The pulse length of the negative ion beam has been successfully extended over 100 s stably. The beam parameter was 500 keV, 154 A/m$^2$ for 118 s, which exceeds the requirement of negative ion beams (500 keV, 130 A/m$^2$, 100 s) for the negative-ion-based neutral beam injector (N-NBI) of JT-60SA. This is the first achievement over 100 s stable beam with intensity of > 75 MW/m$^2$ required...
T.W. Morgan1,*, M. Balden2, T. Schwarz-Selinger2, Y. Li1.3, Th. Loewenhoff4, M. Wirtz4, S. Brezinsek4 and G. De Temmerman5
1 DIFFER - Dutch Institute for Fundamental Energy Research, De Zaale 20, 5612 AJ Eindhoven, the Netherlands
2 Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
3 Eindhoven University of Technology, Department of Mechanical Engineering,...
We present a High Field Side (HFS) Lower Hybrid Current Drive (LHCD) launcher for DIII-D (1) to validate HFS launch scenarios, Figure 1 (a), incorporating a novel traveling-wave power divider and aperture impedance matching structure for good coupling over a wide range of edge density conditions, produced with additive manufacturing from Glen Research Copper 84 (GRCop-84) a high strength, high...
The advanced fabrication method named as the “Advanced Multi-Step Brazing (AMSB)” was newly developed for fabrication of a tungsten (W)/copper alloy divertor heat removal component in the fusion reactor. The AMSB enables production of a rectangle shaped fluid (cooling) flow path channel with leak tightness condition in the copper alloy heat sink. The prototype AMSB component with the rectangle...
The versatility and practicability of a manufacturing route for the plasma-facing material and component (PFMC) are necessary for the final realization of fusion reactors. Currently, the powder metallurgy (PM) route followed by a suitable plastic deformation process (e.g. hot rolling) is the prevalent manufacturing technique for the preparation of tungsten (W) based PFM. However, this route is...
Improvement of deuterium injection power in the negative-ion-based NBIs for LHD are reported. Co-extracted electron current at acceleration of D$^-$ ions limits the injection power. The electron current is reduced by decreasing the extraction gap, and D$^-$ current increased from 46 to 55 A. More electron suppression was achieved by installing a structure named “Electron Fence” (EF), with...
Tokamak discharges with internal transport barrier (ITB) offer compelling features needed for steady state operation of burning plasmas for its improved energy confinement and high bootstrap current associated with large pressure gradient. To develop a stable ITB plasma usable for fusion reactors, it requires a deep physics understanding of ITB formation and its profile control. This paper...
For over three decades, the observation of rapid core confinement improvement upon favourable modifications of edge operating conditions has been a nagging source of puzzlement for experimentalists investigating conditions for a lasting source of fusion energy in tokamaks. The transport properties of drift-wave turbulence and the interaction of the confined plasma with its material boundaries...
Outline A novel scheme to predict the plasma turbulent transport is developed by combining the machine learning technique and the first-principle gyrokinetic simulations. The machine learning technique is applied to find the relevant input parameters of the nonlinear gyrokinetic simulations which should be performed and to optimize the reduced transport model. The developed scheme can...
In view of the severe operating conditions for plasma facing components (PFCs) in future power producing fusion devices, the development of advanced materials is mandatory {1}. The materials not only have to withstand high steady state power loads but also high number of thermal cycles and shocks. Moreover, the change of thermo-mechanical properties by damage, activation and transmutation...
Concepts of the power exhaust and divertor design have been developed, with a high priority in the pre-conceptual design phase of the Japan-Europe Broader Approach DEMO Design Activity (BA DDA). A common critical issue is the large power exhaust in the main plasma and divertor by the radiative cooling with impurity seeding. (i) Different power exhaust concepts in the main plasma and divertor...
This is the first report of spontaneous Internal Transport Barrier (ITB) formation in reversed magnetic shear plasmas by full-$f$ gyrokinetic simulations with kinetic electrons. We found that (1) a strong mean $E_r$ shear is formed near $q_{min}$ region in flux-driven Ion Temperature Gradient (ITG) turbulence, leading to spontaneous reduction of ion turbulent thermal diffusivity, while it is...
An Ion Cyclotron Range of Frequency (ICRF) system can provide power for a number of tasks, experimentally verified on present machines: heating and current drive, first wall conditioning, plasma start-up, removing of impurities from the core, controlling sawteeth and current ramp down assist. The system has a high plug-to-power efficiency and most of the components external to the machine are...
The role of the nonadiabatic electron drive in regulating the isotope mass scaling of gyrokinetic turbulence is assessed in the transition from ion-dominated core transport regimes to electron-dominated edge transport regimes. The scaling of the plasma energy confinement time with hydrogenic isotope mass is of critical importance, as most tokamaks operate with deuterium (D) as the main ion...
WEST Actively Cooled Load Resilient Ion Cyclotron Resonance Heating Results
J.Hillairet1, J.- M.Bernard1, L.Colas1, F.Durand1, W.Helou1,11, G.Lombard1, P.Mollard1, G.Urbanczyk1,2, Y.Song2, Q.Yang2, Z.Chen1,2, Y.Wang2, H.Xu2, S.Yuan2,...
Summary: Aiming to approach a whole-device integrated simulation, this work reports a compact collisionless gyro-Landau-fluid(GLF) multi-mode multi-scale turbulence transport modeling, in which inherent multi-mode turbulence are consistently involved coupling with the evolution of plasma profiles. A massive parallel initial value code—extended fluid code (ExFC), is newly developed to...
A core fluctuation diagnostic based on the phase-contrast technique$^1$ is being designed for the JT-60SA tokamak$^2$, with the assistance of a synthetic diagnostic coupled to a gyrokinetic code. This system will be able to resolve small-scale microturbulence as well as macroscopic fluctuations, with good spatial and temporal resolution, throughout the plasma cross-section and in all plasma...
Design parameters, key physics missions and engineering issues are identified for a new high power density tokamak to develop and test predicted sustainable plasma operating scenarios for a low capital cost fusion pilot power plant. Analysis highlights that low cost requires advanced plasma scenarios with high confinement and capable power handling (Fig 1a), ie a “core-edge” solution. Critical...
The extreme heat flux anticipated in fusion reactor divertor plasma facing components (PFCs) is perhaps the most challenging technology issue for fusion energy development. Most divertor PFCs are designed based on the maximum steady-state operational heat-flux limits of 5 – 10 MW/m$^2$. However, in addition to the steady-state heat flux, the fusion reactor divertor PFCs could also experience...
Advanced positron annihilation studies of CuCrZr alloys for fusion technology
Vladimír Slugeň• , Peter Domonkoš
Institute of Nuclear and Physical Engineering, Slovak University of Technology, Ilkovicova 3, 81219 Bratislava, Slovak Republic
1 Introduction
The precipitation as a consequence of applied heat treatment (HT), observed by Transmission Electron Microscopy (TEM) [1], was the...
Cross-field transport of particles, energy and momentum due to turbulent fluctuations and collisional neoclassical orbital dynamics generally determines the confinement level, and consequently the fusion power production, achievable in magnetic confinement fusion devices. To confidently predict the performance of next-step burning plasma experiments, including ITER, comprehensive models of...
- INTRODUCTION
The production chain of nuclear data libraries, that starts from experiments and models and goes up to
evaluated nuclear cross sections ready to be used in the transport codes, is quite complex [1][2]. For this reason,
nuclear data libraries must undergo extensive quality assessment procedures and Verification & Validation (V&V)
process. This is true also for FENDL...
This study reports a progress toward realizing a high performance Cs-free negative ion source, that produces negative ions by volume production in a magnetized-sheet plasma device (TPDsheet-U). The experimental results show that this performance of the current density of the negative hydrogen ion beam J$_{c}$ without Cs on TPDsheet-U is a pproximately comparable to that of the negative ion...
The use of metallic walls as plasma facing components in tokamaks puts severe constraints on the control of impurity contamination. Heavy impurities like Tungsten are of particular concern due to the high level of radiative losses they can induce. Moreover, their high sensitivity to neoclassical transport mechanisms exacerbated by toroidal rotation or electrostatic potential asymmetry...
- INTRODUCTION
The concept of the ICR plasma heating system for the Ignitor tokamak in order to determine possible solutions was developed. The concept meets the requirements of the Ignitor project for the capabilities of the engineering, physical and energy infrastructures of the Ignitor tokamak site. Currently, the site of the tokamak complex with a strong field T-14 of JSC "SRC RF...
We have demonstrated that the self-generated poloidal electric field, which reduces the electron acceleration efficiency in the spherical tokamak (ST) merging start-up, was successfully controlled by changing the inboard limiter condition. This result suggests that higher electron temperature ST could be formed by the merging start-up scheme with optimized conducting material structure that...
Cooling down of hot wall installed on QUEST that has all-metal plasma facing walls (PFWs) could extend the plasma duration through fuel particle recycling reduction. Particle compression could be observed during the long duration is a charge on a natural divertor configuration with downward ion grad-B drift. These observations could be useful to handle fuel particle balance in steady-state...
The RFX-mod experiment is a fusion device born to operate as Reversed Field Pinch (RFP), with a major radius R= 2 m and minor radius a = 0.459 m, equipped with a first wall fully covered by graphite tiles. Its high versatility allowed operating also as an ohmic Tokamak, with a toroidal field up to 0.55T, extending the parameter range explored by other devices, for example in the very low q (a)...
Megawatt (MW) gyrotrons with a wide frequency range from 14 to 300 GHz are being developed for fusion devices in collaboration with fusion research institutes. (1) In the experimental test of a new 28/35 GHz dual-frequency gyrotron which has achieved world record power of 1.65 MW at 28 GHz, the cooling characteristics of a double-disk sapphire window were evaluated. The output power of 0.13MW...
A prototype of powerful high-voltage neutral beam injector (HV-NBI), based on acceleration of negative hydrogen ions and their neutralization is under development at the Budker Institute of Nuclear Physics (BINP) [1]. The design of BINP high-voltage injector includes several innovative components, important for injector operation stability and an overall efficiency: 1) multi-aperture...
Development of megawatt radiofrequency ion source for the neutral beam injector on HL-2A tokamak
L.W. Yan, G.J. Lei, M. Li, X.M. Zhang, M. Zhao, Y.N. Bu, W.M. Xie, Y.X. Zhang, G.Q. Zou, H.L. Wei, L.P. Huang, S.F. Geng, X.Z, Ma, Q. Yu, J.Y. Cao, Bo Lu, Z.B. Shi, C.P. Zhou, M. Xu and X.R. Duan
Southwestern Institute of Physics (SWIP), Chengdu, Sichuan 610225, China
E-mail:...
We present a novel flowing lithium divertor design that allows low-recycling regime by handling ITER like reactor heat fluxes of $>10 MW/m^2$ with $jxB$ induced flow speeds of centimeters per second, total lithium inventory of $~100 kg$, power consumption of $~1 MW$. Tritium in lithium is then concentrated as LiT crystals with small insitu cylindrical electromagnetic centrifuges without...
The BOUT++ simulations of C-Mod, DIII-D, and EAST H-mode discharges follow the Heuristic-Drift-based (HD) empirical divertor heat flux width scaling of the inverse dependence on the poloidal magnetic field [1,2]. The BOUT++ simulations for ITER and CFETR indicate that divertor heat flux width $\lambda_q$ of the future large machines may no longer follow the $1/B_{pol,OMP}$ scaling, while the...
Thanks to its flexibility and unique control capability due to the advanced MHD modes feedback system made of 192 independently driven saddle coils, the toroidal RFX-mod device (R/a=2m/0.46m) for magnetic confinement of fusion plasmas has been operated to investigate a wide range of experimental conditions. In order to highlight similarities and/or physics peculiarities between various...
Abstract: Electron beam injection (EBI) to spherical tokamak (ST) plasmas which are non-inductively produced by electron Bernstein wave (EBW) has been carried out for the first time in LATE. When an electron beam with energy of 100 $\sim$ 600 eV and current up to 800 A is injected, the electron density increases to more than 30 times the plasma cutoff density and is maintained by EBW and EBI....
Electromagnetic emissions are seen in the frequency range covering the 1st to 7th harmonics of deuterium cyclotron frequencies on NSTX and NSTX-U [jointly, NSTX(-U)]. In many respects the fluctuations are similar to the ion cyclotron emission (ICE) seen in conventional tokamaks. Despite over three decades of experimental and theoretical studies, understanding of this phenomena remains...
The presentation is devoted to the thermal energy confinement study at the compact spherical tokamak (ST) Globus-M2 that was designed to reach toroidal magnetic field as high as $B_T$ =1 T and plasma current $I_p$ = 0.5 MA having a small plasma minor radius a = 0.22-0.23 m. The first neutral beam heating experiments on Globus-M2 were carried out using one deuterium beam with particle energy...
In the TST-2 spherical tokamak (ST), non-inductive start-up by lower-hybrid waves (200 MHz) has been studied and a plasma current of 27 kA was achieved [1]. However, further study is necessary to optimize the current drive [2]. An electron transport model is constructed to simulate electron diffusion in 2-dimensional phase space, and an X-ray emission model is constructed to simulate X-ray...
A series of preparations and experiments has been carried out to study the feasibility of current drive by Lower Hybrid Fast Wave in VEST since 2014[1~7]. The RF system had been prepared and installed until 2017. The power coupling study was conducted at about 3 kW in 2018 as shown in Figure 1(a). It was confirmed that LHFW could be launched by the magnetic probe wave measurement as shown in...
Accurate equilibrium reconstruction is crucial for the operation of MAST-U, as well as for stability analyses and disruption event characterization and forecasting. A neural network trained on ideal MHD stability calculations performed on NSTX data accurately predicts the no-wall stability limit for MAST. Stability calculations in projected high beta MAST-U equilibria show a gap between the...
Accurate prediction of tokamak core plasma temperature, density, and rotation, is essential for interpretation and preparation of current-day fusion experiments, optimization of plasma scenarios, and designing future devices. Time-evolved tokamak simulation on discharge timescales is typically carried out within an ’integrated modelling’ approach, where multiple models representing various...
Spherical Torus (ST) has been considered not only as a fusion neutron source but also as a commercial fusion reactor by noting its compactness and cost-effectiveness. However, compact ST devices may be difficult to reach high temperature with neutral beam injection (NBI) heating because of their small plasma size and weak field strength. Although high magnetic field by adopting high...
Recently, a new spherical Globus-M2 tokamak has begun to operate. This tokamak makes it possible to achieve a toroidal magnetic field of 1 T and a plasma current of up to 0.5 MA. The first neutral beam heating experiments on Globus-M2 demonstrated the increase of the thermal energy up to 8 kJ. This is nearly triple as high as in Globus-M. The energy confinement time increased more than two...
Introduction. - Turbulent transport in magnetically confined plasmas has found to be a global problem where multiple scales play important roles. This is especially true when ultimately dealing with burning plasmas [1,2]. An example - which is the center of the present contribution - is the the interaction between global MHD modes, like Alfven modes (AMs), mesoscale zonal flows (ZF), and...
Here we report our latest investigation of global ion heating/transport process during magnetic reconnection in the central solenoid (CS)-free merging spherical tokamak (ST) formation experiment on TS-6. Using a new 96CH/320CH ion Doppler tomography diagnostics, our full-2D imaging measurement clearly revealed that (i) magnetic reconnection initially forms localized hot spots in the downstream...
The China Fusion Engineering Test Reactor (CFETR) will be a large tokamak ($R_0 = 7$ m, $a = 2.2$ m) operating at moderately high magnetic field ($B_0 = 6.4$ T) with the mission of bridging the technological and scientific gaps between ITER and DEMO. Auxiliary current drive will be needed to supplement the self-driven bootstrap current and provide an MHD-stable current profile. This paper...
Introduction
Gyrotron oscillators and related components for Electron Cyclotron Resonance Heating (ECRH) and Current Drive of magnetically confined nuclear fusion plasmas are a major development at KIT. These activities include both, coaxial cavity gyrotron technology and conventional hollow cavity technology. Although hollow cavity 1 MW-class gyrotrons are widely used, mature and achieved...
Introduction
The low aspect ratio spherical tokamak MEDUSA (Madison Educational Small Aspect Ratio Tokamak) built by the University of Wisconsin-Madison (USA) and donated to Instituto Tecnológico de Costa Rica is currently being re-commissioned at PlasmaTEC. The main characteristics of this device (renamed MEDUSA-CR) are plasma major radius $R_o$ < 0.14 m, plasma minor radius a < 0.10 m,...
In support of establishing an integrated ITER scenario and also in preparation of the next DT JET-ILW campaign a series of experiments at different plasma currents and different auxiliary heating power levels are presently carried out at JET in which fuelling by gas puff and pellets are compared with respect to the energy confinement and impurity behaviour properties (1) . In previous...
We analyse properties of the radial turbulent transport of light to heavy impurities due to trapped-particle-driven turbulence in the core of tokamaks, based on a gyrokinetic bounce-averaged model. In particular, we describe how they depend on impurity concentration, charge, mass, gradients, and on the nature of the underlying dominant instability – either Trapped Electron Mode (TEM) or...
Recently, the high magnetic field tokamaks have attracted wide attention. It is extremely urgent to investigate the influence of high magnetic field on Coulomb collision and plasma transport. The high magnetic field will significantly affect the collision and related processes when the Larmor radius is smaller than Debye length which is the effective space size for Coulomb collision.
For...
Confinement of fast ions, especially fusion alpha particles, is one of the most important issues for a stellarator-based reactor. In classical stellarator designs fast particles are lost on drift timescales because of $\nabla B$ drift. Various optimization schemes aim to modify magnetic configurations to improve confinement of fast ions [1]. Wendelstein-type stellarators use the...
Numerical simulations with the COREDIV [1-3] code of JET hybrid discharge (#92398) with 32MW auxiliary heating, 2.2 MA plasma current and 2.8 T toroidal magnetic field, $H_{98}$ =1.3 without impurity seeding in the ITER-like wall (ILW) corner configuration are presented. The COREDIV code is self-consistent with respect to the core-SOL, as well as to impurities-main plasma and in spite of some...
The description of cross-field transport has long been identified the main limit for the predictive character of mean-field edge plasma codes. The coarse-graining of plasma fluid equations in time and space, by removing the fluctuations from the sought solution, makes it necessary to close the system of equations by an ad-hoc assumption on the nature and level of turbulence-driven transport....
Recent research on MHD instabilities in the VEST (Versatile Experiment Spherical Torus) (1) has been focused on the IRE (Internal Reconnection Event) which occurs frequently during current ramp down phase in spherical torus (2). Through this study, we investigate mechanism of the IRE, which is known to be closely related to major disruptions in conventional tokamaks. During the IREs, there is...
The H-Mode is the main regime of operation for present and future fusion devices like ITER. The transition from L-mode to H-mode (LH transition) has been studied for more than 20 years [1]. One important aspect of the LH transition is the abrupt suppression of the turbulent particle transport at the plasma edge [2]. Turbulence driven flows, i.e. zonal flows are believed to play a major role...
Sharp density and temperature gradients are often observed in tokamaks, for example, during formation of internal transport barriers. Very sharp background gradients tend to drive short scale ion temperature gradient modes (SWITGs) unstable [1]. Because of ultra-short scales of the instability and the absence of separation of scales, neither fluid models nor flux tube based gyrokinetic models...
One of the key issues of present tokamak experiments and future fusion devices operating with high-Z materials as plasma-facing components, such as ITER, is to prevent and control high-Z impurities accumulation. Accumulation of heavy impurities such as tungsten (Z=74, M=183.84u) in the inner core can have very deleterious effects on fusion performance due to large radiative power losses...
Magnetic reconnection is a basic process involving a topological rearrangement of the magnetic field lines on a time scale faster than allowed by classical dissipation mechanisms; it is observed in almost all magnetized plasmas, including those relevant for controlled nuclear fusion experiments [1]. The magnetic energy released during reconnection events can be dissipated - thus contributing...
The present gyrokinetic simulation study reveals roles of kinetic ion dynamics on the electron temperature gradient (ETG) turbulence and transport in magnetic fusion plasma, and provides new insights into a fundamental process in cross-scale interactions in plasma turbulence. The polarization effect due to finite ion gyroradius $\rho_i$ turns out to play essential roles not only in...
A. Introduction:
It is well known that plasma transport across magnetic field is largely controlled by the low frequency drift wave fluctuations. Gyrokinetic simulations play an important role in predicting the transport level due to neoclassical physics or turbulence. One of the leading successful methods is the particle-in-cell (PIC) method. A fully three-dimensional global toroidal code...
Transport in magnetically confined devices is one of the key subjects in the area of fusion relevant plasma research. Both theoretical and experimental investigations have shown that the plasma confinement is largely controlled by drift wave fluctuations and associated anomalous transport across the magnetic field lines, among whom the toroidal electrostatic ion temperature gradient mode (ITG)...
Model-based between-shots and real-time actuator trajectory planning will be critical to achieving high performance scenarios and reliable, disruption-free operation in present-day tokamaks, ITER, and future fusion reactors. Key to the success of such tools is the availability of models that are both accurate enough to facilitate useful decision making and fast enough to enable optimization...
In the last few years, nonlinear modelling and data analysis tools have improved in several respects, in particular to deal with physics issues encountered in magnetically confined toroidal pinches, such as the Reversed Field Pinch and Tokamak configurations. Benchmark-verified codes for 3D nonlinear MHD basic modelling find a reasonable comparison (validation) against a number of experimental...
Presence of a large population of fast particles may qualitatively modify the tokamak equilibrium from the one that can be described by the Grad-Shafranov equation$^1$. Here, we present the first experimental observation of such modification by the lower-hybrid (LH) wave driven fast electrons in a non-inductive plasma. We have performed equilibrium fitting based on the extended...
Multiple blob/plasmoid structures were measured for the first time in current sheet of merging spherical tokamak (ST) plasmas in TS-3U and TS-4U, using new high-resolution and high-accuracy print-circuit-board (PCB) type magnetic probe array. We found (i) formation of multiple current sheet blobs: initially one, finally three or four, partly due to current sheet deformation by Hall effect,...
In this paper we look at the functional requirements that NBI has in the various envisaged plasma scenarios for tokamak fusion reactors of the DEMO and fusion power plant (FPP) class and compare them with the constraints imposed by neutral beamline physics and technology. We show in particular that there is an intermediate beam energy range in which beamlines are unattractive because of size....
The two beam lines of the ITER neutral beam injection (NBI) system will deliver an overall heating power of $33.3\,\mathrm{MW}$ into the plasma [1]. The systems are based on negative hydrogen or deuterium ions generated in large ($2\times1\,\mathrm{m}^2$) and powerful ($\mathrm{P}_{\mathrm{RF}}$ up to $800\,\mathrm{kW}$) radio frequency (RF) driven ion sources. The design of these ion sources...
A negative hydrogen ion source based neutral beam injector system (NNBI) is an important auxiliary heating and current drive system for ITER-like fusion reactor machines. Cs vapour injection into a negative hydrogen ion source is inevitable to achieve higher negative ion production yield through surface process mechanism on a low work-function surface. However, the introduction of Cs vapour...
Turning Tore Supra into the WEST configuration has been achieved through the development of new plasma-facing components (PFCs) with tungsten surfaces in order to provide a full tungsten environment, as foreseen for future fusion devices. In this framework, tungsten-coated PFCs were developed and qualified according to well-defined specifications, including fatigue tests under high heat flux...
Fusion research activities in the Republic of Kazakhstan is carried out under the budget programs of the Ministry of Energy; grant financing of the Ministry of Education and Science; within the framework of the Atom-CIS intergovernmental agreement on the joint use of KTM tokamak and the joint KTM research program of the CIS countries; intergovernmental agreement between Kazakhstan and EURATOM...
The ion source of IPR NBI system is positive hydrogen ion based JET PINI multipole bucket type plasma source. One of its critical components is water cooled Back Plate (BP) shown in fig.1 (inset) [1]. The average heat load on BP is 2 MW/m^2. Assembly of back plate consists of OFHC copper cooling plate of size 588×318×4 mm^3 with 35 inner and 8 outer cooling grooves each of size 4+0.1×1.8+0.2...
Plasma current ramp-up experiment with 28 GHz second harmonic electron cyclotron (EC) wave has been in progress in the QUEST spherical tokamak. Through oblique injection of the EC wave, the observation presents that (i) the highest level of plasma current $I_{p}$ as non-inductive EC ramp-up is attained with almost zero loop voltage, $V_{loop} \sim$ 0, by long-pulse radio frequency (RF)...
Understanding the dynamics of suprathermal ions in a plasma is of paramount importance in the path to designing a fusion reactor. For example, achieving the burning plasma regime requires an adequate confinement of the suprathermal alpha particles arising from the deuterium-tritium reactions, so that they can become a major contributor to plasma heating.
In TORPEX [1], a basic toroidal...
The current drive and heating system is fundamental for prolonged tokamak operation, so that development of adequate Neutral Beam Injectors requires: high current density (>200 A/m2); long operation (1h pulse) and durability (years); good beam quality[1.,2]. Moreover, if net energy production is required, high energy efficiency is required, perhaps with some energy recovery system.
As a...
A novel quasilinear turbulent transport model DeKANIS has been constructed, which is suitable to investigate formation mechanisms of density and temperature profiles. DeKANIS predicts turbulent particle and heat fluxes in a quasilinear limit, considering the diagonal (diffusion) and off-diagonal (pinch) transport mechanisms individually. The predictions are performed quickly with...
To support the R&D of China Fusion Engineering Test Reactor (CFETR) $^1$, a Comprehensive Research Facility for Fusion Technology (CRAFT) program has been launched at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). Within the CRAFT program, a divertor material/component testing project is authorized to address some key R&D issues of plasma-facing materials and components...
DEMO and fusion power plants beyond it require robust materials to ensure durable and safe operation as well as commercially competitive construction and dismantling design. One of the main challenges in the development of those materials is assessment of irradiation effects, originating from the nuclear fusion reaction which generates 14 MeV neutrons damaging the material’s atomic lattice. So...
Recent experiments carried out at the High heat flux test Facility (HHFTF) (1)(2) to study Critical heat Flux (CHF) margins for Plasma Facing components (PFCs) suggest a possible dependence of the CHF on the temporal power profile, leading to a reduction of CHF limits that could impact design margins for Plasma Facing components. This paper reports possibly for the first time, experimental...
The RFX-mod experiment (R/a=2m/0.459m) was a Reversed Field Pinch device, encompassed within a matrix of 48x4=192 independently controlled saddle coils, which characterized plasma current regimes up to 2MA. Based on RFX-mod results, an upgrade of the boundary is being designed and implemented (RFX-mod2), which will start the operation in 2021. The main change compared to the RFX-mod device is...
Understanding the confinement of Fast Ions (FI) in tokamaks is fundamental for the successful operation of ITER and the development of fusion power plants based on DT reactions. Spherical tokamaks make it possible to test confinement and operational regimes in ITER-like scenarios in the presence of energetic particle modes and Alfvén instabilities. Descriptive and predictive modelling of the...
The negative ion beam optics was studied in real and phase spaces. It was found that (i) the negative ion density is the dominant plasma parameter for the meniscus formation, (ii) single beamlet is decomposed by multiple beam components, and (iii) the beamlet focusing by an electrostatic lens in acceleration gap is characterized by the variation of the distance between beam axis of each...
Understanding the effects of neutron irradiation impact on materials is one of the outstanding issues in the development of fusion technologies. The opportunity to learn from material exposure within the Joint European Torus (JET) tokamak environment during deuterium-tritium (D-T) operations and take advantage of the significant 14 MeV neutron fluence to irradiate samples that will be used in...
We report on new results in the theory of electromagnetic turbulence driven intrinsic current. The intrinsic current driven by electromagnetic (EM) micro-turbulence could be important for ITER because its modification to the local current profile may significantly affect the MHD instability. This paper focuses on the intrinsic current driven by both EM electron temperature gradient (ETG)...
In previous work [1 & 2], the author developed a computer code to simulate the cooling processes of a flat tile divertor in both normal and off-normal operation. In the present work, the previous model is modified and updated to deal with the ITER tungsten divertor monoblock in order to simulate its performance under both steady and transient states. The model predicts the thermal response of...
Understanding the effect of high impurity concentration in tokamaks is crucial for future tokamak operation such as ITER and DEMOs, since the impurity in tokamaks dilutes the fuels and reduces fusion power. This can also result in plasma instabilities and affects the overall performance of the machines. On the other hand, impurity radiation in SOL region could mediate the heat load to...
Trustworthy gyrokinetic (GK) or two-fluid (2F) edge turbulence simulations require an accurate representation of collisions in gyro-centre coordinates or by appropriate transport coefficients, respectively. GK collision operators have so far been limited either to models for the (trustworthy) Landau-Fokker-Planck operator which have been transformed to the GK gyro-centre coordinates (1),...
Impurity transport has been a very active area of research in plasma physics due to the concern that high core impurity concentration represents to the performance of future fusion reactors. In stellarators, where neoclassical transport is larger than in tokamaks, the theoretical and numerical impurity transport problem has been practically limited to the framework of neoclassical theory. In...
The transport, accumulation and control of the W impurity ions are very important issues for the development of ITER.
This work is an analysis of the heavy ion turbulent transport. A new pinch mechanism is found. This strongly nonlinear process is theoretically validated in the frame of a complex test-particle model. The conditions for which the pinch velocity $V$ is experimentally relevant...
A device modeling the tokamak KTM lithium divertor manufactured and tested.
Tokamak KTM (Kazakhstan tokamak materials science) is a joint project of Kazakh and Russian scientists and has the status of the first technological tokamak for reactor materials science in the world. The main physical parameters of the KTM tokamak are described in ref. 1.
The main task of KTM is research on the...
Following the remarkable progress in magnetohydrodynamic (MHD) stability control in the advanced beam driven field-reversed configuration (FRC) at TAE Technologies, Inc., turbulent transport has become one of the foremost obstacles on the path towards an FRC-based fusion reactor. Significant efforts have been made to kinetic simulation capabilities in FRC magnetic geometry. The Gyrokinetic...
