An ultraviolet preionization gas switch for fast marx generators

Abstract

The present application relates to a kind of pulse power devices, specifically to a kind of ultraviolet preionization gas switch for fast Marx generator, solve the problem that ultraviolet preionization structure is difficult to be applied in large scale in high-power gas switch.The ultraviolet preionization gas switch for fast Marx generator, including switch shell, and the upper electrode in the switch shell, lower electrode, preionization resistance, resistance connecting plate, trigger electrode;Preionization resistance and resistance connecting plate, trigger electrode coaxial arrangement;The other end of preionization resistance and trigger electrode form preionization gap;Preionization gap is located between upper electrode and lower electrode, and the potential difference between the other end of preionization resistance and one end of trigger electrode, so that preionization gap is broken down, and release ultraviolet light.The present application can realize the characteristics of ultraviolet preionization gas switch low jitter, low trigger threshold, low inductance, high reliability and long life, can satisfy the application demand of fast Marx generator.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of pulsed power devices, specifically to a kind of ultraviolet preionization gas switch for fast Marx generator. BACKGROUND

[0002] High-power gas switch is a kind of device that uses the insulation or breakdown phenomenon of gas medium under the action of voltage to realize circuit breaking and electric energy release. Due to its high voltage resistance, large current, simple structure, low cost and high power, high-power gas switch has been widely used in pulsed power primary energy storage and has become one of the key components in the system.

[0003] Fast Marx generator is a commonly used pulsed power primary energy storage, which has strict requirements for the performance of high-power gas switch, which can be summarized as low jitter, low trigger threshold, low inductance, low self-discharge probability and long service life. Among them, low jitter requires low dispersion of trigger breakdown delay of high-power gas switch, low trigger threshold requires low amplitude of trigger voltage for stable triggering of high-power gas switch, low inductance requires low inductance of high-power gas switch itself, low self-discharge probability requires low probability of self-discharge phenomenon of high-power gas switch during DC voltage resistance, and long service life requires long service life of high-power gas switch itself. To meet the above requirements, an effective measure is to add ultraviolet preionization structure in high-power gas switch. Adding ultraviolet preionization structure can bring the following benefits: first, it can effectively reduce the jitter and trigger threshold of high-power gas switch; second, it is beneficial to the formation of multiple discharge channels in the discharge process of high-power gas switch, thereby reducing the inductance of high-power gas switch itself; third, the formation of multiple discharge channels can also reduce the ablation of arc to the electrode, thereby further improving the service life of high-power gas switch. Sun Tieping et al. introduced a needle-type ultraviolet preionization structure applied to multi-gap gas switch in the paper "Ultraviolet Light Preionization Structure of Multi-Gap Gas Switch" (High Power Laser and Particle Beams, October 2011, Vol. 23, No. 10, pp. 2806-2810), which consists of two preionization needles installed on the trigger electrode, a fixing mechanism and an isolation resistor, which can reduce the trigger jitter of the gas switch by about 20% and reduce the trigger threshold by 5-10 kV. In addition, the L3 company in the United States has also developed a high-power gas switch with needle-type ultraviolet preionization structure, which can reduce the jitter of the gas switch to an excellent level of 1.2 ns.

[0004] The ultraviolet preionization structure has shown good results in reducing the jitter and trigger threshold of the gas switch, but has the following problems:

[0005] 1. The isolation resistor in the ultraviolet preionization structure is installed outside the gas switch housing and needs to be connected in series by multiple resistors to meet the voltage resistance requirement, making the structure loose and complex, and the reliability is low.

[0006] 2. The isolation resistor installed in series outside the gas switch housing has a long length. When voltage is applied, it is easy for surface flashover to occur on the surface of the resistor or along the surface of the switch housing, causing the gas switch to malfunction.

[0007] 3. The UV pre-ionization needle is severely ablated after long-term operation, which affects the UV pre-ionization effect and has an adverse effect on the stability and life of the gas switch.

[0008] The above problems seriously restrict the large-scale application of UV pre-ionization structures in high-power gas switches. Summary of the Invention

[0009] The present invention aims to address the problems of existing ultraviolet pre-ionization structures in high-power gas switches, such as loose and complex structures, low reliability, prone to surface flashover along the switch housing surface, and severe ablation after long-term operation, which affect the ultraviolet pre-ionization effect, stability and life. The present invention provides an ultraviolet pre-ionization gas switch for a fast Marx generator, which has the characteristics of compact structure, low jitter, low trigger threshold, low inductance, high reliability and long life, and can meet the application requirements of fast Marx generators.

[0010] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0011] An ultraviolet pre-ionization gas switch for a fast Marx generator is special in that it comprises a switch housing, and an upper electrode, a lower electrode, a pre-ionization resistor, a resistor connecting plate, and a trigger electrode located inside the switch housing;

[0012] The pre-ionization resistor is coaxially arranged with the resistor connecting plate and the trigger electrode;

[0013] The upper electrode and the lower electrode are in a circular pancake-shaped structure, and are coaxially arranged on the inner side wall of the switch housing via an electrode fixing member.

[0014] One end of the resistor connecting plate is arranged at the front end of the switch housing through the electrode fixing block, and the other end of the resistor connecting plate is connected to one end of the pre-ionization resistor;

[0015] One end of the trigger electrode is arranged at the rear end of the switch housing through an electrode fixing block, and the other end of the trigger electrode and the other end of the pre-ionization resistor form a pre-ionization gap; the pre-ionization gap is located between the upper electrode and the lower electrode; a potential difference is generated between the other end of the pre-ionization resistor and the other end of the trigger electrode, causing the pre-ionization gap to be broken down and releasing ultraviolet light.

[0016] Furthermore, the trigger electrode includes a ring electrode, a pre-ionization needle, and a long connecting plate connected to the pre-ionization needle;

[0017] The annular electrode is sleeved on the outer surface of the pre-ionization needle and the long connecting plate;

[0018] The tip of the pre-ionization needle extends out of the ring electrode and forms a pre-ionization gap with the other end of the pre-ionization resistor;

[0019] The long connecting plate is arranged inside the rear end of the switch housing through the electrode fixing block.

[0020] Further, the pre-ionization resistor includes a trigger needle electrode and a tubular insulator;

[0021] The trigger needle electrode includes a front electrode, a middle needle rod and a rear needle tip connected in sequence;

[0022] The middle needle rod is inserted into the tubular insulator, the rear end needle tip is exposed at one end of the tubular insulator, and a pre-ionization gap is formed between the rear end needle tip and the needle tip of the pre-ionization needle;

[0023] The other end of the tubular insulator is connected to one end of the front electrode; the other end of the front electrode is connected to the other end of the resistor connection plate;

[0024] A wire-wound resistor and a connecting ring are sleeved on the outer surface of the tubular insulator;

[0025] One end of the wirewound resistor is connected to the front-end electrode, and the other end is connected to the connecting ring.

[0026] Furthermore, a first cover plate is provided at the front end of the switch housing, and a trigger introduction member is provided on the first cover plate;

[0027] The electrode fixing block is provided with a stepped hole along the axial direction;

[0028] One end of the resistor connecting plate is inserted into the small end hole of the step hole on the front electrode fixing block of the switch housing, and the large end hole of the step hole is connected to the first cover plate;

[0029] A second cover plate is provided at the rear end of the switch housing, and a gas nozzle is provided on the second cover plate, and the gas nozzle is used to connect to an external gas source;

[0030] One end of the trigger electrode passes through the small end hole of the step hole on the rear end electrode fixing block of the switch housing, and the large end of the step hole is connected to the gas nozzle.

[0031] Furthermore, two annular sealing grooves are provided on the electrode fixing member; the distance between the two annular sealing grooves is 1.2 to 1.4 times the width of the sealing grooves;

[0032] Silicon rubber sealing rings are arranged in the two annular sealing grooves.

[0033] Furthermore, the distance between the rear end needle tip of the trigger needle electrode and the connecting ring is one third of the length of the trigger needle electrode.

[0034] Further, the compressive strength of the upper electrode and the lower electrode is greater than 1800kg / cm 2 The electrode surface roughness is less than or equal to 0.8, the material is graphite, the graphite particle size is less than 1 micron, and the hardness is greater than 85.

[0035] The material of the ring electrode in the trigger electrode is graphite, the graphite particle size is less than 1 micron, the hardness is greater than 85, and the compressive strength is greater than 1800kg / cm 2 .

[0036] Further, the length of the rear end needle tip exposed from the end of the tubular insulator is 1.5-2.5mm, the sharp angle of the rear end needle tip is 20-25 degrees, and the sharp angle guide circle is R0.2-0.4mm.

[0037] The material of the trigger needle electrode is an ablation-resistant metal material, the material of the tubular insulator is alumina ceramic, the wire-wound resistance material is manganese copper alloy, and the connecting sleeve ring material is metal.

[0038] Further, the pre-ionization needle material is an ablation-resistant metal material, the sharp angle thereof is 20-25 degrees, and the needle tip guide circle is R0.2-0.4mm.

[0039] The pre-ionization gap formed between the rear end needle tip and the needle tip of the pre-ionization needle is 1.5mm.

[0040] Further, the trigger introduction piece is a stepped columnar structure, the large end of which is connected to one end of the resistance connecting plate at the large hole end of the stepped hole of the electrode fixing block of the front end of the switch shell, and the small end of the stepped columnar structure extends out of the first cover plate.

[0041] Two annular sealing grooves are arranged on the outer wall of the trigger introduction piece in contact with the first cover plate, and a silicone rubber sealing ring is arranged in the annular sealing groove.

[0042] The materials of the trigger needle electrode and the pre-ionization needle are tungsten-nickel-iron alloy or tungsten-copper alloy.

[0043] Compared with the prior art, the beneficial effects of the technical scheme of the present application are:

[0044] 1. The ultraviolet pre-ionization gas switch for a fast Marx generator forms a pre-ionization gap between the pre-ionization resistance and the trigger electrode, which are originally separate components, and is installed inside the switch shell, so that the structure of the ultraviolet pre-ionization gas switch of the present application is more compact, the assembly is more convenient, large-scale application can be realized, and the reliability of the ultraviolet pre-ionization gas switch for a fast Marx generator is greatly improved.

[0045] 2. The present invention is used in the ultraviolet pre-ionization gas switch of the fast Marx generator. The pre-ionization resistor adopts a single wire-wound resistor with higher reliability to replace the resistor in series of multiple resistors in the traditional ultraviolet pre-ionization gas switch, which effectively improves the reliability of the ultraviolet pre-ionization gas switch.

[0046] 3. In the UV preionization gas switch for a fast Marx generator, the ring electrodes in the upper, lower, and trigger electrodes are all made of graphite with small particle size and excellent mechanical properties. This graphite has excellent hardness and mechanical strength, making it easy to machine and less susceptible to damage from bumps. It also exhibits low jitter and ablation resistance. Consequently, the UV preionization gas switch of the present invention boasts high mechanical strength, low jitter, and electrode ablation resistance.

[0047] 4. The present invention is used in the ultraviolet pre-ionization gas switch of the fast Marx generator. The pre-ionization needle and the trigger needle electrode in the pre-ionization resistor are made of ablation-resistant metal materials, which can reduce electrode ablation, thereby improving the life and reliability of the ultraviolet pre-ionization gas switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The figure is a schematic structural diagram of an embodiment of an ultraviolet pre-ionization gas switch for a fast Marx generator according to the present invention.

[0049] Figure 2 The figure is a schematic structural diagram of a switch housing in an embodiment of an ultraviolet pre-ionization gas switch for a fast Marx generator according to the present invention.

[0050] Figure 3 Schematic diagram of the structure of the pre-ionization resistor in the embodiment of the ultraviolet pre-ionization gas switch for the fast Marx generator of the present invention.

[0051] Figure 4 Schematic diagram of the structure of the trigger electrode in the embodiment of the ultraviolet pre-ionization gas switch for the fast Marx generator of the present invention.

[0052] The accompanying drawings are denoted as follows:

[0053] 1-switch housing, 2-upper electrode, 3-lower electrode, 4-electrode fixing part, 5-pre-ionization resistor, 6-resistance connecting plate, 7-trigger electrode, 8-electrode fixing block, 9-first cover plate, 10-second cover plate, 11-trigger introduction part, 12-gas nozzle, 13-screw; 101-first side plate, 102-second side plate, 103-third side plate, 104-fourth side plate; 501-trigger needle electrode, 502-tubular insulator, 503-wirewound resistor, 504-connecting ring; 701-ring electrode, 702-pre-ionization needle, 703-long connecting plate. DETAILED DESCRIPTION

[0054] like Figure 1 As shown, an ultraviolet pre-ionization gas switch for a fast Marx generator includes a switch housing 1, an upper electrode 2, a lower electrode 3, an electrode fixing member 4, a pre-ionization resistor 5, a resistor connecting plate 6, a trigger electrode 7, an electrode fixing block 8, a first cover plate 9, a second cover plate 10, a trigger introduction member 11, a gas nozzle 12 and a screw 13.

[0055] like Figure 2 As shown, the switch housing 1 is a rectangular parallelepiped structure, comprising a first side panel 101, a second side panel 102, a third side panel 103, and a fourth side panel 104. These panels, together with the first cover panel 9 and the second cover panel 10, form a sealed cavity. Mounting holes are coaxially arranged at the center of each of the first and second side panels 101 and 102 for mounting the electrode holder 4. The switch housing 1 is 300 mm long, 200 mm wide, and 100 mm high, with a wall thickness of 23 mm. The mounting holes are 15 mm in diameter. Ten threaded holes, each 25 mm deep and 12 mm in diameter, are provided at each end of the switch housing 1 for mounting the first and second cover panels 9, 10, and screws 13. Both the internal and external edges of the switch housing 1 have R10 radiused corners.

[0056] In this embodiment, the upper electrode 2 and the lower electrode 3 have the same structure, both being circular and pancake-shaped. M15 threaded holes are provided on both electrodes for connection to the electrode holder 4. Both electrodes are located within the switch housing 1. Both electrodes are 9 mm thick, 50 mm in diameter, and have threaded holes 2.5 mm deep. Both electrodes are made of high-performance graphite with a particle size of 0.9 microns, a hardness of 90, and a compressive strength of 1850 kg / cm. 2 , the electrode surface roughness is 0.8.

[0057] like Figure 1 、 Figure 2As shown, the electrode holder 4 comprises two cylindrical structures, mounted in mounting holes in the first and second side panels 101, 102 of the switch housing 1. One end of the electrode holder 4 is provided with an M15 thread, connected to the upper electrode 2 and lower electrode 3, respectively. The other end of the electrode holder 4 is a frustum, mounted outside the switch housing 1. To ensure the sealing of the entire UV pre-ionization gas switch, annular sealing grooves are provided on the outer walls of the electrode holder 4 where they contact the first and second side panels 101, 102 of the switch housing 1. Silicone rubber sealing rings are installed in these annular sealing grooves. The electrode holder 4 is made of stainless steel, with a diameter of 15 mm and a height of 30 mm. The frustum has a diameter of 25 mm and a thickness of 4 mm. The spacing between the two annular sealing grooves is 4.5 mm, and the groove width is 3.6 mm.

[0058] like Figure 3 As shown, the pre-ionization resistor 5 is composed of a trigger needle electrode 501, a tubular insulator 502, a wire-wound resistor 503, and a connecting collar 504. The trigger needle electrode 501 includes a front electrode, a middle needle shaft, and a rear needle tip, which are connected in sequence. The middle needle shaft is inserted into the tubular insulator 502, and the rear needle tip is exposed at one end of the tubular insulator 502. A pre-ionization gap is formed between the rear needle tip and the tip of the pre-ionization needle 702. The other end of the tubular insulator 502 is bonded to one end of the front electrode. The other end of the front electrode is connected to the other end of the resistor connecting plate 6. The outer surface of the tubular insulator 502 is sheathed with a wire-wound resistor 503 and a connecting collar 504. One end of the wire-wound resistor 503 is connected to the front electrode, and the other end is connected to the connecting collar 504.

[0059] In this embodiment, the trigger needle electrode 501 is 65 mm long. Its front electrode is cylindrical, 20 mm long, and 10 mm in diameter. Its end is provided with an M4 threaded hole with a depth of 10 mm. The combined length of the rear tip and the middle shaft of the trigger needle electrode 501 is 45 mm, with a diameter of 2 mm. The rear tip has a 22-degree angle and a 0.3 mm radius. The rear tip is inserted into the tubular insulator 502, protruding 2 mm from the front end. The tubular insulator 502 is 43 mm long, with an outer diameter of 8 mm and an inner diameter of 2.5 mm. A connecting collar 504 is bonded to its outer surface. The connecting collar 504 has an outer diameter of 12 mm, an inner diameter of 8 mm, and a height of 5 mm. It has an M12 threaded outer surface and is 21.7 mm from the tip of the trigger needle electrode 501. A wirewound resistor 503 is mounted on the outer surface of the tubular insulator 502. One end of the wirewound resistor 503 is connected to the front electrode, and the other end is connected to the connecting collar 504. The trigger needle electrode 501 is made of a tungsten-copper alloy, or in other embodiments, a tungsten-nickel-iron alloy. The tubular insulator 502 is made of alumina ceramic. The wirewound resistor 503 has a resistance of 300 ohms and is made of a manganese-copper alloy. The connecting collar 504 is made of a brass alloy.

[0060] The resistor connecting plate 6 is a rectangular plate-shaped structure with a 10mm long M4 cylindrical screw at its other end, connecting it to the threaded hole of the pre-ionization resistor 5. A through hole with a diameter of 3.5mm and a depth of 15mm is provided at one end of the resistor connecting plate 6, which inserts into the small end hole of the stepped hole in the electrode fixing block 8. The resistor connecting plate 6 is 75mm long, 20mm wide, and 6mm thick, and is made of stainless steel.

[0061] like Figure 4 As shown, the trigger electrode 7 consists of a ring electrode 701, a pre-ionization needle 702, and a long connecting plate 703. The ring electrode 701 is located between the upper electrode 2 and the lower electrode 3, and is 7 mm away from both electrodes. A central through hole with a diameter of 20 mm is provided in the center of the ring electrode 701, coaxial with the upper electrode 2 and the lower electrode 3. A stepped hole is provided on one half of the ring electrode 701. The small end of the stepped hole is an M4 small threaded hole with a depth of 8.5 mm, which is connected to the pre-ionization needle 702. The large end of the stepped hole is an M6 large threaded hole with a depth of 6.5 mm, which is connected to the long connecting plate 703. The other half of the ring electrode 701 is provided with an M12 threaded through hole, which is connected to the connecting collar 504. One end of the long connecting plate 703 is provided with an M6 thread and is connected to the large threaded hole of the ring electrode 701 as a whole. The other end is fixed to the small end of the stepped hole provided axially in the electrode fixing block 8. The outer diameter of the ring electrode 701 is 50mm, the thickness is 22mm, and the material is high-performance graphite. The long connecting plate 703 is 110mm long, 20mm wide, and 6mm thick, and the material is stainless steel. The graphite particle size of the ring electrode 701 is less than 1 micron, the hardness is greater than 85, and the compressive strength is greater than 1800kg / cm 2 .

[0062] The preionization needle 702 is cylindrical, with a needle tip at one end and an M4 screw at the other. The screw end is mounted in a small threaded hole on the inner surface of the ring electrode 701. The needle tip and the trigger needle electrode 501 of the preionization resistor 5 are coplanar and facing each other. The preionization needle 702 is 17.5 mm long, with an 11 mm tip length and a 2 mm diameter. The tip angle is 22 degrees, and the tip radius is 0.3 mm. The preionization needle 702 is made of tungsten-copper alloy. The preionization gap formed between the preionization needle 702 and the rear tip of the preionization resistor 5 is 1.5 mm.

[0063] Two electrode fixing blocks 8 are located at the front and rear ends of the switch housing 1. One end features a rectangular through-hole 20 mm wide, 6 mm thick, and 30 mm deep for securing the resistor connection plate 6 and trigger electrode 7. The other end features a large circular through-hole 18 mm in diameter and 20 mm deep for mounting the trigger lead-in 11 and gas nozzle 12. Electrode fixing blocks 8 are 54 mm long, 103 mm wide, and 50 mm high, and are made of either plexiglass or PEEK.

[0064] The first cover plate 9 is located at the front end of the switch housing 1. Its end face has an 8mm diameter mounting hole at its center for mounting the trigger insert 11. The second cover plate 10 is located at the rear end of the switch housing 1. Its end face has an M14 connection hole for mounting the air nozzle 12. The contact surface between the trigger insert 11 and the first cover plate 9 is provided with an annular sealing groove and a silicone rubber sealing ring. Both the first and second cover plates 9, 10 are 150mm long, 100mm wide, and 16mm thick, and are made of plexiglass. Each of the first and second cover plates 9, 10, has 10 13mm diameter holes on its surface. They are connected to the switch housing 1 via 20 screws 13, forming a seal. The screws 13 are made of PEEK.

[0065] The trigger lead-in 11 is an irregular cylindrical structure consisting of three cylindrical sections with diameters of 3.5 mm, 15 mm, and 8 mm, and lengths of 20 mm, 18 mm, and 41 mm, respectively. The rear end of the trigger lead-in 11 passes through the first cover plate 9 and the electrode fixing block 8, and is inserted into one end of the resistor connecting plate 6. The trigger lead-in 11 is made of stainless steel.

[0066] There is one air nozzle 12 , which is arranged in the air nozzle mounting hole of the second cover plate 10 and is used to inflate and deflate the switch cavity. The material is PEEK.

[0067] The ultraviolet pre-ionization gas switch provided by the present invention has a compact structure, and has the characteristics of low jitter, low trigger threshold, low inductance, high reliability and long life, and can meet the application requirements of fast Marx generators.

[0068] The working process of the above embodiment is as follows:

[0069] First, a positive DC voltage and a negative DC voltage are applied to the upper electrode 2 and lower electrode 3, respectively. A negative trigger voltage is then applied to the trigger lead-in 11. When the trigger voltage is applied to the trigger lead-in 11, the presence of the wirewound resistor 503 creates a potential difference between the trigger needle electrode 501 and the pre-ionization needle 702, causing the pre-ionization gap formed by the trigger needle electrode 501 and the pre-ionization needle 702 to break down and release ultraviolet light. Subsequently, the first main gap formed by the upper electrode 2 and the annular electrode 701 breaks down under the combined action of the positive DC voltage, the negative trigger voltage, and the ultraviolet light. Finally, the second main gap formed by the annular electrode 701 and the lower electrode 3 breaks down, causing the entire ultraviolet pre-ionization gas switch to break down and conduct.

Claims

1. An ultraviolet pre-ionization gas switch for a fast Marx generator, characterized in that: It comprises a switch housing (1), and an upper electrode (2), a lower electrode (3), a pre-ionization resistor (5), a resistor connecting plate (6), a trigger electrode (7), and an electrode fixing block (8) located inside the switch housing (1); The front end of the switch housing (1) is provided with a first cover plate (9), and a trigger introduction member (11) is provided on the first cover plate (9); the electrode fixing block (8) is provided with a stepped hole along the axial direction; one end of the resistor connecting plate (6) is inserted into the small end hole of the stepped hole on the electrode fixing block (8) at the front end of the switch housing (1), and the large end hole of the stepped hole is connected to the first cover plate (9); the rear end of the switch housing (1) is provided with a second cover plate (10), and the second cover plate (10) is provided with a gas nozzle (12), and the gas nozzle (12) is used to connect to an external gas source; one end of the trigger electrode (7) passes through the small hole end of the stepped hole on the electrode fixing block (8) at the rear end of the switch housing (1), and the large hole end of the stepped hole is connected to the gas nozzle (12); The upper electrode (2) and the lower electrode (3) are of a circular pancake-shaped structure, and the upper electrode (2) and the lower electrode (3) are coaxially arranged on the inner side wall of the switch housing (1) via an electrode fixing member (4); The pre-ionization resistor (5), the resistor connecting plate (6), and the trigger electrode (7) are coaxially arranged; one end of the resistor connecting plate (6) is arranged at the front end of the switch housing (1) through an electrode fixing block (8), and the other end of the resistor connecting plate (6) is connected to one end of the pre-ionization resistor (5); The trigger electrode (7) comprises an annular electrode (701), a pre-ionization needle (702), and a long connecting plate (703) connected to the pre-ionization needle (702); the annular electrode (701) is sleeved on the outer surfaces of the pre-ionization needle (702) and the long connecting plate (703); the tip of the pre-ionization needle (702) extends out of the annular electrode (701) and forms a pre-ionization gap with the other end of the pre-ionization resistor (5); the long connecting plate (703) is arranged inside the rear end of the switch housing (1) via an electrode fixing block (8); The pre-ionization resistor (5) comprises a trigger needle electrode (501) and a tubular insulator (502); the trigger needle electrode (501) comprises a front electrode, a middle needle rod and a rear needle tip connected in sequence; the middle needle rod is inserted into the tubular insulator (502), the rear needle tip is exposed from one end of the tubular insulator (502), and a pre-ionization gap is formed between the rear needle tip and the needle tip of the pre-ionization needle (702); the pre-ionization gap is located between the upper electrode (2) and the lower electrode (3); the other end of the tubular insulator (502) is connected to one end of the front electrode; a wire-wound resistor (503) and a connecting ring (504) are sleeved on the outer surface of the tubular insulator (502); one end of the wire-wound resistor (503) is connected to the front electrode, and the other end is connected to the connecting ring (504); A potential difference is generated between the rear end needle tip and the needle tip of the pre-ionization needle (702), so that the pre-ionization gap is broken down and ultraviolet light is released.

2. The ultraviolet pre-ionization gas switch for a fast Marx generator according to claim 1, characterized in that: The electrode fixing member (4) is provided with two annular sealing grooves; the distance between the two annular sealing grooves is 1.2 to 1.4 times the width of the sealing grooves; Silicon rubber sealing rings are arranged in the two annular sealing grooves.

3. The ultraviolet pre-ionization gas switch for a fast Marx generator according to claim 2, characterized in that: The distance between the rear end needle tip of the trigger needle electrode (501) and the connecting ring (504) is one third of the length of the trigger needle electrode (501).

4. The ultraviolet pre-ionization gas switch for a fast Marx generator according to claim 3, characterized in that: The compressive strength of the upper electrode (2) and the lower electrode (3) are both greater than 1800 kg / cm 2 , the material is graphite, the graphite particle size is less than 1 micron, and the hardness is greater than 85; The material of the annular electrode (701) in the trigger electrode (7) is graphite, the graphite particle size is less than 1 micron, and the compressive strength is greater than 1800 kg / cm 2 .

5. The ultraviolet pre-ionization gas switch for a fast Marx generator according to claim 4, characterized in that: The length of the rear end needle tip exposed from the end of the tubular insulator (502) is 1.5-2.5 mm, and the tip angle of the rear end needle tip is 20-25 degrees; The trigger needle electrode (501) is made of ablation-resistant metal material, the tubular insulator (502) is made of alumina ceramics, the wirewound resistor (503) is made of manganese-copper alloy, and the connecting ring (504) is made of metal.

6. The ultraviolet pre-ionization gas switch for a fast Marx generator according to claim 5, characterized in that: The pre-ionization needle (702) is made of ablation-resistant metal material, and its sharp angle is 20-25 degrees; The pre-ionization gap formed between the rear end needle tip and the needle tip of the pre-ionization needle (702) is 1.5 mm.

7. The ultraviolet pre-ionization gas switch for a fast Marx generator according to claim 6, characterized in that: The triggering lead-in member (11) is a stepped columnar structure, the large end of which is located at the large hole end of the stepped hole of the front electrode fixing block (8) of the switch housing (1) and connected to one end of the resistor connecting plate (6), and the small end of the stepped columnar structure passes through the first cover plate (9) and extends outside the first cover plate (9); Two annular sealing grooves are provided on the outer wall of the triggering introducing member (11) in contact with the first cover plate (9), and silicone rubber sealing rings are provided in the annular sealing grooves; The trigger needle electrode (501) and the pre-ionization needle (702) are both made of tungsten-nickel-iron alloy or tungsten-copper alloy.

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