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

Abstract

The application belongs to the technical field of pulsed high magnetic field, and specifically discloses a nanosecond, kilo-Tesla, semi-destructive super strong magnetic field generating device and method. Through the application, the output of the magnetic compression circuit is connected to a solenoid through an electrode plate. The magnetic compression circuit reduces the rising time of the discharge current to several nanoseconds to tens of nanoseconds. Although the inductance of the solenoid is large, the discharge current pulse width is very narrow, and the output voltage of the magnetic compression circuit can be as high as several hundred kilovolts without relying on gas switch control, so the discharge current of the solenoid can still reach several hundred kA. Since the solenoid has a large number of turns and a high current-magnetic field conversion efficiency, a magnetic field of more than 1000T can be generated. At the same time, the extremely short current rising edge can sufficiently reduce the deformation of the coil before the peak magnetic field is reached, ensuring that the peak magnetic field can be generated before the coil is destroyed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of pulsed high magnetic field, more particularly, it relates to a nanosecond, kilotesla, semi-destructive ultra-strong magnetic field generating device and method. BACKGROUND

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

[0003] However, the single-turn coil magnet has a "ceiling" of magnetic field strength. The current world record holder, the German High Magnetic Field Laboratory, has generated a magnetic field of 311 T using a single-turn coil, but this record is close to the limit of a single-turn coil magnet, and no one has broken it 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 indefinitely. Due to the pressure resistance of the gas switch controlling the discharge of the capacitor, the charging voltage of the pulse capacitor cannot be increased indefinitely. Second, the capacity and energy storage of the capacitor cannot be increased indefinitely. Since the current rising edge time 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 in the range of several tens to several hundred microfarads. Third, the discharge current cannot be increased indefinitely. The time of destruction of the single-turn coil by electromagnetic force increases as the discharge current increases, and 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 MA. In addition, the fourth, the total inductance of the discharge circuit must be controlled in the range of several 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 is limited by the charging voltage and capacity of the capacitor and cannot be significantly improved, and the number of turns of the magnet is limited by the inductance of the discharge circuit and can only be controlled at one turn. Therefore, the magnetic field of the single-turn coil is difficult to exceed 300 T, and even if the power supply is upgraded, it does not have the potential to generate a magnetic field of more than 1000 T. SUMMARY

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

[0006] To achieve the above object, in a first aspect, the application provides a nanosecond, kilo-Tesla, semi-destructive super-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 the solenoid through the electrode plates, and the output voltage reaches 10kV-100kV level, the discharge current reaches 100kA-600kA, and the rising edge of the discharge current is nanosecond level;

[0009] The solenoid is wound by a plurality of turns of metal conductors, and the surface of the conductors is provided with an insulating layer.

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

[0011] Preferably, the material of the metal conductor is 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 material of the insulating layer is an epoxy material with an insulation strength of 20-30kV / mm.

[0015] Preferably, the two electrode plates are the same in shape, size and thickness, and the 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 nanofarad level.

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

[0018] Preferably, the withstand voltage of the discharge switch reaches 10kV-100kV level, and the turn-on time is nanosecond level.

[0019] To achieve the above object, in a second aspect, the application provides a strong magnetic field generating method based on the nanosecond, kilo-Tesla, semi-destructive super-strong magnetic field generating device of the first aspect, comprising:

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

[0021] (2) The magnetic switch of the multi-stage magnetic compression circuit is saturated step by step, the electric energy is transferred step by step between the capacitors, the time constant gradually becomes small, and the rising edge of the discharge current gradually becomes short;

[0022] (3) The pulse current with a nanosecond rising edge is applied to the solenoid, and a kilotesla strong magnetic field is generated at the center point of the solenoid.

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

[0024] The present application provides a nanosecond, kilotesla, semi-destructive super 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 several nanoseconds to several tens of nanoseconds through the magnetic compression circuit. Although the inductance of the solenoid is large, the discharge current of the solenoid can still reach several hundred kA because the pulse width of the discharge current is very narrow and the output voltage of the magnetic compression circuit can be as high as several hundred kilovolts. The extremely short current rising edge can sufficiently reduce the deformation of the coil before the peak magnetic field is reached, ensuring that the peak magnetic field can be generated before the coil is destroyed. On the other hand, the solenoid has a high current-magnetic field conversion efficiency due to the large number of turns, so a magnetic field of 1000 T or more can be generated. The electromagnetic force acting on the solenoid in the radial outward direction will drive the coil to deform outward, thereby achieving the "semi-destructive" purpose of destroying only the coil without destroying the internal experimental sample. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a nanosecond, kilotesla, semi-destructive super strong magnetic field generating device structure schematic diagram provided by the present application.

[0026] Figure 2 is the voltage and current waveform of the solenoid during discharge provided by the present application.

[0027] Figure 3 is the magnetic field waveform of the center point of the solenoid during discharge provided by the present application.

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

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

[0030] Semi-destructive: The coil discharge is expanded outward by the electromagnetic force, only the coil is destroyed, and the internal sample is not destroyed.

[0031] The embodiments of the present application are described below with reference to the accompanying drawings.

[0032] As shown in the formula (I), the present application provides a nanosecond, kilo tesla, semi-destructive super strong magnetic field generating device, comprising a multi-stage magnetic compression circuit, a solenoid 2 and two electrode plates 1; Figure 1

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

[0034] The multi-stage magnetic compression circuit is used to discharge to the solenoid through the electrode plate 1, and the output voltage reaches 10kV-100kV level, the discharge current reaches 100kA-600kA, and the rising edge of the discharge current is nanosecond level.

[0035] The solenoid is wound by a plurality of turns of metal conductors, and the surface of the conductor is provided with an insulating layer.

[0036] Preferably, the axial winding number of the solenoid is in the range of [2, 5], and the radial winding number 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 peak value of the discharge current, which is not conducive to improving the magnetic field. At the same time, the inductance and resistance parameters of the coil should be matched with 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 such 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 turn of the coil cannot be too small, otherwise the impact deformation of the coil under the super strong magnetic field cannot be effectively suppressed. At the same time, the cross-sectional area cannot be too large, otherwise the total size of the coil will increase, resulting in insufficient concentration of current density, which will reduce the magnetic field.

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

[0042] Preferably, the material of the insulating layer is an epoxy material with an insulation strength of 20-30kV / mm.

[0043] It should be noted that the insulation 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 the same in shape, size and thickness, and the projections in the radial direction of the solenoid overlap.

[0045] As shown in the formula (I), the present application provides a nanosecond, kilo tesla, semi-destructive super strong magnetic field generating device, comprising a multi-stage magnetic compression circuit, a solenoid 2 and two electrode plates 1;​Figure 1 As shown, the magnetic compression circuit is composed of capacitors and magnetic switches, and the steepening of the discharge current pulse is realized by the saturation of the magnetic switches. Specifically, when the magnetic compression circuit discharges step by step, the time constant of the later stage is smaller than that of the former stage, so the discharge current pulse is increasingly steep.

[0046] Preferably, the number of magnetic switches and capacitors is 2-3, and the number of stages of the magnetic compression circuit is 2-3, for compressing the microsecond-level 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 current rising edge cannot be effectively compressed; at the same time, the number of stages of the magnetic compression circuit cannot be too large, otherwise the control difficulty of the system will be increased.

[0048] Preferably, in the magnetic compression circuit, in order to ensure the highest electric energy transmission efficiency, the capacitance values of the capacitors at each stage are equal, and are nanofarad level, with a withstand voltage of several tens of kilovolts to several hundred kilovolts.

[0049] Preferably, in the magnetic compression circuit, the size, volt-second product and saturation time of the magnetic switch of the former stage are all greater than those of the magnetic switch of the later stage. Therefore, the time constant of the discharge circuit will decrease with the step-by-step saturation of the magnetic switch, and thus the time of the rising edge of the discharge current is shortened.

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

[0051] It should be noted that in the magnetic compression circuit, it is necessary to ensure that the saturation inductance of the magnetic switch of the former stage is much greater than that of the magnetic switch of the later stage, so as to prevent the current from flowing from the capacitor at the stage to the capacitor at the former stage when the capacitor at the stage discharges to the capacitor at the later stage.

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

[0053] It should be noted that the capacitance of the capacitor cannot be too large, otherwise the time constant of the discharge circuit and the rising edge time of the discharge current will be increased. Under the super-strong magnetic field, this means that the coil has a greater possibility of being 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-voltage gas switch. The current rising rate of the switch when turned on is extremely high, and the peak current passing through is extremely large.

[0055] Preferably, the withstand voltage of the discharge switch reaches the level of 10kV-100kV, and the turn-on time is nanosecond level.

[0056] The application provides a strong magnetic field generation method based on the above-mentioned nanosecond, kilotesla, and semi-destructive super-strong magnetic field generation device, which comprises the following steps:

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

[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) applying the pulse current with a nanosecond rising edge to the solenoid to generate a kilotesla-level strong magnetic field at the center point of the solenoid.

[0060] Embodiment

[0061] In the embodiment, the magnetic compression circuit is composed of capacitors (main capacitor, primary capacitor, secondary capacitor, and tertiary capacitor) and magnetic switches (discharge switch, primary magnetic switch, secondary magnetic switch). The main capacitor discharges to the primary capacitor first, and when the voltage of the primary capacitor is the highest, the primary capacitor discharges to the secondary capacitor, and 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 magnet coil is 4.0 mm, and the coil is wound with 10 turns and has an inductance of about 1 microhenry. The cross section of each turn of the coil is 0.5 mm x 0.5 mm. The coil is wound with 5 turns in the axial direction and 2 layers in the radial direction. The capacitance of each capacitor in the magnetic compression circuit is 100 nF, and the capacitance of the main capacitor as the power supply is also 100 nF. The charging voltage of the main capacitor is 100 kV. In the two-stage magnetic compression circuit, the volt-second product of the first-stage magnetic switch is 12 mVs, and the volt-second product of the second-stage magnetic switch is 5 mVs.

[0062] As shown in Figure 2 , the discharge peak current is 600 kA, and the current rise time is only 20-30 nanoseconds. The discharge peak voltage is 160 kV, and the voltage rise time is only 10-150 nanoseconds.

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

[0064] It should be understood that the terms such as "include" and "may include" used in the present application indicate the presence of the disclosed functions, operations, or components, and do not limit one or more additional functions, operations, and components. In the present application, terms such as "include" and / or "have" can be interpreted to mean that a specific characteristic, number, operation, component, assembly, or combination thereof is present, but can not be interpreted to exclude the presence or addition of one or more other characteristics, numbers, operations, components, assemblies, or combinations thereof.

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

[0066] In the description of the embodiments of the present application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be understood broadly, for example, "connection" can be detachable connection, or can be non-detachable connection; can be direct connection, or can be indirect connection through intermediate medium. Among them, "fixed connection" means that the relative positional relationship after connection is unchanged. "Rotational connection" means that the relative rotation after connection is connected. "Sliding connection" means that the relative sliding after connection is connected. The orientation language mentioned in the embodiments of the present application, such as "top", "bottom", "inner", "outer", "left", "right", etc., is only the direction of the drawing, therefore, the orientation language used is to better, more clearly illustrate and understand the embodiments of the present application, and is not to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore, it 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, symmetry, equality, parallel, perpendicular, etc. These limitations are all for the current process level, and are not strictly defined in the mathematical sense, and a small amount of deviation is allowed, approximately symmetrical, approximately equal, approximately parallel, approximately perpendicular, etc. For example, A is parallel to B, which means that A and B are parallel or approximately parallel, the included angle between A and B can be between 0 degrees and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, the included angle between A and B can be between 80 degrees 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 can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A nanosecond-level, kilotascal, semi-destructive ultra-strong magnetic field generator, 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 terminal of the multi-stage magnetic compression circuit and the solenoid. The multi-stage magnetic compression circuit outputs a voltage of 10kV to 100kV and a discharge current of 100kA to 600kA. It is used to discharge to the solenoid through the electrode plate, applying a pulse current with a nanosecond-level rising edge to the solenoid, thereby generating a strong magnetic field of kilotes at the center point of the solenoid. The radially outward electromagnetic force acting on the solenoid by this magnetic field will drive the coil to deform outward, thus achieving the goal of destroying only the coil without destroying the internal experimental sample. The solenoid is made of multiple turns of metal conductor, and the conductor surface is provided with an insulating layer.

2. The ultra-strong magnetic field generating device as described in claim 1, characterized in that, The material of the metallic conductor is copper, tantalum, or tungsten.

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

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

5. The ultra-strong magnetic field generating device as described in claim 1, characterized in that, The insulating layer is made of epoxy material with an insulation strength of 20-30 kV / mm.

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

7. The ultra-strong magnetic field generating device as described in claim 1, characterized in that, The capacitance of the main capacitor in the multi-stage magnetic compression circuit is in the nanofarad range.

8. The ultra-strong magnetic field generating device as described in 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 as described in claim 8, characterized in that, The discharge switch has a withstand voltage of 10kV to 100kV and an opening time of nanoseconds.

10. A method for generating a strong magnetic field based on the nanosecond-level, kilotascal, semi-destructive ultra-strong magnetic field generator according to any one of claims 1 to 9, characterized in that, include: (1) Close 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 saturate step by step, the electrical energy is transferred between the capacitors of each stage, the time constant gradually decreases, and the rising edge of the discharge current gradually shortens. (3) A pulse current with a nanosecond-level rising edge is applied to the solenoid, and a strong magnetic field of kilotes is generated at the center point of the solenoid.

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