Plasma surface interactions between the edge of a magnetically confined plasma and the surrounding wall components lead to detrimental effects for both the wall materials and the plasma, including surface erosion, emission of impurities that radiate and dilute the plasma, loss of fuel through retention in the walls leading to materials property degradation, etc. Understanding and controlling...
The most problematic materials-related challenge for DEMO and future commercial fusion power plants concerns the mitigation of neutron damage, that is, embrittlement by irradiation-induced defects and helium as well as hydrogen transmutation. It has the highest impact on the design and licensing of blanket and divertor structures. As of today, the assumed design limits are highly speculative,...
IFMIF, the International Fusion Materials Irradiation Facility is conceived to generate fusion relevant neutrons with a broad peak at 14 MeV through Li(d,xn) nuclear reactions. IFMIF will enable accelerated neutron irradiation of structural materials at above 20 dpa/fpy (full power year) in 500 cm3 for the high flux test module. IFMIF is presently in its Engineering Validation and Engineering...
A significant part in the EUROfusion materials research programme is to tackle a fusion specific challenge: Neutrons produced by the fusion reaction damage materials by displacing atoms (displacement damage) and they transmute certain elements as well (transmutation damage). That is, on the one hand, materials are damaged by atom displacement, which mainly leads to hardening, embrittlement,...
Synopsis is attached.
Synopsis is attached.
This paper aims to provide the first release of Japanese materials property handbook (MPH) for structural design of DEMO, specifically addressing on F82H as Japanese reduced-activation ferritic/martensitic (RAFM) steel. In parallel, the issues and challenges to facilitate the structural design criteria (SDC) to meet requirements of DEMO specific environments, e.g., multi-axial loading,...
A fusion power plant will produce heat, particle, and neutron fluxes that significantly exceed those in present confinement facilities. These loads will alter the plasma facing materials and components significantly impacting reactor lifetime, performance and safety. Most of these challenges can be addressed with cost effective linear plasma device experiments. The existing devices PISCES and...
1.Introduction
As the world’s electricity demand is increasing rapidly with the growth of developing countries, the world faces many energy-related challenges such as the mitigation of greenhouse gases, fossil fuel depletion, and the safety of nuclear energy. Therefore, the world is considering the development of a next-generation energy source to solve those challenges. In particular,...
One of the most interesting open questions of plasma physics is the formation of mean or large scale magnetic field from random or short scale fluctuations of plasma flows.It is believed that generation of large and intermediate scale magnetic fields via the nonlinear energy transfer from kinetic to magnetic modes through continuously stretching and refolding the magnetic field lines is one of...
One of the pressing problems in the design and construction of nuclear fusion reactors is the selection of candidate materials for its plasma-facing components. The essential constraint is that such a material has to be able to withstand extreme heat fluxes, together with high fluxes of neutrons, ions beams, and He and H isotopes such as deuterium.
The time of interaction, peak power and...
Divertor tokamaks using all-metal plasma-facing components need impurity seeding of nitrogen (N2), neon (Ne), or argon (Ar) for heat load control under high power conditions. Considering present day devices (i.e. AUG), N2 is compatible with both divertor dissipation and good core performance [1].
However, the formation of tritiated ammonia due to chemical reactions between N2 and fuel...
For high-power operations in ITER, it is foreseen to inject extrinsic impurities into the edge plasma to dissipate part of the plasma exhaust power through radiation and maintain the power fluxes to the plasma-facing components within tolerable limits. To date, the best compromise between radiative efficiency$^{1}$ and hot plasma performance$^{2,3}$ has been achieved with the injection of...
To develop innovative materials, components and basic technologies of thermonuclear fusion demonstration plants (DEMO) and hybrid fusion fission systems, sources of D-T fusion neutrons with an energy of 14.1 MeV with an intensity of up to 1019 n/s are needed [1]. The design of such an experimental hybrid thermonuclear source (DEMO-FNS) is currently being carried out at the Kurchatov Institute...
In magnetic confinement experiments, a transient collective plasma flow occurs in the relaxation event of magnetohydrodynamic (MHD) modes such as the internal kink [1], tearing modes [2], and edge-localized modes (ELMs) [3]. The flow induces a transient plasma current, which then generates electromagnetic (EM) waves via the Maxwell equations. In this work, we analyzed the waves associated with...
The Radio Frequency Quadrupole (RFQ) linac accelerating the 125 mA deuteron beam up to 5 MeV is a key component to demonstrate the low energy section of the accelerator system designed for the International Fusion Materials Irradiation Facility (IFMIF). We achieved an unprecedented high current deuteron beam over 125 mA at 5 MeV by using the RFQ and RF system of the Linear IFMIF Prototype...
A system of equations describing the static three-dimensional equilibrium of plasma in a magnetic field with toroidal magnetic surfaces is obtained.
The problem of finding the equilibrium plasma configurations in a magnetic field, $\textbf{B}$, is among the first-priority problems in plasma physics and its applications. The main tool for the calculation of axisymmetric equilibrium magnetic...
Introduction: Since late 1970s, conventional Cr-Mo based ferritic/martensitic steels have been considered as candidate structural materials for fast and fusion reactors because of their higher swelling resistance and better thermal properties than austenitic steels [1]. However, considering the damaging capacity of the high energy fusion neutrons, the Cr-W based reduced activation...
We established a conceptual design of Advanced Fusion Neutron Source (A-FNS). In order to obtain irradiation data required in qualifying materials of fusion DEMO DT reactor, we newly designed nine test modules to be implemented in the A-FNS. The design of test modules is based on a new distinctive maintenance scheme: ‘horizontal maintenance method integrated with the shielding plug’. The...
A new design of the compact helical fusion reactor, FFHR-b2 (Fig. 1), is proposed. The main mission of the FFHR-b2 is to comprehensively demonstrate new technologies of the HTS (High-Temperature Superconducting) magnets, the metal pebble divertor, and the liquid blanket systems under a fusion reactor condition. Verification of TBR (Tritium Breeding Ratio) > 1 and neutron irradiation on HTS...
Spherical Tokamak research gained attention due to natural elongation, high β (∝1/A) and being economical. Pakistan Spherical Tokamak (PST) is in the conceptual and physics design phase. It is a medium size tokamak and some of its basic parameters are; major radius R = 0.5 cm, minor radius a = 0.25cm, Aspect ratio A = 2.0, Elongation κ = 2.0, Toroidal Magnetic Field BT=0.5T. Purpose of this...
Development and testing of an additively manufactured lattice for DEMO limiters
N. Mantel1, T. R. Barrett 1, D. Bowden 1, K. Flinders1, M. Fursdon 1, A. D. L. Hancock 1, I.E. Garkusha3, J. Roberts 1, S.S. Herashchenko3, V.A. Makhlai3, A. von Mueller 2, J.-H. You 2
1 United Kingdom Atomic Energy Authority Culham Science Centre, Abingdon, OX14 3DB, UK
2 Max Planck Institute of Plasma...
The realization of advanced fusion reactors rests with improvement of plasma facing materials for divertors. Thermal stability of the strength of tungsten (W) is one of the critical issues for the improvement. This paper reports development of Dispersion-Strengthened W (DS-W) alloyed with Ti using a new process which is based on a combination of Mechanical Alloying (MA) and Hot Isostatic...
Due to complex non-linear interactions of various phenomena in the tokamak plasmas, integrated modelling is a proper tool to understand physics behind them. TRIASSIC (Tokamak Reactor Integrated Automated Suite for SImulation and Computation), which is a flexible integrated suite of codes for interpretive/predictive analyses, is under development for this purpose by exploiting merits of the...
Thermal and magnetic energy content of the plasma have to be rapidly and uniformly removed during a disruption mitigation attempt so as to prevent damage to the plasma-facing components. Injection of high-Z impurities, either through massive gas injection at the plasma periphery (MGI), or by direct shattered pellet injection (SPI), aims to accomplish this goal by uniformly radiating away the...
In the EAST tokamak, density scaling of n=1 error field penetration has been investigated under auxiliary heated discharges. It is found that the density scaling of resonant magnetic perturbation coil current threshold is about b_r ∞n_e^0.4, where b_r represents the error field amplitude and n_e measured by hydrogen cyanide (HCN) is the line averaged electron density. The results show a weaker...
The key role of plasmoid-mediated magnetic reconnection has been experimentally investigated during transient-coaxial helicity injection (T-CHI) for non-inductive plasma start-up on HIST. The fast magnetic reconnection is required for the flux closure in T-CHI discharges. Here, we have found that, (i) during the helicity injection phase, an current sheet is elongated and broken apart at some...
The WEST tokamak (Tungsten (W) Environment in Steady state Tokamak) aims at testing ITER-like divertor plasma-facing units (PFU) in an integrated tokamak environment, and performing long pulse operation with high fluence. To operate long plasma discharges with power loads in the range of those expected in ITER (10-20 MW.m-2) on the Plasma Facing Components (PFC), infrared (IR) thermography are...
One of the major challenges in the realization of a fusion power reactor is the long-term operation of the in-vessel components and material joints under high flux 14.1 MeV neutron environment under high heat loads. This requires development of radiation resistant materials and joints and their validation under reactor relevant conditions [ 1]. At present, there exists no fusion relevant test...
Applicability of tokamak, helical and laser fusion reactors as a volumetric fusion neutron source has been examined using the systems codes that have been used for the conceptual design of DEMO and commercial reactors. This study has clarified the characteristics of reactor-based volumetric neutron sources that can be designed based on the current physics and engineering basis with a...
Mitigation and control of runaway electrons assume greater significance in modern fusion devices because they are acknowledged, as potential threat to in-vesssel components and source for induced instabilities. Their self-mitigation is possible mainly by the loss of energy due to frictional collisions, radiations and collisionless destabilization of various plasma modes. Several other...
Large amounts of runaway electrons are predicted during ITER disruptions which could lead to severe damage (erosion and melting) and limit the lifetime of the plasma facing components (PFCs) [1]. Indeed, the control and mitigation of the runaway electrons constitute one of the priorities of the disruption mitigation system (DMS) in ITER [2], the injection of high-Z impurities by Shattered...
Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion reactions. In a fusion process, two lighter atomic nuclei combine to form a heavier nucleus, while releasing energy. Devices designed to harness this energy are known as fusion reactors.
Nowaday, Fusion has the potential to provide a safe, cost-efficient and sustainable...
Recently, some experiments with a negative triangularity plasma shape in TCV and DIIID tokamaks show promising performances by the reduced electron heat flux [1] and the increased plasma beta beyond the Troyon limit [2]. Theoretically, the normalized plasma beta may be explained by the reduced localized Mercier/Ballooning mode in the negative triangular shape [3]. For the negative...
Impurities are injected into magnetic fusion devices to improve plasma performance in several ways. Recently low-Z impurities were injected to enhance energy confinement, eliminate edge-localized modes (ELM), increase edge radiated power, reduce fuel recycling, and generally improve wall conditions, in a number of devices [1-10]. These results are enabled by a relatively new apparatus [1]...
In this work, high-purity tungsten was subjected to various types of effects corresponding to the processes of fusion - fission neutrons and thermal effects in the hydrogen and helium atmosphere at a temperature of 1000 K, irradiation by hydrogen and deuterium plasmas.
An important task in the ITER project implementing is to select structural materials with the most appropriate...
In this work, we investigate the stability of intermediate n modes in the negative triangularity tokamaks (NTT) in comparison with the positive triangularity tokamaks (PTT). Two types of scenarios are investigated: the D3D-NTT-experiment-like equilibria and the advanced tokamak scenario to address both the immediate D3D experimental concerns and the future prospect of the steady-state...
The new findings for dynamic process of inward diffusion in the magnetospheric plasma are reported on the RT-1 experiment: (i) The evolution of local density profile in the self-organized process has been analyzed by the newly developed tomographic reconstruction applying a deep learning method $[1]$ . (ii) The impact of gas injection excites low frequency density fluctuation, which continues...
Laser Induced Breakdown Spectroscopy (LIBS) is the most promising method for quantitative in-situ determination of fuel retention in Plasma-Facing Components (PFCs) in magnetically confined plasma like JET, ITER etc. We present here the latest developments in view of ITER requirements since the review described in $[1]$. The studies focused on two main requirements: a) quantification of fuel...
Energetic particle (EP) interactions with thermal plasmas can lead to the excitations of various Alfven eigenmodes (AE) ranging from low frequency beta-induced Alfven eigenmode (BAE), to high frequency reversed shear Alfven eigenmodes (RSAE) and toroidal Alfven eigenmodes (TAE). Furthermore, EP could influence thermal plasma dynamics including the microturbulence responsible for turbulent...
The typical fusion plasma confinement states in tokamaks include low (L) confinement, high (H) confinement and the dithering (D) state which implies intermittent switching from the L- to the H- confinement modes. The H- mode manifests itself by self-organization of a region inside the poloidal separatrix where the transport coefficients are reduced by up to an order of magnitude compared to...
The Fusion Research Group (GIF) of the Autonomous University of Nuevo León (UANL) and the Department of Physics of the Saint Petersburg State University have signed an agreement for scientific-technological cooperation to develop a High Magnetic Field Program on the Spherical Tokamaks: Mexico – Russia. The present study is oriented into the magnetic systems design of our Tokamak magnetic...
Search for physical models which support increased magnetic reconnection rates has proven to be an important pursuit in both laboratory plasmas such as magnetic fusion plasma devices as well as in astrophysical plasmas. Over the years, it has been realized that apart from ion Hall effect, magnetic field structure and flow field structure near a reconnection zone could be crucial in realizing...
The first experiment on T-15MD tokamak at the National Research Center Kurchatov Institute is planned for the end of 2020. T-15MD is the tokamak of D-shaped plasma with aspect ratio $А$~$2.2$, toroidal magnetic field $B_T$ to $2$ T in the center of the vacuum chamber, with a plasma major radius of $1.48$ m, with a minor radius of $0.67$ m, elongation, $k$, to $1.8$ and a triangularity,...
The achievements of the present study are summarized as follows:
- The measurement of neutrons, produced during the acceleration of a 125 mA deuteron beam to from 100 keV to 5 MeV by Linear IFMIF Prototype Accelerator (LIPAc) through its novel RFQ, was performed in order to examine the amount of the beam loss.
- The beam loss was well controlled, and even at a current higher than 100...
On the way toward the realization of a commercial fusion power plant, following the ITER line, the DEMOstration tokamak reactor design has centralized the most of the research and development European efforts over the last decade. However, with the recent start of operation of Wendelstein 7-X, the Helical-Axis Advanced Stellarator (HELIAS) [1] line has raised again interest among the...
Toroidal Alfven eigenmode (TAE) has been found to induce large energetic particle (EP) transport in tokamaks and stellarators. In order to predict the nonlinear saturation amplitude of TAE which determines the EP transport level in burning plasmas such as ITER, we need to understand the TAE nonlinear saturation mechanisms, which could be complicated by the wave-wave and wave-particle...
On the basis of the calculation complex ACDAM-2.0, comparative studies of the nuclear physical characteristics of austenitic chromium-nickel steel EK-164 (Fe-16Cr-19Ni-2Mo-2Mn-Nb-Ti-B) and its manganese modifications EK-164Mn (Fe-16Cr-20Mn-2Mo-Nb-Ti-B) and EK-164MnW (Fe-16Cr-20Mn-2W-Nb-Ti-B) irradiated in typical neutron spectra of cores of fast (BN-600) and fusion (DEMO-C) reactors, and long...
Present activities on the Resonant Antenna Ion Device (RAID) [1] at the Swiss Plasma Center aim at broadening the current knowledge of volume production of negative ions as well as the physics of helicon wave propagation in hydrogen and deuterium plasmas for neutral beam injectors (NBIs) for fusion. In RAID, $H_2$/$D_2$ plasmas are produced and sustained using a steady-state, 10 kW birdcage...
Remarkable progress has been made on the understanding the role of N$_{2}$ and H$_{2}$ puffing on plasma detachment in the divertor simulation experiments using the end-loss region of the tandem mirror device GAMMA 10/PDX. These issues have been experimentally investigated for different target angles using the variable angle V-shaped target system. We have newly observed that Molecular...
Xiang Liu1*, Youyun Lian1, Fan Feng1, Jianbao Wang1, Zhe Chen1, Shasha Liu1, Changsong Liu2, Rui Liu2, Yongqing Chang3, Yingmin Wang4, Jiupeng Song5, Min Xu1 and Xuru Duan1
1Center for Fusion Science, Southwestern Institute of Physics, Chengdu, China
2Institute of Solid State Physics, Chinese Academy of Science, Hefei, China
3School of Materials and Engineering, University of Beijing...
In these studies, the task of beryllium purification from radioactive nuclides from neutron flux during operation as a plasma facing materials of the fusion reactor first wall was solved [1]. ITER requires at least 50 t of beryllium for the first wall of the vacuum chamber, it must be replaced every 5 years of operation when the reactor is operating at the nominal power. Currently, the total...
In fusion tokamaks, high centrally peaked temperatures and plasma currents increase the fusion reactivity, but can also depress the central magnetic safety factor $q$ down to unity or below, destabilizing periodic sawtooth crashes driven by $m=n=1$ MHD instabilities that flatten the temperature and current density over a radius larger than $q=1$. At sufficiently low axis values $q_o <1$, the...
The presence of a plasma-implanted helium nanobubble layer significantly reduces deuterium (D) retention in undamaged commercial ITER grade tungsten (W). In this paper, we show evidence that this phenomenon can survive displacement damage. A He plasma exposure (sample temperature: 643 K, ion flux: 1022 m-2 s-1 at 100 eV, fluence: 1025 m-2)...
Tungsten is an attractive choice for armour material for divertors in fusion reactors, but a globally recognized concern is that the accumulated radiation damage by 14.1 MeV neutrons can significantly enhance its otherwise low H-isotope affinity [ 1]. Lack of a high flux 14.1 MeV neutron source, inaccessibility of the reactor-like conditions and the inherently complex material response to...
The ITER Integrated Modelling & Analysis Suite (IMAS) has been developed to provide a standard framework for supporting scenario preparation and plasma operation through a standardised data model designed to support both simulated and experimental data [1]. The IMAS platform provides a high degree of modularity between physics models and physics workflows. One of the most sophisticated physics...
Impurity seeding in tokamak plasmas is of current interest as it is seen to modify plasma turbulence, improve plasma confinement time, and reduce heat loads on plasma facing materials. In this work, we present numerical simulation studies of Neon, Nitrogen and Argon impurity seeding and compare our results with corresponding seeding experiments on Aditya-U tokamak.
In our simulation study,...
In GAMMA 10/PDX, a divetor simulation experimental module (D-module) was installed for detached plasma study in ITER relevant heat flux conditions. In previous studies, it was difficult to measure far-upstream plasma parameters of the D-module because only probes were used on the target plate. To study the detached plasma structure, a Thomson scattering (TS) system and a microwave...
Spherical tokamaks have small aspect ratio allowing higher β stability limit [1]. The design of spherical tokamak offers higher elongation and also enables to hold higher current. Due to the fact that these machines can potentially offer better performance than the conventional tokamaks, they have gained a lot of interest as a fusion power reactor as well as a rich neutron source [1, 2, 3]....
Abstract: The effect of plasma current $I_{p}$ on the current driven by EC waves is studied via numerical approach. It is find that changing of plasma current has a middle impact on ECCD but a large influence on the Ohkawa mechanism dominant current drive (OKCD). Increasing of plasma current makes the ECCD moves slowly into the core region of tokamak plasma, but makes the OKCD shifts...
Concept of a tokamak with reactor technologies (TRT) is developed to facilitate fast and economically sound transition to the pure fusion reactor as well as to the fusion neutron source (FNS) for the hybrid fusion-fission system. Well controllable steady - state operation and reliable power and particle control in a reactor relevant conditions are principal plasma physics problems to be...
International fusion materials irradiation facility - DEMO oriented neutron source (IFMIF-DONES) is a planned facility dedicated for nuclear fusion relevant material qualification. Facility employs deuteron beam and lithium target based accelerator for high energy neutron production. Neutron energies correspond to the energy of neutrons produced via deuterium tritium fusion reaction....
The Joint European Torus (JET) is operated with the ITER-Like Wall (JET-ILW): beryllium in the main chamber and tungsten in the divertor in order to replicate materials for ITER. We present the first systematic and quantitative study of tritium retention in dust and divertor tiles of JET-ILW by means of tritium imaging plate technique (TIPT) and a full combustion method (FCM). (i)The total...
Accurate modeling of integrated core-pedestal solutions with self-consistent and validated fueling source is critical to the assessment and optimization of fusion performance and the tritium burn fraction in ITER and other future burning tokamak devices. Self-consistent modeling using the stability, transport, equilibrium, and pedestal (STEP) workflow in the OMFIT integrated modeling framework...
Capillary porous systems (CPS) filled with liquid metal (Li, Sn) are considered now as alternative approach for plasma-facing components of heavy loaded divertor in fusion reactor [1]. This approach is comprehensively tested now using different PSI devices as testbed facilities to analyze the material response to extremely high particle and heat fluxes, attributed to the transient events, like...
