查看更多>>摘要：Due to its unique nuclear properties, beryllium stands out as one of the candidate materials for the first wall and neutron multiplier in nuclear fusion reactors. This article provides an overview of the microstructural evolution and property changes in neutron and ion-irradiated beryllium and its alloys, based on both experimental research and computational modeling, as well as the fabrication of beryllium and its alloys. Changes in microstructure, physical and mechanical properties of the beryllium after irradiation are discussed, such as dislocation loops, bubbles, and tritium helium release behavior. Basic physical parameters of beryllium are collated, like displacement threshold energy, sputtering energy, vacancy formation energy, and elemental migration energy, which are the basis for irradiation damage calculation and understanding of experimental phenomena. Some issues that are still unclear or need further study have been identified, including the reason for the formation of hexagonal prism-shaped bubbles in beryllium under high-temperature irradiation, the mechanism behind the slightly higher peak release temperature of helium compared to tritium from beryllium after neutron irradiation, as well as the precise displacement threshold energy of beryllium, among other factors. This can shed light on the understanding of irradiation damage in beryllium and beryllium alloys.
查看更多>>摘要：Tritiated water vapor (HTO) is the dominant source among the radioactive airborne effluent from commercial nuclear power plants. Gas or liquid metal coolant is recognized to be widely used in the advanced nuclear energy systems and fusion reactor. Elemental tritium (HT) would be the dominant form regarding the environmental effluents of advanced nuclear energy systems under the oxygen-free environment. Additionally, tritium release amount would also be higher than current pressurized water reactor. A dynamic modeling scheme was proposed to simulate tritium migration and conversion behaviors in the atmosphere-soil compartments. Atmospheric tritium concentration level was predicted by hourly-resolution wind field data. With regard to HTO discharge source, HTO concentration level in soil moisture was evaluated with consideration of daily-resolution atmospheric HTO concentration data, daily-resolution precipitation and evapotranspiration data. With regard to HT discharge source, HT concentration in air-filled soil porosity, conversion product known as HTO concentration in air-filled and water-filled soil porosity was predicted from the viewpoint of time series. Influence of key parameters such as HT conversion rate and gaseous fraction of conversion product in the soil on HTO distribution was discussed at last. It was indicated that environmental factors such as wind field, conversion rate, precipitation and evapotranspiration rate, gaseous fraction have a significant influence on tritium distribution in atmosphere-soil compartment. Development of time-varying simulation method adopting the above dynamic environmental factors as input data is beneficial for achieving a refined environmental impact assessment.
查看更多>>摘要：In the support of Comprehensive Research Facility for Fusion Technology (CRAFT) Program of China, the high temperature PbLi loop is under development, which will be employed to experimentally study the MagnetoHydroDynamics (MHD) effects for the supercritical carbon dioxide (s-CO2) cOoled Lithium-Lead (COOL) blanket. In the current design, the temperature of PbLi is operating in the range of 300 degrees C-700 degrees C, and the material for components is carefully selected in view of the baseline 550 degrees C. When the temperature is higher than this value, the nickel-based alloy that can resist high temperature is adopted. Otherwise, the stainless steel 316 is used. In this loop, there are two components that are considered as the most critical and fragile due to the highest operating temperature up to 700 degrees C, including the main heater and primary mixer. Therefore, the thermalmechanical analysis and optimization on these two critical components are performed in this paper, and the stress results are evaluated according to the relevant standards. For the main heater, both the PbLi outlet temperature and the structural temperature meet the requirements under the maximum operating condition. Although the stress in some regions exceeds the allowable limits, it can be solved during the manufacturing process. For the primary mixer, the optimization is performed from three aspects, i.e. structural design, structural material, and increasing cold PbLi temperature. The results indicate that one of the designs exhibits better stress performance. Tungsten shows satisfying mechanical properties, but there are challenges in machining. While N06625 can only meet the stress criteria of the external components. The thermal stress is decreased with the reduction of the temperature difference between the hot and cold PbLi. Furthermore, the mixing performance is effectively enhanced by extending the length of the helical and the outlet nozzle. The results can provide data support for the processing and manufacturing of these two critical components to ensure the safe operation of the PbLi loop.
查看更多>>摘要：Plasma shape is a significant factor that must be considered for any Fusion Pilot Plant (FPP) as it has significant consequences for plasma stability and core confinement. A new simulator, NSFsim, has been developed based on a historically successful code, DINA (Khayrutdinov and Lukash, 1993), offering tools to simulate both transport and plasma shape. Specifically, NSFsim is a free boundary equilibrium and transport solver and has been configured to match the properties of the DIII-D tokamak. This paper is focused on validating the Grad-Shafranov (GS) solver of NSFsim by analyzing its ability to recreate the plasma shape, the poloidal flux distribution, and the measurements of the simulated diagnostic signals originating from flux loops and magnetic probes in DIII-D. Five different plasma shapes are simulated to show the robustness of NSFsim to different plasma conditions; these shapes are Lower Single Null (LSN), Upper Single Null (USN), Double Null (DN), Inner Wall Limited (IWL), and Negative Triangularity (NT). The NSFsim results are compared against real measured signals, magnetic profile fits from EFIT (Lao et al., 1985) [1], and another plasma equilibrium simulator, GSevolve (Welander et al., 2019). EFIT reconstructions of shots are readily available at DIII-D, but GSevolve was manually ran by us to provide simulation data to compare against.
查看更多>>摘要：The helium refrigerator, which is a critical infrastructure of the fusion device, should be controlled well and maintain stability. During the operation of one refrigerator in the Comprehensive Research Facility for Fusion Technology, a continuous oscillation behavior was observed in the liquid nitrogen (LN2) cooling system. This paper explores a data-driven Model Predictive Control (MPC) scheme for the LN2 cooling control. Modeling the complex system dynamics under the oscillation disturbance is achieved by the encoder-decoder recurrent neural network, which provides an end-to-end implementation for multistep prediction. The data-driven MPC applies the particle swarm optimization algorithm to find the optimal control actions, in which a novelty particle initialization method is adopted to improve the search efficiency. The performance of the data-driven MPC is evaluated by closed-loop simulation, and the simulation results indicate that the disturbance can be effectively restrained. The proposed scheme shows a promising extension prospect, such as smoothing the pulse heat load disturbance in the fusion cryogenic system.
Salvador, F. M.Bouzan, A. S.Ramos Jr., R.Asnis, Y. P....
1.1-1.7页
查看更多>>摘要：An upgrade of the Tokamak & agrave; Chauffage Alfv & eacute;n Br & eacute;silien (TCABR) is being designed to make it capable of creating a well controlled environment where the impact of resonant magnetic perturbation (RMP) fields on edge localised modes can be addressed over a wide range of (i) plasma shapes, (ii) divertor configurations, (iii) RMP coil geometries and (iv) perturbed magnetic field spectra. To this end, a unique set of in-vessel RMP coils is being designed and, in this work, their conceptual design is presented. This unique set of coils is composed of three toroidal arrays of coils on the low field side and three toroidal arrays of coils on the high field side. Each of these six toroidal arrays is composed of 18 coils thus allowing for the creation of RMP fields with toroidal mode numbers n <= 9 and with increased control of the poloidal mode number spectrum. To study dynamical effects of RMP fields of different toroidal mode numbers, all rotating simultaneously with different velocities, each of the 108 RMP coils will be powered independently by power supplies that can provide voltages of up to 4 kV and electric currents of up to 2 kA, with frequencies varying continuously from 0 Hz up to 10 kHz. A set of physical criteria were used to determine the optimal coil geometry and their respective number of turns to reduce the coil currents and voltages during operation with alternate current. The conceptual design was carried out using both the vacuum approach (no plasma response) and the single-fluid response approach, which accounts for the response of a linear, single-fluid, visco-resistive plasma calculated using the M3D-C1 code.
查看更多>>摘要：The Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) has designed a Six-Around-One cable-in- conduit conductor (CICC) for next-generation nuclear fusion devices in China. This complex design involves intricate heat exchanges among conductor components and considerations of structural stability, necessitating multiple design iterations. The minimum quench energy (MQE) is a crucial parameter for evaluating the CICC's stability and feasibility under operational conditions of low temperatures (4.2 K) and high magnetic fields (20 T). This study has analyzed the MQE of the Six-Around-One CICC using the THEA code, employing a onedimensional model with three thermal and four hydraulic components. To reduce the calculation error of the theoretical model, the helium flow channel of the CICC structure is divided into four areas, and the friction of each flow channel is tested by measuring the inlet and outlet pressures of CICC and its mass flow rate. The four flow channels are the REBCO tapes area, the central spiral tube area of the sub-cable, the gap area between the sub-cable and the jacket, and the central copper tube area. Based on this model, the MQE of the CICC under fast perturbation (0.01 m, 0.1 s) and slow perturbation (10 m, 30 s) conditions is first analyzed. Then, the effect of changes in key parameters in CICC on stability is studied, including thermal resistance (Rth), the mass flow rate of forced helium, the cross-sectional area of copper, and the residual resistivity ratio (RRR) of copper material. By studying the dependence of MQE on various thermal and hydraulic parameters, the key factors of CICC design are determined, and the general design principles of HTS CS coil CICC are proposed. Numerical simulation can reduce the workload in the CICC design process and shorten the overall design cycle.
查看更多>>摘要：Thailand Tokamak- 1 is a compact, circular-shaped tokamak with major and minor radii of 0.65 m and 0.20 m, respectively. It successfully achieved its first plasma in 2023, generating a maximum plasma current of approximately 100 kA, in line with the magnetic field induction work sequence of the magnet system in Thailand Tokamak- 1. This paper presents the design and measurement of the magnet system in Thailand Tokamak- 1, where the vacuum magnetic field was measured using diamagnetic loops and a rack of magnetic probes inserted into a vacuum chamber. Additionally, the Ohmic discharge process and its characteristic behavior in the experiment are described and analyzed.
查看更多>>摘要：Current unbalance caused by impedance disparities among multiple parallel branches can lead to accelerated aging of some power devices and localized overheating, posing a threat to the normal operation of fusion power supplies. A method for improving the current sharing performance of fusion converters with paralleled branches based on structural parameter optimization is proposed in this paper. Firstly, a high-precision converter bridge arm structure is constructed using ANSYS Q3D, and sub-circuits of segmented modules are extracted; subsequently, a circuit model is built in Simplorer, and the current of each branch is obtained through joint simulation with Simplorer; then, with branch current as the matching parameter, an adaptive target optimization algorithm is utilized to iterate and optimize structural parameters, thereby acquiring a set of bridge arm structures with optimal current sharing performance; finally, fine-tuning is conducted considering the actual spatial limitation. To validate the superiority of the proposed method, the current sharing effects of the structures before and after optimization under both steady-state and short-circuit conditions are analyzed and compared. The results indicate that the optimized structure has shown significant improvements in terms of current sharing coefficient, over-current ratio, and maximum turn-off error time. This method could be used for the current sharing design of fusion power supplies and related multiple parallel devices.
查看更多>>摘要：Broadband antennas operating in the gigahertz frequency range are regularly used for plasma reflectometry diagnostics. Due to a lack of space and unique diagnostic constraints, these antennas are often custom in design and frequency range. Recent advances in additive manufacturing of high temperature copper alloys allow for expanded freedom in design of these diagnostic antennas. In this work, a heuristic simulated annealing algorithm is used alongside 3-D finite element simulation to automate the design of a double ridged rectangular horn antenna fora reflectometry diagnostic on the DIII-D tokamak. Optimization of antenna performance given the design constraints results in a compact broadband (6-20+ GHz) antenna design. Measured transmission from the additively manufactured antenna matches simulation within reasonable error, and experimental plasma electron density profiles from the DIII-D high-field side scrape-off layer are shown.
NETL
NSTL
Elsevier