An asymmetric field reversed configuration gradient magnetic compression catalyzed deuterium-deuterium fusion device and a steady-state self-sustained operation method thereof

Abstract

This invention discloses an asymmetric field inverse configuration gradient magnetic compression catalytic D-D fusion device and its steady-state self-sustaining operation method. Addressing the technical barriers of low cross-section, difficulty in self-sustaining, and low energy input efficiency in pure deuterium-deuterium fusion reactions, this invention achieves breakthroughs through the following innovations: 1. Asymmetric field inverse configuration design: avoiding redundancy in traditional symmetric structures, reducing system complexity and manufacturing costs; 2. Helical continuous gradient magnetic compression: forming a continuous and uniform magnetic pressure gradient, stably compressing plasma to extremely high density; 3. Adaptive frequency tracking RMF and multi-stage traveling wave acceleration array: improving RMF coupling efficiency and ion acceleration energy; 4. Gradient magnetic compression and magnetic energy recovery: integrating a superconducting magnetic energy storage module to recover coil discharge energy, reducing system net power consumption; 5. Catalytic D-D fusion and ignition strategy: utilizing D-D reaction products T and ³He for catalytic reaction, combined with trace amounts of tritium ignition during the start-up phase, achieving steady-state self-sustaining operation without external auxiliary heating; 6. Enhanced magnetic mirror confinement of catalytic products: extending the T / ³He confinement time, increasing the probability of catalytic reaction. This device uses pure deuterium fuel (extracted from seawater) and is expected to achieve a significant energy gain within the theoretical energy balance framework. The specific gain level depends on plasma parameter optimization and system commissioning during engineering implementation. It can simultaneously achieve power generation, tritium breeding, and medical isotope preparation. It is suitable for ground-based fusion power plants and space-based fusion drives.

Description

Technical Field

[0001] This invention belongs to the field of magnetic confinement nuclear fusion energy technology, specifically relating to a steady-state field-reversed configuration (FRC) deuterium-deuterium fusion device that employs an asymmetric vacuum chamber structure, a spiral continuous gradient magnetic compression coil confinement coupled with a rotating magnetic field (RMF) injection, and a steady-state self-sustaining operation method for gradient magnetic compression catalytic DD fusion based on this device. Background Technology

[0002] Field inverse configuration (FRC) devices are considered one of the important technological routes for realizing magnetic confinement fusion due to their high specific pressure (β≈1) and simple geometry. However, existing FRC devices generally suffer from the following technical shortcomings: 1. Redundancy in symmetrical structure: Traditional devices usually adopt an axisymmetric structure, with redundant functions at both ends, resulting in high system complexity and high manufacturing cost.

[0003] 2. Non-uniform magnetic compression: Traditional FRC devices use discrete coils, resulting in discontinuous magnetic pressure distribution and limited stability and uniformity of plasma confinement.

[0004] 3. Low RMF injection efficiency: Existing RMF antennas have limited coupling efficiency with plasma, resulting in insufficient ion acceleration.

[0005] 4. Low energy input efficiency: The discharge energy of the magnetic compression coil cannot be effectively recovered, resulting in high system power consumption.

[0006] 5. Reliance on external heating: Existing FRC devices rely on neutral beam injection (NBI) or radio frequency assisted heating to maintain plasma temperature, making it difficult to achieve steady-state self-sustaining operation.

[0007] 6. Low deuterium-deuterium reaction cross-section: Pure DD reaction has a low cross-section and a high ignition temperature (>100 keV), making it difficult to achieve commercially viable energy gains.

[0008] In summary, existing FRC devices face several core technological challenges, including high manufacturing costs due to complex structure, difficulties in energy output due to pulsed operation, limitations in energy gain due to reliance on external heating, difficulties in ignition due to low deuterium-deuterium reaction cross-section, difficulties in steady-state operation due to lack of catalytic methods, and difficulties in commercialization due to low energy input efficiency. This invention provides a systematic solution to these technological barriers. Summary of the Invention

[0009] The technical problem to be solved by this invention is to provide an asymmetric field reverse-configuration gradient magnetic compression catalytic DD fusion device and its steady-state self-sustaining operation method. Through the asymmetric vacuum chamber structure, helical continuous gradient magnetic compression coil constraint, coupling design of rotating magnetic field (RMF) injection and microwave ionization, and energy input efficiency optimization structure, the catalytic reaction chain of pure deuterium-deuterium fuel and steady-state self-sustaining operation are realized, thereby improving energy input efficiency and overall energy gain potential.

[0010] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The asymmetric vacuum chamber includes, along the axial direction, an end A, a conical transition section A, a central polymerization region, a conical transition section B, and an end B; the end A is the fuel injection end, and the end B is the fusion product discharge end; the diameter of the central polymerization region is smaller than the diameter of the two ends, and it is smoothly connected to the two ends through the conical transition sections A and B;

[0011] The superconducting coil system comprises multiple sets of separately arranged superconducting coils, which are disposed on the outer walls of ends A and B. The winding direction and wiring method of each set of superconducting coils are configured such that, after current is applied, each set generates an axial magnetic field B0 (0.3-0.6 T) in the direction from end A to end B, so as to form a uniform background field throughout the entire vacuum chamber. At end A, the superconducting coils and the RMF antenna are arranged in an axially staggered manner to eliminate electromagnetic coupling interference and ensure the purity of the magnetic field. The gradient magnetic compression coil system includes a left coil continuously arranged in a spiral pattern close to the outer wall of the conical transition section A and a right coil continuously arranged in a spiral pattern close to the outer wall of the conical transition section B. The left coil is continuously wound along the conical surface of the conical transition section A to the left end of the central aggregation region, and the right coil is continuously wound along the conical surface of the conical transition section B to the right end of the central aggregation region. The winding direction and connection method of the left and right coils are configured such that axial magnetic fields with opposite directions are generated on the left and right sides of the central aggregation region, thereby forming an axial magnetic field reversal region in the central aggregation region. This axial magnetic field reversal region is coupled with the rotating magnetic field generated by the RMF injection system, constituting a magnetic topology structure in which plasma flows from end A to the central aggregation region and forms a closed magnetic field inverse configuration. This continuous and uniform magnetic field distribution avoids magnetic pressure fluctuations caused by discrete coils, thereby improving the stability and uniformity of plasma confinement. The rotating magnetic field (RMF) injection system includes an RMF antenna disposed on the outer wall of end A, which is used to inject a rotating magnetic field into the deuterium plasma inside end A. The rotating magnetic field transfers angular momentum to the ions through non-contact coupling between the rotating magnetic field and the plasma, thereby achieving axial acceleration of the ions and steady-state maintenance of the FRC angular current, thus eliminating the risk of electrode ablation and plasma short circuit. The microwave ionization system is located at the end of terminal A and is used to ionize the injected deuterium gas and preheat it into deuterium plasma. The central polymerization region is located in the narrow section of the asymmetric vacuum chamber. The deuterium plasma beam injected from end A is compressed from both sides by the gradient magnetic field of the spiral continuous gradient magnetic compression coil in this region, forming a high-temperature, high-density FRC core and undergoing a fusion reaction. The neutron moderation absorption layer is arranged around the outer wall of the vacuum chamber surrounding the central aggregation region. It is composed of lithium-lead or lithium-fluorine beryllium molten salt and metallic beryllium, thereby integrating neutron energy recovery, tritium breeding and isotope preparation functions. The magnetic divertor and energy recovery system are located inside end B and are used to separate fusion products from unreacted fuel and recover the kinetic energy of charged particles.

[0012] Preferably, the internal structure and functional layout of terminal A and terminal B are different: terminal A integrates a microwave ionization chamber, an RMF injection antenna and a fuel injection channel; terminal B integrates a magnetic divertor, a direct energy converter (DEC) and a vacuum pump assembly.

[0013] Preferably, the total length of the asymmetric vacuum chamber is 10-25 m, wherein the length of end A is 4-8 m, the length of the conical transition section A is 2-4 m, the length of the central aggregation region is 1-3 m, the length of the conical transition section B is 2-4 m, and the length of end B is 4-8 m; the diameter of end A and end B is 1.0-1.5 m, the diameter of the central aggregation region is 0.3-0.6 m, and the cone angle of the conical transition section is 15°-25°.

[0014] Preferably, the left and right coils of the gradient magnetic compression coil system are each helical continuous coils with a total number of 20-50 turns. The peak magnetic field of a single coil is 5-10 T, and the turn spacing gradually decreases from 10-20 mm on the side away from the central aggregation area to 5-10 mm on the side of the central aggregation area. The background axial magnetic field is 0.3-0.6 T, so that the peak magnetic compression of the central aggregation area reaches 6-8 T.

[0015] Preferably, the turn spacing distribution of the gradient magnetic compression coil satisfies d(z) = d0·exp(-α·z), where d0 is the initial turn spacing (10-20 mm), α is the gradient coefficient (0.2-0.5 m⁻¹), and z is the axial distance from the central aggregation region.

[0016] Preferably, the RMF antenna is equipped with an adaptive frequency tracking module, which includes a digital phase-locked loop controller and a microwave interferometer density diagnostic unit, used to adjust the RMF frequency according to the real-time plasma density signal, so that the RMF frequency tracks 1 / 2 or 1 / 3 of the plasma rotation frequency harmonic to achieve resonant coupling.

[0017] Preferably, the RMF antenna includes multiple independently driven antennas distributed along the axial direction to form a traveling wave acceleration structure; preferably, it includes four independently driven antennas, with a spacing of 0.8 m between each antenna and phase differences of 0°, 90°, 180°, and 270° respectively.

[0018] Preferably, a set of catalytic product magnetic mirror confinement enhancement coils are set at each end of the central polymerization region. The peak magnetic field of the magnetic mirror confinement enhancement coils is 1-3 T. The winding direction and wiring method of the magnetic mirror coils on both sides are configured such that after current is applied, symmetrical magnetic field peaks are formed at both ends of the central polymerization region. The direction of the magnetic field peaks is the same as the direction of the axial magnetic field generated at the corresponding position by the adjacent gradient magnetic compression left or right coil, so that the magnetic field is superimposed and enhanced, thereby extending the confinement time of T and ³He.

[0019] Preferably, the device further includes a magnetic energy recovery system, which includes a superconducting magnetic energy storage module coupled to the gradient magnetic compression coil system for recovering the discharge energy of the gradient magnetic compression coil; the superconducting magnetic energy storage module uses a yttrium barium copper oxide (YBCO) high-temperature superconducting coil with an operating temperature of 20-30 K.

[0020] Preferably, the magnetic divertor and energy recovery system includes: a divertor magnet disposed on the outer wall of end B, and a modular direct energy converter electrode plate cassette disposed inside the vacuum chamber of end B; the electrode plate cassette is installed via a quick-opening flange on the vacuum chamber wall and connected to an external adjustment driver via a bellows-sealed transmission mechanism on the vacuum chamber wall for real-time adjustment of the electrode plate spacing and angle during operation.

[0021] Preferably, the asymmetric vacuum chamber is made of non-metallic composite material at least in the parts corresponding to the RMF antenna, gradient magnetic compression coil and magnetic mirror confinement enhancement coil.

[0022] Preferably, the device uses pure deuterium-deuterium fuel and utilizes the DD reaction products tritium and helium-3 for catalytic DD fusion during operation: that is, the generated T reacts with D in a DT reaction, and the generated ³He reacts with D in a D-³He reaction; during the start-up phase, a small amount of tritium gas is injected into end A as an igniter, mixed with deuterium gas, with a molar ratio of T2 to D2 of 1:100 to 1:20; when the plasma temperature reaches 50-100 keV, the amount of tritium gas injected is gradually reduced, transitioning to a pure deuterium-deuterium operation mode; the device is configured to compensate for radiation loss power P_rad, plasma transport loss power P_loss, and net power consumption P_B of the magnetic field system by using the self-heating power P_α of α particles and the self-heating power P_cat of the charged products of the catalytic reaction, so as to achieve steady-state self-sustaining operation without external auxiliary heating. S1. Fuel injection and microwave ionization: Pure deuterium gas is injected into terminal A in a steady state flow, and an initial deuterium plasma is formed through a microwave ionization system; during the start-up phase, a small amount of tritium gas is mixed into the deuterium gas, and the molar ratio of T2 to D2 is 1:100 to 1:20.

[0023] S2, RMF injection and FRC formation: A rotating magnetic field is injected into end A through the RMF antenna to drive the plasma to rotate and form a field-reverse magnetic structure. At the same time, the RMF frequency is locked at the harmonic of the plasma rotation frequency through the adaptive frequency tracking module to achieve resonant coupling and accelerate the ion axis to 50-200 keV. S3, Gradient magnetic compression and polymerization compression: Deuterium ions pre-accelerated by RMF flow axially towards the central polymerization region. In the conical transition section, they are subjected to the continuous uniform gradient magnetic field of the gradient magnetic compression coil, which compresses radially and decelerates axially, forming a high-density FRC core in the central polymerization region; the magnetic energy recovery system synchronously recovers the discharge energy of the coil. S4. Catalytic Fusion Reaction and Self-Heating: In the central polymerization region, during the initial stage, deuterium and tritium undergo a DT reaction to rapidly heat the plasma to 50-100 keV; subsequently, it transitions to a pure DD operation mode, where the T and D produced by the DD reaction undergo a catalytic DT reaction, and the ³He produced undergoes a catalytic D-³He reaction with D. The magnetic mirror confinement enhancement coil of the catalytic products extends the confinement time of T and ³He, and alpha particles and protons deposit energy to achieve self-heating; fusion neutrons penetrate the vacuum chamber wall and enter the neutron moderation absorption layer, where they are converted into thermal energy after moderation and absorption, and then multiply tritium through lithium-6 nuclear reactions; S5. Product Separation and Energy Recovery: Fusion products and unreacted fuel flow into terminal B, are separated by a magnetic divertor according to the charge-mass ratio, and the charged particles recover kinetic energy through a direct energy converter. S6. Fuel Cycle and Steady-State Maintenance: Unreacted deuterium and the tritium and helium-3 generated by the reaction are separated and recycled back into the fuel cycle; the tritium that grows in the neutron moderation absorption layer is extracted, purified, and used to supplement the fuel cycle; after transitioning to pure DD mode, the device operates in a state that satisfies P_α + P_cat ≥ P_rad + P_loss + P_B, achieving steady-state self-sustainability. Beneficial effects

[0024] 1. Structural Simplification and Asymmetric Optimization: Through an asymmetric vacuum chamber design, end A is dedicated to fuel injection and RMF acceleration, while end B is dedicated to product discharge and energy recovery. This avoids redundancy in traditional symmetric structures, reducing system complexity and manufacturing costs. More importantly, the asymmetric structure enables the RMF acceleration section, gradient magnetic compression section, central aggregation region, magnetic divertor, and DEC recovery section to form a functionally continuous plasma transport chain with matched physical parameters along the axial direction. The structural parameters (length, diameter, cone angle) of each segment are adapted to the density, temperature, and velocity evolution of the plasma in that segment, producing a synergistic constraint effect that cannot be achieved by a single functional module.

[0025] 2. Uniform and Continuous Magnetic Compression: A spiral-shaped continuous gradient magnetic compression coil is arranged close to the outer wall of the conical transition section, forming a continuous and uniform magnetic pressure gradient. Compared with traditional discrete coils, this improves the stability and uniformity of plasma confinement. The geometric cone angle (15°-25°) of the conical transition section matches the exponential distribution of the coil turn spacing (d(z)=d0·exp(-α·z)), ensuring a smooth increase in magnetic compression intensity along the axial direction. The plasma is continuously compressed as it flows towards the central aggregation region, avoiding the instability of the compression interface caused by discrete coils.

[0026] 3. RMF Non-contact Acceleration and Adaptive Frequency Tracking: Ion acceleration is achieved using the rotating magnetic field of the RMF, eliminating the risks of electrode ablation and plasma short circuits. The adaptive frequency tracking module (digital phase-locked loop controller) locks the RMF frequency at the harmonic of the plasma rotation frequency, achieving resonant coupling and helping to improve the RMF coupling efficiency.

[0027] 4. Multi-stage RMF traveling wave acceleration array: A traveling wave acceleration structure is formed by a 4-stage independently driven antenna array with phase differences of 0°, 90°, 180° and 270° respectively, which helps to improve the ion acceleration efficiency and energy.

[0028] 5. Gradient magnetic compression and magnetic energy recovery: The use of a spiral continuous coil with an exponentially distributed turn spacing helps to improve compression efficiency and peak plasma density; the integrated superconducting magnetic energy storage (SMES) module recovers the coil discharge energy, which helps to reduce the net power consumption of the magnetic compression system.

[0029] 6. Enhanced magnetic mirror confinement of catalytic products: Auxiliary magnetic mirror coils are set at both ends of the central polymerization region. The magnetic mirror coils and gradient magnetic compression coils work together to enhance the magnetic field, which helps to prolong the T / ³He confinement time and increase the probability of catalytic reaction.

[0030] 7. Catalytic DD Fusion and Ignition Strategy: By catalyzing the reaction chain (DD→T+³He→DT / D-³He secondary reaction), the DD reaction products are used as secondary fuels to continue participating in fusion, which helps to increase the total energy output. Adding a small amount of tritium as an igniter during the start-up phase (T2:D2=1:100 to 1:20) helps to lower the ignition threshold.

[0031] 8. Advantages of pure deuterium-deuterium fuel: the fuel source is almost unlimited (extracted from seawater), the neutron energy is low (the average neutron energy of DD is 2.45 MeV, far lower than that of DT at 14.1 MeV), and the reaction products do not contain long-lived high-level waste.

[0032] 9. Multi-scenario application basis: Applicable to ground-based fusion power plants and space-based fusion drives. During device operation, the high-flux neutron field and charged particle stream within the system can be used to arrange target materials at specific locations on end B or the neutron moderation absorption layer to prepare medical radioisotopes, radioactive materials for nuclear batteries, or to perform radiation modification treatments on materials. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention (with annotations of innovative points).

[0034] Figure 2 The curve shows the distribution of the gradient magnetic compression magnetic field and the magnetic mirror superimposed along the axial direction.

[0035] Figure 3 The curves show the relationship between DD and the catalytic reaction cross section and ion temperature.

[0036] Figure 4 A block diagram for optimizing power flow to achieve steady-state self-sustaining energy balance and energy input efficiency.

[0037] Figure 5 This is a schematic diagram of an adaptive frequency tracking RMF system and a multi-stage traveling wave acceleration array.

[0038] Figure 6 This is a diagram showing the Lawson criterion for DD fusion and the device operation window. Detailed Implementation like Figure 1 As shown, the device of the present invention includes an axially extending asymmetric vacuum chamber with a total length of approximately 20 m. From left to right, the asymmetric vacuum chamber comprises: end A (fuel injection end, approximately 4 m in length), conical transition section A (approximately 2 m in length), central polymerization zone (approximately 1 m in length), conical transition section B (approximately 2 m in length), and end B (product discharge end, approximately 4 m in length). The diameters of ends A and B are approximately 1.2 m, the diameter of the central polymerization zone is approximately 0.4 m, and the cone angle of the conical transition section is 20°. The core innovation of this invention lies in the axially integrated coupling design of the asymmetric vacuum chamber and various functional modules. The length of end B is approximately twice that of end A. This is not a simple functional omission, but a physical requirement determined by the expansion characteristics of fusion products: during the movement of fusion products (charged particles, neutrons, and unreacted fuel) from the central polymerization region to end B, sufficient axial space is required to complete (1) plasma expansion and decompression, (2) spatial separation of charged and neutral particles by the magnetic divertor, (3) electrostatic deceleration and recovery of the kinetic energy of charged particles by the DEC electrode plate, and (4) removal of unreacted fuel by the vacuum pump group. End A only needs to accommodate the microwave ionization chamber and the RMF antenna acceleration section, so its length is relatively short. This asymmetric length allocation allows for the specialization of functions at both ends, avoiding redundancy of the FRC forming unit at one end in the traditional symmetric structure.

[0039] Meanwhile, the tapered transition section A's reduced diameter geometry matches the exponential distribution of the coil turn spacing in the gradient magnetic compression coil: as the vacuum chamber diameter decreases, the coil turn spacing decreases synchronously, causing the magnetic pressure (B² / 2μ0) to increase monotonically along the axial direction. The plasma is continuously compressed as it flows towards the central aggregation region, avoiding the instability at the compression interface caused by discrete coils. The tapered transition section B's expanded diameter geometry causes the fusion products to gradually expand after leaving the central aggregation region, reducing the thermal load of the plasma on the inner wall of end B and creating a favorable low-density working environment for the magnetic divertor and DEC. This asymmetric geometry of "reduction-aggregation-expansion" forms a triple coupling of structure-function-physical parameters with gradient magnetic compression, magnetic mirror confinement, and magnetic divertor / DEC recovery, a synergistic effect that cannot be achieved by simply superimposing single functional modules. To ensure that the magnetic field characteristics of each magnet system (including the RMF antenna, gradient magnetic compression coil, magnetic mirror confinement enhancement coil, and superconducting coil) are not affected by the eddy currents or magnetic susceptibility of the vacuum chamber, the asymmetric vacuum chamber is made of composite materials. Specifically:

[0040] (1) End A, tapered transition sections A and B, and end B are made of glass fiber reinforced composite material (GFRP). The inner wall is coated with an aluminum sealing layer with a thickness of 10-50 μm to ensure ultra-high vacuum sealing. At the same time, the thickness of the aluminum layer is much smaller than the skin depth of the high-frequency RMF, and the eddy current loss can be ignored. (2) The central polymerization region is made of silicon carbide fiber reinforced silicon carbide ceramic matrix composite (SiC / SiC) to withstand high flux neutron and high temperature plasma radiation, while maintaining complete non-magnetism; (3) Vacuum sealing is achieved between the sections of the vacuum chamber through metal flanges and sealing gaskets. Among them, the flange end face of the GFRP section is embedded with a metal ring for metal-to-metal sealing.

[0041] Through the above design, the vacuum chamber achieves a magnetic field penetration efficiency of ≥99% and eliminates magnetic field distortion or thermal load caused by eddy currents, thereby ensuring the optimal operating characteristics of each magnet system. The superconducting coil system comprises multiple sets of discretely arranged superconducting coils, positioned on the outer walls of ends A and B. At end A, three sets of superconducting coils are located in the end region, the axial gap region of the RMF antenna array, and near the tapered transition section, respectively. All superconducting coils carry current in the same direction, generating an axial background magnetic field B0 ≈ 0.5 T. The superconducting coils and the RMF antenna are staggered axially to eliminate electromagnetic coupling interference and ensure magnetic field purity. Along the axial direction from the end to the central aggregation area at end A, the functional components are arranged sequentially as follows:

[0042] (1) Fuel injection and microwave ionization region (Z=0~+0.5 m): The end is equipped with a deuterium gas injection channel and a tritium gas injection channel for the start-up stage. The microwave ionization system uses a 2.45 GHz magnetron microwave source to ionize deuterium gas to form initial plasma.

[0043] (2) RMF Rotating Magnetic Field Injection Region (Z=+0.5~+3.5 m): The RMF injection system has a four-stage independently driven antenna array (RMF1-RMF4) arranged on the outer wall of end A. The spacing between each antenna stage is 0.8 m, and the phase differences are 0°, 90°, 180°, and 270° respectively, forming a traveling wave acceleration structure along the axial direction. The RMF antenna is fed by an RF power source with a frequency of 5-20 MHz, generating a rotating transverse magnetic field. The adaptive frequency tracking module (integrating a digital phase-locked loop controller and microwave interferometer density diagnosis) locks the RMF frequency at the 1 / 2 harmonic of the plasma rotation frequency according to the real-time plasma density signal, realizing resonant coupling. like Figure 2 As shown, the gradient magnetic compression coil system includes a left coil and a right coil, which are respectively attached to the outer walls of conical transition sections A and B, and are continuously wound along the conical surface from one end away from the central aggregation region to both ends of the central aggregation region. The turn spacing distribution satisfies d(z) = 15·exp(-0.3·z) (unit mm), where z is the axial distance from the central aggregation region (unit m). The winding direction and wiring method of the left and right coils are configured such that axial magnetic fields with opposite directions are generated on the left and right sides of the central aggregation region, thereby forming an axial magnetic field reversal region in the central aggregation region. This axial magnetic field reversal region is coupled with the rotating magnetic field generated by the RMF injection system, constituting a magnetic topology structure in which plasma flows from end A to the central aggregation region and forms a closed magnetic field inverse configuration.

[0044] In the discharge circuit of the gradient magnetic compression coil, a superconducting magnetic energy storage (SMES) module (using a YBCO high-temperature superconducting coil, operating at 20 K) is integrated. When the coil discharges, the magnetic energy is recovered and stored through the SMES module for excitation of the next pulse. At each end of the central aggregation region, an auxiliary magnetic mirror coil (peak magnetic field 2 T) is installed to extend the confinement time of T and ³He. The magnetic mirror coils are independent of the gradient magnetic compression coils, and the two are spatially staggered along the axial direction: the gradient magnetic compression coils cover the entire conical transition section, while the magnetic mirror coils are only located at local positions at both ends of the central aggregation region (approximately 0.2-0.3 m in length). The winding direction and wiring configuration of the magnetic mirror coils on both sides are such that after current is applied, symmetrical magnetic field peaks are formed at both ends of the central aggregation region, and the direction of these magnetic field peaks is the same as the direction of the axial magnetic field generated at the corresponding position by the adjacent gradient magnetic compression left (or right) coil. This results in the superposition and enhancement of the axial magnetic fields generated by the magnetic mirror coils and the gradient magnetic compression coils at both ends of the central aggregation region, forming a stronger magnetic mirror confinement, which is beneficial for extending the plasma confinement time and improving the fusion reaction efficiency. The magnetic divertor and direct energy converter (DEC) employ an optimized layout design: the magnet coil of the magnetic divertor is located on the outer wall of end B, and the DEC electrode plate is located inside the vacuum chamber of end B, with the DEC electrode plate using a modular, quick-release structure. Specifically:

[0045] - DEC Electrode Plates: The electrode plates are assembled in a removable "cassette" and installed as a whole via a quick-opening flange on the vacuum chamber wall. The cassette uses a ceramic insulated frame, and the electrode plate spacing and angle can be adjusted via a mechanical transmission mechanism sealed by a bellows on the vacuum chamber wall. The operator can adjust these externally without breaking the vacuum.

[0046] The above layout balances the accuracy of magnetic field matching between the magnetic divertor and the DEC with ease of maintenance. The central fusion region is the core area where the fusion reaction occurs. During the start-up phase, deuterium undergoes a DT reaction with a small amount of tritium, rapidly heating the plasma to 50-100 keV. Subsequently, it transitions to a pure DD operation mode, where the T and ³He produced by the DD reaction undergo catalytic DT and D-³He reactions with fresh deuterium fuel.

[0047] The "catalyzed DD fusion" or "catalyzed DD cycle" described in this invention refers to a physical process that utilizes tritium (T) and helium-3 (³He) generated from the DD reaction as secondary fuels to continue participating in the fusion reaction, and is not a chemical catalysis. The specific reaction chain is as follows: - Main reaction: D + D → T (1.01 MeV) + p (3.02 MeV) or D + D → ³He (0.82 MeV) + n (2.45 MeV) - Secondary catalytic reaction: D + T → 4 He (3.5 MeV) + n (14.1 MeV); D + ³He → 4 He(3.6 MeV) + p(14.7 MeV) - Overall effect: Four D nuclei participate in the reaction, releasing a total energy of approximately 43.2 MeV, with each D nucleus releasing an average of 10.8 MeV. The energy output is several times that of a pure D reaction.

[0048] This invention extends the confinement time of fusion products T and ³He in the central polymerization region by using magnetic mirror confinement enhancement coils, thereby promoting the occurrence of secondary reactions and realizing a quasi-self-sustaining catalytic fusion cycle with pure deuterium as the initial fuel, thus eliminating dependence on scarce tritium fuel. The neutron moderation absorber layer employs a composite structure: the inner layer is made of metallic beryllium (50-100 mm), and the outer layer is made of LiPb alloy (200-300 mm). The recovered heat power accounts for a significant proportion of the fusion neutron power. End B is arranged axially in the following order: superconducting coil assembly, magnetic divertor magnet (outer wall), DEC electrode plate cassette (inner), vacuum pump assembly, and fuel recirculation interface. End B is approximately twice the length of end A, providing ample axial space for the expansion, separation, energy recovery, and fuel recirculation of fusion products. During the start-up phase, a small amount of tritium gas (T2) is injected, with a molar ratio of T2 to D2 of 1:100 to 1:20. The plasma is rapidly heated to 50-100 keV using the DT reaction, and then the tritium injection is gradually reduced.

[0049] In steady-state operation, P_α + P_cat ≥ P_rad + P_loss + P_B is satisfied. Where: - P_α represents the self-heating power of the α particles; - P_cat is the self-heating power of the charged products of the catalytic reaction (DT, D-³He); - P_rad represents the power loss from bremsstrahlung and synchrotron radiation; - P_loss is the plasma transport loss power; - P_B is the power consumption of the magnetic field system (net power consumption after deducting magnetic energy recovery).

[0050] Through the above design, the device is expected to achieve a significant energy gain within the theoretical energy balance framework. The specific gain level depends on the optimization of plasma parameters and system debugging during engineering implementation.

Claims

1. An asymmetric field reverse-configuration gradient magnetic compression catalytic DD fusion device, characterized in that, It includes an asymmetric vacuum chamber, a gradient magnetic compression coil system, a rotating magnetic field (RMF) injection system, a microwave ionization system, a superconducting coil system, a central aggregation region, a neutron moderation absorption layer, and a magnetic divertor and energy recovery system; The asymmetric vacuum chamber includes, along the axial direction, an end A, a conical transition section A, a central polymerization region, a conical transition section B, and an end B; the end A is the fuel injection end, and the end B is the discharge end for fusion products and unreacted fuel; the diameter of the central polymerization region is smaller than the diameter of the two ends, and it is smoothly connected to the two ends through the conical transition sections A and B; The superconducting coil system comprises multiple sets of separately arranged superconducting coils, which are disposed on the outer walls of ends A and B. The winding direction and wiring method of each set of superconducting coils are configured such that, after current is applied, each set generates an axial magnetic field B0 (0.3-0.6 T) in the direction from end A to end B, so as to form a uniform background field throughout the entire vacuum chamber. At end A, the superconducting coils and the RMF antenna are arranged in an axially staggered manner to eliminate electromagnetic coupling interference and ensure the purity of the magnetic field. The gradient magnetic compression coil system includes a left coil continuously arranged in a spiral shape close to the outer wall of the conical transition section A and a right coil continuously arranged in a spiral shape close to the outer wall of the conical transition section B. The left coil is continuously wound along the conical surface of the conical transition section A to the left end of the central aggregation region, and the right coil is continuously wound along the conical surface of the conical transition section B to the right end of the central aggregation region. The winding direction and connection method of the left and right coils are configured such that axial magnetic fields with opposite directions are generated on the left and right sides of the central aggregation region, thereby forming an axial magnetic field reversal region in the central aggregation region. This axial magnetic field reversal region is coupled with the rotating magnetic field generated by the RMF injection system, forming a magnetic topology structure in which plasma flows from end A to the central aggregation region and forms a closed magnetic field inverse configuration. The rotating magnetic field (RMF) injection system includes an RMF antenna disposed on the outer wall of the end A for injecting a rotating magnetic field into the deuterium plasma inside the end A; The microwave ionization system is located at the end of the terminal A and is used to ionize the injected deuterium gas and preheat it into deuterium plasma. The central aggregation region is located in the narrow section of the asymmetric vacuum chamber. The deuterium plasma beam injected from end A is compressed from both sides by the gradient magnetic field of the spiral continuous gradient magnetic compression coil in this region, forming a high-temperature and high-density FRC core. The neutron moderation absorption layer is arranged around the outer wall of the vacuum chamber surrounding the central polymerization region, and is composed of a composite of lithium-lead or lithium-fluorine beryllium molten salt and metallic beryllium. The magnetic divertor and energy recovery system are located inside end B and are used to separate fusion products from unreacted fuel and recover the kinetic energy of charged particles.

2. The apparatus according to claim 1, characterized in that, The internal structure and functional layout of terminal A and terminal B are different: terminal A integrates a microwave ionization chamber, an RMF injection antenna and a fuel injection channel; terminal B integrates a magnetic divertor, a direct energy converter (DEC) and a vacuum pump assembly.

3. The apparatus according to claim 1, characterized in that, The total length of the asymmetric vacuum chamber is 10-25 m, wherein the length of end A is 4-8 m, the length of the conical transition section A is 2-4 m, the length of the central aggregation region is 1-3 m, the length of the conical transition section B is 2-4 m, and the length of end B is 4-8 m; the diameter of end A and end B is 1.0-1.5 m, the diameter of the central aggregation region is 0.3-0.6 m, and the cone angle of the conical transition section is 15°-25°.

4. The apparatus according to claim 1, characterized in that, The left and right coils of the gradient magnetic compression coil system are each helical continuous coils with a total of 20-50 turns. The peak magnetic field of a single coil is 5-10 T, and the turn spacing gradually decreases from 10-20 mm on the side away from the central aggregation area to 5-10 mm on the side of the central aggregation area. The background axial magnetic field is 0.3-0.6 T, so that the magnetic compression peak of the central aggregation area reaches 6-8 T.

5. The apparatus according to claim 4, characterized in that, The turn spacing distribution of the gradient magnetic compression coil satisfies d(z) = d0·exp(-α·z), where d0 is the initial turn spacing (10-20 mm), α is the gradient coefficient (0.2-0.5 m⁻¹), and z is the axial distance from the central aggregation region.

6. The apparatus according to claim 1, characterized in that, The RMF antenna is equipped with an adaptive frequency tracking module, which includes a digital phase-locked loop controller and a microwave interferometer density diagnostic unit. This module is used to adjust the RMF frequency according to the real-time plasma density signal, so that the RMF frequency tracks 1 / 2 or 1 / 3 of the plasma rotation frequency harmonic, thereby achieving resonant coupling.

7. The apparatus according to claim 1, characterized in that, The RMF antenna includes multiple independently driven antennas distributed along the axial direction to form a traveling wave acceleration structure; preferably, it includes four independently driven antennas, with a spacing of 0.8 m between each antenna and phase differences of 0°, 90°, 180°, and 270° respectively.

8. The apparatus according to claim 1, characterized in that, A set of catalytic product magnetic mirror confinement enhancement coils are set at each end of the central aggregation region. The peak magnetic field of the magnetic mirror confinement enhancement coils is 1-3 T. The winding direction and wiring method of the magnetic mirror coils on both sides are configured such that after current is applied, symmetrical magnetic field peaks are formed at both ends of the central aggregation region. The direction of the magnetic field peaks is the same as the direction of the axial magnetic field generated by the adjacent gradient magnetic compression left or right coil at the corresponding position, so that the magnetic field is superimposed and enhanced, thereby extending the confinement time of T and ³He.

9. The apparatus according to claim 1, characterized in that, The device also includes a magnetic energy recovery system, which includes a superconducting magnetic energy storage module coupled to the gradient magnetic compression coil system for recovering the discharge energy of the gradient magnetic compression coil; the superconducting magnetic energy storage module uses a yttrium barium copper oxide (YBCO) high-temperature superconducting coil with an operating temperature of 20-30K.

10. The apparatus according to claim 1, characterized in that, The magnetic divertor and energy recovery system includes: a divertor magnet disposed on the outer wall of end B, and a modular direct energy converter electrode plate cassette disposed inside the vacuum chamber of end B; the electrode plate cassette is installed via a quick-opening flange on the vacuum chamber wall and connected to an external adjustment driver via a bellows-sealed transmission mechanism on the vacuum chamber wall, for real-time adjustment of the electrode plate spacing and angle during operation.

11. The apparatus according to claim 1, characterized in that, The RMF injection system has a rotating magnetic field frequency of 5-20 MHz, a transverse magnetic field strength of 5-80 mT, and a penetration depth of 1-2 m.

12. The apparatus according to claim 1, characterized in that, The neutron moderation absorption layer comprises an inner moderation region and an outer absorption and breeding region: the inner moderation region is made of beryllium metal or beryllium carbide, with a thickness of 50-100 mm; the outer absorption and breeding region is made of LiPb alloy or FLiBe molten salt, with a thickness of 200-400 mm; the heat power recovered by the neutron moderation absorption layer accounts for a large proportion of the fusion neutron power.

13. The apparatus according to claim 1, characterized in that, The device uses pure deuterium-deuterium fuel and utilizes the DD reaction products tritium and helium-3 for catalytic DD fusion during operation: the generated T reacts with D in a DT reaction, and the generated ³He reacts with D in a D-³He reaction. During the startup phase, a small amount of tritium gas is injected into end A as an igniter, mixed with deuterium gas, with a molar ratio of T2 to D2 of 1:100 to 1:

20. When the plasma temperature reaches 50-100 keV, the amount of tritium gas injected is gradually reduced, transitioning to a pure deuterium-deuterium operating mode. The device is configured to compensate for radiation loss power P_rad, plasma transport loss power P_loss, and net power consumption P_B of the magnetic field system by using the self-heating power P_α of α particles and the self-heating power P_cat of the charged products of the catalytic reaction, in order to achieve steady-state self-sustaining operation without external auxiliary heating.

14. The apparatus according to claim 1, characterized in that, The asymmetric vacuum chamber is made of non-metallic composite material at least in the parts corresponding to the RMF antenna, gradient magnetic compression coil and magnetic mirror confinement enhancement coil, in order to eliminate eddy current loss and ensure magnetic field penetration efficiency.

15. A method for steady-state self-sustaining operation of gradient magnetic compression catalytic DD fusion based on the device according to any one of claims 1-14, characterized in that, Includes the following steps: S1. Fuel injection and microwave ionization: Pure deuterium gas is injected into terminal A in a steady flow, and initial deuterium plasma is formed through a microwave ionization system; During the start-up phase, a small amount of tritium gas is mixed into the deuterium gas, and the molar ratio of T2 to D2 is 1:100 to 1:

20. S2, RMF injection and FRC formation: A rotating magnetic field is injected into end A through the RMF antenna to drive the plasma to rotate and form a field-reverse magnetic structure. At the same time, the RMF frequency is locked at the harmonic of the plasma rotation frequency through the adaptive frequency tracking module to achieve resonant coupling and accelerate the ion axis to 50-200 keV. S3, Gradient magnetic compression and polymerization compression: Deuterium ions pre-accelerated by RMF flow axially towards the central polymerization region. In the conical transition section, they are subjected to the continuous uniform gradient magnetic field of the gradient magnetic compression coil, which compresses radially and decelerates axially, forming a high-density FRC core in the central polymerization region; the magnetic energy recovery system synchronously recovers the discharge energy of the coil. S4. Catalytic Fusion Reaction and Self-Heating: In the central polymerization region, during the initial stage, deuterium and tritium undergo a DT reaction to rapidly heat the plasma to 50-100 keV; subsequently, it transitions to a pure DD operation mode, where the T and D produced by the DD reaction undergo a catalytic DT reaction, and the ³He produced undergoes a catalytic D-³He reaction with D. The magnetic mirror confinement enhancement coil of the catalytic products extends the confinement time of T and ³He, and alpha particles and protons deposit energy to achieve self-heating; fusion neutrons penetrate the vacuum chamber wall and enter the neutron moderation absorption layer, where they are converted into thermal energy after moderation and absorption, and then multiply tritium through lithium-6 nuclear reactions; S5. Product Separation and Energy Recovery: Fusion products and unreacted fuel flow into terminal B, are separated by a magnetic divertor according to the charge-mass ratio, and the charged particles recover kinetic energy through a direct energy converter. S6. Fuel Cycle and Steady-State Maintenance: Unreacted deuterium and the tritium and helium-3 generated by the reaction are separated and recycled back into the fuel cycle; the tritium that grows in the neutron moderation absorption layer is extracted, purified, and used to supplement the fuel cycle; after transitioning to pure DD mode, the device operates in a state that satisfies P_α + P_cat ≥ P_rad + P_loss + P_B, achieving steady-state self-sustainability.

16. The method according to claim 15, characterized in that, In step S3, the turn spacing distribution of the gradient magnetic compression coil satisfies d(z) = d0·exp(-α·z), forming an exponentially growing magnetic pressure gradient pointing towards the central aggregation region, which increases the density of the single-beam deuterium plasma in the central aggregation region to 5×10² under bilateral magnetic compression. 0 ~ 2×10²¹ m⁻³, temperature increased to 50-100 keV; the magnetic compression ratio R = B_p / B0 is 10-15.

17. The method according to claim 15, characterized in that, During the steady-state operation of the device, a target material is arranged at a specific position on end B or the neutron moderation absorption layer using the high-flux neutron field and charged particle stream within the system to prepare medical radioactive isotopes, radioactive materials for nuclear batteries, or to perform radiation modification treatment on the materials.

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