Magnet coils, assemblies, and plasma generation devices for field-shifting devices

Abstract

The application discloses a magnet coil, an assembly and a plasma generating device for a field reversed configuration device, and relates to the technical field of nuclear fusion and plasma magnetic confinement. The magnet coil comprises a multi-turn coil winding and a terminal structure. The outgoing head end and tail end of the multi-turn coil winding extend in the circumferential direction and form a circumferential overlapping area before being led out to the terminal, so that the coil has the same number of solid conductor passes at any angle segment of the 360-degree circumference, thereby eliminating the current path gap of the lead position and forming a circumferentially distributed uniform equivalent magnetic field. The terminal has an array of holes to connect multiple coaxial cables, achieving shunt and low-inductance power supply. The coil assembly is further radially rigidly locked by a modular fastening support assembly composed of an open shell and a super bolt. The application significantly reduces the power supply threshold, guarantees the high uniformity of the confinement magnetic field, and effectively overcomes the electromagnetic destructive force under a strong magnetic field.

Description

Technical Field

[0001] This invention relates to the field of nuclear fusion and plasma magnetic confinement technology, and more specifically, to a magnet coil for a field inversion device, a magnet coil assembly, and a field inversion plasma generation device including the assembly. Background Technology

[0002] Reverse-field pinching (reverse-field θ-pinch) technology is currently the most common and effective method for forming FRC plasma. The specific process of forming FRC plasma using reverse-field θ-pinch is as follows: First, a certain amount of neutral gas is injected into a vacuum chamber, and simultaneously, the θ-pinch coil is discharged to apply an initial bias magnetic field. The purpose of this initial bias magnetic field is to create a suitable plasma environment. When the bias magnetic field reaches its maximum value, the θ-pinch coil is discharged again to generate a high-frequency oscillating magnetic field in the vacuum chamber. This high-frequency oscillating magnetic field ionizes the gas in the vacuum chamber, generating plasma, which freezes onto the initial bias magnetic field. Subsequently, the current in the θ-pinch coil rises rapidly, causing the main magnetic field to reverse rapidly, and the magnetic flux coupled with the internal plasma completes magnetic reconnection at the end. This magnetic reconnection process forms a more stable and compact plasma.

[0003] In the specific process of forming FRC plasma using the anti-field θ-pinch, its circuit topology typically includes four core branches: a bias branch for biasing the formation region before power-on to ensure plasma stability and controllability; an ionization branch for pre-ionizing the formation region before main discharge; a field-reverse branch for main discharge of the formation region after ionization to generate the required magnetic field and plasma; and a follow current branch for continuing current in the formation region after main discharge to maintain plasma stability and extend discharge time.

[0004] Because FRC devices require extremely high magnetic field strength (up to 10T or more), existing magnet coils generally employ a single-turn coil structure. This single-turn structure has the following significant drawbacks: 1) Extremely high power requirements: A single-turn coil requires a power supply with an extremely large instantaneous peak current to achieve the required ampere-turns and magnetic field strength, resulting in extremely high cost and technical barriers for the power supply.

[0005] 2) Severe electromagnetic damage: Under ultra-large pulse current, a single-turn coil will be subjected to extremely large radial expansion force and axial force, which can easily lead to coil deformation or even structural failure. Existing devices often find it difficult to achieve a reliable fixed connection in a compact space.

[0006] Therefore, there is an urgent need for a new type of magnet coil and component structure that can reduce power requirements, ensure magnetic field uniformity, and resist extreme electromagnetic forces. Summary of the Invention

[0007] The main objective of this invention is to provide a magnet coil, component, and plasma generation device for a field inversion device, in order to solve the technical problems of existing single-turn coils having large current requirements, easy gaps in the circumferential magnetic field, and difficulty in confining extreme electromagnetic forces.

[0008] To achieve the above objectives, this application provides a magnet coil for a field reversal device, comprising: A multi-turn coil winding, wherein the multi-turn coil winding has a lead-out start end and a lead-out tail end; The terminal block structure is connected to the first and last ends of the outgoing wire, respectively, for electrical connection with an external power supply. Before exiting the terminal structure, the lead-out end and the lead-out end of the multi-turn coil winding extend circumferentially to form a circumferential overlapping area. Within the circumferential overlapping area, the lead-out conductor and the lead-out conductor extend in parallel along the circumferential path, ensuring that the multi-turn coil winding has the same number of solid conductors passing through any angle segment of the complete 360-degree circumference. This eliminates current path gaps at the lead-out position when energized, forming a uniformly distributed equivalent current and magnetic field in the circumferential direction.

[0009] In one embodiment, the multi-turn coil winding is an N-turn winding structure, where N is an integer greater than or equal to 2, and is wound in an axially parallel and close-fitting manner; Within the circumferential overlap area, the first turn of the conductor that begins winding and the Nth turn of the conductor that ends winding are parallel to each other in the axial direction and are staggered to compensate for each other, so that the multi-turn coil winding maintains the total number of conductor cross-sections of N layers within the cross-section including the wiring lead-out position.

[0010] In one embodiment, N=3.

[0011] In one embodiment, the terminal block structure includes two parallel conductive plates, each with a plurality of wiring holes arranged in an alternating array, configured to connect to multiple cables to form a multi-cable parallel power supply circuit, thereby reducing the current carrying capacity requirement of a single cable.

[0012] In one embodiment, the coil is powered by a coaxial coil, and the multi-cable is a coaxial cable.

[0013] In one embodiment, the terminal block structure further includes an insulating isolation pad and two sets of insulating clamps; The insulating isolation pad is sandwiched between the two parallel conductive plates and is configured to provide interlayer electrical insulation and maintain a preset physical distance. The two sets of insulating clamps are respectively attached to the outer sides of the two parallel conductive plates and locked by multiple sets of through fastening components, so that the two parallel conductive plates are pressed inward against the insulating isolation pad, thereby resisting the electromagnetic repulsion force generated when a reverse pulse current is applied.

[0014] In one embodiment, the outer conductor of the multi-turn coil winding, as well as the extended regions of the lead-out end and the lead-out end, are covered with an integrally cured insulating layer structure.

[0015] This application also provides a magnet coil assembly, including: The modular fastening support assembly and multiple magnet coils as described above are arranged coaxially and parallel along the axial direction and are integrally installed and locked inside the modular fastening support assembly.

[0016] In one embodiment, four magnet coils are installed within the modular fastening support assembly. The terminal structures of adjacent magnet coils along the axial direction are staggered in sequence at a preset angle in the circumferential direction. The preset angle includes 180 degrees, in order to balance the overall force on the magnet coil assembly and avoid cable interference in space.

[0017] In one embodiment, the modular fastening support assembly includes a split-type housing module that is integrally covered outside the plurality of magnet coils, and a plurality of super bolts; The split-type housing module includes an upper housing and a lower housing that are connected to each other. The upper housing and the lower housing are joined together to form a continuous inner cavity for coaxially accommodating the plurality of magnet coils. The multiple super bolts are located on the outside of the upper and lower housings and are configured to secure the upper and lower housings radially to rigidly constrain the electromagnetic force generated by the magnet coil when a large current is applied.

[0018] This application also provides a field-reversed plasma generation device, comprising: Vacuum chamber; and As described above, the magnet coil assembly is sleeved outside the vacuum chamber and configured to bias, pre-ionize, and main discharge the gas inside the vacuum chamber to generate and confine field-inverted plasma through a magnetic reconnection process.

[0019] The beneficial effects of this invention are as follows: 1) By replacing the traditional single-turn coil with a multi-turn winding structure, the operating current is reduced to one-third of the original under the same magnetic field requirements. Through the design of the circumferential overlap area of ​​the start and end conductors, the inherent current path gap at the lead-out position of the multi-turn coil is eliminated from the physical structure, ensuring the high uniformity of the 360-degree circumferential magnetic field, which is crucial for the stable confinement of plasma.

[0020] 2) The terminal block structure adopts a parallel plate with an array of staggered holes, which can accommodate a large number of coaxial cables. This multi-cable parallel power supply method not only reduces the current carrying capacity of a single cable, but also significantly increases the conductive contact area, forcing a uniform current distribution, thereby fundamentally reducing the parasitic inductance of the overall circuit and meeting the requirement for rapid current rise during the reverse discharge stage.

[0021] 3) Multiple coils are combined into a module and encapsulated as a whole using a split housing and super bolts. This heavy-duty mold-type fastening structure can apply huge preload in the radial direction, overcoming the destructive Lorentz expansion force generated by the coil under a strong magnetic field of 10T; at the same time, the 180-degree staggered lead-out of the terminal structure effectively balances the overall force and avoids physical interference from dense cables, greatly reducing the overall assembly difficulty of the FRC device. Attached Figure Description

[0022] Figure 1 This is a three-dimensional schematic diagram of the main structure of the magnet coil used in the field reversal device in an embodiment of the present invention; Figure 2 This is a three-dimensional schematic diagram of a magnet coil with an insulating coating and coaxial terminals in an embodiment of the present invention; Figure 3 This is a partially enlarged schematic diagram of the magnet coil wiring terminal in an embodiment of the present invention; Figure 4 This is a three-dimensional schematic diagram of the magnet coil assembly in an embodiment of the present invention; Figure 5 This is a front view schematic diagram of the terminal block structure in an embodiment of the present invention; Figure 6 This is a side view sectional transition diagram of the terminal block structure in an embodiment of the present invention.

[0023] Figure label: 1. Magnet coil; 2. Coil winding; 3. Terminal structure; 31. Conductive plate; 32. Wiring hole; 33. Cable; 34. Insulating isolation pad; 35. Insulating clamp; 4. Modular fastening support assembly; 41. Super bolt; 5. Insulation layer structure. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0025] Example 1: Magnet Coil

[0026] like Figure 1 , Figure 5 and Figure 6 As shown, this embodiment of the invention provides a magnet coil 1 for a field reversal device. The magnet coil 1 mainly consists of a multi-turn coil winding 2 and a terminal block structure 3. The multi-turn coil winding has a lead-in end for current inflow and a tail end for current outflow. The terminal block structure 3 is connected to the lead-in end and the tail end respectively, for electrical connection to an external power supply or a freewheeling circuit.

[0027] Before exiting the terminal structure, the lead-out ends of the multi-turn coil winding extend circumferentially to form a circumferential overlap area. The core of this circumferential overlap area design lies in ensuring that the lead-out conductor and the tail conductor of the multi-turn coil winding extend parallel to each other in the circumferential direction before exiting the terminal structure. This guarantees that the number of conductor layers flowing along any circumferential angle section, including the exit area, is consistent, eliminating the current path gap at the exit position of traditional multi-turn series coils.

[0028] Specifically, the multi-turn coil winding has an N-turn winding structure, where N is an integer greater than or equal to 2, and is wound in a parallel axial direction. In the circumferential overlap area, the first turn of the conductor at the beginning of the winding and the Nth turn of the conductor at the end of the winding are parallel to each other in the axial direction and are staggered to compensate for each other, so that the multi-turn coil winding maintains the total number of conductor cross-sections of N layers in the cross-section including the connection point.

[0029] It should be understood that this principle applies to any number of turns N greater than or equal to 2. For example, when N=2, the beginning and end ends are radially superimposed or axially extended side by side within a certain angle on the circumference, ensuring that there are always two layers of conductor within that angle segment, and the remaining angle segments are also covered by two turns of conductor, thus ensuring that the number of conductor layers is consistent across any angle cross-section; when N=4, the four ends of the four turns of conductor are staggered on the circumference, and each end overlaps with the corresponding part of the adjacent turn in the circumferential direction, which can also achieve the same number of conductor layers across any angle cross-section.

[0030] Those skilled in the art will understand that, regardless of the specific number of turns, as long as the design principle of "the beginning and end ends being staggered and partially overlapping in the circumferential direction to maintain a constant number of conductor layers at any angle" is followed, the technical effect of the present invention can be achieved.

[0031] The following detailed description uses N=3 as a preferred embodiment. Figure 1 and Figure 6 As shown, since the coil is wound with 3 turns continuously, in order to avoid the local dip in magnetic field strength caused by only 2 turns of conductor in the fan-shaped area where the current enters and exits (i.e., the first turn has just started and the third turn has finished leading out), the present invention designs a circumferential overlapping area before the coil lead-out terminal.

[0032] Specifically, the first turn of conductor (starting end) and the third turn of conductor (ending end) do not immediately bend radially and lead out. Instead, they continue to extend parallel to each other along the geometric trajectory of the ring for the same central angle. Within this overlapping area, the starting and ending conductors are axially parallel and staggered, ensuring that the coil maintains a total of three conductor cross-sections across any radial section, including the lead-out points. This design completely eliminates current path gaps, creating a perfectly distributed equivalent current in the ring, thereby generating a highly uniform θ-pinch confinement magnetic field.

[0033] Terminal block structure reference Figure 2 , Figure 3 and Figure 5 The terminal block structure 3 includes two parallel conductive plates 31. Considering the extremely high pulse discharge current, multiple wiring holes 32 are machined on the conductive plates 31 in a staggered array. In practical applications, multiple coaxial cables are connected to these wiring holes respectively. On the one hand, the multiple cables shunt the current, reducing the cable insulation and current-carrying pressure of a single cable; on the other hand, the array-type power supply greatly expands the current injection area, avoiding localized overheating, and significantly reducing the lead inductance of the power supply circuit.

[0034] In some embodiments, the conductive plate 31 is a pure copper plate.

[0035] from Figure 6 As can be seen from the side view, the 3-turn coil conductors are bent in a stepped manner and overlap each other when they converge to the terminal block. They can be fixed by integral machining or brazing to ensure that the contact resistance is reduced to a minimum.

[0036] like Figure 2 As shown, due to the extremely high instantaneous voltage of the FRC main discharge, the outer surface of the coil conductor and the extended areas at both ends are covered with an integrally solidified insulating layer structure 5.

[0037] Furthermore, to ensure electrical safety and structural stability under extreme discharge conditions, the terminal block structure also includes two key auxiliary insulation and fastening technical features in its parallel conductive plate area, see [link to relevant documentation]. Figure 3 .

[0038] In some embodiments, an insulating isolation pad 34 is sandwiched between two parallel conductive plates 31. As a rigid filling core, this pad not only precisely defines and maintains the physical distance between the first and last terminals, but also acts as the main insulating layer, effectively blocking the discharge path under tens of kilovolts of high voltage during the main discharge, preventing phase-to-phase short circuits or arc breakdowns.

[0039] In some embodiments, high-strength insulating clamps 35 are symmetrically attached to the outermost sides of the two conductive plates 31 and locked in place by multiple sets of through fastening components. Since the two parallel conductive plates generate extremely strong outward electromagnetic repulsion when ultra-large pulse currents in opposite directions are applied, the insulating clamps 35, together with the fastening components, firmly press the conductive plates 31 inward onto the central insulating isolation pad 34.

[0040] The two features mentioned above together form a highly rigid sandwich-type fastening assembly from the inside out, completely eliminating the structural risks of deformation, tearing, or loosening of coaxial cable interfaces under high voltage and high current impact on the terminal block.

[0041] Example 2: Magnet Coil Assembly

[0042] refer to Figure 4 This invention also provides a magnet coil assembly that solves the structural support problem under extreme electromagnetic forces.

[0043] The assembly includes a modular fastening support assembly 4 and multiple magnet coils housed therein. Preferably, there are four magnet coils, which are arranged coaxially and parallel along the same central axis.

[0044] To balance the enormous reaction force of the coil assembly during discharge and to prevent the dense coaxial cables from interfering with each other in the installation space, the terminals of the four coils are staggered sequentially at a predetermined angle in the circumferential direction. In this embodiment, a 180-degree horizontal cross-directional arrangement is preferred.

[0045] Modular fastening support assembly, reference Figure 4 The modular fastening support assembly includes a split housing module and multiple super bolts 41 distributed on the outside. In one embodiment, the split housing module is divided into an upper housing and a lower housing.

[0046] After the upper and lower shells are closed, they form a continuous inner cavity that secures the four magnet coils. The super bolt 41, through a split multi-screw pre-tightening mechanism, can apply radial pre-tightening force to the upper and lower shells, completely locking the two halves of the shell. When a very large current is passed through the coil to generate a transient strong magnetic field of more than 10T, this rigid shell module can effectively counteract the radially outward expanding Lorentz force generated by the coil, ensuring that the coil deformation is within a safe range.

[0047] Example 3: Field-inverted plasma generation device

[0048] This invention also provides an FRC device, which includes a vacuum chamber and the magnet coil assembly described in Embodiment 2 above.

[0049] The magnet coil assembly is housed in the outer perimeter of the vacuum chamber. During the operating cycle, the external power supply controls the coil discharge through multiple sets of coaxial cables, sequentially executing the bias, pre-ionization, main discharge, and freewheeling stages. Under a safe, stable, and uniform magnetic field output, the coil assembly ionizes the neutral gas in the vacuum chamber and forms a long-life, high-parameter field-inverted plasma target through a magnetic reconnection mechanism.

[0050] The beneficial effects of this invention are: 1) By replacing the traditional single-turn coil with a multi-turn winding structure, the operating current is reduced to one-third of the original under the same magnetic field requirements. Through the design of the circumferential overlap area of ​​the start and end conductors, the inherent current path gap at the lead-out position of the multi-turn coil is eliminated from the physical structure, ensuring the high uniformity of the 360-degree circumferential magnetic field, which is crucial for the stable confinement of plasma.

[0051] 2) The terminal block structure adopts a parallel plate with an array of staggered holes, which can accommodate a large number of coaxial cables. This multi-cable parallel power supply method not only reduces the current carrying capacity of a single cable, but also significantly increases the conductive contact area, forcing a uniform current distribution, thereby fundamentally reducing the parasitic inductance of the overall circuit and meeting the requirement for rapid current rise during the reverse discharge stage.

[0052] 3) Multiple coils are combined into a module and encapsulated as a whole using a split housing and super bolts. This heavy-duty mold-type fastening structure can apply huge preload in the radial direction, overcoming the destructive Lorentz expansion force generated by the coil under a strong magnetic field of 10T; at the same time, the 180-degree staggered lead-out of the terminal structure effectively balances the overall force and avoids physical interference from dense cables, greatly reducing the overall assembly difficulty of the FRC device.

[0053] The embodiments described above are merely further illustrations of the present invention and are not intended to limit the present invention in any other way. The present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding modifications and changes based on the present invention, but all such modifications and changes should fall within the protection scope of the present invention.

Claims

1. A magnet coil for a field inversion configuration device, characterized in that, include: A multi-turn coil winding, wherein the multi-turn coil winding has a lead-out start end and a lead-out tail end; The terminal block structure is connected to the first and last ends of the outgoing wire, respectively, for electrical connection with an external power supply. Before exiting the terminal structure, the lead-out end and the lead-out end of the multi-turn coil winding extend circumferentially to form a circumferential overlapping area. Within the circumferential overlapping area, the lead-out conductor and the lead-out conductor extend in parallel along the circumferential path, ensuring that the multi-turn coil winding has the same number of solid conductors passing through any angle segment of the complete 360-degree circumference. This eliminates current path gaps at the lead-out position when energized, forming a uniformly distributed equivalent current and magnetic field in the circumferential direction.

2. The magnet coil according to claim 1, characterized in that: The multi-turn coil winding has an N-turn winding structure, where N is an integer greater than or equal to 2, and is wound axially side by side. Within the circumferential overlap area, the first turn of the conductor that begins winding and the Nth turn of the conductor that ends winding are parallel to each other in the axial direction and are staggered to compensate for each other, so that the multi-turn coil winding maintains the total number of conductor cross-sections of N layers within the cross-section including the wiring lead-out position.

3. The magnet coil according to claim 2, characterized in that: N=3。 4. The magnet coil according to claim 1, characterized in that: The terminal block structure includes two parallel conductive plates, each with multiple wiring holes arranged in an alternating array, configured to connect to multiple cables to form a multi-cable parallel power supply circuit, thereby reducing the current carrying capacity requirement of a single cable.

5. The magnet coil according to claim 4, characterized in that: The coil is powered by a coaxial coil, and the multi-cable is a coaxial cable.

6. The magnet coil according to claim 4, characterized in that: The terminal block structure also includes an insulating isolation pad and two sets of insulating clamps; The insulating isolation pad is sandwiched between the two parallel conductive plates and is configured to provide interlayer electrical insulation and maintain a preset physical distance. The two sets of insulating clamps are respectively attached to the outer sides of the two parallel conductive plates and locked by multiple sets of through fastening components, so that the two parallel conductive plates are pressed inward against the insulating isolation pad, thereby resisting the electromagnetic repulsion force generated when a reverse pulse current is applied.

7. The magnet coil according to claim 1, characterized in that: The conductor exterior of the multi-turn coil winding, as well as the extended areas at the beginning and end of the lead wire, are all covered with an integrally cured insulating layer structure.

8. A magnet coil assembly, characterized in that, include: The modular fastening support assembly and a plurality of magnet coils as described in any one of claims 1-7, wherein the plurality of magnet coils are arranged coaxially and parallel along the axial direction and are integrally installed and locked inside the modular fastening support assembly.

9. The magnet coil assembly according to claim 8, characterized in that: The modular fastening support assembly contains four magnet coils. The terminal structures of adjacent magnet coils along the axial direction are staggered in sequence at a preset angle in the circumferential direction. The preset angle includes 180 degrees, in order to balance the overall force on the magnet coil assembly and avoid cable interference in space.

10. The magnet coil assembly according to claim 8, characterized in that: The modular fastening support assembly includes a split-type housing module that is entirely covered by the multiple magnet coils, and multiple super bolts; The split-type housing module includes an upper housing and a lower housing that are connected to each other. The upper housing and the lower housing are joined together to form a continuous inner cavity for coaxially accommodating the plurality of magnet coils. The multiple super bolts are located on the outside of the upper and lower housings and are configured to secure the upper and lower housings radially to rigidly constrain the electromagnetic force generated by the magnet coil when a large current is applied.

11. A field-inverted plasma generation device, characterized in that, include: Vacuum chamber; as well as The magnet coil assembly as described in any one of claims 8 to 10, wherein the magnet coil assembly is sleeved outside the vacuum chamber and configured to bias, pre-ionize, and main discharge the gas inside the vacuum chamber to generate and confine field-inverted plasma through a magnetic reconnection process.

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