Fusion Engineering and Design最新文献

Different from the design of nuclear fission power plant, the design of fusion power plant needs to consider the problem of discontinuous fusion energy output from nuclear island. This paper proposed an energy output equilibrium scheme for fusion power plant. Based on analysis and comparison, thermal energy storage method was adopted, and two system operation schemes for fusion power plant were further proposed. Finally, system thermal storage calculation and analysis were conducted under WCCB blanket and HCCB blanket respectively, and conclusions were drawn on the applicable system operation scheme under different blankets. This study provides research foundation and engineering reference for the design and construction of future fusion power plants.

The mechanical vibration and its profound impacts on the magnetic diagnostic measurement have been observed on the J-TEXT tokamak. To explain the low frequency magnetic oscillation induced by the vibration, an analytical model has been developed. The comparisons between the experimental results and the analytical model indicate that the vibration of the vacuum vessel is along two keystones of J-TEXT. Through vibration measurements of J-TEXT components, we have identified that the origin of vibration is the rapid change of the pre-magnetization field. Additionally, it is found that the relative vibrations between magnetic diagnostics and toroidal magnetic fields contribute to the low frequency magnetic oscillation. The results obtained in this work are not only important for the prediction of vibration in fusion devices, but also helpful for experimenters to input corrections in obtained diagnostic results.

Tensile testing of small-size specimens has been widely used to evaluate the influence of neutron irradiation on the mechanical properties for structural materials of fusion reactors. In recent years, researchers have been trying to standardize small-size specimen tensile test method. In the present paper, we have investigated the influence of dimensional deviation and thickness non-uniformity on the tensile results of small-size specimen by both experiments and finite element simulations, based on one of the candidate structural materials of fusion reactor, i.e. CLF-1 steel. It was found that under the conditions of small grain size, small metallurgical defect size and suitable specimen preparation, the tensile results of SS-J3 specimen could be close to the results of large-size specimen. Slightly higher yield and ultimate strengths for small specimens may be caused by the surface treatment of the wheel grinding. The repeatability of ultimate strength was better than that of yield strength, and the repeatability of elongation was worse than that of strength. For tensile tests on eight SS-J3 specimens, the maximum difference in total elongation was about 3 %. With ±0.1 mm deviation of thickness and parallel width, the maximum variation in total elongation was about 1.8 %. The ductility properties were sensitive to specimen's thickness non-uniformity, the measured uniform and total elongations would obviously decrease even with 0.01 mm thickness non-uniformity.

Real-time plasma control systems are at the heart of operation of modern tokamaks. The control system of the TCV tokamak has recently seen a major upgrade in terms of its hardware and software components. Control algorithms are entirely programmed and tested in MATLAB/Simulink(R), executable code is automatically generated and interfaced to run-time parameters and signals through introspection using the MARTe2 software framework. The primary control system (used for coil currents, plasma current, position, shape and density control) has been upgraded by installing new analog signal inputs/output hardware, connected to two real-time computers that can operate in parallel. In addition, an EtherCAT-based real-time industrial network has been deployed to operate distributed low Input/Output count subsystems, greatly boosting the system flexibility and reach. The majority of TCV’s real-time codes have been ported to this new approach, such as the real-time equilibrium reconstruction (LIUQE), real-time Magneto-Hydro-Dynamics mode analysis algorithms, and a real-time plasma supervision, actuator management and plasma event monitor, including real-time plasma analysis using neural networks, and plasma disruption avoidance control schemes.

Switching network unit (SNU) is one of the important systems in the power supply system of fusion devices, which excites and establishes plasma current. A mechanical switch has been designed for SNU backup protection, which can short-circuit other components in case of SNU failure to prevent further deterioration of the situation. An optimized contact system is used in this switch to improve the maintainability of the contacts. A detailed structural design was carried out for the switch, and the final prototype test results verified that it meets the relevant design requirements. This backup protection scheme can provide a certain reference for the engineering design and reliable operation of SNU.

Ten cryo-vacuum pumps (CVPs) were installed in the subdivertor region of each island divertor in the stellarator Wendelstein 7-X (W7-X) and operated for the first time during the recently completed plasma campaign OP2.1. A pumping speed of 70 ± 1 $\frac{{\text{m}}^3}{\text{s}}$ was measured during dedicated tests with known hydrogen gas injection. Based on a conductance model, the estimated pumping speed ranges from 86-93 $\frac{{\text{m}}^3}{\text{s}}$ for different sticking coefficients between 0.6 and 0.8. After completion of the initial tests the CVPs were operated successfully throughout the campaign, with regeneration performed once a week. Neutral gas pressures in the subdivertor in the range of 10⁻⁴ mbar are well within the molecular flow regime and limit the particle exhaust capabilities of the CVPs. Simulations of the neutral gas pressure in the three-dimensional complex geometry of the subdivertor were performed using the DIVGAS code based on the direct simulation Monte Carlo method and a model implemented in the steady-state thermal package in ANSYS, which are in agreement with the measured values during plasma operation.

A multifunctional liquid metal loop named MaTHE-XJTU (Magneto-Thermo-Hydrodynamic Experiments-Xi'an Jiaotong University) that utilizes eutectic alloy GaInSn as a working fluid has been designed and constructed. The function of the MaTHE-XJTU facility is to study the magnetohydrodynamic (MHD) flow and mixed convection characteristics under the coupling effect. The main operating parameters of the loop are: the maximum magnetic field intensity is 3T, the effective magnetic field region is 300 mm × 800 mm × 1000 mm, the maximum flow rate of electromagnetic pump (EM pump) is 8 m³/h, the maximum pressure head of EM pump is 0.5 MPa. The paper describes the major components and basic operation procedures of the loop, the related flow diagnostics method, and near-future experiments. This loop could provide a high-parameter experimental platform (Ha∼10⁴, Gr∼10⁹, Re∼10⁴) for investigations that improve the present understanding of magnetohydrodynamic and heat transfer performance in liquid metal blankets.

The packing factor is an important parameter for describing the internal structural features in pebble beds, which have a significant influence on the heat and mass transfer behavior and the thermo-mechanical properties of the pebble bed. A comprehensive understanding of the packing structure is essential for the design and optimization of the pebble bed and can promote the application of the pebble bed. In this work, an improved line-based averaging method was proposed to calculate the local packing factor or local porosity distribution and validated by comparing the results with those obtained from experimental and numerical studies of cylindrical packed pebble bed. Furthermore, the local packing factor distributions in the angular-radial plane of the cylindrical pebble bed were revealed for the first time. In addition, the line-based averaging method has been applied to reveal the local packing factor distributions in the annular pebble beds, U-shaped pebble beds and hexagonal pebble beds. The main feature of this method is the ability to calculate and plot contour maps of local packing factor or porosity distributions for columnar pebble beds of arbitrary shapes, especially the local packing factor distributions in the cross-sectional plane and the angular-radial plane.