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RSS2024 Vol. 11, No. 3
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2024, 11(3): 1-1.
Abstract:
Controlled nuclear fusion energy is a technical means to obtain energy through constrained and controlled thermonuclear fusion reactions, which is also an energy acquisition method that human beings have not fully mastered. The research on controlled nuclear fusion energy has been carried out for more than half a century, but it is still a common challenge faced by human beings. It is also one of the important research fields that can fully reflect the national scientific and technological innovation capabilities. So far, China has achieved a series of phased results in the field of controlled nuclear fusion research. As a participating country, it has participated in the largest international scientific and technological cooperation project in the world, namely the ITER. The construction of national major scientific and technological infrastructures such as the EAST, China HL-3, and CRAFT has also greatly promoted the development of China's magnetic confinement nuclear fusion research. As a field of in-depth interdisciplinary integration, the research on controlled nuclear fusion energy has not only promoted the advancement of the corresponding technology but also driven the development of related technologies such as superconducting technology, material science, and power supply technology and facilitated the emergence of sophisticated technologies. During the development of nuclear fusion research, China has gradually built an independent talent system of science, engineering, technology, and management for controlled nuclear fusion, which has enhanced China's core competitiveness in the field of international nuclear fusion research.
Nuclear fusion research still faces significant challenges, including physical challenges centered on burning plasma, fusion reactor material challenges focused on neutron irradiation resistance, and tritium self-sufficiency technology challenges centered on tritium production cladding. To solve these problems, many researchers should overcome difficulties and forge ahead. Given the urgent need for the transformation of the national energy structure, the strong support of the country, and the unremitting efforts of generations of nuclear fusion researchers, it is believed that the development of controlled nuclear fusion energy in China will become a reality shortly although there are still numerous challenges to overcome in fusion energy research at this stage.
China Energy Engineering Corporation Limited and China Southern Power Grid, as important members of the Controlled Nuclear Fusion Innovation Consortium, jointly established the energy technology journal Southern Energy Construction through cooperation between their Guangzhou-based organizations and collaborated with Nuclear Techniques, the journal of the Chinese Nuclear Society, to create this special issue on controlled nuclear fusion. This special issue is open to submissions from professional research institutes, higher education institutions, and energy enterprises involved in controlled nuclear fusion research in China, aiming to build an academic exchange platform based on industry-university-research-application collaboration for the integration of controlled nuclear fusion science, technology and engineering. Fusion energy, as a type of potentially significant base load energy, will play an irreplaceable role in future energy supply. Therefore, this journal will continue to focus on the latest research results in China's nuclear fusion field and support the research, development, and academic cultural dissemination of new energy represented by nuclear fusion energy through a series of special issues in the future.
2024, 11(3): 1-13.
doi: 10.16516/j.ceec.2024.3.01
Abstract:
Introduction Fusion energy has the characteristics of large energy released through reactions, safe and reliable operation, abundant fuel sources, and low environmental pollution. Therefore, it is expected to become a commercial energy source that can be supplied in the market on a large scale, providing stable energy output and power supply in the future. To popularize the development path of magnetic confined fusion energy in China, the article reviews the discovery and realization path of fusion energy. Method The article provided an overview of the early research and development process of magnetic confined fusion energy in China by the method of literature review. The paper took the development of magnetic confined fusion energy as an example to provide a preliminary overview of the construction of typical research devices in China, such as tokamak, stellarator, spherical tokamak, reversed field pinch, magnetic mirror field, linear plasma, and dipole magnetic field devices. Result Based on the construction and researches of these devices, China has cultivated a group of scientific and technological talents in the field of magnetic confined fusion research, achieving significant progress. In addition, the article provides an overview of international cooperation in fusion energy research, as well as the International Thermonuclear Experimental Reactor (ITER) project that China is participating in construction. Conclusion Although the current research on fusion energy still needs to overcome significant challenges from various aspects, such as fusion plasma physics, fusion reactor materials, and tritium self-sustaining technology, it is believed that the magnetic confined fusion energy in China will turn from a blueprint into a reality in the future thanks to the urgent need for energy structure transformation and the strong support for fusion researches in China.
2024, 11(3): 14-22.
doi: 10.16516/j.ceec.2024.3.02
Abstract:
Introduction In magnetic confinement fusion research, electron cyclotron heating (ECH) and current drive means are widely implemented for applications including, but not limited to, plasma initiation, heating, non-inductive current drive, and magnetohydrodynamic instability control. In recent years, ECH-related technologies have experienced significant development in response to the development needs of future fusion reactors, and ECH has become one of the main auxiliary heating means in magnetic confinement fusion devices. Method Firstly, the ECH system was introduced, and its components, characteristics and application status were described; then the development status and trends of ECH system-related technologies were discussed with emphasis on four aspects. Result Combined with the research status and application requirements of ECH-related technologies, the important and difficult points in developing each related technology are identified. Conclusion Based on the development status and trends of ECH-related technologies, the article forecasts future research directions and applications of ECH system-related technologies in diverse aspects, including high-frequency and multi-frequency gyrotrons (microwave sources), the intelligent control technology of ECH system, the high-efficiency current drive technology, and the gyrotron-based collective Thomson scattering technology.
2024, 11(3): 23-35.
doi: 10.16516/j.ceec.2024.3.03
Abstract:
Introduction Pulse inductor is an important component of the oscillation discharge circuit in the quench protection system. In the oscillating discharge circuit, the pulse inductor and charging capacitor are used to oscillate and generate high pulse currents, causing the current flowing through the vacuum circuit breaker to reverse and create an artificial zero-crossing point, thus completing the switch breaking. However, under the condition of 120 kA current, due to the action of the electromagnetic force, the connecting bar below the pulse inductor will deform, causing equipment damage and greatly reducing the reliability of the auxiliary oscillation zero-crossing circuit. Therefore, it is necessary to conduct electromagnetic field analysis on the 120 kA pulse inductor and optimize the electromagnetic field distribution around it. Method Firstly, the commutation process of the auxiliary oscillation zero-crossing circuit was analyzed to establish a three-dimensional model of the pulse inductor, and the concept of magnetic field shielding percentage was introduced. Secondly, the influence of shielding plates with different materials and shapes on electromagnetic field distributions was calculated by using finite element simulation. Then the influence of different materials and shapes on shielding percentage was analyzed, and eddy current losses under different shapes were calculated. Finally, the deformation degree of the connecting bar under different shielding structures was calculated in the structural module. Result The results show that the use of different materials or structures in the shielding plates influences the magnetic induction intensity and electromagnetic force received by the connecting bar. Conclusion The circular aluminum shielding plate has a better optimization effect for the electromagnetic field distribution. This method also lays a foundation for the electromagnetic shield design of pulse inductors.
2024, 11(3): 36-46.
doi: 10.16516/j.ceec.2024.3.04
Abstract:
Introduction By adding parallel electron viscosity into the normal equation of resistance tearing mode, the nonlinear behavior of double tearing mode (DTM) mediated by parallel electron viscosity is numerically investigated considering the magnetohydrodynamics in a periodic cylinder. Method The evolution of magnetic islands and magnetic flux during the nonlinear behavior stage of double tearing mode mediated by parallel electron viscosity were analyzed, to study the changes of the magnetic field topology in different phases and associated kinetic characteristics for different distances between the two resonant rational flux surfaces. In addition, the nonlinear driving for each case was discussed. Result The results show that the distance between the two resonant rational flux surfaces has a significant impact on the nonlinear behavior of double tearing mode. Rapid magnetic reconnection would occur at an intermediate distance, resulting in the fastest and most severe damage to the configuration. Conclusion The results of this study provide a reference for the configuration design and operational control of tokamaks.
2024, 11(3): 47-55.
doi: 10.16516/j.ceec.2024.3.05
Abstract:
Introduction The inertial electrostatic confinement (IEC) fusion facility is a small fusion device. This paper aims to solve the problems of IEC fusion devices, such as the cathode melting, the very low Q value, and so on. Method This paper first analyzed the reasons for these problems, and then a new type of inner ion source IEC fusion was proposed to decrease the ion loss during the confinement process, solve the cathode melting, and increase the vacuum in the device and the Q value. Result At last, the improvement of neutron yield is qualitatively analyzed through the estimation, the very complex ion motion inside the fusion device is simulated through numerical simulation calculation, and anisotropic ion motion trajectories are obtained. Conclusion Based on estimation and numerical simulation results, the feasibility of the IEC with an inner ion source is confirmed, which can solve the problems of cathode melting and low Q value.
2024, 11(3): 56-64.
doi: 10.16516/j.ceec.2024.3.06
Abstract:
Introduction In recent years, as the installed capacity of the fusion device has been increasing, the power supply system of the device requires high-amplitude and long-pulse power output, which causes a strong power impact on the grid, and even power supply disconnection in severe cases to pose a serious threat to the safety of the fusion device. Additionally, the high-amplitude pulses also result in a lot of redundancy in the power supply system design. Method To solve these problems, this paper proposed a novel fusion power supply topology with energy storage, that is, the power supply system was designed with energy storage to mitigate the impact of pulse power on the grid. During the operation of the power supply, the grid provided steady-state power while the energy storage device delivered pulse power, effectively reducing the cost of the power supply. Result According to the experience in industrial power supply and distribution, this paper presents the calculation formulas for the selection of key components in different topologies and conducts a cost analysis and comparison for different power supply topologies based on simulation data. Conclusion The experimental results show that the new power supply topology not only reduces the power impact on the grid and improves the energy utilization of the power supply system, but also reduces transformer capacity, thus it is cost-efficient.
2024, 11(3): 65-74.
doi: 10.16516/j.ceec.2024.3.07
Abstract:
Introduction The superconducting tokamak serves as the foundation for steady-state operation. Timely and reliable quench detection is the key to ensuring the secure operation of superconducting magnets, which has the highest level of safety in fusion device operation. Method In this paper, an overview of the principles and implementation approaches of quench voltage detection for fusion magnets was provided. It briefly summarized the research progress of quench detection and the quench detection schemes adopted by mainstream tokamak devices and introduced the basic principles and processes of quench voltage detection. Taking the experimental advanced superconducting tokamak (EAST) as an example, this paper analyzed the interference sources and coupling mechanisms of quench voltage detection, proposed a two-stage decoupling compensation scheme, and established an optimization analysis model for primary compensation and a dynamic compensation mechanism for plasma-coupling interferences. Result The experimental results indicate that the compensation scheme can achieve a high noise suppression ratio greater than 99.9%, which can effectively improve the signal-to-noise ratio (SNR) and reliability of quench detection. Conclusion The established optimization analysis model for primary compensation and the dynamic compensation mechanism for plasma-coupling interferences can be extended to other tokamak devices, thereby providing necessary accumulation for the design of quench detection and the secure operation of magnets in future fusion reactors.
2024, 11(3): 75-80.
doi: 10.16516/j.ceec.2024.3.08
Abstract:
Introduction As a clean and efficient energy source, nuclear fusion promises to achieve global sustainable development in the future. For the first wall of Chinese helium-cooled solid breeder test blanket module, the temperature fields of helium, argon and nitrogen as coolants were calculated based on the design scheme of four coolant channels proposed by the Nuclear Thermal Security and Standardization Research Team. Method To calculate the heat transfer of different coolants in the first wall of the cladding module of fusion reactor, the B.S. Putukhov formula is used to calculate the heat transfer. Result Research indicates that the temperature field variations in the Be panel and RAFM steel are similar for helium, argon, and nitrogen as coolants. The maximum temperatures in the temperature fields are below the allowable temperature, meeting the safety requirements for temperatures. Nitrogen as a coolant offers the largest safety margin, followed by argon, with helium presenting a relatively smaller safety margin. Conclusion This study provides more optimization options for selecting the coolant for the first wall of the test blanket module of nuclear fusion reactor, thereby enhancing the safety margin of the first wall of the test blanket module of nuclear fusion reactor.
2024, 11(3): 81-86.
doi: 10.16516/j.ceec.2024.3.09
Abstract:
Introduction High energy, strong current, and long pulse neutral beam negative ion source technology are one of the core technologies for achieving combustion conditions in magnetic confinement fusion reactor plasma. To meet the beam diagnostic requirements of the long pulse high-power negative ion source experimental platform under the parameters of 200 kV/20 A, a calorimeter target has been developed for intercepting negative ion beams or neutral beams, diagnosing the power density distribution and beam divergence angle of the two beams, as well as the neutralization efficiency of negative ions and other performance parameters. Method Based on the existing structure of the experimental platform vacuum chamber and the size of the extraction electrode, the Matlab program was used to obtain the power density distribution and beam spot size of the negative ion beam generated by the negative ion source at the front end of the calorimeter target at a beam divergence angle of 1° under this parameter. Subsequently, the physical structure of the calorimeter target with a V-shaped target plate was designed. On this basis, Workbench software was used to simulate the thermal load of the oxygen-free copper V-shaped target plate structure under full power operation and obtain the temperature distribution of the calorimeter target during long pulse operation with a water flow rate of 80 m3/h. The highest temperature was 610 °C. Results Based on the simulation calculation results, and in combination with the engineering structure and diagnostic requirements of the experimental platform, the engineering design of the calorimeter target was completed. Conclusion The calorimeter target adopts magnetic fluid vacuum sealing to achieve the opening and closing of the V-shaped target plate, and a thermocouple array is arranged on the back of the target plate to monitor the temperature of the target plate in real time. The calorimeter target engineering has a compact structure, and its installation size can be compatible with ion beam diagnostic vacuum chambers and neutral beam diagnostic vacuum chambers, meeting diagnostic requirements and enabling safe operation with long pulses.
2024, 11(3): 87-95.
doi: 10.16516/j.ceec.2024.3.10
Abstract:
Introduction The purpose of this study is to explore the impact of the spatial magnetic field generated by nuclear fusion devices on magnetic devices and to gain an in-depth understanding of the magnetic field shielding characteristics in a complex electromagnetic environment. Method In the research process, the switch power supply and electronic transformer in the nuclear fusion internal power supply system were selected as the specific research objects. By analyzing in detail the impact of the magnetic field on the loss and the characteristic changes under different directions of the magnetic field, as well as by exploring the key factors affecting the magnetic field shielding effectiveness and the application of different materials, the research objectives were achieved. Result The results indicate that the loss of magnetic components significantly increases in a strong magnetic field environment, and the degree of influence of different directions of magnetic fields on component characteristics varies. By comparing and analyzing the shielding effects of different materials, it is found that materials with high conductivity and magnetic permeability have better application prospects in shielding design. Additionally, optimizing the shielding structure can further improve shielding effectiveness and reduce the impact of magnetic fields on magnetic components. Conclusion By systematically analyzing the impact of strong magnetic fields on magnetic components and the shielding effectiveness of nuclear fusion devices, key references are provided for testing the equipment's magnetic field tolerance and verifying shielding design. Future work will focus on further optimizing shielding materials and structural design to improve the stability and reliability of magnetic components in strong magnetic field environments.
2024, 11(3): 96-109.
doi: 10.16516/j.ceec.2024.3.11
Abstract:
Introduction Plasma disruption poses a significant threat to the tokamak nuclear device during its running and can cause damage to the device. Such damage can be reduced by adopting the disruption mitigation system, which has an action time highly dependent on the real-time running plasma disruption prediction system for predicting the plasma disruption moment. The deep-learning-based neural network has been used to train plasma disruption prediction models, and the real-time running of the deep-learning-based disruption prediction models requires a huge amount of real-time data from multiple diagnostics. Method The article proposed a design scheme for a real-time data acquisition system. The real-time data acquisition and transmission system was designed based on the modular structure and divided into the multiple channels acquisition module, ADC converting control and data reading module, data grouping and packing module and data transmission network module. The data transmission network module was developed on the hardware UDP network stack running on the FPGA at a speed of 10 G. This hardware UDP network stack featured a deterministic data transmission process, enabling a very low transmission latency of the system. Result The real-time data acquisition system has a sampling rate reaching 2 MSa/s, a data throughput rate exceeding 9.3 Gb/s, and a data transmission latency of less than 10 μs. Conclusion This data acquisition system facilitates the fast transmission of diagnostic data streams to disruption prediction models. The high sampling rates enable the system to perform real-time transmission of one-dimensional diagnostics such as radiation and electron temperature, improving the temporal resolution of data. The high data throughput rate can increase the transmission volume of diagnostic data, and the low data transmission latency can reduce the time required for disruption prediction models to obtain diagnostics data.
2024, 11(3): 110-116.
doi: 10.16516/j.ceec.2024.3.12
Abstract:
Introduction As a new form of nuclear energy utilization that is green and clean, nuclear fusion is regarded as the "ultimate energy" of mankind in the future and also as an inevitable route for China's energy development. In thermonuclear fusion power plants, China Fusion Engineering Test Reactors (CFETR) have periodic and pulse energy output, while turbine generator units operate stably and continuously. Therefore, an energy storage island is required between a nuclear island and a conventional island for energy storage buffering. To realize such a buffering function, a suitable operation mode needs to be selected for the energy storage system. Method The coupling and decoupling operation of the nuclear island and conventional island corresponded to different operation modes of the energy storage island. Based on the power output characteristics of CFETR, different operation mode schemes were analyzed and compared from aspects such as system configuration, equipment design and operation control. Result The results show that the decoupling operation mode of a nuclear island and conventional island is superior in terms of power generation efficiency, maturity of equipment design technology and operation control of generator units, so it is recommended to adopt the decoupling operation mode for the energy storage system in a thermonuclear fusion power plant. Conclusion Most of the decoupling operation mode schemes for the energy storage system adopt mature technologies, so they can be put into commercial applications on a large scale and provide support for the commercial design of thermonuclear fusion power plants.
2024, 11(3): 117-125.
doi: 10.16516/j.ceec.2024.3.13
Abstract:
Introduction This study aims to develop an efficient and reliable pulse power supply system based on supercapacitors (SC) for toroidal field (TF) coils in nuclear fusion magnet power systems to address high power demands while improving energy storage efficiency and system stability. Method A pioneering pulse power supply structure was devised employing Modular Multilevel Converter (MMC) technology, leveraging the high power density and swift charging-discharging capabilities of SC as primary energy storage units. This design targeted the high-frequency pulse operation requirements of TF coils. Additionally, the benefits of integrating supercapacitors with MMC technology, including system flexibility and scalability, were explored. Result The study demonstrates that the developed power supply system effectively meets the pulse operation requirements of nuclear fusion reactors, guaranteeing efficient energy delivery and conversion. Conclusion The supercapacitor-based pulse power supply system offers an efficient energy solution for nuclear fusion devices, enhancing energy conversion efficiency, operational stability and device reliability. Subsequent research will focus on optimizing the power structure and performance for diverse applications.
2024, 11(3): 126-136.
doi: 10.16516/j.ceec.2024.3.14
Abstract:
Introduction In order to adapt to the periodic output characteristics of CFETR fusion reactors, the fusion power plant adopts a helium-molten salt energy storage-water (steam) power cycle three-circuit system. The parameters and thermal scheme of the three-circuit steam cycle have a significant impact on the investment and power generation benefit of the power generation island. High parameters and complex thermal schemes can improve cycle efficiency but increase initial investment; low parameters and simple thermal schemes have lower cycle efficiency but significantly reduce initial investment. Therefore, the selection of steam parameters and thermal schemes for the three-circuit system should comprehensively consider power generation efficiency and initial investment and should be selected based on the principle of optimal comprehensive economy. Method Based on the simulation software Ebsilon, modeling and simulation were carried out in this study to examine the performance of the thermal cycle under different regeneration schemes and different main steam and reheat parameters. By calculating different thermal schemes and parameter combinations, the total efficiency and output power under each operating condition were obtained, and the investment in the main equipment of the three-circuit system and its variation with parameters were analyzed. Result Taking into account the total investment and returns of the energy storage island and the conventional island, it is recommended to adopt a thermal scheme with 9-stage regeneration, and main steam parameters of 12.4 MPa, and 540 ℃. Conclusion The three-circuit steam parameters and thermal scheme proposed in the study have reference value for subsequent research on fusion power generation technology and engineering design.
2024, 11(3): 137-145.
doi: 10.16516/j.ceec.2024.3.15
Abstract:
Introduction Facing the rapid transfer of extreme fault energy of the HL-3 fusion scientific apparatus, it is required to configure a large-capacity bypass switch for short-circuit protection. Method Based on the parameters of HL-3 magnet power supply, and in combination with power electronic converter technology and thyristor trigger application foundation, this paper integrated the practical experience of power electronic converter engineering, and used the following means and methods at the harsh working conditions of multi-parallel thyristor consistency conduction and stable current sharing in fast impact application: the equal length type improvement of parallel branch conductive circuit; consistency screening of parallel component parameters, differential selection of component position and parameters in parallel arm; physically forced current sharing by adding a series resistance on the side of the silicon controlled rectifier, calculation of the thermal stability of the additional resistance, and checking calculation of the electrodynamics impact of the parallel bridge arm; thyristor high-frequency pulse train strong trigger. Result A stable crowbar bypass protection electronic switch system for high-capacity fusion of 220 kA class of thyristor was deduced and designed, which was verified by experimental simulation and 160 kA impact test under actual load, and the matching requirements of large-capacity bypass switch for HL-3 protection were realized. Conclusion Under thermal and stability checking calculation, it is completely feasible to realize the matching application of large-capacity crowbar in fusion by adopting comprehensive means such as circuit improvement, additional physical force current sharing, component parameter screening and assembly, and trigger mode adjustment.
2024, 11(3): 146-151.
doi: 10.16516/j.ceec.2024.3.16
Abstract:
Introduction The 3.7 GHz high-power TH2103A klystrons are widely used in the tokamak experimental device. To simplify the HV power supply system (removing the vacuum tetrode in the anode modulation), a power supply mode based on voltage division mode is introduced into the TH2103A klystron of the HL-2A device. To operate the klystron safely in this power supply mode, a system for measuring and protecting the anode current of TH2103A klystron is developed. Method According to the analysis of the characteristics of the anode current in this power supply mode, the anode current showed the condition of normal, forward overcurrent, or reverse overcurrent. In the case of forward overcurrent or reverse overcurrent, it meant that many electrons were bombarding or flowing out of the anode. They were very dangerous to the klystron, which usually may cause overcurrent of the klystron titanium pump, or even damage the klystron. Therefore it was important to accurately measure the anode current and cut off the high voltage to protect the klystron in case of overcurrent. The principle and power supply mode and the principle and implementation plan of the anode protection system were described in this paper. Result In this paper, the effectiveness and reliability of the anode current measurement and protection system were confirmed. Conclusion The power supply mode and the anode current measurement and protection system of this paper are of important reference significance for the operation and maintenance of TH2103A klystron.
2024, 11(3): 152-158.
doi: 10.16516/j.ceec.2024.3.17
Abstract:
Introduction Neutral beam injection (NBI) is an important means of plasma heating and current driving on HL-3 Tokamak. The NBI heating system involves multiple disciplines and fields such as vacuum, power electronics, mechanics, automatic control, and gas discharge. The control system is the basic guarantee for the reliable operation of the NBI heating system, enabling remote control of the field equipment of the heating system, the real-time monitoring of the running state, and the logic control of the discharge experiment. Method The hardware configuration of the PLC system was determined based on the requirement of NBI heating beamline, and the distributed I/O system was set up with Siemens S7-416 as the main controller, Profibus-DP network and industrial Ethernet as the basis, and optical fiber as the transmission medium. Configuration software STEP7 was used to realize hardware configuration, communication connection, and program writing, and interface software WinCC was used to complete centralized management, process monitoring, and information archiving. Result The PLC system can monitor the field equipment status in real time, exchange data with the NBI control system, and instruct field devices to work stably. In addition, the graphical user interface can realize the visualization of experiment processes and real-time display of vacuum value, flow rate, and temperature, providing timely state information for operators. Conclusion The whole PLC system is efficient, reliable, reproducible, well-compatible, and scalable, which can be used to monitor and control the field equipment of the NBI beamline.
