flat electrode; The pressurizing device is used to pass a first DC high voltage and a pulse voltage to the inner flat electrode and apply them to the sample to be measured; the outer flat electrode is used to pass a second DC high voltage and apply it to the sample to be measured; the amplitudes of the first DC high voltage and the second DC high voltage are equal.

2. The high voltage electrode device for measuring the spatial charge distribution of thick samples according to claim 1, characterized in that: The inner and outer flat electrodes on the upper surface of the upper flat electrode have the same height; the insulating tube on the upper surface of the upper flat electrode is higher than the inner and outer flat electrodes to form an annular convex structure; the annular convex structure is used to increase the insulation distance to prevent the influence of surface discharge caused by applying high voltage when measuring a thick sample to be measured.

3. The high voltage electrode device for measuring the spatial charge distribution of thick samples according to claim 2, characterized in that: The pressurizing device comprises: a pressure equalizing ball, a high-pressure guide rod and a DC isolation circuit; One end of the high-voltage guide rod is threadedly connected to the pressure-equalizing ball, and the other end of the high-voltage guide rod is connected to the inner flat electrode; the pressure-equalizing ball is used to access high-voltage direct current and pass into the inner flat electrode through the high-voltage guide rod; The DC isolation circuit is connected to the high-voltage conductor; the DC isolation circuit is used to access the pulse voltage and pass it into the inner flat electrode through the high-voltage conductor.

4. The high voltage electrode device for measuring the spatial charge distribution of thick samples according to claim 3, characterized in that: The DC isolation circuit includes: a DC isolation capacitor and a BNC connector; One pin of the DC blocking capacitor is connected to the high-voltage guide rod, and the other pin of the DC blocking capacitor is connected to the BNC connector; the DC blocking capacitor is used to isolate the DC high voltage from the pulse voltage; the BNC connector is used to access the pulse voltage and introduce it into the high-voltage guide rod after passing through the DC blocking capacitor.

5. The high voltage electrode device for measuring the spatial charge distribution of thick samples according to claim 4, characterized in that: The pressurizing device further comprises: a metal shielding shell and an epoxy resin insulating layer; The metal shielding shell is a sleeve structure; the metal shielding shell is sleeved on the high-voltage guide rod, the high-voltage guide rod is located at the axial position of the metal shielding shell, and the high-voltage guide rod does not contact the metal shielding shell; an epoxy resin insulation layer is filled between the metal shielding shell and the high-voltage guide rod; The DC blocking capacitor is arranged in the epoxy resin insulating layer, and the BNC connector is arranged on the metal shielding shell; The metal shielding shell is grounded and used for shielding external interference signals; the epoxy resin insulation layer is used for preventing insulation breakdown between the high-voltage guide rod and the metal shielding shell.

6. The high voltage electrode device for measuring the spatial charge distribution of thick samples according to claim 1, characterized in that: When the thickness sample to be measured is a solid sample, a semi-conductive layer is provided in the hollow part of the insulating tube, the inner flat electrode contacts the solid sample through the semi-conductive layer, and the semi-conductive layer, the insulating tube and the outer flat electrode are all in close contact with the solid sample without air gap; When the thickness sample to be measured is a liquid sample, a chamfered structure is provided at the hollow part of the insulating tube, the inner flat electrode is in direct contact with the liquid sample, and the insulating tube and the outer flat electrode are in close contact with the liquid sample without air gap.

7. The high voltage electrode device for measuring the spatial charge distribution of thick samples according to claim 1, characterized in that: The area of ​​the upper plate electrode is smaller than that of the lower plate electrode.

8. The high voltage electrode device for measuring the spatial charge distribution of thick samples according to claim 5, characterized in that: The inner flat electrode, the outer flat electrode and the lower flat electrode are all metal electrodes; The high-voltage guide rod and the metal shielding shell are both made of metal aluminum.

9. A method for measuring the spatial charge distribution of a thick sample, characterized in that: The method is applied to the high-voltage electrode device according to any one of claims 1 to 8, and the method comprises: The thickness sample to be measured is placed between the lower flat electrode and the upper flat electrode; Connecting a pressurizing device to the inner flat electrode in the upper flat electrode; A first DC high voltage is supplied to the pressure device, and a second DC high voltage is supplied to the outer plate electrode in the upper plate electrode; the amplitudes of the first DC high voltage and the second DC high voltage are equal; The pressurizing device is supplied with a pulse voltage; The spatial charge distribution of the thick sample to be measured is measured at the lower flat electrode.

10. The method for measuring spatial charge distribution of thick samples according to claim 9, characterized in that: The step of placing the thickness sample to be measured between the lower flat electrode and the upper flat electrode specifically includes: When the thickness sample to be measured is a solid sample, place the thickness sample to be measured on the lower flat electrode; After silicone oil is dripped onto the upper surface of the thick sample to be measured, a semi-conductive layer is placed, and silicone oil is applied on the surface of the semi-conductive layer; Align and clamp the semi-conductive layer to the hollow part of the insulating tube of the upper flat electrode, so that the insulating tube, the outer flat electrode and the semi-conductive layer are in close contact with the thick sample to be measured without air gap; When the thick sample to be measured is a liquid sample, immerse the lower flat electrode in the liquid sample; The upper plate electrode is immersed in the liquid sample and vacuumed in a vacuum drying oven so that there are no bubbles between the thick liquid sample to be tested and the upper plate electrode.

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