Dr
Shizuo Inoue
(Japan Atomic Energy Agency)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
We report a numerical study of a mode locking in tokamaks, which reveals an active stabilization effect of the control field against the locking event. We developed the resistive MHD simulation code “AEOLUS-IT”, which can simulate mode locking, where the magnetic island interacts with error/control field, under JT-60SA class high magnetic Reynolds number condition. The developed code...
Dr
Victor Lukash
(National Research Centre «Kurchatov Institute», Pl. Kurchatova 1, Moscow 123182, Russia)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Disruption mitigation with use of the massive injection of noble gases (MGI) is widely used and experimentally validated on contemporary tokamaks. The disruption mitigation system (DMS) in ITER is aiming to subsequently or simultaneously achieve a solution for 3 main goals including mitigation of the heat loads on the plasma facing components during thermal quenches (TQs), keeping tolerable...
Dr
Jungpyo Lee
(MIT Plasma Science and Fusion Center, USA)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
In this study, the maximum achievable elongation in a tokamak against the n=0 MHD resistive wall mode is investigated theoretically and compared with experimental observations. A highly elongated plasma is desirable to increase plasma pressure and confinement for high fusion power output. However, there is a limit on the maximum achievable elongation which is set by vertical instabilities...
Dylan Brennan
(Princeton Plasma Physics Laboratory)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Well before ITER operations begin, we must have a comprehensive understanding of the potential for runaway electron generation, as well as methods for their control and mitigation, as the destructive potential to the plasma facing components is severely intolerable. This makes for a unique situation in requiring an assessment based on plasma theory and computation well before validation...
Dr
Jose Ramon Martin-Solis
(Universidad Carlos III de Madrid)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Runaway electrons (REs) generated during disruptions are usually found to deposit their energy in very short pulses and on localized areas of the plasma facing components (PFCs). In ITER, there is serious concern about the potential that large amounts of MeV REs generated during the disruption current quench (CQ) have for erosion / melting of the PFCs. Although zero-dimensional (0-D) modeling...
Dr
Ryosuke Ikeda
(Japan Atomic Energy Agency)
18/10/2016, 08:30
FIP - Fusion Engineering, Integration and Power Plant Design
Poster
Mega-watt gyrotrons with frequency tuning have become essential devices in fusion science to perform effective EC H&CD. JAEA is developing two types of multi-frequency gyrotrons equipped with a triode magnetron injection gun for ITER and JT-60SA. A TE31,11 mode, which is a candidate mode for 170 GHz oscillation, has sufficient margin for cavity heat-load in 1 MW operation, and it has a great...
Dr
Tsuyoshi Kariya
(Plasma Research Center, University of Tsukuba)
18/10/2016, 08:30
FIP - Fusion Engineering, Integration and Power Plant Design
Poster
Megawatt (MW) gyrotrons with a wide frequency range from 14 to 300 GHz are being developed for the collaborative Electron Cyclotron Heating (ECH) study of advanced fusion devices and DEMO reactor. (1) In the first experiment of 300 GHz gyrotron, an output power of over 0.5 MW with TE32,18 single-mode was achieved with a pulse width of 2 ms. This is the first report of MW level oscillation with...
Prof.
Volodymyr Mykhaylenko
(Pusan National University)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Numerous experimental observations from number of tokamaks and stellarators have found large nearly sonic magnetic field aligned (parallel) shear flows that are peaked at the last closed flux surfaces and extend for a few centimeters into the plasma and into the far SOL. The important consequence is that these plasma regions are unstable in the presence of shear flows. The shear flows along...
Dr
Remir Shurygin
(NRC ‘Kurchatov Institute’, Moscow, Russia)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Numerical calculations of nonlinear MHD equations in frames of reduced two-fluid Braginskij equations for geodesic acoustic modes (GAM) with n = 0, m = 0, +1, -1 in high collisional edge tokamak plasma were performed. N = 0, m = 0, +1, -1. It was shown that with account of parallel dissipation (finite conductivity sigma//) allows us to obtain the steady state equilibrium solutions for GAMs....
Prof.
Zhongtian Wang
(School of Science, Xihua University;Southwestern Institute of Physics)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
An e-fishbone frequency jump has been observed on Tore Supra , which is important for the redistribution of energetic electrons and energetic particle losses. E-fishbone periodic frequency jump phenomena are also observed on HL-2A . Soft X-ray tomography shows that the poloidal and toroidal mode numbers are 1/1 and 2/2 with the frequency jump. In this paper we present a theoretical base of the...
Prof.
Masaru FURUKAWA
(Graduate School of Engineering, Tottori University)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The theory of matched asymptotic expansion for resistive MHD is well established for linear modes [1] and for weakly nonlinear evolution [2]. Since then many applications of the Rutherford equation [2] have made much progress in fusion research, especially in the neoclassical tearing mode (NTM) studies [3]. However, the theoretical framework is still based on the Rutherford equation...
Mr
PATRICK MAGET
(CEA)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The confinement degradation of Tokamak plasma by magnetic islands motivates numerous approaches to better understand their dynamics and possible suppression. We report here on nonlinear simulations using a consistent two-fluid implementation of neoclassical friction forces in the framework of the toroidal Magneto-Hydro-Dynamic model of the XTOR code, recently improved with the implementation...
Dr
Junya Shiraishi
(Japan Atomic Energy Agency)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
We found that inclusion of self-consistent rotation effect in the energetic particles’ dynamics has significant impact on resistive wall mode (RWM) stability in tokamaks. For the first time, we apply the extended kinetic-magnetohydrodynamic (MHD) theory for rotating plasmas to energetic particles. The theory invokes an extended energy exchange term between the MHD mode and energetic particles’...
Dr
JUNICHI HIRATSUKA
(Japan Atomic Energy Agency)
18/10/2016, 08:30
FIP - Fusion Engineering, Integration and Power Plant Design
Poster
In order to realize the negative-ion-based neutral beam (NB) systems for ITER and JT-60SA, development of the Multi-Aperture and Multi-Grid (MAMuG) electrostatic accelerator is one of common critical issues. For these NB injectors, 5- and 3-stage MAMuG accelerators are being developed to achieve the acceleration of negative ion beams up to 1 MeV, 40 A (200 A/m^2) for 3600 s and 0.5 MeV, 22 A...
Dr
Nikolay Ivanov
(Kurchatov Institute)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The non-axisymmetric halo current arising due to loss of plasma vertical equilibrium, the so-called vertical displacement event (VDE), during plasma disruption in vertically elongated tokamak can be one of possible sources of helical magnetic perturbation. This perturbation penetrate into plasma producing magnetic islands in the vicinity of resonant magnetic surface with the same helicity....
Prof.
Bruno Coppi
(M.I.T.)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
In the context of a two-fluid theory of magnetic reconnection [1], when the longitudinal electron thermal conductivity is relatively large, the perturbed electron temperature tends to become singular [2] in the presence of a reconnected field component and an electron temperature gradient. A transverse thermal diffusivity is introduced in order to remove this singularity while a finite...
Linjin Zheng
(University of Texas at Austin)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
MHD stability of ITER H-mode confinement is investigated with bootstrap current included for equilibrium, together with diamagnetic drift and rotation effects for stability. The ITER pedestal has high temperature, so the bootstrap current is large and diamagnetic effects are important. We construct numerically ITER equilibria with bootstrap current taken into account.Especially, we have...
Dr
Alexandre Fil
(Princeton University)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
In this paper we present high level simulations and modeling of pedestal control for NSTX-U. Real-time pedestal control is a crucial topic for future fusion reactors and ITER where pedestal has to be kept Edge-Localized-Modes (or ELMs) free. We developed and tested many different control schemes to adjust and regulate the pedestal at DIII-D and we plan to test them on NSTX-U. But to do this it...
Prof.
Grigory Denisov
(Institute of Applied Physics Russian Academy of Sciences)
18/10/2016, 08:30
FIP - Fusion Engineering, Integration and Power Plant Design
Poster
Gyrotrons for plasma fusion installations usually operate at frequencies 40-170 GHz. Requested output power of the tubes is about 1 MW and pulse duration is between seconds and thousands seconds. To provide operation with indicated parameters the gyrotrons have very large transverse cavity sizes, output barrier windows made of CVD diamond discs, effective collectors with particle energy...
Dr
Marina Becoulet
(IRFM/CEA)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The non-linear MHD modelling of full ELM crash dynamics was performed using JOREK code for KSTAR pulse parameters and compared to the ECEI diagnostic observations. Some experimentally observed trends were reproduced in modelling. In particular the localization of the peeling-ballooning modes in the pedestal region inside the separatrix, the most unstable modes toroidal numbers and structures,...
Dr
Shimpei Futatani
(Barcelona Supercomputing Center)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
ITER operation relies on the achievement of the H-mode confinement regime, which is expected to lead to the quasi-periodic triggering of ELMs (Edge Localized Modes). The energy fluxes associated with natural ELMs will produce excessive erosion and/or damage on the plasma facing component. Controlled triggering of ELMs by the injection of small pellets at frequencies exceeding those of natural...
Dr
Francois Orain
(Max Planck Institute for Plasma Physics, Garching, Germany)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
One of the foreseen methods to control the Edge Localized Modes (ELMs) in ITER is the application of Resonant Magnetic Perturbations (RMPs), proved capable to mitigate or suppress ELMs in existing tokamaks. However the significant uncertainties that remain regarding the way plasma flows and ELMs interact with RMPs must be overcome to give reliable predictions for ITER. This work aims at...
Dr
Stephen jardin
(UsPPPL)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The goal of the present work is to better understand and develop a predictive capability for when approaching and crossing a MHD linear instability boundary leads to a thermal quench and subsequent disruption (hard limit), and when it just leads to increased transport or small amplitude oscillations (soft limit). Understanding the difference between hard and soft limits is crucial for...
Jacob King
(Tech-X Corporation)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
It is desirable to have an ITER H-mode regime that is quiescent to edge-localized modes (ELMs). ELMs deposit large, localized and impulsive heat loads that can damage the divertor. A quiescent regime with edge harmonic oscillations (EHO) or broadband MHD activity is observed in some DIII-D, JET, JT-60U, and ASDEX-U discharge scenarios [Garofalo et al, PoP (2015); Burrell et al., PoP (2012);...
Dr
FENG LIU
(University of Nice)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Non-linear MHD simulations of DIII-D QH-mode plasmas have been performed with the non-linear MHD code JOREK as a first step towards determining whether the physics mechanisms leading to the QH-mode behaviour would be at work in ITER plasmas and thus whether this confinement regime can be considered as an alternative to the controlled Type I ELMy H-mode for ITER high Q operation. In the...
Prof.
Abhijit Sen
(Institute for Plasma Research)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
We report on nonlinear simulation studies on the dynamical behaviour of ELMs under the influence of RMPs and/or the presence of pellet injection using a two-fluid
initial value electromagnetic nonlinear global code (CUTIE). The full set of model fluid equations are solved for the so-called mesoscale, an intermediate scale between
the device size and the ion gyroradius, incorporating...
Dr
Juhyung Kim
(National Fusion Research Institute)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
We investigate the effect of resistivity, mainly on pitch resonant responses induced by plasma rotation. As a confirmation of the newly developed code, we report that the detailed physics may not be important since the pitch resonant response is relatively weak at high resistivity and the penetration is strongly dependent on plasma rotation at low resistivity. At low resistivity, ion...
Dr
Zhirui Wang
(Princeton Plasma Physics Laboratory)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Externally applied, nonaxisymmetric magnetic perturbations can strongly modify tokamak plasmas, leading to the plasma response. Plasma response, often closely related to the resonant field amplification and to the ELM control using magnetic coils, has been systematically observed in tokamak experiments. In particular, the importance of drift kinetic effects on modifying the plasma response has...
Dr
Vladimir Pustovitov
(National Research Centre “Kurchatov Institute”)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The paper is devoted to theoretical description of plasma stability in toroidal fusion systems with a resistive wall. Its aim is elimination of contradictions between different approaches and between theory and experiment. The study is related to two predictions stated as theorems, see [H. Tasso and G. N. Throumoulopoulos, Phys. Plasmas 18, 070702 (2011)] and references therein. One is that an...
Dr
ZHIBIN GUO
(University of California, San Diego)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
We demonstrate E × B shear governs the dynamics of the cross phase of the peeling-ballooning-(PB)mode-driven heat flux, and so determines the evolution from the edge-localized (ELMy) H mode to the quiescent (Q) H mode. A physics-based scaling of the E × B shearing rate for accessing the QH mode is predicted. The ELMy H mode to the QH-mode evolution is shown to follow from the conversion from a...
Dr
Fatima Ebrahimi
(Princeton University/PPPL)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
In a low-aspect-ratio Spherical Torus (ST), and in particular in an ST-based fusion reactor, due to the restricted space for a central solenoid, elimination of the central solenoid, and thus non-inductive current-drive techniques, is necessary. Transient Coaxial Helicity Injection (CHI) is a leading candidate for plasma start-up and current formation in NSTX-U. In NSTX, transient CHI has...
Dr
Indranil Bandyopadhyay
(ITER-India, Institute for Plasma Research)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Accurate modeling of major disruption (MD) and vertical displacement events (VDEs) in ITER is necessary to determine the halo current amplitude during these events and hence the electromagnetic loads on the machine components. The modeling of these events were originally done by DINA code and the results were later validated by TSC simulations and they both agree remarkably well when similar...
Dr
Joachim Geiger
(Max-Planck-Institute for Plasma Physics, Greifswald, Germany)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Wendelstein 7-X aims at quasi-steady-state operation to demonstrate the reactor-viability of stellarators optimized with respect to MHD-equilibrium and -stability, low neoclassical transport, small bootstrap current and good fast-particle confinement. To reach this goal an island divertor is foreseen for particle and energy exhaust, which utilizes the naturally occurring boundary islands...
Allan Reiman
(Princeton Plasma Physics Lab)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
In toroidal MHD equilibria, pressure can generally be regarded as constant on the flux surfaces. The regions near small magnetic islands, and those near the X-lines of larger islands, are exceptions. We show that the variation of the pressure within the flux surfaces in those regions has significant consequences for the pressure driven current. We further show that the consequences are...
Dr
Ahmet Aydemir
(National Fusion Research Institute, Daejeon, Korea)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Explosive growth of a ballooning finger is demonstrated in nonlinear magnetohydrodynamic calculations of high-beta disruptions in tokamaks. The explosive finger is formed by an ideally unstable n=1 mode, dominated by an m/n=2/1 component. The quadrupole geometry of the 2/1 perturbed pressure field provides a generic mechanism for the formation of the initial ballooning finger and its...
Tommaso BOLZONELLA
(ItRFX)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
A careful numerical evaluation of MHD stability and of active control strategies is of paramount importance to reach one of the main goals of JT-60SA (Super Advanced) device, namely the development and qualification of high beta_N, steady-state regimes for future reactors like DEMO. Thanks to its powerful and flexible additional systems for heating and current drive, to its shaping...
Dr
Jong-Kyu Park
(Princeton Plasma Physics Laboratory)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Control of toroidal rotation is an important issue for tokamaks and ITER since the rotation and its shear can significantly modify plasma stability from microscopic to macroscopic scales. A potentially promising actuator for the rotation control is the non-axisymmetric (3D) magnetic perturbation, as it can substantially alter toroidal rotation by neoclassical toroidal viscosity (NTV). The...
Dr
Akinobu Matsuyama
(Japan Atomic Energy Agency)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Runaway electron (RE) generation after major disruptions is simulated over a full current quench (CQ) timescale, which covers both fast MHD events and slow RE avalanche amplification. A novel 3D RE analysis code EXTREM allows us to study (1) fast, global transport of REs with macroscopic MHD modes and (2) the RE generation triggered by electric fields induced owing to fast MHD dynamics (i.e.,...
Dr
Hideo Nuga
(Kyoto University)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The suppression and mitigation of runaway electron (RE) is an urgent issue of large scale tokamak operation. The contribution of hot-tail effect, which arises from the fast thermal quench, is studied using Fokker-Planck simulation. It is found that if the thermal quench is fast enough to invoke the hot-tail effect, it may produce seed REs and enhance total RE current even in a high electron...
Prof.
Katsuji ICHIGUCHI
(National Institute for Fusion Science)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Effects of the poloidal shear rotation on the magnetohydrodynamic (MHD) stability of interchange modes in a Large Helical Device (LHD) configuration are numerically studied. This simulation is the first three-dimensional (3D) full-MHD nonlinear analysis for heliotron plasmas including the flow.
In LHD, the highest average beta value of 5.1% is successfully obtained in the configuration where...
Dr
Emanuele Poli
(Max-Planck-Institute for Plasma Physics, Germany)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Our present understanding of the physics of the tearing mode (TM) still does not allow a quantitative prediction of TM evolution in fusion reactors. The early phase of a TM, in particular, is determined by a complex interplay of different processes. We investigate the physics of the TM via gyrokinetic (GK) simulations in toroidal geometry using the code GKW. Two routes are followed, namely...
254.
Towards powerful negative ion beams at the test facility ELISE for the ITER and DEMO NBI system
Prof.
Ursel Fantz
(Max-Planck-Institut fuer Plasmaphysik)
18/10/2016, 08:30
FIP - Fusion Engineering, Integration and Power Plant Design
Poster
The negative ion source test facility ELISE represents an important step in the European R&D roadmap towards the neutral beam injection (NBI) systems at ITER. ELISE provides early experience with operation of large RF-driven negative hydrogen ion sources. Its source area is 1x0.9 m2 and the net extraction area of 0.1 m2, formed by 640 apertures, corresponds to a half-size ITER source. The test...
Dr
Hideaki Miura
(National Institute for Fusion Science)
18/10/2016, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Nonlinear growth of ballooning modes in a heliotron device is studied by means of two-fluid numerical simulations. A model to substitute an influence of the scales smaller than the grid size, Sub-Grid-Scale (SGS), on the scales larger than the Grid Scale (GS) is introduced. A simulation with the SGS model, a Large Eddy Simulation (LES), of two-fluid MHD model successfully shows growth of the...
