A low electromagnetic interference pulsed high magnetic field device and equipment for laser plasma

Abstract

The present invention discloses a low electromagnetic interference pulsed high magnetic field device and equipment for laser plasma, including: a transmission cable, which is a three-coaxial structure; a metal shielding box, which is connected to the metal shielding layer at one end of the transmission cable and grounded; a trigger switch, the return electrode of the trigger switch is connected to the outer electrode; an energy storage capacitor, which is located inside the metal shielding box and is insulated and separated from the metal shielding box; a vacuum target chamber, in which a magnetic field coil is arranged, and the magnetic field coil is respectively connected to the core electrode and the outer electrode at the other end of the transmission cable. The transmission cable of the present invention adopts a three-coaxial structure, and a metal shielding layer is added outside the outer electrode that conducts the return current. The metal shielding layer is connected to the metal shielding box used to shield the electromagnetic radiation of the energy storage capacitor and grounded, forming a fully enclosed shield for the device as a whole, which can greatly reduce the electromagnetic radiation interference generated by the pulsed large current.

Description

Technical Field

[0001] The invention relates to the field of strong electromagnetic field interference resistance, and in particular to a low electromagnetic interference pulse strong magnetic field device and equipment for laser plasma. Background Art

[0002] Laser plasma generated by the interaction between high-power lasers and matter is widely used in many application fields such as laser vacuum coating, extreme ultraviolet lithography light source, desktop high-brightness light source, laser accelerator, transient imaging of biological samples, and basic scientific research fields such as experimental research on nuclear fusion and celestial processes. These studies and applications need to be carried out in a vacuum target chamber or a target chamber filled with a specific medium. Laser ablation of the target material placed inside the target chamber produces laser plasma.

[0003] In order to control laser plasma, a pulsed strong magnetic field device is often required. The pulsed strong magnetic field device controls the laser plasma so as to optimize certain physical effects. The pulsed strong magnetic field device used for laser plasma is usually placed outside the target chamber of the laser plasma. The pulsed high current is generated by the instantaneous discharge of high-voltage capacitors. The pulsed high current enters the target chamber through the transmission line passing through the target chamber, and finally generates a pulsed strong magnetic field on the magnetic field coil surrounding the laser plasma.

[0004] However, the pulsed high current generated by the pulsed high magnetic field equipment is accompanied by strong electromagnetic radiation, which will seriously interfere with the electromagnetic environment of the laser plasma, generate strong electromagnetic interference signals on the target chamber wall and the experimental equipment around the target chamber, and even burn the electronic circuits of the experimental equipment. Therefore, the pulsed high magnetic field equipment is required to have the function of reducing electromagnetic interference. Summary of the invention

[0005] The purpose of the present invention is to provide a low electromagnetic interference pulsed high magnetic field device for laser plasma, which can solve the above-mentioned technical problems. The specific scheme is as follows:

[0006] According to the specific embodiments disclosed in the present invention, the first aspect of the present invention provides a low electromagnetic interference pulsed high magnetic field device for laser plasma, comprising: a transmission cable, the transmission cable is a three-coaxial structure, comprising: a core electrode, a first insulating layer, an outer electrode, a second insulating layer and a metal shielding layer sequentially covering the core electrode from the inside to the outside;

[0007] A metal shielding box, connected to the metal shielding layer at one end of the transmission cable and grounded;

[0008] A trigger switch, wherein the return electrode of the trigger switch is connected to the outer electrode;

[0009] An energy storage capacitor is located inside the metal shielding box and is insulated from the metal shielding box; a return electrode of the energy storage capacitor is connected to the outer electrode at the same end, and an outflow electrode of the energy storage capacitor is connected to the trigger switch;

[0010] A vacuum target chamber is provided with a magnetic field coil therein, and the magnetic field coil is respectively connected to the core electrode and the outer electrode at the other end of the transmission cable.

[0011] Preferably, it also includes: a high voltage DC power supply arranged in the metal shielding box;

[0012] The input end of the high-voltage direct current power supply is connected to the power grid through the transmission cable, and the output end is connected to the energy storage capacitor through the transmission cable to charge the energy storage capacitor.

[0013] Preferably, it also includes: a battery, an isolation transformer and a metal electromagnetic shielding cage,

[0014] The battery and the isolation transformer are located between the high-voltage DC power supply and the power grid;

[0015] The electromagnetic shielding cage is used to accommodate the battery and the isolation transformer, and the electromagnetic shielding cage is connected to the metal shielding layer and is grounded.

[0016] Preferably, the cable connected to the trigger switch is a three-coaxial structure, and the shielding layer of the trigger switch is connected to the metal shielding layer.

[0017] Preferably, the vacuum target chamber is only connected to the metal shielding layer.

[0018] Preferably, it further comprises: a lead shielding cylinder; the magnetic field coil is connected to the transmission cable through an electrode lead, the electrode lead is coated with an insulating layer and is arranged in the lead shielding cylinder.

[0019] Preferably, the lead shielding cylinder is a conical structure.

[0020] Preferably, the grounding wire of the electromagnetic shielding cage, the grounding wire of the metal shielding box, and the grounding wire of the high-voltage DC power supply are all the transmission cables and are grounded independently.

[0021] Preferably, the transmission cable is a one-to-many structure, and the multi-end end of the transmission cable is connected to the energy storage capacitor end.

[0022] According to the specific embodiments disclosed in the present invention, a second aspect of the present invention provides a pulsed magnetic field laser plasma control device, including the low electromagnetic interference pulsed high magnetic field device for laser plasma of the first aspect.

[0023] Compared with the prior art, the above solution of the embodiment disclosed in the present invention has at least the following beneficial effects:

[0024] The transmission cable adopts a three-coaxial structure, and a metal shielding layer is added to the outer electrode that conducts the return current. The metal shielding layer is connected to and grounded with a metal shielding box used to shield the electromagnetic radiation of the energy storage capacitor, forming a fully enclosed shield for the device as a whole, which can greatly reduce the electromagnetic radiation interference caused by large pulse currents. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the disclosure of the present invention, and together with the specification, are used to explain the principles disclosed in the present invention. Obviously, the drawings described below are only some embodiments disclosed in the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0026] Figure 1 A schematic structural diagram of a low electromagnetic interference pulsed high magnetic field device for laser plasma provided by an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of the structure of an energy storage capacitor provided in an embodiment of the present invention;

[0028] Figure 3 A schematic diagram of the structure of a trigger switch provided in an embodiment of the present invention;

[0029] Figure 4 A schematic diagram of the structure of a transmission cable provided by an embodiment of the present invention;

[0030] Figure 5 A schematic diagram of a vacuum target chamber provided by an embodiment of the present invention;

[0031] Figure 6 This is a comparative test chart of the electromagnetic radiation shielding effect provided by an embodiment of the present invention.

[0032] Reference numerals:

[0033] 1 transmission cable, 11 core electrode, 12 first insulation layer, 13 outer electrode, 14 second insulation layer, 15 metal shielding layer, 2 metal shielding box,

[0034] 3 trigger switch, 31 trigger switch return electrode, 32 trigger switch center electrode, 33 trigger switch shielding layer, 34 transmission optical fiber, 35 trigger laser,

[0035] 4 energy storage capacitor, 41 outflow electrode of energy storage capacitor, 42 return electrode of energy storage capacitor,

[0036] 5 vacuum target chamber, 51 magnetic field coil, 52 lead shielding tube, 53 electrode lead,

[0037] 6 high voltage DC power supply, 61 charging cable. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such product or device. In the absence of more restrictions, the elements defined by the sentence "comprises a" do not exclude the presence of other identical elements in the product or device including the elements.

[0040] The following is combined with Figure 1-6 Alternative embodiments of the present invention are described in detail.

[0041] The working principle of the pulsed high magnetic field equipment is as follows: the input end of the high-voltage DC power supply is connected to the power grid, and the output end is connected to the energy storage capacitor; the charging command issued by the computer is converted into an optical signal, and transmitted to the high-voltage DC power supply through the insulator optical fiber to execute the charging command, and the high-voltage DC power supply is used to charge the energy storage capacitor.

[0042] When the energy storage capacitor is charged to the required voltage, the pulse laser is focused on the central electrode of the large current trigger switch, and the laser ablates the central electrode or the insulating gas between the central electrodes, thereby generating free electrons. Finally, the trigger switch is turned on by electron avalanche, so that the large current from the energy storage capacitor passes through the trigger switch and enters the transmission cable. The transmission cable connected to the energy storage capacitor transmits the large current to the magnetic field coil inside the target chamber to generate a pulsed strong magnetic field.

[0043] The control circuit board of the high-voltage DC power supply is connected to the low-voltage ground to protect the circuit board; the residual charge after discharge is discharged to the high-voltage ground through mechanical switch control; the high-voltage DC power supply is separated from the power grid by batteries and isolation transformers to prevent electromagnetic interference from propagating to the power grid.

[0044] This pulsed high magnetic field structure will generate strong electromagnetic interference during high voltage charging, current transmission and pulsed magnetic field generation. Therefore, the first aspect of the present invention provides a low electromagnetic interference pulsed high magnetic field device for laser plasma, comprising:

[0045] A transmission cable 1, wherein the transmission cable 1 is a three-coaxial structure, comprising: a core electrode 11, a first insulating layer 12, an outer electrode 13, a second insulating layer 14 and a metal shielding layer 15 covering the core electrode 11 from the inside to the outside;

[0046] The metal shielding box 2 is connected to the metal shielding layer 15 at one end of the transmission cable 1 and is grounded;

[0047] A trigger switch 3, wherein the return electrode 31 of the trigger switch 3 is connected to the outer electrode 13;

[0048] The energy storage capacitor 4 is located inside the metal shielding box 2 and is insulated from the metal shielding box 2; the return electrode 42 of the energy storage capacitor 4 is connected to the outer electrode 13 at the same end, and the outflow electrode 41 of the energy storage capacitor 4 is connected to the trigger switch 3;

[0049] The vacuum target chamber 5 has a magnetic field coil 51 disposed therein, and the magnetic field coil 51 is respectively connected to the core electrode 11 and the outer electrode 13 at the other end of the transmission cable 4 .

[0050] This embodiment suppresses the electromagnetic interference generated by large current during transmission by adding a metal shielding layer to the outer layer of the three coaxial cables. At the same time, the metal shielding box is used to shield the electromagnetic radiation generated when the energy storage capacitor is charged. The metal shielding box is connected to the metal shielding layer of the transmission cable with a coaxial structure and grounded, forming a fully enclosed shielding for the entire device, which can greatly reduce the electromagnetic radiation interference generated by the pulsed large current.

[0051] Figure 4 This is a schematic diagram of the internal structure of the transmission cable. In this embodiment, except for the magnetic field coil, all other circuits including: electrical energy storage container, trigger switch, high-voltage DC power supply, ground wire, charging line, etc. use the coaxial structure, and parallel positive and negative electrodes (transmission line, capacitor, switch, feed-through, high-voltage DC power supply) or single-core wire (ground wire, power supply line) cannot be used.

[0052] like Figure 4 As shown, the core electrode 11 of the coaxial structure is used to conduct the outgoing current, and the outer electrode 13 is used to conduct the return current and shield the electromagnetic radiation. In addition, the outer electrode 13 conducting the return current is coated with a second insulating layer 14 to isolate it from the coaxial grounded metal shielding layer 15. The design of this three-coaxial structure can ensure that no electromagnetic interference is generated in other places except the magnetic field coil during the large current transmission process.

[0053] like Figure 1 As shown, when the current passes through the vacuum target chamber 5, only the metal shielding layer 15 of the transmission cable is connected to the vacuum target chamber 5, while the core electrode 11 for conducting the outgoing current and the outer electrode 13 for conducting the return current are not electrically connected to the vacuum target chamber 5, thereby ensuring that electromagnetic interference will not be conducted to the vacuum target chamber 5 through the transmission cable 1.

[0054] Furthermore, Figure 5 The internal arrangement of the vacuum target chamber 5 is shown, including: a magnetic field coil 51, a lead shielding tube 52, and an electrode lead 53. The electrode lead 53 is only used for conducting electricity to enable the magnetic field coil 51 to generate a pulsed strong magnetic field, and the electrode lead 53 must be as short as possible.

[0055] In order to suppress the electromagnetic radiation emitted from the magnetic field coil, the electrode lead wire 53 of this embodiment is coated with an insulating layer on the outside, and a lead wire shielding cylinder 52 is arranged around it. The lead wire shielding cylinder 52 is connected to the metal shielding layer 15 of the transmission cable 1. The lead wire shielding cylinder 52 is a conical structure, and the head opening size close to the magnetic field coil 51 is small, so that the lead wire of the magnetic field coil can pass through. Thereby, the leakage of electromagnetic radiation is blocked, and the interference of electromagnetic radiation is further suppressed.

[0056] The present invention further improves the energy storage capacitor and the trigger switch part, such as Figure 2 and Figure 3 Generally, the outer shell of the energy storage capacitor is used to conduct the return current, so the outer side of the energy storage capacitor 4 is separated from the sealed grounded metal shielding box 2 by an insulator, and the metal shielding box 2 is connected to the metal shielding layer 15 .

[0057] Inside the metal shielding box 2, a trigger switch 3 is provided in addition to the energy storage capacitor 4. The return electrode 31 of the trigger switch 3 and the return electrode 42 of the energy storage capacitor 4 are both connected to the outer electrode 13. The trigger switch 3 is also provided with a shielding layer 33, and the shielding layer 33 of the trigger switch and the metal shielding box 2 are both connected to the metal shielding layer 15.

[0058] The outflow electrode 41 of the energy storage capacitor is connected to the trigger switch center electrode 32. When the pulse laser emitted by the trigger laser 35 is focused on the trigger switch center electrode 32 through the transmission optical fiber 34 to generate a certain amount of free electrons, the switch is turned on by electron avalanche, and the large current from the energy storage capacitor 4 passes through the trigger switch 3 and enters the transmission cable 1. In this process, electromagnetic radiation is further suppressed by connecting the trigger switch and the energy storage capacitor to the metal shielding layer of the transmission cable.

[0059] The electromagnetic radiation generated by the battery and the isolation transformer between the high-voltage DC power supply and the power grid is shielded by an electromagnetic shielding cage. The electromagnetic shielding cage covers the battery and the isolation transformer, and the electromagnetic shielding cage is connected to the metal shielding layer and grounded, while the high-voltage DC power supply is also placed in the metal shielding box.

[0060] Finally, in this embodiment, in addition to the conductive circuit being a three-coaxial structure, the grounding wire must also be a coaxial structure with an outer shielding layer, and the common bare copper tape or single-core wire cannot be used as the grounding wire; and the low-voltage ground, high-voltage ground, and low-voltage ground of the high-voltage DC power supply must be independent of each other.

[0061] As an optional implementation, when there are very sensitive electrical devices, the battery can be physically disconnected from the grid before charging is completed and before discharging, and only the battery can be used to power the high-voltage power supply to further suppress the propagation of electromagnetic interference to the grid.

[0062] As an optional implementation, the transmission cable can adopt a one-to-many structure. The large current flowing out of the energy storage capacitor passes through the trigger switch and enters the three-coaxial structure transmission cable in the form of multiple flexible cables in parallel. The multiple parallel flexible cables are then gathered and connected to the vacuum flange of the vacuum target chamber through a transmission cable. The use of multiple flexible cables in parallel can facilitate use and cable processing.

[0063] In summary, this embodiment generally suppresses electromagnetic interference by shielding any equipment that may generate electromagnetic radiation, electrical connections, or transmission lines.

[0064] Example 1

[0065] The low electromagnetic interference pulsed high magnetic field device for laser plasma of the present invention is set up as follows and the voltage is tested.

[0066] The high-voltage DC power supply charges the 5μF energy storage capacitor to 40kV, and the pulse laser with 100mJ pulse energy, 10ns pulse width, and 1064nm wavelength is transmitted through the optical fiber and focused to the inside of the trigger switch to ablate the switch electrode and turn on the trigger switch.

[0067] The trigger switch electrode is made of tungsten copper, with a center electrode diameter of 4cm and a return electrode diameter of 5cm. The large pulse current is transmitted to the flange of the vacuum target chamber through 6 parallel three-coaxial transmission cables made of copper material, which are 3m long and 1cm thick. It is then transformed into a single three-coaxial transmission cable made of stainless steel with a thickness of 5cm and transmitted into the interior of the vacuum target chamber.

[0068] Inside the vacuum target chamber, the current is connected to the magnetic field coil wound with 1 cm diameter copper wire through the electrode lead, generating a current pulse with a peak intensity of 100 kA on the magnetic field coil and a magnetic field with a peak intensity of 20 T inside the coil.

[0069] A conical lead shielding tube made of copper is put on the lead of the magnetic field coil to block the leakage of electromagnetic radiation. The opening diameter of the head of the conical shielding tube is 2mm, so that the electrode lead of the magnetic field coil can pass through. The tail diameter of the conical lead shielding tube is 5cm, and it is connected to the metal shielding layer of the transmission cable with copper foil tape.

[0070] Figure 6 b is the electromagnetic interference waveform detected by the original device. Figure 6 a is a test effect diagram obtained after using the device of this embodiment, and it can be clearly seen that the electromagnetic waves are effectively suppressed.

[0071] Example 2

[0072] Compared with Example 1, the DC charging voltage is reduced to 20 kV, the magnetic field coil is changed to be wound with a 1 mm diameter copper wire wrapped with a polyimide insulation film, the coil diameter is 12 mm, and it is wound with two turns, and other settings are the same.

[0073] A second aspect of the present invention provides a pulsed magnetic field laser plasma control device, which uses the above-mentioned low electromagnetic interference pulsed high magnetic field device for laser plasma for control to reduce electromagnetic interference.

[0074] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other. For the system or device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0075] The above embodiments are only used to illustrate the technical solutions disclosed in the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments disclosed in the present invention.

Claims

1. A low electromagnetic interference pulsed high magnetic field device for laser plasma, characterized in that: include: A transmission cable, the transmission cable is a three-coaxial structure, comprising: a core electrode, a first insulating layer, an outer electrode, a second insulating layer and a metal shielding layer covering the core electrode in sequence from inside to outside; A metal shielding box, connected to the metal shielding layer at one end of the transmission cable and grounded; A trigger switch, wherein the return electrode of the trigger switch is connected to the outer electrode; An energy storage capacitor is located inside the metal shielding box and is insulated from the metal shielding box; a return electrode of the energy storage capacitor is connected to the outer electrode at the same end, and an outflow electrode of the energy storage capacitor is connected to the trigger switch; A vacuum target chamber, in which a magnetic field coil is arranged, and the magnetic field coil is respectively connected to the core electrode and the outer electrode at the other end of the transmission cable; Also included: a lead shielding barrel; The magnetic field coil is connected to the transmission cable through an electrode lead, and the electrode lead is covered with an insulating layer and arranged in the lead shielding cylinder; The lead wire shielding barrel is connected to the metal shielding layer of the transmission cable.

2. The device according to claim 1, characterized in that Also includes: A high voltage DC power supply disposed in the metal shielding box; The input end of the high-voltage direct current power supply is connected to the power grid through the transmission cable, and the output end is connected to the energy storage capacitor through the transmission cable to charge the energy storage capacitor.

3. The device according to claim 2, characterized in that Also includes: Batteries, isolation transformers and metal electromagnetic shielding cages, The battery and the isolation transformer are located between the high-voltage DC power supply and the power grid; The electromagnetic shielding cage is used to accommodate the battery and the isolation transformer, and the electromagnetic shielding cage is connected to the metal shielding layer and is grounded.

4. The device according to claim 1, characterized in that The cable connected to the trigger switch is a three-coaxial structure, and the shielding layer of the trigger switch is connected to the metal shielding layer.

5. The device according to claim 1, characterized in that The vacuum target chamber is only connected to the metal shielding layer.

6. The device according to claim 1, characterized in that The lead shielding tube is a conical structure.

7. The device according to claim 3, characterized in that The grounding wire of the electromagnetic shielding cage, the grounding wire of the metal shielding box, and the grounding wire of the high-voltage DC power supply are all the transmission cables and are independently grounded.

8. The device according to any one of claims 1 to 7, characterized in that: The transmission cable is a one-to-many structure, and the multi-end end of the transmission cable is connected to the energy storage capacitor end.

9. A pulsed magnetic field laser plasma control device, characterized in that: The invention comprises the device described in any one of claims 1 to 8.

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