A method for shaping the energy of a steep pulse based on a pulse shaping circuit

Abstract

The present application relates to the technical field of steep pulse shaping of pulse forming circuit, and particularly relates to a steep pulse energy shaping method based on a pulse forming circuit, which comprises: charging an energy storage capacitor group in a preset charging period, and initially gating a shaping network composed of PFN segments and Blumlein transmission line segments and an impedance gradient matching network; triggering a shaping switch to output a test pulse when a charging voltage reaches a target value, obtaining an incident component and a reflected component through an output sampling branch and generating a reflected characteristic quantity; the reflected characteristic quantity performs gating update on the matching network segment impedance configuration and the shaping network segment combination according to the minimum reflection criterion, and triggers a retest test pulse to obtain a retest reflected characteristic quantity; triggering a working pulse output when the retest reflected characteristic quantity is less than or equal to a reflected judgment threshold, and obtaining a steep pulse energy shaping result at a load end. The present application improves impedance matching consistency and waveform stability through reflected quantity closed-loop gating.

Description

Technical Field

[0001] This invention relates to the field of steep-edge pulse shaping technology for pulse shaping circuits, and more particularly to a steep-edge pulse energy shaping method based on pulse shaping circuits. Background Technology

[0002] With the development of high-voltage pulse power supplies, high-speed power devices, and electromagnetic energy modulation technology, pulse shaping circuits have continued to evolve in areas such as high repetition rate energy release, transient excitation, and load-side waveform consistency control. Existing pulse technologies typically use energy storage capacitor banks as energy sources, fast shaping switches as gating devices, and pulse shaping networks to constrain the rise edge, amplitude flatness, and effective pulse width of the output pulse. In terms of shaping networks, pulse shaping networks (PFNs) composed of multiple inductors and capacitors have the characteristics of configurable discrete segments and easy expansion of energy levels. Blummlein shaping structures based on the equivalent characteristic impedance of transmission lines have the characteristics of good flat-top retention and strong waveform symmetry. Therefore, combining PFN segments with Blummlein transmission line segments and switching the segments through a gating switch array has gradually become a circuit solution that balances high voltage carrying capacity and waveform adjustability. At the same time, to reduce reflections and ringing caused by the equivalent impedance of connecting conductors, interfaces, and load ends, existing technologies often introduce matching networks or absorption branches, such as impedance gradient matching networks, which improve energy coupling and return attenuation through segmented characteristic impedance transitions.

[0003] However, existing pulse shaping circuits still commonly suffer from reflection and echo problems caused by impedance mismatch after the shaping network is connected to the load. On the one hand, the equivalent output impedance of the shaping network and the equivalent impedance of the load deviate under different operating conditions. After the parasitic inductance and capacitance of the wiring and the transient characteristics of the switching, the incident wave and the reflected wave are easily superimposed, resulting in square top collapse, amplitude fluctuation, leading edge overshoot and tail drag, which causes the effective pulse width to decrease and the energy density to become discrete. On the other hand, the matching network with fixed parameters is difficult to cover the range of changes in the equivalent impedance of the load. When the matching is insufficient, the echo is aggravated. When the matching is excessive, the damping introduces additional losses and sacrifices the steep edge characteristics, making it difficult to balance reflection suppression, steep edge maintenance and energy utilization. Furthermore, existing segment selection is usually based on offline design and empirical tuning, lacking a gated triggering and retest judgment mechanism based on circuit sampling feedback. This makes it difficult for the segment configuration to quickly converge to a low reflection state after switching energy levels or changing load conditions, resulting in insufficient predictability and consistency of the output waveform.

[0004] Given that existing pulse shaping networks suffer from impedance mismatch when connected to the load, leading to reflections and echoes, which in turn cause a decrease in square-top flatness and a shortening of the effective pulse width, this invention is proposed. Therefore, the problem to be solved by this invention is: how to introduce a segmented gating network with a gradually varying impedance matching network into a pulse shaping circuit composed of an energy storage capacitor bank, a shaping switch, a PFN segment, and a Blumlein transmission line segment, and to establish a gating update and retest judgment gate control process under the minimum reflection criterion based on the reflection characteristics of the test pulse, so that the load end obtains a pulse energy shaping result with a steep edge and flat amplitude. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract and title of the invention. Such simplifications or omissions shall not be used to limit the scope of the present invention.

[0006] In view of the aforementioned existing problems, the present invention is proposed.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a steep-edge pulse energy shaping method based on a pulse shaping circuit, comprising: charging the energy storage capacitor bank in the pulse shaping circuit within a preset charging cycle, and initially gating the shaping network and impedance gradient matching network composed of PFN segments and Blumlein transmission line segments.

[0009] After the charging voltage of the energy storage capacitor bank reaches the target value, the forming switch is triggered to output a test pulse, and the reflection characteristic of the test pulse is obtained in the output sampling branch.

[0010] Based on the reflection characteristic quantity, the segmented impedance configuration of the impedance gradient matching network and the segment combination of the shaping network are selected and updated using the minimum reflection criterion. After completion, the shaping switch is triggered to output a retest test pulse to obtain the retest reflection characteristic quantity of the retest test pulse.

[0011] When the retested reflection characteristic is less than or equal to the reflection determination threshold, the forming switch is triggered to output a working pulse, and a steep-edge pulse energy forming result is obtained at the load terminal connected to the output terminal of the pulse forming circuit.

[0012] In a second aspect, the present invention provides a computer device, comprising:

[0013] One or more processors;

[0014] The memory stores operable instructions that, when executed by the one or more processors, cause the one or more processors to perform operations, including the flow of the steep-edge pulse energy shaping method based on the aforementioned pulse shaping circuit.

[0015] Thirdly, the present invention provides a computer-readable medium for storing software, the software including instructions executable by one or more computers, the instructions causing the one or more computers to perform operations, the operations including the flow of the steep-edge pulse energy shaping method based on the aforementioned pulse shaping circuit.

[0016] The beneficial effects of this invention are as follows: By charging the energy storage capacitor bank and initially gating the PFN segment, Blumlein transmission line segment, and impedance gradient matching network, a shaped topology matching the target energy level is formed, reducing the uncertainty of the initial output waveform and improving the consistency of the shaping starting point; by outputting test pulses and extracting reflection characteristics in the output sampling branch, a quantitative characterization of the impedance deviation between the shaping network and the load end is obtained, reducing reliance on empirical parameter tuning; by using the minimum reflection criterion to gating, updating, and retesting the segmented impedance configuration and segment combination, the top collapse caused by echoes and ringing is suppressed, improving flatness and effective pulse width; when the retested reflection characteristics meet the judgment threshold, the working pulse is triggered to output, obtaining the steep-edge pulse energy shaping result at the load end, improving energy utilization and output waveform repeatability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0018] Figure 1 This is a schematic flowchart of the steep-edge pulse energy shaping method based on a pulse shaping circuit as shown in this invention.

[0019] Figure 2 This is a flowchart illustrating the gating and updating method of the present invention;

[0020] Figure 3 This is a schematic diagram showing the load-side voltage waveform and key indicators of the present invention.

[0021] Figure 4 This is a schematic diagram of the cumulative energy curve and total energy labeling shown in this invention;

[0022] Figure 5 This is a schematic diagram illustrating the change of the reflection feature quantity as a function of the gating iteration number, as shown in this invention. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort should fall within the scope of protection of this invention.

[0025] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0026] According to an embodiment of the present invention, in combination Figure 1 The flowchart shown illustrates a steep-edge pulse energy shaping method based on a pulse shaping circuit, which specifically includes the following steps:

[0027] S1. Within a preset charging cycle, the energy storage capacitor bank in the pulse shaping circuit is charged, and the shaping network and impedance gradient matching network composed of PFN segments and Blumlein transmission line segments are initially gated. It should be noted that in this step:

[0028] S1.1 At the start of the preset charging cycle, the energy storage capacitor bank in the pulse shaping circuit and the charging power supply are connected through the charging switch to form a charging circuit.

[0029] In a preferred embodiment, the pulse shaping circuit includes a charging power supply, a charging switch, an energy storage capacitor bank, a charging current limiting branch, a discharging isolation branch, and a voltage sampling branch.

[0030] In a preferred embodiment, the preset charging cycle is based on the periodic timing trigger of the control unit: when the periodic timing arrives, the control unit first keeps the forming switch in the off state, and keeps the PFN segment gating switch, Blumullein gating switch and matching network gating switch in the off state; then the control unit outputs a gate drive to the charging switch, so that the charging power supply forms a closed loop with the energy storage capacitor bank through the charging current limiting branch, and the energy storage capacitor bank begins to accumulate charge.

[0031] As an example, the charging current limiting branch is a resistor-inductor series circuit, where the inductor value is determined by the constraint of the transient current rise rate during switch conduction; the discharge isolation branch can be a combination of a unidirectional isolation device and a damping resistor to suppress the spikes coupled back from the forming network side during the charging phase.

[0032] The preset charging cycle in this embodiment can be set according to the target pulse repetition frequency. For example, when the target repetition frequency is 100 Hz, the preset charging cycle is 10 ms; when the target repetition frequency is 50 Hz, the preset charging cycle is 20 ms. This embodiment does not impose a unique requirement on it.

[0033] S1.2 During the conduction of the charging circuit, the terminal voltage of the energy storage capacitor bank is collected as the charging voltage, and the nominal impedance level of the load is read at the load terminal connected to the output terminal of the pulse shaping circuit.

[0034] It should be noted that the charging circuit is conducting, which includes: the charging switch being in the conducting state, a continuous current path being formed between the charging power output terminal and the two ends of the energy storage capacitor bank, and no open circuit fault alarm in the charging current limiting branch.

[0035] Furthermore, during the conduction of the charging circuit, the control unit periodically samples the terminal voltage of the energy storage capacitor bank through the voltage sampling branch. The voltage sampling branch can be a combination of a high-voltage divider and an isolated sampling module: the output of the voltage divider is isolated and amplified before being sent to the analog-to-digital conversion channel; the sampling period is 50 μs; in order to suppress the influence of switching spikes on the sampling, a first-order low-pass network is connected in series at the front end of the isolated sampling module, and consistency verification is performed on three consecutive samples on the control unit side. The verification rules include: the difference between two adjacent samples does not exceed 0.3% of the voltage after voltage division conversion, which is considered a pass.

[0036] To avoid introducing additional high-energy tests, this embodiment preferably adopts a configuration memory reporting method: after the load end performs a power-on self-test, it sends the impedance range code to the control unit through an isolated communication interface; the control unit maps the range code to the nominal impedance level of the load; wherein the nominal impedance level of the load is divided into common load ranges, such as 25 Ω range, 50 Ω range, 75 Ω range, and 100 Ω range.

[0037] S1.3. Determine the initial segment identifier in the shaping segment selection table according to the charging voltage and the nominal impedance level of the load, and close the PFN selection switch and the Blumlein selection switch in sequence according to the initial segment identifier to complete the initial selection of the shaping network composed of PFN segments and Blumlein transmission line segments.

[0038] Specifically, the shaped segment gating table is a table of segment correspondence obtained by offline calibration for different charging voltage levels and nominal load impedance levels. The entries in the shaped segment gating table are stored in the form of initial segment identifiers, which include PFN segment gating identifiers, Blumlein transmission line segment gating identifiers, and segment gating identifiers for impedance gradient matching networks.

[0039] In a preferred embodiment, after receiving the charging voltage, the control unit maps the charging voltage to a charging voltage level code (e.g., 18 kV to 20 kV is mapped to level code V3, and 20 kV to 22 kV is mapped to V4); simultaneously, it maps the read nominal load impedance level to an impedance level code (e.g., 50 Ω is mapped to Z2); then, using the charging voltage level code-impedance level code as an index, it searches the forming segment gating table and reads the initial segment identifier in the corresponding entry; the control unit issues gating switch closing commands in the order of PFN first, then Blumlein, and inserts a fixed delay (e.g., 5 ms) between adjacent closings to allow the switch state to stabilize and complete the state readback; when the PFN and Blumlein gating state readbacks are consistent, the initial segment identifier is recorded as effective.

[0040] As an example, the PFN segment gating identifier: PFN consists of 8 segments connected in series, and the identifier is PFN-1...PFN-8 to indicate which segment is closed; for example, PFN-5 indicates that the gating switch matched to the 5th segment is closed, and the gating switches of the remaining segments are open.

[0041] As an example, the Blumlein transmission line segment gating identifier: Blumlein consists of 3 switchable segments, identified by BL-1…BL-3; for example, BL-2 indicates that the gating switch of the second segment is closed.

[0042] As an example, the segmented selection identifier of the impedance gradient matching network: the matching network consists of 4 segments of impedance gradient units, and the identifier is MN-1...MN-4 to indicate which segment it is connected to; for example, MN-3 indicates that the matching network is connected to the 3rd segment, forming a preset segmented impedance configuration.

[0043] S1.4 After the initial selection of the forming network is completed, close the matching network selection switch according to the initial segment mark to connect to the impedance gradient matching network and complete the initial selection of the impedance gradient matching network.

[0044] In a preferred embodiment, the matching network gating switch is composed of multiple high-voltage relays. After confirming that the PFN and Blumlein gating status are consistent, the control unit reads the impedance gradient matching network segment gating identifier in the initial segment identifier and outputs a closing command to the corresponding matching network gating switch, so that the first few segments of the matching network are connected to the output channel according to a preset topology. In order to avoid the switching transient from causing disturbance to the voltage of the energy storage capacitor bank, the matching network gating can be arranged when the charging voltage is close to the target charging voltage and the charging voltage change rate is lower than a threshold. The threshold is: the charging voltage increment of three consecutive sampling points is less than 0.2% of the full scale.

[0045] It should be noted that the PFN segment, Blumlein transmission line segment, and impedance gradient matching network are all switchable structures. Different combinations correspond to different equivalent output impedances, equivalent transmission delays, and equivalent waveform shaping capabilities. The initial selection is completed during the charging phase because the charging voltage and the nominal impedance level of the load determine the energy release intensity and impedance mismatch risk during subsequent discharge. The initial segment identifier is obtained by looking up the table based on these two factors before connecting to the matching network. This allows the reflection amount to be controlled within a small range during the first test pulse phase, reducing overvoltage and waveform distortion caused by reflection.

[0046] Preferably, the initial segment identifier brings the available combinations obtained from offline calibration to the online process in advance, so that the trial range of the first test pulse converges and the number of repeated switching is reduced; the impedance gradient matching network is pre-connected during the charging stage, so that the load equivalent impedance seen by the formed network is closer to the expected value, thereby making it easier for the subsequent rising edge and square top to fall into the target range.

[0047] S2. After the charging voltage of the energy storage capacitor bank reaches the target value, the forming switch is triggered to output a test pulse, and the reflection characteristic of the test pulse is obtained in the output sampling branch. It should be noted that in this step:

[0048] S2.1 Within a preset charging cycle, the terminal voltage of the energy storage capacitor bank is sampled through the voltage sampling branch to obtain the charging voltage, and the difference between the charging voltage and the target charging voltage is compared.

[0049] Specifically, methods for comparing the difference between the charging voltage and the target charging voltage include:

[0050] When the absolute value of the difference is less than or equal to the voltage tolerance threshold (which is 1% to 2% of the target charging voltage), the charging voltage of the energy storage capacitor bank reaches the target value.

[0051] When the absolute value of the difference is greater than the voltage tolerance threshold, the charging circuit remains open and the energy storage capacitor bank continues to be charged until the absolute value of the difference is less than or equal to the voltage tolerance threshold.

[0052] In a preferred embodiment, the control unit continuously reads the voltage sampling branch output within a preset charging cycle and uses the voltage divider conversion value as the charging voltage; the target charging voltage is given by the working level, for example, for a 50 Ω load and a target pulse energy level, the target charging voltage is 20 kV and the voltage tolerance threshold is 200 V.

[0053] S2.2 When the charging voltage of the energy storage capacitor bank reaches the target value, a test trigger signal is output to the test trigger control terminal, and the forming switch is closed within the calibrated pulse width of the test trigger signal (the equivalent discharge duration is shorter than the working pulse to reduce the energy of a single test and suppress heat accumulation), so that the forming network and the impedance gradient matching network release a test pulse to the load terminal.

[0054] In a preferred embodiment, the test trigger control terminal and the forming switch are isolated trigger links. After the control unit determines that the charging voltage has reached the target value, it first outputs a trigger request to the test trigger control terminal. The test trigger control terminal then outputs a test trigger signal to the driver of the forming switch. The forming switch can be a gas switch, a magnetic switch, or a solid-state switch array. After receiving the test trigger signal, the corresponding driver controls the conduction duration of the forming switch according to the calibrated pulse width, so that the forming network and the matching network release a low duty cycle test pulse to the load.

[0055] For example, when the equivalent width of the working pulse is 200 ns, the calibration pulse width of the test trigger signal can be taken as 50 ns to 80 ns.

[0056] S2.3 During the test pulse output, the incident amplitude and the reflected amplitude are obtained by the output sampling branch respectively, and the reflection characteristic quantity is generated based on the amplitude ratio of the incident amplitude and the reflected amplitude.

[0057] In this embodiment, the output sampling branch is set on the transmission channel between the output end of the pulse shaping circuit and the load end, and separates the incident component propagating along the load direction from the reflected component reflected back from the load end. The separated output is isolated and attenuated before entering the high-speed sampling module.

[0058] Furthermore, the control unit uses the test trigger time as the time reference and takes the peak values ​​of the incident component waveform and the reflection component waveform within a preset sampling window (such as 150ns after triggering) as the incident amplitude and the reflection amplitude.

[0059] As an example, the mathematical expression for the reflection feature is as follows:

[0060] ;

[0061] in, It is a reflection characteristic quantity; This refers to the reflection amplitude read within a preset sampling window on the reflection component channel of the output sampling branch; This refers to the incident amplitude value read within a preset sampling window on the incident component channel of the output sampling branch; This is used to perform the absolute value operation on the amplitude.

[0062] Preferably, the reflection characteristics are sensitive to impedance mismatch, and the observability of impedance mismatch is related to the incident amplitude. When the charging voltage does not reach the target value, the insufficient incident amplitude will lead to a decrease in the resolution of the reflection characteristics, making the judgment basis for subsequent gating updates unstable. By testing the trigger link to output a low duty cycle test pulse and extracting the reflection characteristics, the equivalent mismatch degree of the forming network, matching network, and load channel can be obtained without introducing additional external measurement equipment, which can be used for subsequent segmented gating updates. Compared with the scheme of passively observing the waveform at the load end only during the working pulse stage, this embodiment introduces a priori detection link of test pulse and reflection characteristics, so that the gating update can complete the convergence judgment before the working pulse, reducing the risk of overshoot and distortion caused by the working pulse directly hitting the mismatched load.

[0063] S3. Based on the reflection characteristic quantity, the segmented impedance configuration of the impedance gradient matching network and the segment combination of the shaping network are updated using the minimum reflection criterion. After completion, the shaping switch is triggered to output a retest test pulse, and the retest reflection characteristic quantity of the retest test pulse is obtained. (Refer to...) Figure 2 In this step, it is important to note that:

[0064] S3.1. Based on the reflection characteristic quantity, the gating control unit is triggered to enter the gating update process and obtain the matching segment identifier and shaping segment identifier of the current gating. The matching segment identifier is the segmented impedance configuration of the impedance gradient matching network, and the shaping segment identifier is the segment combination of the shaping network.

[0065] In a preferred embodiment, after obtaining the reflection characteristic, the control unit compares the reflection characteristic with a preset reflection judgment threshold. When the reflection characteristic is greater than the reflection judgment threshold, the control unit enters the gating update process. After entering the process, the control unit first reads the effective initial segment identifier from the current gating status register, and uses the impedance gradient matching network segment gating identifier as the current matching segment identifier, and uses the combination of the PFN segment gating identifier and the Blumlein transmission line segment gating identifier as the current forming segment identifier. At the same time, the control unit reads the status readback bit of each gating switch. If the readback is inconsistent with the register, an anomaly is recorded and the update is limited to only one switch before retesting, so as to avoid the uncertainty introduced by multiple switches.

[0066] S3.2 Output candidate selection instructions according to the single-variable switching rules, wherein the single-variable switching rules include: when keeping the forming segment identifier unchanged, only switch the matching segment identifier between adjacent segments to obtain the first candidate group; and when keeping the matching segment identifier unchanged, only switch the forming segment identifier between adjacent segment combinations to obtain the second candidate group.

[0067] It should be noted that the single-variable switching rule in this embodiment comes from the sensitivity assessment of adjacent segments during the offline calibration stage: under the same forming segment identifier, the effect of switching of adjacent matching network segments on the reflection feature quantity is monotonically or nearly monotonically changing; under the same matching segment identifier, the combined switching of adjacent forming segments has a more significant effect on the rising edge and square top indices; based on this rule, the online update preferably adopts a strategy of switching only one variable per round, so as to attribute the change of reflection feature quantity to a single switching action.

[0068] For example, if the current initial segment identifier is PFN-5 / BL-2 / MN-3, the first candidate group can be constructed by changing the adjacent segments of the matching segment identifier while keeping the forming segment identifier unchanged, thus forming two candidates, MN-2 and MN-4. Their initial segment identifiers are PFN-5 / BL-2 / MN-2 and PFN-5 / BL-2 / MN-4, respectively. The second candidate group can be constructed by changing the adjacent combinations of the forming segment identifier while keeping the matching segment identifier unchanged. For example, if the adjacent PFN segments are PFN-4 and PFN-6, and the adjacent Blumlein segments are BL-1 and BL-3, then candidates can be generated under the premise that the constraint is changed only when PFN or only Blumlein is changed each time, such as PFN-4 / BL-2 / MN-3, PFN-6 / BL-2 / MN-3, PFN-5 / BL-1 / MN-3, and PFN-5 / BL-3 / MN-3.

[0069] S3.3 Trigger test pulses for the first candidate group and the second candidate group one by one and generate corresponding candidate reflection characteristic quantities. Use the smallest amplitude of the candidate reflection characteristic quantity as the minimum reflection criterion to determine the target candidate gating instruction.

[0070] Specifically, the control unit executes the first and second candidate groups sequentially: first, it sends a candidate gating instruction to the gating control unit; after the gating status is consistent, it triggers the forming switch to output a test pulse; then, it obtains the candidate reflection characteristic quantity corresponding to the candidate according to S2.3, and binds the candidate reflection characteristic quantity with the candidate identifier and stores it in the candidate result table; for the same candidate, in order to reduce the influence of random fluctuations, two test pulses can be output continuously and the larger of the candidate reflection characteristic quantities can be taken as a conservative value; when the difference between the two exceeds 20%, the candidate is marked as an unstable candidate and eliminated.

[0071] Furthermore, the minimum reflection criterion in this embodiment is as follows: after eliminating unstable candidates, the remaining candidates are sorted in ascending order of candidate reflection feature quantity, and the candidate gating instruction corresponding to the smallest one is taken as the target candidate gating instruction; when there are ties for the smallest one, the candidate that only switches the matching segment identifier is selected first, so as to reduce the disturbance to the pulse width and rising edge.

[0072] It should be noted that the control unit in this embodiment is the gate control body of the pulse shaping circuit, and the gating control unit is the gating execution module driven by the control unit. The gating execution module is electrically connected to the PFN segment gating switch, the Blumlein gating switch and the matching network gating switch to perform segment switching and status readback.

[0073] S3.4 Update the matching segment identifier and shaping segment identifier according to the target candidate gating instruction to complete the gating update of the segmented impedance configuration of the impedance gradient matching network and the segment combination of the shaping network.

[0074] In a preferred embodiment, the control unit sends the target candidate gating instruction to the gating control unit. After the gating control unit completes the switch switching, it reads back the final state. The control unit writes the readback result into the current initial segment identifier register and simultaneously writes the update sequence number, reflection feature quantity, and trigger timestamp. When the reflection feature quantity is still not up to standard in subsequent retests, the next round of updates continues to construct adjacent candidates starting from the current initial segment identifier in the register, thereby forming a continuous and traceable gating update link.

[0075] It should be noted that both the impedance gradient matching network and the shaping network are segmented and switchable structures. Changes in the equivalent impedance at the load end and the parasitic parameters of the transmission channel will be directly reflected in the changes in the reflection characteristic quantity. In this embodiment, the purpose of gating and updating based on the minimum reflection criterion is that when the reflection characteristic quantity decreases, the coupling efficiency of the incident energy to the load is improved, the overshoot and ringing caused by the reflection circuit are reduced, and the flatness of the load end and the rising edge can obtain more stable results. The single-variable switching rule makes the correspondence between each round of switching action and the change in the reflection characteristic quantity clearer.

[0076] In an example gating update process, the reflection feature quantity changes with the iteration rounds as follows: Figure 5 As shown, the reflection characteristic gradually decreases and tends to be near the threshold.

[0077] S4. When the re-measured reflection characteristic is less than or equal to the reflection judgment threshold, the shaping switch is triggered to output a working pulse, and a steep-edge pulse energy shaping result is obtained at the load terminal connected to the output terminal of the pulse shaping circuit. It should be noted that the following points are important in this step:

[0078] S4.1 When the retested reflection characteristic quantity is greater than the reflection judgment threshold (e.g., 0.10), output the gating update instruction and return to step S3 to execute the next round of gating update.

[0079] S4.2 When the re-measured reflection characteristic quantity is less than or equal to the reflection judgment threshold, the shaping switch is triggered to output a working pulse, and a steep-edge pulse energy shaping result is obtained at the load terminal connected to the output terminal of the pulse shaping circuit (e.g., Figure 3 (As shown).

[0080] Specifically, the load terminal connected to the output terminal of the pulse shaping circuit receives the output working pulse. During the output of the working pulse, the load terminal voltage waveform and load terminal current waveform of the working pulse are obtained by the load terminal sampling branch. Based on the load terminal voltage waveform and load terminal current waveform, a steep-edge pulse energy shaping result is generated. The steep-edge pulse energy shaping result includes pulse rising edge index, square top flatness index, effective pulse width index, and pulse energy index.

[0081] It should be noted that the reflection determination threshold in this embodiment is determined by combining the allowable waveform overshoot at the load end and the withstand voltage margin of the matching network. When the reflection characteristic is too large, the superposition of the reflected wave and the incident wave can easily form a local overvoltage at the forming network node, and the top ripple and ringing at the load end will increase. Setting the threshold to 0.10 can usually limit the peak value of the reflection component to within 10% of the incident peak value, so that the overshoot risk in the working pulse stage is within a controllable range.

[0082] In a preferred embodiment, the load-side sampling branch includes a voltage sampling channel and a current sampling channel; wherein the voltage sampling channel may be a combination of a high-frequency high-voltage divider and an isolation sampling module; the current sampling channel may be a combination of a Rogowski coil or a current transformer and an integration / conditioning module; both channels are connected to the same high-speed sampling module and share a trigger reference, the trigger reference being the synchronous output of the forming switch trigger signal.

[0083] As an example, the pulse rise time indicator is the time taken for the load-side voltage waveform to rise from 10% of its peak value to 90% of its peak value; its mathematical formula is as follows:

[0084] ;

[0085] in, As the rising edge indicator, This refers to the moment when the load-side voltage waveform first reaches 10% of its peak value. This is the moment when the load-side voltage waveform first reaches 90% of its peak value.

[0086] As an example, the flatness index for the top of the square is: within the time window of the square top, the flatness is measured by the ratio of the difference between the maximum and minimum values ​​of the load-side voltage to the average value; its mathematical formula is as follows:

[0087] ;

[0088] in, This is an index for the flatness of the square top. This represents the maximum value of the load terminal voltage within the square-top time window. This represents the minimum load-side voltage within the square-top time window. This is the average value of the load terminal voltage within the square-top time window, which is from 20 ns after the rising edge ends to 20 ns before the falling edge begins.

[0089] As an example, the effective pulse width specification is defined as the duration during which the load-side voltage waveform is higher than 50% of its peak value; its mathematical formula is as follows:

[0090] ;

[0091] in, For effective pulse width index, This refers to the moment when the load-side voltage waveform first reaches 50% of its peak value during the rise process. This refers to the moment when the load-side voltage waveform last reaches 50% of its peak value during the decline process.

[0092] As an example, pulse energy index: (Refer to...) Figure 4 The instantaneous power at the load end is obtained by integrating the power over the time window corresponding to the effective pulse width; the mathematical formula is as follows:

[0093] ;

[0094] in, For pulse energy indicators, This is the voltage waveform at the load end. This is the current waveform at the load end. Let the time infinitesimal element be an integral with upper and lower limits. and .

[0095] As an example, if the peak voltage at the load terminal of the working pulse is 10 kV, the peak current at the load terminal is 200 A, the rise time is 18 ns, the effective pulse width is 210 ns, the square top flatness is 0.035, and the energy is 42 J.

[0096] In a preferred embodiment, the pulse shaping circuit serves as the pulse power stage of the high-voltage pulse generation circuit, with a nominal 50 Ω equivalent load at the load end, a target charging voltage of 20 kV, a voltage tolerance threshold of 200 V, and a reflection determination threshold of 0.10.

[0097] In this application scenario, at the start of stage S1, the charging switch is closed, and the voltage at the end of the energy storage capacitor bank rises to 19.92 kV within 4.8 ms and enters the final convergence stage. After the control unit reads that the nominal impedance level of the load is 50 Ω, it obtains the initial segment identifier PFN-5 / BL-2 / MN-3 by querying the shaping segment selection table, and sequentially closes the PFN selection switch and the Blumlein selection switch, connecting to the third segment of the matching network. Then, in stage S2, after determining that the charging voltage has reached the target value, a test trigger signal with a calibrated pulse width of 60 ns is output, and the shaping switch closes and releases a test pulse. The output sampling branch separates the incident component peak value of 9.6 kV and the reflection component peak value of 1.2 kV, with a reflection characteristic of 0.125, which is greater than the reflection judgment threshold. In stage S3, the first candidate groups MN-2 and MN-4 are constructed and tested one by one. When switching to PFN-5 / BL-2 / MN-4, the incident component peak value is 9.5 kV and the reflection component peak value is 0.7 kV. kV, reflection characteristic 0.074; this candidate is ranked smallest in the candidate result table, written as the current initial segment identifier and triggers the retest test pulse, the retest reflection characteristic is stable within 0.08; entering the S4 stage, the control unit triggers the shaping switch to output working pulse, the load end sampling branch records the load end voltage peak 10.0 kV, the load end current peak 198 A, the rise edge index 18 ns, the square top flatness 0.035, the effective pulse width 210 ns, and the energy index 42 J; the above indicators are consistent with the target under the same range, forming a traceable steep edge pulse energy shaping result record.

[0098] Preferably, during the test pulse stage, the segment combination and segment matching have been adjusted to a low reflection state, and the energy release during the working pulse stage is closer to the load absorption condition, reducing the risk of waveform distortion and overshoot at the load end. At the same time, the synchronous sampling of the load end voltage waveform and the load end current waveform solidifies the forming effect in an indexed manner, which facilitates the comparison of the forming quality of different segment combinations.

[0099] Other aspects disclosed in the embodiments of the present invention also provide a computer device including one or more processors and a memory.

[0100] The memory is used to store operable instructions that, when executed by the one or more processors, cause the one or more processors to perform operations, including the flow of the steep-edge pulse energy shaping method based on the pulse shaping circuit of the foregoing embodiments, especially... Figure 1 The flowchart of the method is shown.

[0101] Other aspects disclosed in the embodiments of the present invention also propose a computer-readable medium for storing software including instructions executable by one or more computers, which, upon execution, cause the one or more computers to perform operations including the flow of the steep-edge pulse energy shaping method based on pulse shaping circuits of the foregoing embodiments, particularly... Figure 1 The flowchart of the method is shown.

[0102] It should be recognized that embodiments of the present invention may be implemented or carried out by computer hardware, a combination of hardware and software, or by computer instructions stored in a non-transitory computer-readable storage medium.

[0103] The method can be implemented using standard programming techniques, including a non-transitory computer-readable storage medium configured with a computer program in the computer program, wherein the storage medium is configured such that the computer operates in a specific and predefined manner.

[0104] Each program can be implemented in a high-level procedural or object-oriented programming language to communicate with the computer system; however, if required, the program can be implemented in assembly or machine language.

[0105] In any case, the language can be either compiled or interpreted.

[0106] Furthermore, for this purpose, the program can run on programmed application-specific integrated circuits.

[0107] The processes described herein (or variations and / or combinations thereof) can be executed under the control of one or more computer systems configured with executable instructions, and can be implemented by hardware or a combination thereof as code (e.g., executable instructions, one or more computer programs, or one or more applications) that commonly executes on one or more processors. The computer program includes a plurality of instructions executable by one or more processors.

[0108] Furthermore, the method can be implemented in any suitable computing platform, including but not limited to personal computers, minicomputers, mainframes, workstations, networked or distributed computing environments, standalone or integrated computer platforms, or in communication with charged particle tools or other imaging devices.

[0109] Various aspects of the present invention can be implemented in machine-readable code stored on a non-transitory storage medium or device, whether portable or integrated into a computing platform, such as a hard disk, optical read and / or write storage medium, RAM, ROM, etc., such that it can be read by a programmable computer, and when the storage medium or device is read by the computer, it can be used to configure and operate the computer to perform the processes described herein.

[0110] Furthermore, machine-readable code, or parts thereof, can be transmitted via wired or wireless networks.

[0111] When such media includes instructions or programs that combine with a microprocessor or other data processor to implement the steps described above, the invention described herein includes these and other different types of non-transitory computer-readable storage media.

[0112] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A steep-edge pulse energy shaping method based on a pulse shaping circuit, characterized in that, include: Within a preset charging cycle, the energy storage capacitor bank in the pulse shaping circuit is charged, and the shaping network and impedance gradient matching network composed of PFN segments and Blumlein transmission line segments are initially selected. At the start of the preset charging cycle, the energy storage capacitor bank in the pulse shaping circuit and the charging power supply are connected through a charging switch to form a charging circuit. During the conduction of the charging circuit, the terminal voltage of the energy storage capacitor bank is collected as the charging voltage, and the nominal impedance level of the load is read at the load terminal connected to the output terminal of the pulse shaping circuit. Based on the charging voltage and the nominal impedance level of the load, the initial segment identifier is determined in the shaping segment selection table, and the PFN selection switch and the Blumlein selection switch are closed sequentially according to the initial segment identifier to complete the initial selection of the shaping network composed of the PFN segment and the Blumlein transmission line segment. After the shaping network completes the initial selection, the matching network selection switch is closed according to the initial segment identifier to connect to the impedance gradient matching network, thus completing the initial selection of the impedance gradient matching network. After confirming that the PFN and Blumlein gating states are consistent, the control unit reads the impedance gradient matching network segment gating identifier in the initial segment identifier and outputs a closing command to the corresponding matching network gating switch, so that the first few segments of the matching network are connected to the output channel according to the preset topology. To avoid the switching transients from disturbing the voltage of the energy storage capacitor bank, the matching network gating can be scheduled when the charging voltage is close to the target charging voltage and the charging voltage change rate is lower than a threshold. The threshold is: the charging voltage increment of three consecutive sampling points is less than 0.2% of the full scale. The shaped segment gating table is a segment correspondence table obtained by offline calibration for different charging voltage levels and nominal load impedance levels. The entries of the shaped segment gating table are stored in the form of the initial segment identifier, wherein the initial segment identifier includes the PFN segment gating identifier, the Blumlein transmission line segment gating identifier, and the segment gating identifier of the impedance gradient matching network. After the charging voltage of the energy storage capacitor bank reaches the target value, the forming switch is triggered to output a test pulse, and the reflection characteristic of the test pulse is obtained in the output sampling branch. Obtaining the reflection characteristic of the test pulse includes: within the preset charging cycle, sampling the terminal voltage of the energy storage capacitor bank through the voltage sampling branch to obtain the charging voltage, and comparing the difference between the charging voltage and the target charging voltage; when the charging voltage of the energy storage capacitor bank reaches the target value, outputting a test trigger signal to the test trigger control terminal, and closing the shaping switch within the calibrated pulse width of the test trigger signal, so that the shaping network and the impedance gradient matching network release a test pulse to the load terminal; during the test pulse output, obtaining the incident amplitude and the reflection amplitude respectively by the output sampling branch, and generating the reflection characteristic based on the amplitude ratio of the incident amplitude and the reflection amplitude; The output sampling branch is set on the transmission channel between the output end of the pulse shaping circuit and the load end, and separates the incident component propagating along the load direction from the reflected component reflected back from the load end. The separated output is isolated and attenuated before entering the high-speed sampling module. The control unit uses the test trigger time as the time reference and takes the peak values ​​of the incident component waveform and the reflected component waveform within the preset sampling window as the incident amplitude and the reflected amplitude, respectively. The preset sampling window is 150ns after the trigger. Based on the reflection characteristic quantity, the segmented impedance configuration of the impedance gradient matching network and the segment combination of the shaping network are selected and updated using the minimum reflection criterion. After completion, the shaping switch is triggered to output a retest test pulse to obtain the retest reflection characteristic quantity of the retest test pulse. The method for gating and updating based on the reflection characteristics includes: triggering a gating control unit to enter a gating update process based on the reflection characteristics, and obtaining the currently gating matching segment identifier and shaping segment identifier, wherein the matching segment identifier is the segmented impedance configuration of the impedance gradient matching network, and the shaping segment identifier is the segment combination of the shaping network; outputting candidate gating instructions according to a single-variable switching rule, wherein the single-variable switching rule includes: when keeping the shaping segment identifier unchanged, switching the matching segment identifier only between adjacent segments to obtain a first candidate group; and when keeping the matching segment identifier unchanged, switching the shaping segment identifier only between adjacent segment combinations to obtain a second candidate group; triggering test pulses for the first candidate group and the second candidate group one by one and generating corresponding candidate reflection characteristics, and determining the target candidate gating instruction based on the minimum amplitude of the candidate reflection characteristics as the minimum reflection criterion; updating the matching segment identifier and the shaping segment identifier according to the target candidate gating instruction to complete the gating update of the segmented impedance configuration of the impedance gradient matching network and the segment combination of the shaping network; The univariate switching rule is derived from the sensitivity assessment of adjacent segments during the offline calibration phase: under the same forming segment identifier, the effect of switching adjacent matching network segments on the reflection feature quantity is monotonically or nearly monotonically changing; under the same matching segment identifier, the combined switching of adjacent forming segments has a more significant effect on the rising edge and square top indices; based on this rule, the online update adopts a strategy of switching only one variable per round in order to attribute the change in reflection feature quantity to a single switching action; The minimum reflection criterion is as follows: after eliminating unstable candidates, the remaining candidates are sorted in ascending order of their reflection feature values, and the candidate gating instruction corresponding to the smallest value is taken as the target candidate gating instruction; when there are ties for the smallest value, the candidate that only switches the matching segment identifier is selected first to reduce the disturbance to the pulse width and rising edge. The method for comparing the retested reflection feature quantity with the reflection determination threshold includes: when the retested reflection feature quantity is greater than the reflection determination threshold of 0.10, outputting a gating update instruction and returning to the previous step to execute the next round of gating update; When the retested reflection characteristic is less than or equal to the reflection determination threshold, the forming switch is triggered to output a working pulse, and a steep-edge pulse energy forming result is obtained at the load terminal connected to the output terminal of the pulse forming circuit. The working pulse is received at the load terminal connected to the output terminal of the pulse shaping circuit. During the output of the working pulse, the load terminal voltage waveform and the load terminal current waveform of the working pulse are obtained by the load terminal sampling branch. The steep-edge pulse energy shaping result is generated based on the load terminal voltage waveform and the load terminal current waveform. The steep-edge pulse energy shaping result includes pulse rise edge index, square top flatness index, effective pulse width index and pulse energy index.

2. The steep-edge pulse energy shaping method based on a pulse shaping circuit according to claim 1, characterized in that, A method for comparing the difference between the charging voltage and the target charging voltage includes: When the absolute value of the difference is less than or equal to the voltage tolerance threshold, the charging voltage of the energy storage capacitor bank reaches the target value; When the absolute value of the difference is greater than the voltage tolerance threshold, the charging circuit is kept on and the energy storage capacitor bank continues to be charged until the absolute value of the difference is less than or equal to the voltage tolerance threshold.

3. A computer device, characterized in that, include: One or more processors; The memory stores operable instructions that, when executed by the one or more processors, cause the one or more processors to perform operations, including the flow of the steep-edge pulse energy shaping method based on a pulse shaping circuit as described in any one of claims 1 to 2.

4. A computer-readable medium for storing software, characterized in that: The software includes instructions executable by one or more computers, which, upon execution, cause the one or more computers to perform operations including the flow of the steep-edge pulse energy shaping method based on a pulse shaping circuit as described in any one of claims 1 to 2.

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