Coaxial matching type PFL-Max generator and fast front edge quasi-square wave pulse generation method

Abstract

The present application relates to pulse power device, to solve the problem that the output pulse of PFL-Marx generator is influenced by switch conduction process, ground structure capacitance, loop inductance and the like in its superposition process, and it is difficult to output fast front, square wave high voltage pulse.A coaxial matching type PFL-Marx generator is provided, comprising an outer cylinder, an external connection module, a plurality of annular pulse forming line modules, a short circuit switch and a charging isolation inductor, the outer cylinder comprises an outer cylinder straight section and an outer cylinder taper section, the plurality of annular pulse forming line modules are located in the outer cylinder, the annular pulse forming line module comprises coaxially arranged high-voltage electrodes, low-voltage electrodes and connecting support insulators, the high-voltage electrodes and the low-voltage electrodes are provided with coaxially wound pulse forming lines, the charging isolation inductor is connected between the electrodes of the same name of adjacent annular pulse forming line modules, a plurality of internal short circuit switches are respectively arranged between adjacent annular pulse forming line modules, one side of the external short circuit switch is connected with the outer base, and the other side is connected with the external load.

Description

Technical Field

[0001] This invention relates to pulse power devices, specifically to a coaxial matched PFL-Max generator and a method for generating fast-leading quasi-square wave pulses. Background Technology

[0002] A pulsed power device is a device that compresses long-duration, low-power electrical energy into high-power, short pulses. It is widely used in high-power microwaves, high-energy rays, and high-energy particle accelerators. To maximize its practical value, miniaturization of pulsed power devices is a crucial direction in this technological field. Furthermore, to achieve higher electron beam quality, pulsed power devices generally require the generation of fast-leading quasi-square wave pulses. Traditional pulsed power devices use coaxial pulse-forming lines with oil, water, or gas as energy storage media to generate square waves, often resulting in large size and weight, making miniaturization difficult.

[0003] The PFL-Marx generator is a pulse power device that uses a pulse forming line or artificial line as the energy storage unit of the Marx generator. It has the natural advantage of integrating voltage boosting and pulse modulation, and is one of the most promising types for realizing the modularization and miniaturization of pulse power devices. Therefore, a great deal of research has been carried out both domestically and internationally in this area. For details, please refer to articles such as "Zhang H, Shu T, A, et al. A compact 4GW pulse generator based on pulse forming network-Marx for high-power microwave application[J]. Review of Scientific Instruments, 2021, 92(6):64707.", "Song F, Li F, Zhang B, et al. Recent advances in compact repetitive high-power Marx generators[J]. Laser and Particle Beams, 2019, 37(1):110-121.", and "Tewari SV, Umbarkar SB, Agarwal R. Development and Analysis of PFN Based Compact Marx Generator Using Finite Integration Technique for an Antenna Load[J]. IEEE Transactions on Plasma Science, 2013, 41(10Part-1):2684-2690.".

[0004] However, since the output pulse of a PFL-Marx generator is formed by superimposing high-voltage pulses from multi-stage pulse forming lines or artificial lines, the superposition process is often affected by the switching conduction process, ground capacitance, and loop inductance. As a result, PFL-Marx generators often have slow leading edges and poor flat-top quality, making it difficult to output fast-leading quasi-square wave pulses. Although the Marx generator developed in the paper "Lassalle F, Morell A, Loyen A, et al. Development and Test of a 400-kV PFN Marx With Compactness and Rise Time Optimization[J].IEEE Transactions on PlasmaScience,2018,46(10Part-1):3313-3319." can output leading edges as fast as 5ns, its flat-top oscillation is large, making it difficult to output fast-leading, quasi-square wave high-voltage pulses. Furthermore, because the Marx generator consists of multi-stage pulse forming line modules, switches, and inductor connections, the connection structure is numerous and complex, often resulting in insufficient structural stability and poor environmental adaptability, thus limiting its application scope.

[0005] Therefore, it is imperative to seek a generator that is compact, stable, and whose output energy from each stage of the pulse forming line can be superimposed in an orderly and efficient manner, while reducing the influence of stray capacitance and other factors on the output pulse, so as to output fast-leading, quasi-square wave high-voltage pulses. Summary of the Invention

[0006] This invention addresses the problem in the prior art where the output pulse of a PFL-Marx generator is affected by factors such as the switching conduction process, the structural capacitance to ground, and the loop inductance during its superposition process, resulting in a slow pulse leading edge, poor flat-top quality, and difficulty in outputting fast-leading, quasi-square wave high-voltage pulses. Therefore, a coaxial matching type PFL-Marx generator is proposed.

[0007] To achieve the above objectives, the technical solution proposed by this invention is as follows:

[0008] A coaxial matched PFL-Marx generator includes an outer cylinder, an external connection module, multiple ring pulse forming line modules, a short-circuit switch, and a charging isolation inductor, and is characterized by:

[0009] The outer cylinder includes a straight section and a tapered section, with one end of the straight section connected to the small end of the tapered section; multiple annular pulse forming line modules are located inside the outer cylinder and are coaxially arranged with the outer cylinder;

[0010] The external connection module includes an outer cylinder support plate, an inner base, an outer base, and an annular insulating support plate sandwiched between the inner base and the outer base; the outer cylinder support plate is connected to the other end of the straight section of the outer cylinder, and the annular insulating support plate is connected to the large end of the tapered section of the outer cylinder;

[0011] The annular pulse forming line module includes a high-voltage electrode, a low-voltage electrode, and a connecting support insulator arranged coaxially. The high-voltage electrode and the low-voltage electrode are two annular structures with the same outer diameter. A pulse forming line is arranged coaxially between them. The pulse forming line is connected to the high-voltage electrode and the low-voltage electrode through transmission line leads that are evenly distributed along its circumference.

[0012] One end of the connecting support insulator passes through the low-voltage electrode and connects to the high-voltage electrode, while the other end connects to the high-voltage electrode of the adjacent annular pulse forming line module; the low-voltage electrode of the first annular pulse forming line module is connected to the outer cylinder support plate, and the high-voltage electrode of the last annular pulse forming line module is connected to the inner base; the high-voltage electrodes and low-voltage electrodes of adjacent annular pulse forming line modules are connected to each other and to each other through charging isolation inductors.

[0013] The short-circuit switch includes multiple internal short-circuit switches and one external short-circuit switch. The multiple internal short-circuit switches are respectively disposed between adjacent annular pulse forming line modules; one side of the external short-circuit switch is connected to the outer base, and the other side is connected to the external load.

[0014] Furthermore, an elastic support pad is provided between the low-voltage electrode and the pulse forming line.

[0015] The high-voltage electrodes and connecting support insulators of multiple annular pulse forming line modules are connected in series to form a stable columnar structure. The central axis of this columnar structure coincides with the central axis of the cavity formed by the outer cylinder and the external connecting module. The multiple annular pulse forming line modules are pressed and fixed together with the adjacent high-voltage electrodes by elastic support pads. When the PFL-Marx generator discharges, the internal short-circuit switch closes and conducts sequentially from the first annular pulse forming line module to the last annular pulse forming line module. The conical section of the outer cylinder is designed to approximately meet the impedance matching conditions while ensuring reliable insulation.

[0016] Furthermore, the inner radius R of the outer cylindrical conical section satisfies the following formula:

[0017]

[0018] Where r is the outer radius of the high-voltage and low-voltage electrodes within the annular pulse forming line module; Z0 is the matching impedance of the PFL-Marx generator; ε ris the relative permittivity of the insulating gas inside the outer cylinder; L is the total axial length of multiple series-connected annular pulse forming line modules;

[0019] A coordinate system is established with the center of the high-voltage electrode of the last annular pulse forming line module as the origin, and the direction pointing from the last annular pulse forming line module to the first annular pulse forming line module as the positive direction. t represents the coordinate on the axis of the annular pulse forming line module; L1 represents the axial length of the outer cylinder conical section, and L1... <L。

[0020] The closing sequence of the internal short-circuit switch satisfies the following formula:

[0021]

[0022] Where i is the stage number of the internal short-circuit switch, t i t0 is the conduction time of the i-th stage internal short-circuit switch, t0 is the closing time of the first stage internal short-circuit switch, and d i Let be the axial distance between the i-th stage internal short-circuit switch and the first stage internal short-circuit switch, and c be the speed of light in vacuum.

[0023] Furthermore, the outer ring surfaces of both the high-voltage and low-voltage electrodes are smooth curved surfaces. The purpose of designing them as smooth curved surfaces is twofold: firstly, to achieve a uniform electric field and improve insulation reliability; and secondly, to form a short transmission line between the electrodes and the outer cylinder for impedance matching.

[0024] Furthermore, the internal short-circuit switch is located inside the connecting support insulator;

[0025] The charging isolation inductor is connected to the inner ring surface of the high-voltage electrode and the low-voltage electrode, which helps to reduce electric field distortion and achieve a compact design.

[0026] Furthermore, the internal short-circuit switch and the external short-circuit switch are ring structures; adopting a ring structure can reduce the structural inductance on the one hand, and on the other hand, it is easy to form multiple parallel discharge channels in the ring direction when conducting, thereby reducing the inductance of the switch discharge channel.

[0027] The internal short-circuit switch and the external short-circuit switch are semiconductor switches or hermetically sealed gas switches.

[0028] Among them, the internal short-circuit switches are closed and turned on in sequence according to the set timing by using the full triggering method, or the closing and turning are achieved by using the first few triggering switches + the subsequent self-breakdown switch. The overvoltage coefficient of the self-breakdown switch is adjusted so that the overvoltage turn-on timing is close to the set timing condition.

[0029] When a gas switch is used, a sealed structure is employed to prevent gas discharge products from affecting the insulation of other locations. Furthermore, the cavity formed between the outer cylinder, the external connection module, and the annular pulse forming line module is filled with insulating gas.

[0030] The insulating gas inside the cavity is SF6 gas or a mixture of SF6 and N2.

[0031] Furthermore, the pulse forming line is a ring-wound coaxial transmission line, a ring-shaped flat line, or an artificial line.

[0032] Furthermore, this invention also proposes a method for generating fast-leading quasi-square wave pulses using a coaxial matched PFL-Marx generator, which is characterized by including the following steps:

[0033] Step 1: Connect the high voltage output terminal of the external charging power supply to the high voltage electrode on the annular pulse forming line module near the outer cylinder support plate. Connect the ground terminal of the external charging power supply to the straight section of the outer cylinder. Each annular pulse forming line module is charged in parallel through its charging isolation inductor.

[0034] Step 2: When the charging voltage of the loop pulse forming line module reaches the set value, the internal short-circuit switch closes sequentially from the first loop pulse forming line module to the last loop pulse forming line module according to the set timing.

[0035] Step 3: The voltage pulses output by each loop pulse forming line module are sequentially and losslessly superimposed and transmitted to the external load. Finally, they are output to the external load by the external short-circuit switch, thus obtaining the fast leading edge quasi-square wave pulse of the coaxial matched PFL-Marx generator.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] [1] In the coaxial matching type PFL-Marx generator of the present invention, multiple annular pulse forming line modules are connected in series through high voltage electrodes and connecting support insulators to form a stable columnar structure. The two ends of the columnar structure are connected to the outer cylinder through external connection modules to form a complete columnar structure generator, which makes the overall structure of the generator compact and enhances the stability of the generator.

[0038] [2] The coaxial matching type PFL-Marx generator of the present invention designs the cavity formed by the annular pulse forming line module, the outer cylinder and the external connection module as a coaxial structure. The transmission line lead is evenly arranged along the circumference of the annular pulse forming line module. The short-circuit switch adopts a ring structure, which enables the current generated during the formation of the high voltage pulse to be transmitted evenly, reducing the circuit inductance of the generator, and achieving the effect of shortening the leading edge of the output pulse and reducing the flat-top oscillation of the output pulse.

[0039] [3] In the coaxial matching type PFL-Marx generator of the present invention, the outer circular surfaces of the high voltage electrode and the low voltage electrode in the annular pulse forming line module are designed as smooth curve structures. On the one hand, it plays the role of uniform electric field and improving insulation reliability. On the other hand, it forms a short transmission line with the outer cylinder to achieve impedance matching.

[0040] [4] In the coaxial matching type PFL-Marx generator of the present invention, the short-circuit switch and the charging isolation inductor are set inside the ring pulse forming line module, so that the electric field distribution in the generator is uniform, the insulation reliability is improved, the electric field distortion is reduced, and the compact design is achieved.

[0041] [5] The outer cylinder cone section of the coaxial matching type PFL-Marx generator of the present invention is designed by calculation to match the short transmission line formed between the high voltage electrode and the low voltage electrode of the annular pulse forming line module and the outer cylinder. The impedance of the outer cylinder cone section meets the impedance matching condition, and the conduction sequence of the internal short-circuit switch meets the transmission time matching condition. This allows the energy output by each stage of the annular pulse forming line module to be superimposed in an efficient and orderly manner, thereby outputting a fast leading edge quasi-square wave pulse.

[0042] [6] The short-circuit switch of the coaxial matching PFL-Marx generator of the present invention adopts a ring structure, which can reduce the structural inductance on the one hand, and on the other hand, it is easy to form multiple parallel discharge channels in the ring direction when conducting, thereby reducing the inductance of the switch discharge channel. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the coaxial matching PFL-Marx generator of the present invention;

[0044] Figure 2 This is a cross-sectional view of the annular pulse forming line module, the internal short-circuit switch, and the charging isolation inductor in an embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of the structure of the annular pulse forming line module in an embodiment of the present invention;

[0046] Figure 4 This is a schematic diagram of the voltage waveform of the fast-leading quasi-square wave pulse output by the coaxial matched PFL-Marx generator in an embodiment of the present invention;

[0047] Reference numerals: 1-Charging isolation inductor; 2-Outer cylinder support plate; 3-Internal short-circuit switch; 4-Annular pulse forming line module; 5-Outer cylinder; 6-Inner base; 7-Annular insulating support plate; 8-Outer base; 9-External short-circuit switch; 10-Pulse forming line; 11-High voltage electrode; 12-Low voltage electrode; 13-Connecting support insulator; 14-Elastic support pad; 15-Transmission line lead-out component. Detailed Implementation

[0048] like Figure 1 and Figure 2 As shown, a coaxial matching type PFL-Marx generator of the present invention includes an outer cylinder 5, multiple annular pulse forming line modules 4, a short-circuit switch, multiple charging isolation inductors 1, and an external connection module. The outer cylinder 5 includes a straight section and a tapered section, with one end of the straight section connected to the small end of the tapered section. The multiple annular pulse forming line modules 4 are located inside the outer cylinder 5 and are coaxially arranged with the outer cylinder 5.

[0049] The external connection module includes an outer cylinder connection support plate 2, an inner base 6, an outer base 8, and an annular insulating support plate 7 sandwiched between the inner base 6 and the outer base 8; the outer cylinder support plate 2 is connected to the other end of the straight section of the outer cylinder, and the annular insulating support plate 7 is connected to the large end of the conical section of the outer cylinder; the annular pulse forming line module 4 is located in the cavity formed by the outer cylinder 5 and the external connection module, and the annular pulse forming line module 4 coincides with the central axis of the cavity; the cavity formed between the outer cylinder 5, the external connection module, and the annular pulse forming line module 4 is filled with insulating gas, which is SF6 gas or a mixture of SF6 and N2 gas.

[0050] Depend on Figure 3 As can be seen, the annular pulse forming line module 4 includes a high-voltage electrode 11, a low-voltage electrode 12, and a connecting support insulator 13 arranged coaxially. The high-voltage electrode 11 and the low-voltage electrode 12 are two annular structures with the same outer diameter. The radial outer contours of the high-voltage electrode 11 and the low-voltage electrode 12 are both smooth curved surfaces, which on the one hand play the role of uniform electric field and improving insulation reliability, and on the other hand form a short transmission line with the outer cylinder 5 to achieve impedance matching. A coaxially coiled pulse forming line 10 is arranged between the high-voltage electrode 11 and the low-voltage electrode 12. The pulse forming line 10 is connected to the high-voltage electrode 11 and the low-voltage electrode 12 through the transmission line lead-out piece 15 that is evenly distributed along its circumference, so that the current is uniformly transmitted during the pulse forming process and the inductance is reduced.

[0051] One end of the connecting support insulator 13 is used to support the high-voltage electrode 11 after passing through the low-voltage electrode 12, and the other end is used to support the high-voltage electrode 11 of the adjacent annular pulse forming line module 4; multiple annular pulse forming line modules 4 are connected in series, and short transmission lines are formed between adjacent annular pulse forming line modules 4 and the outer cylinder 5; wherein the outer cylinder support plate 2 is used to support the low-voltage electrode 12 of the first annular pulse forming line module 4, and the high-voltage electrode 11 of the last annular pulse forming line module 4 is fixed on the inner base 6; the high-voltage electrodes 11 and the low-voltage electrodes 12 of adjacent annular pulse forming line modules 4 are electrically connected to each other through the charging isolation inductor 1;

[0052] After the high voltage electrodes 11 and connecting support insulators 13 of multiple annular pulse forming line modules 4 are connected in sequence, multiple annular pulse forming line modules 4 are connected in series and form a stable columnar structure. The central axis of the columnar structure coincides with the central axis of the cavity formed by the outer cylinder 5 and the external connecting module. Multiple annular pulse forming line modules 4 are pressed and fixed together with the adjacent high voltage electrodes 11 by elastic support pads 14.

[0053] The short-circuit switch includes multiple internal short-circuit switches 3 and one external short-circuit switch 9. The multiple internal short-circuit switches 3 are respectively disposed between adjacent annular pulse forming line modules 4. One side of the external short-circuit switch 9 is connected to the outer base 8, and the other side is connected to the external load. When the PFL-Marx generator discharges, the internal short-circuit switches 3 close sequentially from the first annular pulse forming line module 4 to the last annular pulse forming line module 4 to conduct.

[0054] The charging isolation inductor 1 is connected between the same electrodes of adjacent ring pulse forming line modules 4. That is, the high voltage electrode 11 and the low voltage electrode 12 of the two adjacent ring pulse forming line modules 4 are connected through the charging isolation inductor 1.

[0055] like Figure 2 As shown, the internal short-circuit switch 3 and the charging isolation inductor 1 are both installed inside the annular pulse forming line module 4. One side of the internal short-circuit switch 3 is connected to one side of the electrode of the annular pulse forming line module 4 via a thread, while the other side is pressed onto the other side of the next-stage annular pulse forming line module 4 via an elastic electrical contact. The outer side of the annular pulse forming line module 4 is sequentially connected to the high-voltage electrode 11 and the connecting support insulator 13, forming a stable annular columnar structure.

[0056] The inner base 6 and the outer base 8 clamp and fix the inner ring surface of the annular insulating support plate 7. The outer ring of the annular insulating support plate 7 is adapted and connected to the large end of the outer cylinder cone section. In this way, the annular columnar structure formed by multiple annular pulse forming line modules 4, the outer cylinder and the external connection module form a stable structure with both ends fixed. One side of the external short circuit switch 9 is connected to the other side of the outer base 8, and the other side of the external short circuit switch 9 is connected to the external load.

[0057] The outer surface contour of the annular columnar structure is a periodic segmented smooth curved surface formed by the high voltage electrode 11 and low voltage 12 of the annular pulse forming line module 4. The outer surfaces of multiple series-connected annular pulse forming line modules 4 and the inner surface of the outer cylinder 5 form multiple short transmission lines with a coaxial structure. Under the premise of ensuring reliable insulation between the outer surfaces of multiple series-connected annular pulse forming line modules 4 and the inner surface of the outer cylinder 5, the impedance of the short transmission lines is made close to the matching state with that of the generator. The outer cylinder 5 is designed as a structure of an outer cylinder conical section + an outer cylinder straight section. This can reduce and avoid the reflection of the pulse when passing through the short transmission lines during the pulse forming process, so that the high voltage pulse output by the annular pulse forming line module 4 can be transmitted to the external load with high efficiency.

[0058] The inner radius R of the outer conical section of outer cylinder 5 should meet the following impedance matching conditions:

[0059]

[0060] Where r is the outer radius of the high-voltage electrode 11 and the low-voltage electrode 12 within the annular pulse forming line module 4; Z0 is the matching impedance of the generator; ε r is the relative permittivity of the insulating gas inside the outer cylinder 5; L is the total axial length of the multi-stage series-connected annular pulse forming line module 4;

[0061] A coordinate system is established with the center of the high-voltage electrode 11 of the last annular pulse forming line module 4 as the origin, and the direction pointing from the last annular pulse forming line module 4 to the first annular pulse forming line module 4 as the positive direction. t represents the coordinate on the axis of the annular pulse forming line module 4; L1 represents the axial length of the outer cylinder conical section, and L1... <L。

[0062] The calculated inner radius R of the outer cylinder cone section ensures reliable insulation between the outer cylinder and the annular pulse forming line module electrode.

[0063] The closing timing of the internal short-circuit switch 3 of the coaxial matched PFL-Marx generator satisfies the following formula:

[0064]

[0065] Where i is the stage number of the internal short-circuit switch 3, and t i t0 is the conduction time of the i-th stage internal short-circuit switch 3, t0 is the closing time of the first stage internal short-circuit switch 3, and d i Let be the axial distance between the i-th stage internal short-circuit switch 3 and the first stage internal short-circuit switch 3, and let c be the speed of light in vacuum.

[0066] In this way, when the pulse generated by the current-stage annular pulse forming line module 4 is transmitted to the i-th stage annular pulse forming line module 4, the annular pulse forming line module 4 just starts to output pulses and synchronously and efficiently superimposes them onto the main pulse.

[0067] Among them, the internal short-circuit switch 3 is a gas switch, which adopts the full triggering method to achieve the above timing, or adopts the method of several stage triggering switches + subsequent self-breakdown switch. By adjusting the overvoltage coefficient of the self-breakdown switch, the overvoltage conduction timing is made close to the above timing conditions. When a gas switch is selected, the gas switch is a sealed structure to avoid the gas discharge products from damaging the insulation of other locations. The gas switch is a ring structure, which reduces the structural inductance on the one hand, and makes it easy to form multiple conduction channels in parallel in the ring direction, thereby reducing the inductance of the switch channel.

[0068] Meanwhile, this invention also proposes a method for generating fast-leading quasi-square wave pulses using a coaxial matched PFL-Marx generator, comprising the following steps:

[0069] Step 1: When the coaxial matching type PFL-Marx generator is running, connect the high voltage output terminal of the external charging power supply to the high voltage electrode 11 of the first annular pulse forming line module 4, and connect the ground terminal of the external charging power supply to the straight section of the outer cylinder. Each annular pulse forming line module 4 is charged in parallel through the charging isolation inductor 1 on it.

[0070] Step 2: When the charging voltage of the ring pulse forming line module 4 reaches the set value, the internal short-circuit switch 3 closes sequentially from the first ring pulse forming line module 4 to the last ring pulse forming line module 4 according to the set timing.

[0071] Step 3: The voltage pulses output by each loop pulse forming line module 4 are sequentially and losslessly superimposed and transmitted to the external load. Finally, they are output to the external load by the external short-circuit switch 9. The charging isolation inductor 1 is equivalent to a short circuit during charging, which realizes the isolation between each loop pulse forming line module 4 during the pulse forming process; thus, the fast leading edge quasi-square wave pulse of the coaxial matched PFL-Marx generator is obtained.

[0072] like Figure 4 As shown, the waveform obtained by the coaxial matched PFL-Marx generator is a high-quality fast-rising-edge quasi-square wave pulse, and the voltage efficiency generated under its matching conditions can reach over 95%.

Claims

1. A coaxial matched PFL-Marx generator, comprising an outer cylinder (5), an external connection module, multiple annular pulse forming line modules (4), a short-circuit switch, and a charging isolation inductor (1), characterized in that: The outer cylinder (5) includes a straight section and a tapered section, with one end of the straight section connected to the small end of the tapered section; multiple annular pulse forming line modules (4) are located inside the outer cylinder (5) and are coaxially arranged with the outer cylinder (5); The external connection module includes an outer cylinder support plate (2), an inner base (6), an outer base (8), and an annular insulating support plate (7) sandwiched between the inner base (6) and the outer base (8); the outer cylinder support plate (2) is connected to the other end of the straight section of the outer cylinder, and the annular insulating support plate (7) is connected to the large end of the conical section of the outer cylinder; The annular pulse forming line module (4) includes a high-voltage electrode (11), a low-voltage electrode (12) and a connecting support insulator (13) arranged coaxially. The high-voltage electrode (11) and the low-voltage electrode (12) are two annular structures with the same outer diameter. A pulse forming line (10) is arranged coaxially between them. The pulse forming line (10) is connected to the high-voltage electrode (11) and the low-voltage electrode (12) through transmission line leads (15) evenly distributed along its circumference. One end of the connecting support insulator (13) passes through the low-voltage electrode (12) and connects to the high-voltage electrode (11), and the other end is connected to the high-voltage electrode (11) of the adjacent annular pulse forming line module (4); wherein the low-voltage electrode (12) of the first annular pulse forming line module (4) is connected to the outer cylinder support plate (2), and the high-voltage electrode (11) of the last annular pulse forming line module (4) is connected to the inner base (6); the high-voltage electrodes (11) of adjacent annular pulse forming line modules (4) are connected to each other and the low-voltage electrodes (12) are connected to each other through a charging isolation inductor (1); The short-circuit switch includes multiple internal short-circuit switches (3) and one external short-circuit switch (9). The multiple internal short-circuit switches (3) are respectively arranged between adjacent annular pulse forming line modules (4); one side of the external short-circuit switch (9) is connected to the outer base (8), and the other side is connected to the external load.

2. The coaxial matched PFL-Marx generator according to claim 1, characterized in that: An elastic support pad (14) is also provided between the low-voltage electrode (12) and the pulse forming line (10).

3. A coaxial matched PFL-Marx generator according to any one of claims 1 or 2, characterized in that, The inner radius R of the outer cylinder cone section satisfies the following formula: ； Where r is the outer radius of the high-voltage electrode (11) and the low-voltage electrode (12) within the annular pulse forming line module (4); Z0 is the matching impedance of the PFL-Marx generator; ε r L is the relative permittivity of the insulating gas inside the outer cylinder (5); L is the total axial length of the multiple series-connected annular pulse forming line modules (4); A coordinate system is established with the center of the high-voltage electrode (11) of the last annular pulse forming line module (4) as the origin and the direction from the last annular pulse forming line module (4) to the first annular pulse forming line module (4) as the positive direction. t is the coordinate on the axis of the annular pulse forming line module (4); L1 is the axial length of the outer cylinder cone section, and L1 <L。 4. A coaxial matched PFL-Marx generator according to claim 3, characterized in that, The internal short-circuit switch (3) must satisfy the following closing timing formula when it is closed: ； Where i is the stage number of the internal short-circuit switch (3), and t i t0 is the conduction time of the i-th stage internal short-circuit switch (3), t0 is the closing time of the first stage internal short-circuit switch (3), and d i Let be the axial distance between the i-th internal short-circuit switch (3) and the first internal short-circuit switch (3), and c be the speed of light in vacuum.

5. A coaxial matched PFL-Marx generator according to claim 4, characterized in that: The outer ring surfaces of both the high-voltage electrode (11) and the low-voltage electrode (12) are set as smooth curved surfaces.

6. A coaxial matched PFL-Marx generator according to claim 5, characterized in that: The internal short-circuit switch (3) is located inside the connecting support insulator (13); The charging isolation inductor (1) is connected to the inner ring surface of the high voltage electrode (11) and the low voltage electrode (12).

7. A coaxial matched PFL-Marx generator according to claim 6, characterized in that: The internal short-circuit switch (3) and the external short-circuit switch (9) are ring structures; The internal short-circuit switch (3) and the external short-circuit switch (9) are semiconductor switches or hermetically sealed gas switches.

8. A coaxial matched PFL-Marx generator according to claim 7, characterized in that: The cavity formed between the outer cylinder (5), the external connection module and the annular pulse forming line module (4) is filled with insulating gas; The insulating gas inside the cavity is SF6 gas or a mixture of SF6 and N2.

9. A coaxial matched PFL-Marx generator according to claim 8, characterized in that: The pulse forming line (10) is a ring-wound coaxial transmission line, a ring-shaped flat line, or an artificial line.

10. A method for generating a fast-leading quasi-square wave pulse using a coaxial matched PFL-Marx generator, employing a coaxial matched PFL-Marx generator as described in any one of claims 1-9, characterized in that... Includes the following steps: Step 1: Connect the high voltage output terminal of the external charging power supply to the high voltage electrode (11) of the first annular pulse forming line module (4), connect the ground terminal of the external charging power supply to the straight section of the outer cylinder, and charge each annular pulse forming line module (4) in parallel through the charging isolation inductor (1) on it. Step 2: When the charging voltage of the ring pulse forming line module (4) reaches the set value, the internal short circuit switch (3) closes and conducts sequentially from the first ring pulse forming line module (4) to the last ring pulse forming line module (4) according to the set timing. Step 3: The voltage pulses output by each ring pulse forming line module (4) are sequentially and losslessly superimposed and transmitted to the external load end. Finally, they are output to the external load by the external short-circuit switch (9), thereby obtaining the fast leading edge quasi-square wave pulse of the coaxial matched PFL-Marx generator.

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