A high-resolution spatial charge in-situ tester under x-ray irradiation

Abstract

The application provides a high-resolution space charge in-situ tester under X-ray irradiation, comprising an X-ray source, a pulse power supply, a direct current power supply and a space charge testing device; wherein the space charge testing device comprises a first electrode unit and a second electrode unit oppositely arranged along a first direction, and has a gap for accommodating a sample to be tested between the first electrode unit and the second electrode unit; the first electrode unit is provided with an avoiding hole penetrating through along the first direction, the avoiding hole is communicated with the gap, the X-ray source is arranged on a side of the avoiding hole away from the second electrode unit, and X-rays emitted by the X-ray source can enter the gap through the avoiding hole; the pulse power supply and the direct current power supply are connected to the first electrode unit, and are used for applying a first electric signal to the sample to be tested and generating an acoustic signal on the sample to be tested; an acoustic signal pickup module is arranged in the second electrode unit, and is used for picking up the acoustic signal and converting the acoustic signal into a second electric signal.

Description

Technical Field

[0001] This application belongs to the field of material space charge testing technology, specifically relating to a high-resolution in-situ space charge tester under X-ray irradiation. Background Technology

[0002] Space charge, as a key indicator reflecting the internal charge behavior of dielectric materials, is an important parameter characterizing the electrical properties of materials. In power equipment such as high-voltage DC cables and power transformers, the distribution and dynamic changes of space charge directly affect the insulation reliability and service life of the equipment. For power equipment in spacecraft, due to the large amount of X-rays present in space, the electrical performance of the equipment is affected by X-rays. Studying the space charge distribution of materials under X-ray irradiation can reveal the long-term stability of spacecraft materials in the deep space environment.

[0003] Electroacoustic pulse method is a commonly used technique for testing space charge distribution. The principle of this method is to apply a pulse voltage to the test sample. The space charge in the test sample generates an acoustic signal due to the electric field. A piezoelectric sensor is used to convert the acoustic signal into an electrical signal. By detecting the waveform of the electrical signal, the charge distribution of the test sample can be calculated.

[0004] Currently, foreign scholars have used the electroacoustic pulse method to test the space charge distribution of materials under electron beam irradiation and proton irradiation, proposing characterization and testing methods for the microscopic properties of materials under different radiation environments, and designing testing instruments based on the electroacoustic pulse method. However, the characteristics of X-rays are different from those of electrons and protons. Electron beam irradiation and proton irradiation cannot reflect the penetration effect of real cosmic photons, and high-resolution space charge devices for irradiation effects both domestically and internationally all use non-in-situ testing. Currently, there is no effective testing instrument for in-situ testing of space charge under X-ray irradiation. Summary of the Invention

[0005] This invention provides a high-resolution in-situ space charge tester under X-ray irradiation, aiming to solve the problem that it is difficult to test space charge under X-ray irradiation in the prior art.

[0006] This invention provides a high-resolution in-situ space charge testing instrument under X-ray irradiation, comprising: an X-ray source, a pulsed power supply, a DC power supply, and a space charge testing device; wherein, The space charge testing device includes a first electrode unit and a second electrode unit arranged opposite to each other along a first direction, and there is a gap between the first electrode unit and the second electrode unit for accommodating the test sample. The first electrode unit is provided with a clearance hole that extends through the first direction. The clearance hole communicates with the gap. The X-ray source is located on the side of the clearance hole away from the second electrode unit. X-rays emitted by the X-ray source can enter the gap through the clearance hole. The pulse power supply and the DC power supply are connected to the first electrode unit. The pulse power supply and the DC power supply are used to apply a first electrical signal to the test sample and generate an acoustic signal on the test sample. The second electrode unit is provided with an acoustic signal pickup module. The acoustic signal pickup module is used to pick up the acoustic signal and convert the acoustic signal into a second electrical signal. The second electrical signal is used to characterize the space charge distribution of the test sample.

[0007] Optionally, the first electrode unit includes a first housing, a second housing, a support, and a first electrode; wherein, The second housing, the bracket, and the first electrode are sequentially arranged in the first housing along the first direction. The second housing is located on the side of the first housing close to the X-ray source and opposite to the X-ray source. The first electrode is located on the side of the first housing close to the second electrode unit and opposite to the second electrode unit. One end of the bracket is connected to the second housing and the other end is connected to the first electrode. The pulse power supply and the DC power supply are connected to the first electrode. The clearance hole passes through the second housing, the bracket, and the first electrode in sequence, and the X-rays emitted by the X-ray source can pass through the second housing, the bracket, and the first electrode in sequence to enter the gap.

[0008] Optionally, the second housing is a lead cylinder, and the side of the bracket away from the clearance hole is wrapped with lead sheeting to collimate and shield the X-rays emitted by the X-ray source. The bracket is insulated from the first electrode.

[0009] Optionally, the first housing includes a side surface disposed opposite to the second direction, the first direction and the second direction being perpendicular, the side surface being provided with a first interface, the first housing being provided with a second interface on the side away from the second electrode unit, the pulse power supply being connected to the first interface, the DC power supply being connected to the second interface, and the first interface and the second interface being connected to the first electrode; The first electrode unit further includes a matching resistor, an isolation capacitor, and a current-limiting resistor. The first housing and the bracket enclose a receiving cavity. The matching resistor, the isolation capacitor, and the current-limiting resistor are disposed in the receiving cavity. The matching resistor and the isolation capacitor are connected between the first interface and the first electrode. The current-limiting resistor is connected between the second interface and the first electrode.

[0010] Optionally, the cavity is filled with insulating material.

[0011] Optionally, the second electrode unit further includes a third housing and a second electrode, wherein the second electrode is disposed on the side of the third housing close to the first electrode and opposite to the first electrode, and the acoustic signal pickup module is disposed in the third housing and connected to the second electrode.

[0012] Optionally, the acoustic signal pickup module includes a piezoelectric sensor connected to the side of the second electrode away from the first electrode unit, and the piezoelectric sensor is made of polyvinylidene fluoride-trifluoroethylene copolymer (P(VDF-TrFE)).

[0013] Optionally, the pulse width of the pulse power supply is less than 2 ns, and the thickness of the piezoelectric film is less than 5 μm.

[0014] Optionally, it further includes a fixing rod and a fastener, one end of the fixing rod being connected to the first electrode unit and the other end being connected to the second electrode unit, the first electrode unit and the fastener being connected to the fixing rod and movable along the first direction, the fastener being used to control the first electrode unit to move along the first direction to change the size of the gap.

[0015] Optionally, it also includes a shielding ring disposed between the first electrode unit and the second electrode unit. The shielding ring, the first electrode unit, and the second electrode unit enclose the gap, which is a closed space used to accommodate the test sample and shield against electromagnetic interference from the external environment.

[0016] Optionally, the system also includes an oscilloscope and a computer. The acoustic signal acquisition module is electrically connected to the oscilloscope, which is used to acquire the second electrical signal. The computer is electrically connected to the oscilloscope, which is used to calculate the space charge distribution of the test sample based on the second electrical signal.

[0017] This invention provides a high-resolution in-situ space charge testing instrument under X-ray irradiation, comprising: an X-ray source, a pulsed power supply, a DC power supply, and a space charge testing device. The space charge testing device consists of a first electrode unit and a second electrode unit arranged opposite to each other. The test sample is placed between the first and second electrode units. The DC power supply is applied to the test sample to generate a bias electric field. The pulsed power supply applies a pulsed high-voltage signal to the test sample, thereby generating an acoustic signal. The acoustic signal acquisition module captures the acoustic signal generated by the test sample and converts it into a second electrical signal, calculating the space charge distribution of the test sample. The X-ray source generates continuous X-rays from the first electrode unit side to avoid interference from the X-rays on the acoustic signal acquisition module on the second electrode unit side. A clearance hole is added to the first electrode unit to allow X-rays to pass through the first electrode unit and reach the test sample, serving a collimation function, thus enabling in-situ testing of the space charge of the test sample under X-ray irradiation.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the overall structure of a high-resolution in-situ space charge tester under X-ray irradiation according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the first electrode unit according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the second electrode unit according to an embodiment of the present invention; Figure 4 This is a flowchart of in-situ space charge testing according to an embodiment of the present invention; Figure 5 These are the emitted X-ray energy spectra of X-ray sources with different operating voltages according to embodiments of the present invention.

[0020] Figure 6 shows the space charge distribution of polyimide material under a polarization electric field of 80 kV / mm. Figure 6(a) shows the space charge after 30 min of polarization, and Figure 6(b) shows the space charge after 30 min of depolarization. Figure 7 shows the space charge distribution of polyimide material obtained by in-situ testing under X-ray irradiation. Figure 7(a) shows the space charge after 30 min of polarization, and Figure 7(b) shows the space charge after 30 min of depolarization.

[0021] Reference numerals: 1: First electrode unit; 11: First housing; 111: Cover plate; 1111: First interface; 1112: Second interface; 112: Receiving cavity; 113: Side; 12: Second housing; 13: Support; 131: Lead sheet; 14: First electrode; 15: Clearance hole; 16: Matching resistor; 17: Isolation capacitor; 18: Current limiting resistor; 19: Cable; 2: Second electrode unit; 21: Third housing; 22: Second electrode; 221: Piezoelectric coating plate; 222: Electrode structure plate; 23: Acoustic signal Pickup module; 231: Piezoelectric sensor; 232: Metal clamping post; 233: Banana head; 234: Insulating collar; 235: Silicone rubber; 236: Coaxial connector; 237: Non-polar polyvinylidene fluoride filler; 238: Shielding shell; 24: Amplifier; 3: X-ray source; 4: Pulse power supply; 41: Pulse trigger source; 5: DC power supply; 6: Oscilloscope; 7: Computer; 8: Fixing rod; 9: Fastener; 10: Shielding ring; 100: Sample; 200: Semiconductor layer; X: First direction; Y: Second direction. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the fixed scope of the present invention.

[0023] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0024] In dielectric materials, the generation, accumulation, and dissipation of space charge profoundly affect the material's core electrical properties, such as electric field distribution, breakdown characteristics, and aging process. When a dielectric material is subjected to external factors such as an electric field, the migration and trapping-detrapping behavior of charge carriers within the material leads to the accumulation of space charge, causing electric field distortion. This results in the local electric field strength of the material far exceeding the average level, thereby accelerating insulation aging and even inducing electrical breakdown.

[0025] This phenomenon is widespread in power equipment such as high-voltage DC cables and power transformers that are subjected to electric fields for extended periods. The distribution and dynamic changes of space charge directly affect the insulation reliability and service life of these power equipment. The electroacoustic pulse method is a commonly used technique for testing space charge. This method works by applying a pulse voltage to the test sample. The accumulated space charge in the sample generates an acoustic signal due to the electric field. A piezoelectric sensor converts this acoustic signal into an electrical signal. By detecting the waveform of this electrical signal, the distribution of space charge in the test sample can be calculated. Furthermore, a DC voltage is applied to the test sample to simulate the working electric field environment of the dielectric material under test in practical applications.

[0026] This invention provides a high-resolution in-situ space charge tester under X-ray irradiation, comprising: an X-ray source 3, a pulse power supply 4, a DC power supply 5, and a space charge testing device; wherein, the space charge testing device includes a first electrode unit 1 and a second electrode unit 2 arranged opposite to each other along a first direction X, with a gap between the first electrode unit 1 and the second electrode unit 2 for accommodating a test sample 100; the first electrode unit 1 is provided with a clearance hole 15 extending along the first direction X, the clearance hole 15 communicating with the gap, the X-ray source 3 is disposed on the side of the clearance hole 15 away from the second electrode unit 2, and the X-rays emitted by the X-ray source 3 can enter the gap through the clearance hole 15; the pulse power supply 4 and the DC power supply 5 are connected to the first electrode unit 1, the pulse power supply 4 and the DC power supply 5 are used to apply a first electrical signal to the test sample 100 and generate an acoustic signal on the test sample 100, the second electrode unit 2 is provided with an acoustic signal pickup module 23, the acoustic signal pickup module 23 is used to pick up the acoustic signal and convert the acoustic signal into a second electrical signal, the second electrical signal being used to characterize the space charge distribution of the test sample 100.

[0027] In this embodiment, X-ray source 3 provides the X-rays required for the test, pulse power supply 4 generates a pulsed high-voltage signal, the waveform of which is a lightning pulse with a half-peak width in the nanosecond range, and DC power supply 5 generates a stable DC high voltage. Pulse power supply 4 and DC power supply 5 are connected to a space charge testing device, which applies a first electrical signal to the test sample 100. The first electrical signal includes the pulsed high-voltage signal generated by pulse power supply 4 and the bias electric field generated by DC power supply 5. Under the action of the first electrical signal, the test sample 100 generates an acoustic signal. The space charge testing device collects the generated acoustic signal and converts it into a second electrical signal. Calculations on the second electrical signal yield the space charge distribution in the test sample 100.

[0028] The space charge testing device includes a first electrode unit 1 and a second electrode unit 2 arranged opposite to each other, with a gap between them. A test sample 100 is placed in the gap, and a semiconducting layer 200 is disposed above the test sample 100 to improve the acoustic impedance matching between the test sample 100 and the first electrode unit 1. The first electrode unit 1 is typically positioned above the second electrode unit 2. The electric field and X-rays required for the test are applied to the test sample 100 through the first electrode unit 1. The second electrode unit 2 is equipped with an acoustic signal pickup module 23 for acquiring the acoustic signal generated by the test sample 100 and converting it into a second electrical signal.

[0029] like Figure 1 As shown, the X-ray source 3 is positioned on the side of the first electrode unit 1 away from the second electrode unit 2, thus keeping the X-ray source 3 away from the acoustic signal pickup module 23 in the second electrode unit 2. X-rays are high-energy electromagnetic waves, which can interfere with the acoustic signal pickup module 23. In this embodiment, positioning the X-ray source 3 on the side away from the second electrode unit 2 can reduce this interference and ensure the accuracy of the measurement results.

[0030] Accordingly, the first electrode unit 1 is designed with a clearance hole 15 for X-rays to pass through. The clearance hole 15 runs through the entire first electrode unit 1 and is aligned with the emitting end of the X-ray source 3 to form an X-ray optical path. The X-rays propagate along the clearance hole 15 to the gap and are applied to the test sample 100.

[0031] The high-resolution in-situ space charge analyzer under X-ray irradiation in this embodiment of the invention can effectively generate continuous energy X-rays and analyze and test the space charge of materials under X-ray irradiation. By designing an obstacle avoidance hole 15 in the first electrode unit 1, it is ensured that X-rays can directly irradiate the test sample 100, realizing in-situ testing of the space charge of the test sample 100 under X-ray irradiation. It has a simple structure, is easy to operate, safe and reliable, and highly adaptable.

[0032] In some optional embodiments, the high-resolution space charge in situ tester further includes an oscilloscope 6 and a computer 7. The acoustic signal pickup module 23 is electrically connected to the oscilloscope 6, which is used to acquire a second electrical signal. The computer 7 is electrically connected to the oscilloscope 6, which is used to calculate the space charge distribution of the test sample 100 based on the second electrical signal.

[0033] In this embodiment, the oscilloscope 6 outputs the second electrical signal as a voltage waveform, which is then processed by the computer 7 to reflect the space charge distribution inside the test sample 100. Simultaneously, the high-resolution in-situ space charge tester also includes a pulse trigger source 41, which outputs a trigger signal and is connected to the pulse power supply 4 and the oscilloscope 6, respectively, triggering the pulse power supply 4 and the oscilloscope 6.

[0034] The X-ray source 3, pulse power supply 4, DC power supply 5, and oscilloscope 6 are all connected to computer 7, and the entire process of in-situ space charge testing under X-ray irradiation is controlled by the software on computer 7. The software on computer 7 has the following functions: X-ray source 3 control, DC high voltage source control, noise acquisition settings, noise reduction control, single and continuous space charge acquisition, and space charge data processing.

[0035] In some optional embodiments, the first electrode unit 1 includes a first housing 11, a second housing 12, a support 13, and a first electrode 14; wherein the second housing 12, the support 13, and the first electrode 14 are sequentially arranged in the first housing 11 along the first direction X, the second housing 12 is arranged on the side of the first housing 11 near the X-ray source 3 and opposite to the X-ray source 3, the first electrode 14 is arranged on the side of the first housing 11 near the second electrode unit 2 and opposite to the second electrode unit 2, one end of the support 13 is connected to the second housing 12, and the other end is connected to the first electrode 14, and the pulse power supply 4 and the DC power supply 5 are connected to the first electrode 14; the clearance hole 15 sequentially penetrates the second housing 12, the support 13, and the first electrode 14, and the X-rays emitted by the X-ray source 3 can sequentially pass through the second housing 12, the support 13, and the first electrode 14 to enter the gap.

[0036] like Figure 2 As shown, the first electrode unit 1 consists of a first housing 11 and a support 13, a second housing 12, and a first electrode 14 disposed in the first housing 11. The centers of the second housing 12, the support 13, and the first electrode 14 are located on the same axis, and a hole is cut out in the center. They are connected sequentially along the first direction X to form a clearance hole 15 that penetrates the first housing 11, so that X-rays pass through the second housing 12, the support 13, and the first electrode 14 in sequence and enter the gap, irradiating the test sample 100 disposed in the gap.

[0037] The second housing 12 is used to guide the X-ray source 3 to align with the clearance hole 15. The second housing 12 is located on the side of the first housing 11 near the X-ray source 3 and protrudes from the outer surface of the first housing 11, and is aligned with the emitting end of the X-ray source 3. When the X-ray source 3 is working, it can partially extend into the cavity of the second housing 12, and the size of the cavity of the second housing 12, i.e., the clearance hole 15, is adapted to the size of the X-ray source 3, forming a closed X-ray light path in the clearance hole 15, preventing X-rays from leaking into the external environment and causing harm to the personnel.

[0038] The first electrode 14 is used to apply DC voltage and pulse voltage to the test sample 100. The first electrode 14 is located on the side of the first housing 11 near the second electrode unit 2 and opposite to the second electrode unit 2. The pulse power supply 4 and the DC power supply 5 are connected to the first electrode 14. During testing, the test sample 100 is placed between the first electrode 14 and the second electrode unit 2. The pulse voltage generated by the pulse power supply 4 and the DC voltage generated by the DC power supply 5 are applied to the test sample 100 through the first electrode 14.

[0039] The bracket 13 is connected between the second housing 12 and the first electrode 14. The bracket 13 has a certain height so that the X-ray source 3 and the second electrode unit 2 maintain a sufficient safe distance to prevent high-energy X-rays from penetrating the second electrode unit 2 and affecting the acoustic signal pickup module 23.

[0040] Specifically, the second housing 12 and the support 13 are hollow cylindrical structures, the first electrode 14 is an annular electrode, and the second housing 12, the support 13, the first electrode 14, and the X-ray source 3 are all located at the very center of the first housing 11. The X-rays emitted by the X-ray source 3 can pass through the center of the first electrode unit 1 and irradiate the sample 100 to be tested. The first housing 11, the second housing 12, and the support 13 are all made of metal to shield against electromagnetic interference from the external environment. The first housing 11, the second housing 12, and the support 13 can be separate structures or integrally formed structures. The cross-sections of the first housing 11, the second housing 12, and the support 13 can be circular, square, or other shapes.

[0041] In some alternative embodiments, the first housing 11 includes a side 113 disposed opposite to the second direction YY, the first direction X being perpendicular to the second direction Y. The side 113 is provided with a first interface 1111, and the side of the first housing 11 away from the second electrode unit 2 is provided with a second interface 1112. The pulse power supply 4 is connected to the first interface 1111, and the DC power supply 5 is connected to the second interface 1112. The first interface 1111 and the second interface 1112 are connected to the first electrode 14. The first electrode unit 1 also includes a matching resistor 16, an isolation capacitor 17, and a current-limiting resistor 18. The first housing 11 and the bracket 13 enclose a receiving cavity 112. The matching resistor 16, the isolation capacitor 17, and the current-limiting resistor 18 are disposed in the receiving cavity 112. The matching resistor 16 and the isolation capacitor 17 are connected between the first interface 1111 and the first electrode 14, and the current-limiting resistor 18 is connected between the second interface 1112 and the first electrode 14.

[0042] The side 113 of the first housing 11 is provided with a first interface 1111 for connecting the pulse power supply 4, and the cover plate 111 on the top of the first housing 11 is provided with a second interface 1112 for connecting the DC power supply 5.

[0043] The pulse power supply 4 is connected to the first electrode unit 1 via the first interface 1111. A matching resistor 16 and an isolation capacitor 17 are connected within the receiving cavity 112. The other side of the isolation capacitor 17 is connected to the first electrode 14. The matching resistor 16 is a non-inductive resistor with a resistance of 50Ω. The isolation capacitor 17, with a capacitance in the pF range, concentrates the output voltages of the DC power supply 5 and the pulse power supply 4 onto the test sample 100. Furthermore, the first interface 1111 is located at the bottom of the side panel 113, opposite the first electrode unit 1 along the second direction Y. This allows the pulse power supply 4 to be connected from the side of the first electrode unit 1, reducing the non-coaxial transmission distance, ensuring impedance matching of the lines, and guaranteeing undistorted pulse signal transmission.

[0044] The DC power supply 5 is connected to the first electrode unit 1 via the second interface 1112. After being connected to the first electrode 14 via the current limiting resistor 18 in the receiving cavity 112, the current limiting resistor 18 protects the circuit devices. When the test sample 100 experiences insulation breakdown or surface flashover, the current limiting resistor 18 can limit the line current and prevent large current from damaging the power supply.

[0045] In this embodiment, the components are connected via a high-voltage insulated cable 19. Existing high-resolution space charge testers use a side-feed method to input pulse signals and DC high-voltage signals, requiring the cable 19 to be bent in an L-shape. Since the pulse signal has a half-peak width in the nanosecond range and a high frequency, the L-shape bend alters the physical structure of the cable 19, leading to pulse waveform distortion, increased loss, and the introduction of electromagnetic interference. This system adopts a side-feed method and improves the line connection. To avoid the L-shape bend, the first interface 1111, which connects to the pulse power supply 4, is located on the side of the first electrode 14. The first interface 1111 is directly connected to the first electrode 14 via a shielded BNC cable 19 and an isolation capacitor 17. This design significantly reduces the non-coaxial transmission distance, maximizes line impedance matching, and ensures that the pulse signal is not distorted.

[0046] The high-resolution space charge in-situ tester in this embodiment can generate at least 30kV high voltage when it is working. Therefore, the first enclosure 11 needs to have good voltage withstand performance. The DC high voltage path needs to be equipped with a megohm-level large resistor as a current limiting resistor 18. The current limiting resistor 18 has a certain length, so the first enclosure 11 needs to reserve enough space.

[0047] In some alternative embodiments, the cavity 112 is filled with insulating material.

[0048] To ensure good insulation performance of the first enclosure 11, polyimide film tape is adhered to the inner wall of the first enclosure 11, and the cavity 112 is filled with insulating materials such as epoxy resin. Various circuit components are then cast within the cavity 112. The breakdown field strength of epoxy material is generally greater than 20kV / mm, while that of air is 3kV / mm. Therefore, after casting epoxy material, the withstand voltage of the first enclosure 11 will be significantly improved, ensuring good insulation between the internal components.

[0049] In specific applications, in order to facilitate the setting and connection of various circuit devices in the cavity 112 and to insulate the first housing 11, the first housing 11 can be composed of a detachable cover plate 111 and a cylindrical body. The cover plate 111, the cylindrical body and the support 13 surround and form the cavity 112.

[0050] In some alternative embodiments, the second electrode unit 2 further includes a third housing 21 and a second electrode 22. The second electrode 22 is disposed on the side of the third housing 21 near the first electrode 14 and opposite to the first electrode 14. The acoustic signal pickup module 23 is disposed inside the third housing 21 and connected to the second electrode 22.

[0051] The second electrode 22 is a stainless steel plate, consisting of two parts: a piezoelectric coating plate 221 and an electrode structure plate 222. The piezoelectric coating plate 221 is positioned at the center of the second electrode 22 and coaxially with the first electrode 14. The piezoelectric coating plate 221 is fastened to the electrode structure plate 222 by studs, together forming the second electrode 22. The acoustic signal pickup module 23 is connected below the piezoelectric coating plate 221. In this embodiment, the piezoelectric coating plate 221 is made of double-sided coated sapphire glass. The propagation loss of acoustic signals in sapphire is lower than that in aluminum, ensuring that the pulsed acoustic signal is not distorted and further improving the system resolution.

[0052] In some alternative embodiments, the acoustic signal pickup module 23 includes a piezoelectric sensor 231 connected to the side of the second electrode 22 away from the first electrode unit 1. The piezoelectric sensor 231 is made of polyvinylidene fluoride-trifluoroethylene copolymer (P(VDF-TrFE)).

[0053] like Figure 3 As shown, the acoustic signal acquisition module 23 consists of a piezoelectric sensor 231, a metal clamping post 232, a banana-shaped connector 233, an insulating collar 234, silicone rubber 235, a coaxial connector 236, and a shielding shell 238. An amplifier 24 is also connected between the acoustic signal acquisition module 23 and the oscilloscope 6. The acoustic signal acquisition module 23 is used to acquire the acoustic signal generated by the second electrode 22 and convert it into a second electrical signal for output.

[0054] The piezoelectric sensor 231 is attached to the lower surface of the piezoelectric coating plate 221. The piezoelectric sensor 231 is a thin film structure that can convert mechanical vibrations caused by acoustic signals into electrical signals, thereby realizing the acquisition of acoustic signals and the output of electrical signals.

[0055] The piezoelectric sensor 231 is made of polyvinylidene fluoride-trifluoroethylene copolymer (P(VDF-TrFE)) piezoelectric film. This type of piezoelectric film has a good piezoelectric effect, which can ensure the sensitivity and accuracy of the conversion process, detect weak acoustic signals, and is suitable for the acquisition of acoustic signals of different frequencies.

[0056] A metal clamping post 232 is connected below the piezoelectric sensor 231 to ensure good electrical contact and to lead out the electrical signal. The metal clamping post 232 is filled with non-polar polyvinylidene fluoride (α-PVDF) 237, which has the same acoustic impedance as the P(VDF-TrFE) piezoelectric film and is used for sound wave absorption.

[0057] A banana plug 233 is connected below the metal clamping post 232 and then to a coaxial connector 236 to output electrical signals. An insulating collar 234 is wrapped around the outside of the metal clamping post 232, and silicone rubber 235 is placed underneath; both are used to buffer acoustic signals and absorb sound waves. The outer shielding box is used to shield external electromagnetic noise, ensuring that effective signals can be captured and enhancing signal stability.

[0058] The electrical signal converted by the acoustic signal acquisition module 23 is connected to the amplifier 24 via a coaxial cable. The amplifier 24 has a wide bandwidth, high gain, and low noise figure. The gain of the amplifier 24 in this instrument is 63dB, and the bandwidth is 1kHz~1GHz. The signal amplified by the amplifier 24 is transmitted to the oscilloscope 6 via the coaxial cable. The oscilloscope 6 must have a high sampling rate to acquire the corresponding voltage waveform. Subsequently, the data is processed by the computer 7 to reflect the space charge distribution inside the test sample 100.

[0059] In addition, in some optional embodiments, the pulse width of the pulse power supply 4 is less than 2 ns and the thickness of the piezoelectric film is less than 5 μm.

[0060] The resolution of the space charge meter based on the electroacoustic pulse method is mainly determined by the pulse power supply 4 and the piezoelectric film. The propagation waveform of the piezoelectric film is the propagation waveform of the pressure wave in the piezoelectric sensor 231. When both the pulse power supply 4 and the propagation waveform of the piezoelectric film are standard pulse square waves, the half-width Δ of the pulse power supply 4 is... t FWHMThe maximum value of the propagation time Δt of the sound wave in the piezoelectric sensor 231 is the time resolution of the detection device. In practical applications, the time resolution is the half-width of the peak after the convolution of the pulse power supply 4 and the propagation waveform of the piezoelectric film. The theoretical spatial resolution is the product of the time resolution and the sound velocity of the test sample material, as shown below: (1) (2) (3) in, d sense The thickness of the piezoelectric sensor is in meters (m). v sense The speed of sound wave propagation in the piezoelectric sensor is expressed in m / s. FWHM out The half-width at half-maximum (WHM) of the waveform after convolution is the temporal resolution of the instrument, measured in seconds. v samp The speed of sound wave propagation in the test sample is expressed in m / s. R abs This represents the spatial resolution of the instrument, measured in meters (m).

[0061] Taking a set of typical parameters as an example, the pulse power supply half-width Δ of this instrument t FWHM =1ns, piezoelectric film thickness is 3.5μm, Δ t =1.46ns. After the above convolution process, the temporal resolution of this instrument is 1.54ns. The theoretical spatial resolution (polyimide material): R abs = FWHM out × v samp = 1.54ns×2200m / s = 3.34μm, which is a high-resolution space charge tester.

[0062] The embodiments of the present invention achieve nanosecond-level time resolution by designing an ultra-narrow pulse width power supply 4 and an ultra-thin piezoelectric sensor 231, which has high-resolution characteristics and can realize high-resolution space charge testing.

[0063] In addition, in some optional embodiments, a fixing rod 8 and a fastener 9 are also included. One end of the fixing rod 8 is connected to the first electrode unit 1 and the other end is connected to the second electrode unit 2. The first electrode unit 1 and the fastener 9 are connected to the fixing rod 8 and can move along the first direction X. The fastener 9 is used to control the first electrode unit 1 to move along the first direction X to change the size of the gap.

[0064] Multiple fixing rods 8 and fasteners 9 are used. The fixing rods 8 are mounted on the second electrode unit 2, and the first electrode unit 1 is movably connected to the fixing rods 8. The fixing rods 8 are used to fix the position of the first electrode unit 1, ensuring that the first electrode unit 1 and the second electrode unit 2 are aligned. The fasteners 9 are used to fix the height of the first electrode unit 1, especially the first electrode 14. Multiple fasteners 9 are set at the same height on the fixing rods 8 to ensure that the first electrode 14 is horizontal. In addition, by adjusting the height of the fasteners 9, the height of the first electrode unit 1 and the height of the gap between the first electrode 14 and the second electrode 22 can be adjusted, thereby controlling the distance between the test sample 100 and the first electrode 14, realizing both "contact" and "non-contact" testing schemes.

[0065] In practical applications, the fixing rod 8 is a screw, and the fastener 9 is a nut.

[0066] Since the test requires the use of X-rays to irradiate the test sample 100, the space charge testing device must be radiation shielded to ensure that the X-rays are confined in a closed space throughout the entire test process, preventing X-rays from leaking into the external environment and causing harm to the operators.

[0067] In some alternative embodiments, the second housing 12 is a lead cylinder, and the side of the bracket 13 away from the avoidance hole 15 is wrapped with lead sheet 131 to collimate and shield the X-rays emitted by the X-ray source 3. The bracket 13 is insulated from the first electrode 14.

[0068] Lead can effectively shield X-rays, and the lead sheet 131 included on the outer surface of the lead-made second housing 12 and support 13 confines the X-rays within the clearance hole 15 during propagation.

[0069] Furthermore, the first housing 11 and the second electrode 22 are made of stainless steel to form a complete X-ray shielding layer to prevent X-ray penetration and leakage.

[0070] In addition, in some optional embodiments, a shielding ring 10 is also included. The shielding ring 10 is disposed between the first electrode unit 1 and the second electrode unit 2. The shielding ring 10, the first electrode unit 1 and the second electrode unit 2 enclose a gap. The gap is a closed space used to accommodate the test sample 100 and shield it from electromagnetic interference from the external environment.

[0071] The shielding ring 10, together with the first electrode unit 1 and the second electrode unit 2, surrounds the test sample 100, forming a closed space that can shield against electromagnetic interference from the external environment and prevent environmental noise from interfering with the effective signal.

[0072] The high-resolution in-situ space charge tester under X-ray irradiation in this embodiment of the invention not only measures the steady-state X-ray radiation space charge of materials, but also has excellent electromagnetic shielding and X-ray collimation shielding performance. The first housing 11 and the third housing 21 of the space charge testing device are made of aluminum and stainless steel, respectively. The X-ray optical path is equipped with a lead shielding structure, including a lead-made second housing 12 and a support 13 wrapped with lead sheeting 131, ensuring that the X-rays emitted from the X-ray source 3 only irradiate the sample under test, effectively eliminating the influence of X-rays on the acoustic signal pickup module 23. A double-layer electrical shield is used below the second electrode 22, with the acoustic signal pickup module 23 shielding shell 238 and the third housing 21 respectively installed. All components are connected by shielded wires to prevent electromagnetic interference from affecting the measurement results.

[0073] like Figure 4 As shown, the testing procedure using the instrument of this invention is as follows: The test sample 100 was cleaned with anhydrous ethanol. A thin metal film was then deposited on one side of the test sample 100 using a sputtering apparatus. The diameter of the deposited film was slightly larger than the outer diameter of the first electrode 14. The cross-sectional area of ​​the deposited film was denoted as [missing information]. S sam Short-circuit both sides of the test sample 100 with tin foil, place it in an oven in advance, and perform high-temperature treatment at 80℃ for 3 hours to eliminate the original residual charge in the test sample 100.

[0074] Clean both sides of the semiconductive layer 200, the first electrode 14, and the upper area of ​​the second electrode 22 with anhydrous ethanol. Place the test sample 100 and the semiconductive layer 200 sequentially, and finally install the first electrode unit 1 and tighten the fastener 9. The side of the test sample 100 coated with the metal film contacts the semiconductive layer 200. Silicone oil is applied between the second electrode 22 and the test sample 100, and to the underside of the first electrode 14 to enhance acoustic coupling. The thickness of the test sample 100 is denoted as [missing information]. d sam .

[0075] Place the second housing 12 and the X-ray source 3 together, ensuring that the X-ray source 3, the second housing 12, the support 13 and the first electrode 14 are coaxial.

[0076] All connections to the instrument were checked and found to be correct.

[0077] Turn on the power supply to amplifier 24 to provide power for its normal operation.

[0078] Turn on pulse trigger source 41 and set the pulse trigger signal frequency and amplitude.

[0079] Turn on Oscilloscope 6 and scale the window to a suitable position, ensuring sufficient resolution and sampling rate.

[0080] Turn on computer 7, start the space charge waveform acquisition software, and set parameters such as the number of sampling points, sampling time interval, and data storage path. The total sampling time is the number of sampling points multiplied by the sampling time interval.

[0081] Open the X-ray source 3 control software and preset the operating voltage during irradiation. U X Operating current I X To produce a certain dose rate D X X-ray radiation.

[0082] Turn on the pulse power supply 4 and enable the output. Observe the weak response signal that appears in the oscilloscope 6. Fine-tune the waveform to keep it in the middle of the window.

[0083] Turn on DC power supply 5 and enable output, gradually increasing the output voltage to the reference voltage at a rate of 500V / s. V REF At both ends of the test sample 100, E REF = V REF / d sam To obtain the reference bias electric field, click the acquisition button in the test software to acquire the current space charge reference waveform.

[0084] Turn on X-ray source 3 to generate irradiation at a certain dose rate, and then immediately continue to increase the output voltage to the test voltage at a rate of 500V / s. V SC At both ends of the test sample 100, E SC = V SC / d sam To test the bias electric field, click the acquisition button in the testing software. The software will continuously acquire the space charge waveform of the test sample 100 under the polarization electric field at set time intervals. Generally, the acquisition time of the space charge polarization waveform under the bias electric field is not less than 30 minutes, and the interval is set to 2~10 seconds.

[0085] After the preset time is reached, the data acquisition will automatically interrupt. Reset the sampling interval and number of sampling points, turn off the X-ray radiation source, set the DC power supply output to zero, and click the acquisition button in the test software to continue acquiring the space charge waveform of the test sample 100 during the short-circuit depolarization process. Generally, the acquisition time for the space charge depolarization waveform under short-circuit conditions should not be less than 30 minutes. The depolarization waveform changes rapidly in the early stages of the test; therefore, a sampling interval of 1-3 seconds is more appropriate.

[0086] After the preset time is reached again, the data acquisition will be automatically interrupted, the experiment will be stopped, and the power supplies of pulse power supply 4, pulse trigger source 41, amplifier 24 and oscilloscope 6 will be turned off.

[0087] Use a discharge rod to contact the upper surface of the first housing 11 to complete the discharge of the space charge testing device housing. Remove the X-ray source 3 and place it in a safe position. Remove the second housing 12, unplug the high-voltage output cable 19 of the DC power supply 5 from the second interface 1112, and unplug the output cable 19 of the pulse power supply 4 from the first interface 1111.

[0088] Loosen the fasteners 9 on the cover plate 111, remove the entire first electrode unit 1, take out the test sample 100 and the semiconductive layer 200, and clean the two sides of the semiconductive layer 200, the first electrode 14 and the upper area of ​​the second electrode 22 with anhydrous ethanol.

[0089] Open the waveform recovery processing software in Computer 7, and set the experimental conditions for this experiment, such as a test sample thickness of 100 mm. d sam The relative permittivity of the sample to be tested is 100. ε r The longitudinal wave velocity of the test sample 100 v sam Reference voltage V REF After processing the waveform file (save path, etc.), performing deconvolution, attenuation compensation, dispersion compensation, and bias electric field calibration, the polarization / depolarization space charge waveform of the test sample 100 under the experimental conditions can be obtained. ρ SC ( x , t ).

[0090] The space charge waveform at each time point ρ SC ( x , t According to equation (4), the positions are respectively... x By integrating, we can obtain the curve of the total charge changing with time. Q C ( t ): (4) Adjust test voltage V SC Operating voltage of X-ray source 3 U X Operating current I X It can be used to test dielectric materials under different bias electric fields. E SCand different X-ray radiation dose rates D X The space charge experiment under the influence of X-ray source 3 can be used to study the changes in space charge distribution and total charge with experimental conditions. Furthermore, the effect of X-ray irradiation on the test results can be studied without turning on the X-ray source 3.

[0091] According to the above testing procedure, the high-resolution space charge in-situ tester under X-ray irradiation in this embodiment can be used to perform "contact" and "non-contact" in-situ tests of the space charge of materials under X-ray irradiation.

[0092] Example 1: The high-resolution in-situ space charge tester under X-ray irradiation in this embodiment is used to perform "contact" in-situ testing of the space charge of materials under X-ray irradiation.

[0093] In this embodiment, the X-ray source 3 operates at a voltage of 0~70kV, a current of 0~1000μA, and a maximum power of 12W. At maximum power, it can generate X-rays with a dose rate of 742mGy / s. Its emission energy spectrum at different operating voltages is as follows: Figure 5 As shown. The second chamber 12 has an outer diameter of 28 mm, an inner diameter of 14 mm, and a height of 24 mm. It can collimate the X-rays emitted from the X-ray source 3, ensuring that the X-rays only irradiate the test sample 100. The test sample 100 is a circular sheet of polyimide material with a diameter of 100 mm and a thickness of 125 μm. The first electrode 14 on the test sample 100 has a diameter of 26 mm. The reference voltage set by the DC power supply 5 is... V REF = 1kV, the bias electric field under the reference voltage is V REF = 8kV / mm. Test voltage V SC = 10kV, the bias electric field under the test voltage is E SC = V SC / d sam = 80kV / mm. The pulse power supply 4 has an amplitude of 2kV, a pulse width of 1ns, and a trigger frequency of 200Hz. By tightening the fastener 9, the first electrode 14 is brought into close contact with the semiconductive layer 200 and the test sample 100, and the space charge distribution of the polyimide material under different experimental conditions is tested using a contact method.

[0094] Figure 6 shows the contact polarization / depolarization space charge test results of a 125 μm thick, 100 mm diameter polyimide material under an 80 kV / mm bias electric field. No X-ray irradiation was performed during the test. The results indicate that after applying the polarization voltage, opposite polarity charges (charges with the opposite polarity to the induced charges at the electrodes) accumulate near the electrodes within the material, and the charge density increases slowly over time. After depolarization, the peak value of the induced charge at the interface gradually decreases, but the decay of the internal charge is quite slow; however, the positive charge accumulated near the cathode increases, indicating a large accumulation of positive charge within the sample.

[0095] Figure 7 shows the results of contact polarization / depolarization space charge testing of a 125 μm thick, 100 mm diameter polyimide material under the combined action of X-ray irradiation and an 80 kV / mm bias electric field. The X-ray tube accelerating voltage was 50 kV, the tube current was 200 μA, and the generated X-ray irradiation dose rate was 106 mGy / s. The test results show that after X-ray irradiation, the induced charge at the electrodes and the internal space charge of the material are different: after 1800 s of polarization, the cathode charge peak slightly decreased, the anode charge peak slightly increased, the opposite polarity charge peak near the anode increased, and the overall sample accumulated more negative charge; during depolarization, the negative charge peak at the cathode was significantly injected into the bulk; other areas had more residual positive space charge, which turned into positive charge accumulation after depolarization.

[0096] Example 2: The high-resolution space charge in-situ testing instrument under X-ray irradiation in this embodiment is used to perform "non-contact" in-situ testing of the space charge of materials under X-ray irradiation. To simulate the real space environment, the first electrode 14 is moved upward, and a millimeter-level gap is maintained between the first electrode 14 and the test sample 100, so as to realize "non-contact" in-situ testing of space charge under X-ray irradiation.

[0097] In this embodiment, the X-ray source 3 operates at a voltage of 0~70kV, a current of 0~1000μA, and a maximum power of 12W. At maximum power, it can generate X-rays with a dose rate of 742mGy / s. Its emission energy spectrum at different operating voltages is as follows: Figure 5 As shown. The second chamber 12 has an outer diameter of 28 mm, an inner diameter of 14 mm, and a height of 24 mm. It can collimate the X-rays emitted from the X-ray source 3, ensuring that the X-rays only irradiate the test sample 100. The test sample 100 is a circular sheet of polyimide material with a diameter of 100 mm and a thickness of 125 μm. The first electrode 14 on the test sample 100 has a diameter of 26 mm, and the distance between the test sample 100 and the first electrode 14 is 1 mm. The reference voltage set by the DC power supply 5 is... V REF = 1kV, the bias electric field under the reference voltage is V REF= 8kV / mm. Due to the presence of an air gap, the test voltage should not be too high. V SC = 1.25~3.75kV, the bias electric field under the test voltage is E SC = V SC / d sam = 10~30kV / mm. The pulse power supply amplitude is 2kV, the pulse width is 1 ns, and the trigger frequency of the pulse power supply 4 is 200Hz. By adjusting the position of the fastener 9, a gap of approximately 1mm is left between the first electrode 14 and the test sample 100, so as to test the space charge distribution of the polyimide material under different experimental conditions in a non-contact manner.

[0098] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0099] Although alternative embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make further changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the alternative embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0100] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used merely to distinguish one entity from another, and do not necessarily require or imply any such actual relationship or order between these entities. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or terminal device that includes that element.

[0101] The technical solution provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the principle and implementation of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A high-resolution in-situ space charge analyzer under X-ray irradiation, characterized in that, include: X-ray source, pulse power supply, DC power supply, and space charge testing device; among which... The space charge testing device includes a first electrode unit and a second electrode unit arranged opposite to each other along a first direction, and there is a gap between the first electrode unit and the second electrode unit for accommodating the test sample. The first electrode unit is provided with a clearance hole that extends through the first direction. The clearance hole communicates with the gap. The X-ray source is located on the side of the clearance hole away from the second electrode unit. X-rays emitted by the X-ray source can enter the gap through the clearance hole. The pulse power supply and the DC power supply are connected to the first electrode unit. The pulse power supply and the DC power supply are used to apply a first electrical signal to the test sample and generate an acoustic signal on the test sample. The second electrode unit is provided with an acoustic signal pickup module. The acoustic signal pickup module is used to pick up the acoustic signal and convert the acoustic signal into a second electrical signal. The second electrical signal is used to characterize the space charge distribution of the test sample.

2. The high-resolution in-situ space charge tester according to claim 1, characterized in that, The first electrode unit includes a first housing, a second housing, a support, and a first electrode; wherein, The second housing, the bracket, and the first electrode are sequentially arranged in the first housing along the first direction. The second housing is located on the side of the first housing close to the X-ray source and opposite to the X-ray source. The first electrode is located on the side of the first housing close to the second electrode unit and opposite to the second electrode unit. One end of the bracket is connected to the second housing and the other end is connected to the first electrode. The pulse power supply and the DC power supply are connected to the first electrode. The clearance hole passes through the second housing, the bracket, and the first electrode in sequence, and the X-rays emitted by the X-ray source can pass through the second housing, the bracket, and the first electrode in sequence to enter the gap.

3. The high-resolution in-situ space charge tester according to claim 2, characterized in that, The second housing is a lead cylinder, and the side of the bracket away from the clearance hole is covered with lead sheeting to collimate and shield the X-rays emitted by the X-ray source. The bracket is insulated from the first electrode.

4. The high-resolution in-situ space charge tester according to claim 2, characterized in that, The first housing includes sides arranged opposite each other along a second direction, the first direction and the second direction being perpendicular. The side is provided with a first interface, and the side of the first housing away from the second electrode unit is provided with a second interface. The pulse power supply is connected to the first interface, the DC power supply is connected to the second interface, and the first interface and the second interface are connected to the first electrode. The first electrode unit further includes a matching resistor, an isolation capacitor, and a current-limiting resistor. The first housing and the bracket enclose a receiving cavity. The matching resistor, the isolation capacitor, and the current-limiting resistor are disposed in the receiving cavity. The matching resistor and the isolation capacitor are connected between the first interface and the first electrode. The current-limiting resistor is connected between the second interface and the first electrode.

5. The high-resolution in-situ space charge tester according to claim 4, characterized in that, The cavity is filled with insulating material.

6. The high-resolution in-situ space charge tester according to claim 2, characterized in that, The second electrode unit further includes a third housing and a second electrode. The second electrode is disposed on the side of the third housing close to the first electrode and opposite to the first electrode. The acoustic signal pickup module is disposed in the third housing and connected to the second electrode.

7. The high-resolution in-situ space charge tester according to claim 6, characterized in that, The acoustic signal pickup module includes a piezoelectric sensor, which is connected to the side of the second electrode away from the first electrode unit. The piezoelectric sensor is made of polyvinylidene fluoride-trifluoroethylene copolymer (P(VDF-TrFE)).

8. The high-resolution in-situ space charge tester according to claim 7, characterized in that, The pulse width of the pulse power supply is less than 2ns, and the thickness of the piezoelectric film is less than 5μm.

9. The high-resolution in-situ space charge tester according to claim 1, characterized in that, It also includes a fixing rod and a fastener. One end of the fixing rod is connected to the first electrode unit and the other end is connected to the second electrode unit. The first electrode unit and the fastener are connected to the fixing rod and can move along the first direction. The fastener is used to control the first electrode unit to move along the first direction to change the size of the gap.

10. The high-resolution in-situ space charge analyzer according to claim 1, characterized in that, It also includes a shielding ring, which is disposed between the first electrode unit and the second electrode unit. The shielding ring, the first electrode unit and the second electrode unit enclose the gap, which is a closed space. The gap is used to accommodate the test sample and shield against electromagnetic interference from the external environment.

11. The high-resolution in-situ space charge tester according to claim 1, characterized in that, It also includes an oscilloscope and a computer. The acoustic signal acquisition module is electrically connected to the oscilloscope, which is used to acquire the second electrical signal. The computer is electrically connected to the oscilloscope, which is used to calculate the space charge distribution of the test sample based on the second electrical signal.

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