Fusion Engineering and Design最新文献

High Voltage Bushing (HVB) of the Indian Test Facility (INTF) of ITER Diagnostic Neutral Beam (DNB) is a porcelain-based 100 kV vacuum feedthrough. This will be used to feed the High Voltage (HV) supplies, coming from the HV deck to the Beam Source (BS) for the production of 100 kV H^- beam under high vacuum, therefore, it has two major functions: 1. Isolate 100 kV feedlines from grounded vessel and 2. Forms vacuum boundary with 25 feedline penetrations of different kinds. INTF HVB has been designed with rigorous iterations of design optimization for vacuum, mechanical, and electrical requirements. After design, the development of INTF HVB required several prototyping activities to address the challenges in establishing the appropriate bonding methodology with high vacuum compatibility, handling procedure of large size (∼800 mm diameter and 530 mm height) insulator, prior assessments of tolerances due to as-built ovality in insulator and testing & qualification at various steps, to establish the implementation plan for manufacturing and assembly. As a result, techniques, based on prototyping, manifest to solve the challenges were utilized in the manufacturing, leading to the successful development of the HVB.

An option for the Intermediate Coupling Design (ICD) of the European Demonstration Fusion Reactor (DEMO) Balance of Plant (BOP) configuration for Helium-Cooled Pebble Bed (HCPB) Breeding Blanket (BB) concept consists of the Primary Heat Transport System (PHTS), the Intermediate Heat Transfer System (IHTS), using HITEC salt as coolant, equipped with a thermal Energy Storage System (ESS), and the Power Conversion System (PCS). The aforementioned BOP configuration is capable of producing electricity continuously during the pulse time (2 h) and dwell time (10 min) of DEMO plant operation.

The present study reports on the current (2023) thermal system design of DEMO HCPB ICD BOP for 12 operational states defined by the DEMO Design Central Team (DCT) in 2021. It was shown that the PCS is able to accommodate all of the 12 operational points defined based on the uncertainties of the energy map, provided that an additional bypass line at the outlet of the Divertor Cassettes (DIV-CAS) Heat Exchanger (HX) towards the low-pressure part of the feedwater line (to the condenser in this investigation) is installed in the system. This line is activated only in the cases, where the feedwater flow to the low temperature DEMO heat sources HXs is needed to be higher than that necessary to remove BB power at the Steam Generators (SGs). In all the other cases, the bypass line remains unused. Additionally, perspective improvements of DEMO HCPB BOP regarding thermal ESS, as well as PCS are discussed.

This study uses numerical simulations to investigate the effects of magnetic field topology resulting from various polywell fusion setup configurations, including the cube configuration (6 coils), dodecahedron configuration (12 coils), double-layer configuration (14 coils) and disco configuration (26 coils). The results suggest that increased number of magnetic coils and magnitude of magnetic flux density through increased coil current leads to a longer electron confinement time. This is shown by the increased magnetic flux density and magnetic well width with increasing number of coils. In addition, each configuration is investigated to predict the capacity of electron confinement. Numerical electron injections are applied to each magnetic field topology to determine the decay behavior of electron numbers, from which the electron confinement time is calculated.

The MEMENTO (MEtallic Melt Evolution in Next-step TOkamaks) code is a new numerical implementation of the physics model originally developed for the MEMOS-U code with the objective to self-consistently describe the generation of melt and its subsequent large scale dynamics in fusion devices and to assess the damage of metallic reactor armor under powerful normal and off-normal plasma events. The model has been validated in multiple dedicated EUROfusion experiments. MEMENTO solves the heat and phase transfer problem coupled with the incompressible Navier–Stokes equations in the shallow water approximation for the thin liquid film over the solid metal and with the current propagation equations on a domain that features a time-evolving deforming metal-plasma interface. The code utilizes non-uniform and adaptive meshing along with sub-cycling in time facilitated by the AMReX open-source framework as well as AMReX’s built-in parallelization capabilities.

The EAST (Experiment Advanced Superconductor Tokamak) Radial Neutron Camera (RNC) is designed to measure the temporal and spatial distribution of fast neutrons. The system primarily consists of detector components, shielding collimators, support structure, and data acquisition system. We have studied on the neutronic transport through MCNP with EAST reference D-D neutron source (EAST #77160), and calculated the plasma neutron source chord integral along the observation sightlines and scattering neutrons from structural facilities. Contribution matrixes, incorporating both uncollided and scattered neutrons determines the response from the neutron source to every detector unit. We evaluate the RNC primarily through the variation of the RNC sightlines to improve detector performance by reducing interference particles, thereby laying the foundation for subsequent upgrades. Benefiting from these measurements, we can better study the detector signals in relation to corresponding plasma configurations in the future.

The Breeding Blanket (BB) is a crucial component in the EU DEMO Fusion Reactor. It has three main important functions: ensuring the thermal power deposition and consequent efficient extraction to achieve a positive net electrical power generation, guaranteeing adequate radiation shielding for personnel and sensible devices working in the Plant, and self-production of enough Tritium to fulfill the reactor self-sufficiency. In past studies, four blanket concepts have been investigated to support achieving these goals. Breeding blanket designs primarily revolve around lithium-containing ceramics, focusing on lithium-orthosilicate and lithium-lead. During the pre-conceptual phase, two blanket options were selected as driven concepts: HCPB (Helium-Cooled Pebble Bed) and WCLL (Water-Cooled Lithium Lead). The HCPB concept employs lithium orthosilicate ceramic pebble beds with lithium titanium oxide as the breeding material. Hexagonal blocks with Be12Ti are positioned around the breeding material tubes and act as the neutron multiplier. In the case of the WCLL concept, LiPb is used as both the breeding material and the neutron multiplier.

Safety is a top priority in the EU DEMO project, and the approach to evaluating potential activities and doses to workers and the environment reflects this commitment. This study presents neutron flux and specific activity calculations for the EU DEMO breeding materials. The MCNP6 (Monte Carlo N-Particles) was harnessed to estimate neutron spectra in the blanket's breeding material, while the FISPACT-II code was meticulously employed for activation calculations. The nuclear data libraries FENDL 3.2 and TENDL - 2017 were used for transport and activation calculations, respectively, ensuring the highest level of accuracy and reliability in our findings.

The increase of tungsten sputtering yield with fluence was investigated during plasma (≤100 eV) irradiation. This analysis focused on the combined effects of surface binding energy and surface morphology caused by Ar retention. As post-mortem analysis, Ar concentration was measured with SIMS (Secondary Ion Mass Spectroscopy) and TDS (Thermal Desorption Spectroscopy). The Ar concentration saturated at 21 % of W number density during the sputtering process. The corresponding change in surface morphology causes a change in the local ion incident angle, which leads to a sputtering yield increase of 10 %. The increased Ar concentration leads to a decrease in surface binding energy and a change in surface morphology which increases W sputtering yield from 0.02 to 0.03 by ion energy 80 eV. Over time, W sputtering yield reaches saturation as a function of saturated Ar concentration. This result implies that the synergistic role of Ar concentration and surface morphology on sputtering yield. This sputtering yield enhancement occurs more seriously in the realistic condition of plasma-facing materials that face low-energy plasma.

Large capacity fusion devices power supply poses a significant challenge to the stability of power grid, as it can lead to power outages and jeopardize the safety of fusion devices. And traditional distribution methods result in a significant waste of resources. This paper proposes novel topologies with integrated energy storage. In these topologies, high-amplitude pulsed power is supplied by the energy storage devices, while low-amplitude stable power is obtained from the grid. This decouples the pulsed power from power grid, and significantly reducing its impact. Moreover, it can reduce the design capacity of distribution equipment and lowers investment costs. To optimize the deployment of the energy storage device, a hybrid topology is proposed, which further reducing the cost of the novel power supply. Additionally, a cost model for the fusion power supply is developed and validated using simulation data from ITER. Through the case study shows that the HEPS topology saves more than 10 % of the investment cost and about 60 % of the annual operating cost compared to the traditional converter topology.

In this study, neutron irradiation for the Li₂TiO₃-Li₄SiO₄ biphasic ceramics was conducted at Kyoto University Research Reactor (KUR). The tritium thermal desorption spectroscopy (tritium-TDS) and the electron spin resonance (ESR) were performed in the radiation-controlled area at Shizuoka University. It was confirmed that the tritium desorption peculiarities were dependent on the phase ratio of Li₂TiO₃ and Li₄SiO₄ in the ceramic and the neutron fluence. The tritium migration process in biphasic ceramics was intensively studied based on the diffusion and de-trapping kinetics. A tritium release model was established with the consideration of the tritium trapping by irradiation defects and diffusion/migration process from bulk to surface. The experimental data can be well reproduced by the proposed simulation code. The kinetic parameters obtained by the simulating process were almost consistent with the experimental results. The effects of grain size and phase ratio on the tritium release characteristics were also investigated. The simulation code can be also applied to pellets or pebbles. Besides, the simulation code was adapted to understand the tritium release behavior in the working condition of fusion reactors. It was found that the tritium release could reach a steady state when the blanket was operated at higher temperatures. The tritium retention in ceramics after the shutdown of the reactor was confirmed. The tritium inventory can be reduced by controlling the temperature of the blanket system.

Fast digitizers are employed in a variety of experimental contexts, including for microwave measurements from fusion plasma diagnostics. However, most existing commercial digitizers used for this purpose are severely limited by their onboard memory. Here we present a system developed from mostly commercially available hardware components capable of acquiring essentially indefinitely (here $\sim$10 s) while meeting the target performance of 5 GHz analog bandwidth with a rate of 10 billion samples per second and 8 bits per sample. At its core is a field-programmable gate array (FPGA) receiving data from a high-performance analog-to-digital converter (ADC). The data are continuously streamed with a maximum throughput of 120 Gb/s from the FPGA to a computer over optical fiber in the form of raw Ethernet packets, allowing the use of entirely standard networking hardware in the PC. Whilst this technology is transferable to a range of applications, we are motivated by the demands of microwave scattering measurements, for which the new digitizer increased the acquisition duty cycle from 6% to 100%. In this paper we describe our digitization system, demonstrate its capability, and then use it to acquire data from microwave diagnostics at the ASDEX Upgrade and Wendelstein 7-X fusion experiments.