High-intensity magnetic field system

Abstract

The invention belongs to the technical field of pulsed high-intensity magnetic fields, and particularly discloses a high-intensity magnetic field system. Wherein the control module provides a reset signal for the magnetic switch reset circuit and provides a trigger signal for the RSD pre-trigger circuit; after the RSD pre-trigger circuit receives the trigger signal, the RSD pre-trigger circuit reversely charges the RSD to trigger the RSD to be conducted; after the magnetic switch is saturated and the RSD is reversely charged, the discharging main circuit feeds pulse current with the amplitude and the current rise rate higher than a preset threshold value into the single-turn coil, and then a high-intensity magnetic field is generated in the single-turn coil. The high-amplitude magnetic field can be generated in the single-turn coil by repeatedly discharging for multiple times.

Description

Technical Field

[0001] The present application belongs to the technical field of pulsed high-intensity magnetic field, and more specifically, relates to a high-intensity magnetic field system. Background Art

[0002] Destructive pulse magnetic fields do not need to consider the reuse of magnets, nor do they need to consider magnet reinforcement and heat dissipation designs. Compared with non-destructive strong magnetic fields, the overall circuit structure is greatly simplified and can have a higher magnetic field peak. A single-turn coil is a mainstream destructive pulse magnet. According to previous experimental data, the peak magnetic field that can be generated by a destructive pulse strong magnetic field system in a single-turn coil can reach 100T-300T; a single-turn coil consists of only one turn of metal coil. When discharged, a pulse width of several microseconds and a peak current of several million amperes are fed into it to generate an ultra-strong magnetic field of more than 100T.

[0003] The discharge circuit using a single-turn coil as a load has a simple structure and is basically equivalent to an RLC second-order circuit. The main control switch of the traditional discharge circuit is basically a gas switch. After the gas switch is closed, the main capacitor discharges the load single-turn coil, generating a pulse magnetic field with a high amplitude at the center of the single-turn coil. Gas switches have advantages such as high withstand voltage and high current rise rate. However, the gas switch has a short life and can only be discharged once, and its current limit is about 100kA. In order to generate a super-strong magnetic field of several hundred T, the peak current of the main circuit will reach 1-3MA during discharge, and the current rise rate of the single-turn coil will reach MA / μs level. To achieve this indicator, the single-turn coil destructive strong magnetic field system using a gas switch requires about 10 gas switches to be used in parallel, but the current gas switch opening jitter time is too large, almost occupying half of the discharge rising edge. Therefore, the single-turn coil destructive strong magnetic field system using a gas switch as the main switch has problems such as high cost, large amount of charge transferred during discharge, short switch life, and huge jitter when multiple gas switches are used in parallel and cannot be solved. Summary of the invention

[0004] In view of the defects of the prior art, the purpose of this application is to provide a strong magnetic field system, which aims to solve the problem that a single-turn coil destructive strong magnetic field system using a gas switch as the main switch requires multiple gas switches to achieve a high-amplitude magnetic field, so there is huge jitter when multiple gas switches are used in parallel, resulting in a long instantaneous discharge rising edge time and high cost.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides a strong magnetic field system, including a discharge main circuit, an RSD (Reversely Switched Dynistor) pre-trigger circuit, a magnetic switch reset circuit and a control module; The output end of the control module is connected to the magnetic switch reset circuit and the RSD pre-trigger circuit; the demagnetization coil in the magnetic switch reset circuit is wound on the magnetic switch; the RSD pre-trigger circuit is connected to the RSD ends of the discharge main circuit; The main discharge circuit includes a main capacitor, a magnetic switch, an RSD and a single-turn coil; the anode of the RSD is connected to the anode of the main capacitor through the magnetic switch; the cathode of the RSD is connected to the cathode of the main capacitor through the single-turn coil; The control module is used to provide a reset signal for the magnetic switch reset circuit and a trigger signal for the RSD pre-trigger circuit; the reset signal is used to control the current to flow through the demagnetization coil in the magnetic switch reset circuit, generating a demagnetization magnetic field in the magnetic switch core for reset; the RSD pre-trigger circuit is used to reverse charge the RSD to trigger its conduction after receiving the trigger signal; the discharge main circuit is used to feed a pulse current with an amplitude and current rise rate higher than a preset threshold to the single-turn coil after the magnetic switch is saturated and the RSD is reversely charged, thereby generating a strong magnetic field in the single-turn coil.

[0006] Further preferably, in order to withstand the high-amplitude pulse current of the main discharge circuit, the anode of RSD is connected to the anode of the main capacitor through a copper bar passing through the magnetic switch; the cathode of the main capacitor is connected to one end of the single-turn coil through the copper bar, and the other end of the single-turn coil is connected to the cathode of RSD through the copper bar.

[0007] Further preferably, the magnetic switch is a ring structure composed of a magnetic core and epoxy pressed on the outer layer of the magnetic core, and the main capacitor current-carrying copper bar passes through the magnetic switch.

[0008] Further preferably, the single-turn coil includes a magnet coil and two electrode plates; the magnet coil is a turn of wire, two ends of the magnet coil are welded to the outer surfaces of the two electrode plates, and the two electrode plates are two metal plates arranged in parallel.

[0009] Further preferably, according to the actual required current peak value, voltage resistance and high current rise rate, multiple RSD series-parallel mixtures are set, and multiple groups of RSDs correspond to multiple copper bars, each of the two ends of a single-turn coil is connected to a copper bar, and the multiple copper bars are connected to a copper bar at one end of the single-turn coil through an adapter.

[0010] In the second aspect, based on the above-mentioned strong magnetic field system, the present application provides a corresponding strong magnetic field acquisition method, which specifically includes the following steps: Based on the reset signal, the magnetic switch is reset to make the magnetic material in the magnetic switch at the negative saturation point of the hysteresis loop. The magnetic switch is equivalent to a circuit breaker, isolating the RSD from the main capacitor voltage. The main capacitor is charged by a main capacitor charging power supply, and the RSD pre-trigger capacitor is charged by a RSD pre-trigger capacitor charging power supply; When the main capacitor and the RSD pre-trigger capacitor are fully charged, based on the trigger signal, the RSD pre-trigger circuit switch is controlled to close, so that the RSD pre-trigger capacitor reversely charges the RSD, which is the RSD pre-trigger stage; When the amount of charge reversely charged into the RSD by the RSD pre-trigger capacitor during the RSD pre-trigger process makes the RSD forward conduction degree meet the actual demand, and at the same time, after the magnetic switch is saturated and turned on, the main capacitor discharges to the single-turn coil through the magnetic switch and RSD. The single-turn coil is fed with a pulse current having an amplitude and a current rise rate higher than a preset threshold, generating a strong magnetic field at the center of the single-turn coil.

[0011] Further preferably, in the RSD pre-trigger stage, the main capacitor applies a positive voltage to the magnetic switch, the magnetic switch moves from the negative saturation point of the hysteresis loop to the positive saturation point of the hysteresis loop, the inductance of the magnetic switch changes from large to small, and after positive saturation, the magnetic switch is equivalent to a short circuit, the magnetic switch is turned on, the main capacitor discharges, and a strong magnetic field is generated in the center of the single-turn coil.

[0012] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art: The present application provides a strong magnetic field system, in which a semiconductor RSD is introduced into the strong magnetic field system. RSD is a new type of high-power pulse semiconductor with strong current carrying capacity and a high current rise rate. Therefore, the single-turn coil destructive strong magnetic field system of the present application can better achieve the goal of passing a current with a higher amplitude and rise rate in the main discharge circuit, thereby generating a stronger magnetic field in the single-turn coil. Compared with a destructive pulse strong magnetic field system using multiple gas switches in parallel, the structure of the present application is simpler, the system occupies a smaller space volume, can repeatedly discharge multiple times to generate a high-amplitude magnetic field in a single-turn coil, and the cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the structure of a strong magnetic field system provided in an embodiment of the present application; Figure 2 It is a structural schematic diagram of a strong magnetic field system based on a specific RSD pre-trigger circuit provided in an embodiment of the present application; Figure 3 It is a schematic diagram of the single-turn coil structure provided in an embodiment of the present application; Figure 4 It is a schematic diagram of the main circuit current during discharge provided in an embodiment of the present application; Figure 5 It is a schematic diagram of the central magnetic field simulation of a single-turn coil provided in an embodiment of the present application. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0015] The term "and / or" in this article is a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The symbol " / " in this article indicates that the associated objects are in an or relationship, for example, A / B means A or B.

[0016] The terms “first”, “second” and the like in the specification and claims herein are used to distinguish different objects rather than to describe a specific order of the objects.

[0017] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0018] In the description of the embodiments of the present application, unless otherwise specified, “plurality” means two or more than two.

[0019] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0020] like Figure 1 As shown, the present application provides a strong magnetic field system, including a discharge main circuit, an RSD (Reversely Switched Dynistor) pre-trigger circuit, a magnetic switch reset circuit and a control module; the magnetic switch reset circuit is used to reset the magnetic switch; the RSD pre-trigger circuit is used to reverse charge the RSD to trigger its conduction; the control module is used to send a reset signal and a trigger signal to respectively control the operation of the reset circuit and the closure of the switch in the RSD pre-trigger circuit, thereby making the RSD pre-trigger circuit and the reset circuit operate; the discharge main circuit is used to generate a pulse current with an ultra-high amplitude and a current rise rate in the circuit after the magnetic switch is saturated and the RSD is reversely charged, and this pulse current is fed into a single-turn coil to generate an ultra-strong magnetic field at the center of the single-turn coil; Further preferably, the main discharge circuit includes a main capacitor, a magnetic switch, an RSD and a single-turn coil; wherein the discharge voltage of the main capacitor and the RSD pre-trigger capacitor are both 30 kV, and the capacitance is both 10.4 μF; The anode of the main capacitor in the main discharge circuit is connected to the anode of the RSD through a copper bar; one end of the copper bar is connected to the anode of the main capacitor, and the other end is connected to the anode of the RSD through a magnetic switch; the cathode of the main capacitor is connected to one end of the single-turn coil through a copper bar, and the other end of the single-turn coil is connected to the cathode of the RSD through a copper bar; The magnetic switch is a ring structure made of special magnetic conductive material as the magnetic core, and epoxy is pressed on the outer layer of the magnetic core; the single-turn coil is a specially made magnet, the coil of the magnet is only one turn of wire, and the two ends of the magnet coil are welded to the outer surface of two electrode plates, which are two parallel metal plates; Further preferably, the magnetic switch in the main circuit can be penetrated by a plurality of copper bars, each copper bar being connected to a group of RSDs; Further preferably, the connection between the RSD and the single-turn coil is made of a copper bar, multiple groups of RSD correspond to multiple copper bars, and each of the two ends of the single-turn coil is connected to only one copper bar, and the multiple copper bars are connected to a copper bar at one end of the single-turn coil through an adapter; Further preferably, in order to withstand high current peak, high withstand voltage and high current rise rate, the RSD device can be composed of a plurality of RSDs connected in series and parallel according to actual conditions; like Figure 2 As shown, the RSD pre-trigger circuit includes an RSD pre-trigger capacitor and an RSD pre-trigger circuit switch; the anode of the RSD pre-trigger capacitor is connected to the cathode of the RSD through a copper bus; the cathode of the RSD pre-trigger capacitor is connected to the anode of the RSD through the RSD pre-trigger circuit switch; the RSD pre-trigger circuit switch controls the triggering of the RSD pre-trigger circuit, and also controls the operation of the entire destructive strong magnetic field system; Further preferably, the RSD pre-trigger circuit switch may be a gas switch, a ball gap switch, a thyristor or an IGBT; Further preferably, the RSD pre-trigger circuit can realize synchronous triggering and opening of multiple groups of serial-parallel RSDs; Further preferably, the RSD pre-trigger circuit switch may be composed of a plurality of switches connected in series and in parallel.

[0021] The specific operation process of the strong magnetic field system provided by this application is as follows: Before discharge, the control module first sends a reset signal to control the operation of the magnetic switch reset circuit and perform a reset operation on the magnetic switch, so that the magnetic material in the magnetic switch is at the negative saturation point of the hysteresis loop. At this time, the relative magnetic permeability of the magnetic material is large, so the inductance of the magnetic switch will be very large in a short time after the trigger switch is closed, resulting in a large inductive reactance. The magnetic switch is equivalent to an open circuit in the main circuit, which will isolate the RSD from the main capacitor voltage; after the magnetic switch is reset, the main capacitor charging power supply and the RSD pre-trigger capacitor charging power supply are started to charge the main capacitor and the RSD pre-trigger capacitor respectively, and the two capacitors are charged until the charging is completed; the control module sends a trigger signal to the gas switch, and after controlling the trigger switch in the RSD pre-trigger circuit to close, the RSD pre-trigger capacitor will reversely charge the RSD; at this time, the RSD, the RSD pre-trigger capacitor, the stray inductance of the RSD pre-trigger circuit and the non-ideal impedance of the RSD pre-trigger circuit constitute a series RLC second-order circuit; the charging current waveform of the RSD pre-trigger capacitor to reversely charge the RSD is a pulse current wave lasting 2μs-3μs; wherein, the RSD can be equivalent to a diode; The characteristic of RSD is that it needs to inject charge into RSD in reverse before it is turned on. This process is the pre-triggering process of RSD, and the larger the pre-charge amount, the higher the current rise rate that RSD can withstand when discharging in the main circuit after it is turned on. Among them, the pre-charge amount charged by the RSD pre-trigger capacitor to RSD is the integral of the pre-charge current of RSD pre-trigger capacitor to RSD over time, and the integral time is the duration of the pre-charge current. After the gas switch is closed, the RSD pre-trigger capacitor reversely charges the RSD, and the magnetic switch in the main circuit isolates the RSD from the main capacitor for a short period of time. The isolation time is basically equal to the pre-charging time of the RSD pre-trigger circuit. During this isolation time, the voltage of the main capacitor will not affect the RSD pre-charging circuit, ensuring that the reverse charging process of the RSD pre-trigger capacitor to the RSD is not affected, thereby triggering the RSD normally. Furthermore, during the RSD pre-triggering period, the magnetic switch gradually moves from the negative saturation point of the hysteresis loop to the positive saturation point of the hysteresis loop due to the positive voltage of the main capacitor, and the inductance of the magnetic switch also changes from large to small. After positive saturation, the magnetic switch can be approximated as a short circuit, that is, the magnetic switch is turned on; it takes about 2μs for the magnetic switch to work from the negative saturation point to the positive saturation point. During this period of time, it plays a role in isolating the main capacitor and RSD, preventing the main capacitor voltage from affecting the pre-triggering process of the RSD; The magnetic switch is turned on after saturation, and the inductance can be ignored. At this time, the RSD pre-triggering process has also been completed. After the RSD is successfully triggered, the main capacitor discharges to the single-turn coil through the magnetic switch, RSD and the impedance of the main discharge circuit line. The single-turn coil flows through a pulse current with an ultra-high amplitude and current rise rate, generating an ultra-strong magnetic field at the center of the single-turn coil. Among them, each device is connected with a copper busbar, and the main circuit discharge circuit can be equivalent to a second-order RLC series circuit. Figure 3 The figure shows a schematic diagram of a single-turn coil magnet provided in an embodiment of the present application; the coil of the magnet is only one turn of wire, and the outer surfaces of the two electrode plates are respectively welded to the two ends of the magnet coil; the electrode plates are two parallel copper plates, which are connected to the copper bar in the main circuit; after the main capacitor is discharged, the pulse current is fed into the single-turn coil through the electrode plate, and a super-strong magnetic field is generated in the center of the single-turn coil magnet; Figure 4 The figure shows a simulation diagram of the loop line current during the main loop discharge process of an embodiment of the present application; the current peak exceeds 300kA, the current rise rate exceeds 200kA / μs, and a single RSD can withstand a voltage of 3kV and a current rise rate of up to 100kA / μs. A single chip can pass a pulse current with a peak value of 80-100 kA. In this embodiment, 4-5 groups of RSD groups are connected in parallel to share the current, and each group of RSD groups is divided into 10-15 pieces in series.

[0022] Figure 5 The figure shows a schematic diagram of the simulation of the magnetic field at the center of a single-turn coil during the main circuit discharge process of an embodiment of the present application. The magnetic induction intensity reaches a peak value of 78T at 1.3μs.

[0023] In summary, compared with the prior art, the present application has the following advantages: The present application provides a strong magnetic field system, which introduces semiconductor RSD into the destructive strong magnetic field system. RSD is a new type of high-power pulse semiconductor with high voltage resistance, strong current carrying capacity and high current rise rate. Therefore, the single-turn coil destructive strong magnetic field system of the present application can better achieve the goal of passing a current with a higher amplitude and rise rate in the main discharge circuit, thereby generating a stronger magnetic field in the single-turn coil. Compared with the destructive pulse strong magnetic field system using multiple gas switches in parallel, the structure of the present application is simpler, and multiple discharges can be repeated to generate a high-amplitude magnetic field in the single-turn coil, and the cost is reduced. The system occupies a smaller space volume.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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 strong magnetic field system, characterized in that: It includes a discharge main circuit, an RSD pre-trigger circuit, a magnetic switch reset circuit and a control module; The output end of the control module is connected to the magnetic switch reset circuit and the RSD pre-trigger circuit; the demagnetization coil in the magnetic switch reset circuit is wound around the magnetic switch; the RSD pre-trigger circuit is connected to both ends of the RSD of the discharge main circuit; The main discharge circuit includes a main capacitor, a magnetic switch, an RSD and a single-turn coil; the anode of the RSD is connected to the anode of the main capacitor through the magnetic switch; the cathode of the RSD is connected to the cathode of the main capacitor through the single-turn coil; The control module is used to provide a reset signal for the magnetic switch reset circuit and a trigger signal for the RSD pre-trigger circuit; the reset signal is used to control the current to flow through the demagnetization coil in the magnetic switch reset circuit, and generate a demagnetization magnetic field in the magnetic switch core for reset; the RSD pre-trigger circuit is used to reverse charge the RSD to trigger its conduction after receiving the trigger signal; The main discharge circuit is used to feed a pulse current with an amplitude and a current rise rate higher than a preset threshold to the single-turn coil after the magnetic switch is saturated and the RSD is reversely charged, thereby generating a strong magnetic field in the single-turn coil.

2. The strong magnetic field system according to claim 1, characterized in that: In order to withstand the high-amplitude pulse current of the main discharge circuit, the anode of the RSD is connected to the anode of the main capacitor through a copper bar passing through the magnetic switch; the cathode of the main capacitor is connected to one end of the single-turn coil through a copper bar, and the other end of the single-turn coil is connected to the cathode of the RSD through a copper bar.

3. The strong magnetic field system according to claim 1 or 2, characterized in that: The magnetic switch is a ring structure composed of a magnetic core and epoxy pressed on the outer layer of the magnetic core, and the main capacitor current-carrying copper bar passes through the magnetic switch.

4. The strong magnetic field system according to claim 1, characterized in that: The single-turn coil comprises a magnetic coil and two electrode plates; the magnetic coil is a turn of wire, two ends of the magnetic coil are welded to the outer surfaces of two electrode plates, and the two electrode plates are two metal plates arranged in parallel.

5. The strong magnetic field system according to claim 2, characterized in that: According to the actual required current peak value, voltage resistance and high current rise rate, multiple RSDs are set up in series and parallel, and multiple groups of RSDs correspond to multiple copper bars. The two ends of the single-turn coil are respectively connected to a copper bar, and the multiple copper bars are connected to a copper bar at one end of the single-turn coil through an adapter.

6. A method for obtaining a strong magnetic field based on the strong magnetic field system according to any one of claims 1 to 5, characterized in that: The specific steps include: Based on the reset signal, the magnetic switch is reset to make the magnetic material in the magnetic switch at the negative saturation point of the hysteresis loop. The magnetic switch is equivalent to a circuit breaker, isolating the RSD from the main capacitor voltage. The main capacitor is charged by a main capacitor charging power supply, and the RSD pre-trigger capacitor is charged by a RSD pre-trigger capacitor charging power supply; When the main capacitor and the RSD pre-trigger capacitor are fully charged, based on the trigger signal, the RSD pre-trigger circuit switch is controlled to close, so that the RSD pre-trigger capacitor reversely charges the RSD; When the amount of charge reversely charged into the RSD by the RSD pre-trigger capacitor during the RSD pre-trigger process makes the RSD forward conduction degree meet the actual needs, and at the same time, after the magnetic switch is saturated and turned on, the main capacitor discharges to the single-turn coil through the magnetic switch and RSD, and the single-turn coil is fed with a pulse current with an amplitude and current rise rate higher than the preset threshold, generating a strong magnetic field in the center of the single-turn coil.

7. The method for obtaining a strong magnetic field of a strong magnetic field system according to claim 6, characterized in that: In the RSD pre-trigger stage, the main capacitor applies a positive voltage to the magnetic switch, and the magnetic switch moves from the negative saturation point of the hysteresis loop to the positive saturation point of the hysteresis loop. The inductance of the magnetic switch changes from large to small. After positive saturation, the magnetic switch is equivalent to a short circuit. The magnetic switch is turned on, the main capacitor discharges, and a strong magnetic field is generated in the center of the single-turn coil.

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