Nanosecond, kilotesla and semi-destructive ultra-strong magnetic field generating device and method

Abstract

The invention belongs to the technical field of pulsed high-intensity magnetic fields, and particularly discloses a nanosecond, kilotesla and semi-destructive ultra-strong magnetic field generation device and method. According to the application, the output of the magnetic compression circuit is connected to the solenoid through the electrode plate, the rising edge time of the discharge current is reduced to several nanoseconds to dozens of nanoseconds through the magnetic compression circuit, and although the inductance of the solenoid is relatively large, the pulse width of the discharge current is very narrow; and the output voltage of the magnetic compression circuit can reach hundreds of kilovolts without depending on gas switch control, so that the discharge current of the solenoid can still reach hundreds of kA. As the number of turns of the solenoids is large and the solenoids have high current-magnetic field conversion efficiency, a magnetic field of more than 1000T can be generated. Meanwhile, the extremely short current rising edge can fully reduce deformation of the coil before the coil reaches a peak magnetic field, and it is ensured that the peak magnetic field can be generated before the coil is damaged.

Description

Technical Field

[0001] The present application belongs to the field of pulsed strong magnetic field technology, and more specifically, to a nanosecond-level, kilo-tesla, semi-destructive ultra-strong magnetic field generating device and method. Background Art

[0002] At present, the method of generating an ultra-strong magnetic field of more than 100T under "semi-destructive" conditions without destroying the experimental samples is to use a pulse capacitor as a power source to discharge into a single-turn coil destructive magnet. The principle of generating an ultra-strong magnetic field with a single-turn coil magnet is to feed a large current of one million amperes into a metal coil with a cross-sectional size and diameter of only millimeters. Since the current rising edge is extremely short, the single-turn coil can generate a peak magnetic field before it is destroyed by electromagnetic force and Joule heat.

[0003] However, there is a "ceiling" for the magnetic field strength of a single-turn coil magnet. The current world record holder, the German High Magnetic Field Laboratory, once used a single-turn coil to generate a magnetic field of 311T, but this record is close to the limit of a single-turn coil magnet and has not been broken so far.

[0004] There are four main difficulties in further improving the magnetic field of a single-turn coil magnet: First, the charging voltage of the capacitor cannot be increased infinitely. Restricted by the withstand voltage of the gas switch that controls the discharge of the capacitor, the charging voltage of the pulse capacitor cannot be increased infinitely. Second, the capacity and storage energy of the capacitor cannot be increased infinitely. Since the time of the current rising edge must be less than the destruction time of the single-turn coil magnet, the time constant of the discharge circuit must be strictly controlled. Under the condition that it is difficult to reduce the inductance of the single-turn coil, the capacitance value of the capacitor can only be controlled within tens to hundreds of microfarads. Third, the discharge current cannot be increased infinitely. The time when the single-turn coil is destroyed by the electromagnetic force advances with the increase of the discharge current. When the discharge current is large enough, the magnet may be destroyed before the peak magnetic field is generated. The first three aspects determine that the maximum discharge current can only be maintained at 1-4 megaamperes. In addition, fourth, the total inductance of the discharge circuit must be controlled within tens of nH, so the coil can only have one turn, which significantly reduces the current-magnetic field conversion efficiency. In summary, the discharge current of the single-turn coil cannot be significantly increased due to the limitations of the capacitor charging voltage and capacity, and the number of turns of the magnet can only be controlled in one turn due to the limitation of the inductance of the discharge circuit. Therefore, the magnetic field of a single-turn coil is unlikely to exceed 300T, and even if the power supply is fully upgraded, it does not have the potential to generate a magnetic field of more than 1000T. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of this application is to provide a nanosecond, kilotesla, semi-destructive ultra-strong magnetic field generating device and method, aiming to solve the bottleneck problem encountered when a single-turn coil magnet further enhances the magnetic field.

[0006] To achieve the above-mentioned purpose, in a first aspect, the present application provides a nanosecond, kilo-Tesla, semi-destructive ultra-strong magnetic field generating device, comprising a multi-stage magnetic compression circuit, a solenoid, and two electrode plates;

[0007] The two electrode plates are connected to the output end of the multi-stage magnetic compression circuit and the solenoid;

[0008] The multi-stage magnetic compression circuit is used to discharge to the solenoid through the electrode plate, and the output voltage reaches 10kV to 100kV, the discharge current reaches 100kA to 600kA, and the rising edge of the discharge current is in the nanosecond level;

[0009] The solenoid is formed by winding a plurality of turns of a metal conductor, and an insulating layer is arranged on the surface of the conductor.

[0010] Preferably, the number of axial winding turns of the solenoid is in the range of [2, 5], and the number of radial winding turns is in the range of [2, 5].

[0011] Preferably, the metal conductor is made of copper, tantalum or tungsten.

[0012] Preferably, the inner diameter of the solenoid is in the order of millimeters, and the cross-sectional area of ​​each turn of the conductor is in the order of square millimeters.

[0013] Preferably, the longitudinal section of the solenoid is square or circular.

[0014] Preferably, the insulating layer is made of epoxy material with a dielectric strength of 20 to 30 kV / mm.

[0015] Preferably, the two electrode plates are of the same shape, size and thickness, and their projections in the radial direction of the solenoid overlap.

[0016] Preferably, the capacitance of the main capacitor in the multi-stage magnetic compression circuit is in the nanofarad level.

[0017] Preferably, the discharge switch in the multi-stage magnetic compression circuit is a high-pressure gas switch.

[0018] Preferably, the withstand voltage of the discharge switch reaches 10 kV to 100 kV, and the opening time is in nanoseconds.

[0019] To achieve the above objectives, in a second aspect, the present application provides a method for generating a strong magnetic field based on the nanosecond-level, kilo-tesla, semi-destructive ultra-strong magnetic field generating device described in the first aspect, comprising:

[0020] (1) closing the discharge switch in the multi-stage magnetic compression circuit to control the main capacitor to discharge;

[0021] (2) The magnetic switches of the multi-stage magnetic compression circuit are gradually saturated, the electric energy is gradually transferred between the capacitors at each stage, the time constant gradually decreases, and the rising edge of the discharge current gradually shortens;

[0022] (3) A pulse current with a nanosecond rising edge is applied to the solenoid, generating a kilotesla-level strong magnetic field at the center of the solenoid.

[0023] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:

[0024] The present application proposes a nanosecond-level, kilo-tesla, semi-destructive ultra-strong magnetic field generating device and method. The output of the magnetic compression circuit is connected to a solenoid through an electrode plate. During discharge, on the one hand, the rising edge time of the discharge current is reduced to a few nanoseconds to tens of nanoseconds through the magnetic compression circuit. Although the inductance of the solenoid is relatively large, the discharge current pulse width is very narrow and the output voltage of the magnetic compression circuit can be as high as hundreds of kilovolts, so the discharge current of the solenoid can still reach hundreds of kA. The extremely short current rising edge can fully reduce the deformation of the coil before reaching the peak magnetic field, ensuring that the peak magnetic field can be generated before the coil is destroyed; on the other hand, since the solenoid has a large number of turns and a high current-magnetic field conversion efficiency, it can generate a magnetic field of more than 1000T. The radially outward electromagnetic force acting on the solenoid will drive the coil to deform outward, thereby achieving the "semi-destructive" purpose of only destroying the coil without destroying the internal experimental sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of a nanosecond-level, kilo-tesla, semi-destructive ultra-strong magnetic field generating device provided in an embodiment of the present application.

[0026] Figure 2 These are the voltage and current waveforms of the solenoid provided in the embodiment of the present application during discharge.

[0027] Figure 3 It is the magnetic field waveform of the center point of the solenoid provided in the embodiment of the present application when discharging.

[0028] In all drawings, the same reference numerals are used to denote the same elements or structures, where: 1 - electrode plate, 2 - solenoid. DETAILED DESCRIPTION

[0029] For ease of understanding, the English abbreviations and related technical terms involved in the embodiments of the present application are explained and described below.

[0030] Semi-destructive: The coil discharge expands outward due to electromagnetic force, which only destroys the coil but not the internal sample.

[0031] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0032] like Figure 1 As shown, the present application provides a nanosecond, kilo-Tesla, semi-destructive ultra-strong magnetic field generating device, comprising a multi-stage magnetic compression circuit, a solenoid 1 and two electrode plates 2;

[0033] The two electrode plates 2 are connected to the output end of the multi-stage magnetic compression circuit and the solenoid 1;

[0034] The multi-stage magnetic compression circuit is used to discharge to the solenoid through the electrode plate 2, and the output voltage reaches 10kV to 100kV, the discharge current reaches 100kA to 600kA, and the rising edge of the discharge current is in the nanosecond level;

[0035] The solenoid is formed by winding a plurality of turns of a metal conductor, and an insulating layer is arranged on the surface of the conductor.

[0036] Preferably, the number of axial winding turns of the solenoid is in the range of [2, 5], and the number of radial winding turns is in the range of [2, 5].

[0037] It should be noted that the number of turns of the coil cannot be too large, otherwise the excessive coil inductance will reduce the discharge current peak value, which is not conducive to improving the magnetic field. At the same time, the inductance and resistance parameters of the coil must be kept matching the impedance of the magnetic compression circuit.

[0038] Preferably, the material of the metal conductor is copper, tantalum or tungsten. It should be noted that these metals have high electrical conductivity and high density.

[0039] Preferably, the inner diameter of the solenoid is in the order of millimeters, and the cross-sectional area of ​​each turn of the conductor is in the order of square millimeters.

[0040] It should be noted that the cross-sectional area of ​​each coil turn cannot be too small, otherwise the coil cannot be effectively suppressed from impact deformation under a strong magnetic field. At the same time, the cross-sectional area cannot be too large, otherwise the overall size of the coil will increase, resulting in insufficient concentration of current density, which will in turn reduce the magnetic field.

[0041] Preferably, the longitudinal section of the solenoid is square or circular.

[0042] Preferably, the insulating layer is made of epoxy material with a dielectric strength of 20 to 30 kV / mm.

[0043] It should be noted that the dielectric strength of the insulating layer should be high enough because there is a large potential difference between the turns of the solenoid during discharge.

[0044] Preferably, the two electrode plates are of the same shape, size and thickness, and their projections in the radial direction of the solenoid overlap.

[0045] like Figure 1 As shown, the magnetic compression circuit is composed of a capacitor and a magnetic switch, and the steepening of the discharge current pulse is achieved by means of the saturation of the magnetic switch. Specifically, when the magnetic compression circuit discharges step by step, the time constant of the latter stage is smaller than that of the former stage, so the discharge current pulse becomes steeper and steeper.

[0046] Preferably, the number of magnetic switches and capacitors is 2-3, and the number of levels of the magnetic compression circuit is 2-3, which is used to compress the microsecond discharge current pulse to the nanosecond level.

[0047] It should be noted that the number of stages of the magnetic compression circuit cannot be too small, otherwise the rising edge of the current cannot be effectively compressed; at the same time, the number of stages of the magnetic compression circuit cannot be too many, otherwise it will increase the control difficulty of the system.

[0048] Preferably, in the magnetic compression circuit, in order to ensure the highest power transmission efficiency, the capacitance values ​​of capacitors at each level are equal, all in the nanofarad level, and the withstand voltage is tens of kilovolts to hundreds of kilovolts.

[0049] Preferably, in the magnetic compression circuit, the size, volt-second product and saturation time of the front-stage magnetic switch are greater than those of the rear-stage magnetic switch. Therefore, the time constant of the discharge circuit decreases with the gradual saturation of the magnetic switch, thereby shortening the time of the rising edge of the discharge current.

[0050] Preferably, the saturation time of each level of magnetic switch is equal to the time when the voltage of the capacitor of that level reaches the maximum, so as to ensure that the energy of the capacitor of the previous level is fully transferred to the capacitor of that level before saturation.

[0051] It should be noted that in the magnetic compression circuit, the saturation inductance of the front-stage magnetic switch must be much larger than the saturation inductance of the rear-stage magnetic switch to prevent the current from flowing from the current-stage capacitor to the front-stage capacitor when the current is discharged from the current-stage capacitor to the rear-stage capacitor.

[0052] Preferably, the capacitance of the main capacitor in the multi-stage magnetic compression circuit is in the nanofarad level, and the charging voltage is in the range of tens of kilovolts to hundreds of kilovolts.

[0053] It should be noted that the capacitance should not be too large, otherwise the time constant of the discharge circuit and the rising edge time of the discharge current will increase. In an ultra-strong magnetic field, this means that the coil is more likely to be destroyed by electromagnetic force before the peak magnetic field is generated.

[0054] Preferably, the discharge switch in the multi-stage magnetic compression circuit is a high-pressure gas switch. The current rise rate of the switch when turned on is extremely high, and the peak current passing through the switch is extremely large.

[0055] Preferably, the withstand voltage of the discharge switch reaches 10 kV to 100 kV, and the opening time is in nanoseconds.

[0056] The present application provides a method for generating a strong magnetic field based on the above-mentioned nanosecond-level, kilo-tesla, semi-destructive ultra-strong magnetic field generating device, comprising:

[0057] (1) closing the discharge switch in the multi-stage magnetic compression circuit to control the main capacitor to discharge;

[0058] (2) The magnetic switches of the multi-stage magnetic compression circuit are gradually saturated, the electric energy is gradually transferred between the capacitors at each stage, the time constant gradually decreases, and the rising edge of the discharge current gradually shortens;

[0059] (3) A pulse current with a nanosecond rising edge is applied to the solenoid, generating a kilotesla-level strong magnetic field at the center of the solenoid.

[0060] Example

[0061] In this embodiment, the magnetic compression circuit is composed of capacitors (main capacitor, primary capacitor, secondary capacitor, tertiary capacitor) and magnetic switches (discharge switch, primary magnetic switch, secondary magnetic switch). The main capacitor first discharges to the primary capacitor. When the voltage of the primary capacitor is the highest, the primary capacitor discharges to the secondary capacitor. When the voltage of the secondary capacitor is the highest, the secondary capacitor discharges to the tertiary capacitor. Each discharge step corresponds to a magnetic switch. The inner diameter of the magnetic coil is 4.0mm, with 10 turns and an inductance of about 1 microhenry. The cross-section of each turn of the coil is 0.5mm×0.5mm. The coil is wound axially for 5 turns and radially for 2 layers. The capacitance value of each capacitor in the magnetic compression circuit is 100nF, and the capacitance value of the main capacitor as a power supply is also 100nF. The charging voltage of the main capacitor is 100kV. In the two-stage magnetic compression circuit, the volt-second product of the first-stage magnetic switch is 12mVs, and the volt-second product of the second-stage magnetic switch is 5mVs.

[0062] like Figure 2 As shown in the figure, when the discharge peak current is 600kA, the current rise time is only 20 to 30 nanoseconds. When the discharge peak voltage is 160kV, the voltage rise time is only 10 to 150 nanoseconds.

[0063] like Figure 3 As shown, the rising edge of the magnetic field is less than 0.1 microsecond, and when the discharge current is maximum, the peak magnetic field at the center of the coil is as high as 1000T.

[0064] It should be understood that expressions such as "including" and "may include" that may be used in the present application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In the present application, terms such as "including" and / or "having" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0065] In addition, in the present application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0066] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the relative position relationship after connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0067] In addition, in the embodiments of the present application, the mathematical concepts mentioned are symmetry, equality, parallelism, verticality, etc. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense, and allow a small amount of deviation, approximation to symmetry, approximation to equality, approximation to parallelism, approximation to verticality, etc. are all possible. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0068] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A nanosecond, kilo-tesla, semi-destructive ultra-strong magnetic field generating device, characterized in that: It includes a multi-stage magnetic compression circuit, a solenoid and two electrode plates; The two electrode plates are connected to the output end of the multi-stage magnetic compression circuit and the solenoid; The multi-stage magnetic compression circuit is used to discharge to the solenoid through the electrode plate, and the output voltage reaches 10kV to 100kV, the discharge current reaches 100kA to 600kA, and the rising edge of the discharge current is in the nanosecond level; The solenoid is formed by winding a plurality of turns of a metal conductor, and an insulating layer is arranged on the surface of the conductor.

2. The ultra-strong magnetic field generating device according to claim 1, characterized in that: The material of the metal conductor is copper, tantalum or tungsten.

3. The ultra-strong magnetic field generating device according to claim 1, characterized in that: The inner diameter of the solenoid is in the millimeter order, and the cross-sectional area of ​​each turn of the conductor is in the square millimeter order.

4. The ultra-strong magnetic field generating device according to claim 1, characterized in that: The longitudinal section of the solenoid is square or circular.

5. The ultra-strong magnetic field generating device according to claim 1, characterized in that: The material of the insulating layer is an epoxy material with a dielectric strength of 20 to 30 kV / mm.

6. The ultra-strong magnetic field generating device according to claim 1, characterized in that: The two electrode plates are identical in shape, size and thickness, and their projections in the radial direction of the solenoid overlap.

7. The ultra-strong magnetic field generating device according to claim 1, characterized in that: The capacitance of the main capacitor in the multi-stage magnetic compression circuit is in the nanofarad level.

8. The ultra-strong magnetic field generating device according to claim 1, characterized in that: The discharge switch in the multi-stage magnetic compression circuit is a high-pressure gas switch.

9. The ultra-strong magnetic field generating device according to claim 8, characterized in that: The withstand voltage of the discharge switch reaches 10kV to 100kV, and the opening time is nanosecond level.

10. A method for generating a strong magnetic field based on the nanosecond-level, kilo-tesla, semi-destructive ultra-strong magnetic field generating device according to any one of claims 1 to 9, characterized in that: include: (1) closing the discharge switch in the multi-stage magnetic compression circuit to control the main capacitor to discharge; (2) The magnetic switches of the multi-stage magnetic compression circuit are gradually saturated, the electric energy is gradually transferred between the capacitors at each stage, the time constant gradually decreases, and the rising edge of the discharge current gradually shortens; (3) A pulse current with a nanosecond rising edge is applied to the solenoid, generating a kilotesla-level strong magnetic field at the center of the solenoid.

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