Ms
Rachael McDermott
(Germany)
10/10/2012, 08:30
Poster
Recently, ASDEX Upgrade has made significant contributions to momentum transport studies thanks to the upgrade of the core charge exchange recombination spectroscopy system, which now produces much higher quality ion temperature and toroidal rotation profiles. This upgrade enabled the development of an intrinsic rotation database that contains over 200 observations. The edge rotation on AUG is...
Mr
Yuejiang SHI
(Republic of Korea)
10/10/2012, 08:30
Poster
Toroidal rotation is important for control of stability and transport in tokamaks. Intrinsic rotation is self-generated by ambient turbulence via the non-diffusive residual stress, which motivates the question of how macroscopic rotation profiles will evolve in response to changes in the ambient micro-turbulence. One ‘control knob’ for the micro-turbulence population is the heating mix of NBI...
Mr
Hajime Urano
(Japan)
10/10/2012, 08:30
Poster
Dependence of heat transport on isotopic composition is investigated in conventional H-mode plasmas for the application to ITER. The identical profiles of electron density, electron temperature and ion temperature are obtained for hydrogen and deuterium plasmas while the required power becomes clearly larger for hydrogen, resulting in the reduction of the heat diffusivity for deuterium.
The...
Mr
Hiromi Takahashi
(Japan)
10/10/2012, 08:30
Poster
Realization of high-T_i plasmas is one of the most important issues in helical plasmas, which have an advantage for steady-state operation comparison with tokamak plasmas. Since 2010, newly installed perpendicular-NBI with the beam energy of 40 keV has been operational in the Large Helical Device (LHD) and the total-heating power of perpendicular-NBIs increased from 6 MW to 12 MW. Such...
Mr
Matthew Reinke
(USA)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
In the Alcator C-Mod tokamak, strong, steady-state variations of molybdenum density within a flux surface are routinely observed in plasmas using hydrogen minority ion cyclotron resonant heating. In/out asymmetries, up to a factor of 2, occur with either inboard or outboard accumulation depending on the major radius of the minority resonance layer. Quantitative comparisons between existing...
Mr
Mario Podesta
(USA)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
The National Spherical Torus Experiment (NSTX) is investigating the use of lithium as a candidate plasma-facing material to handle the large power flux to the wall of fusion devices. To investigate the possible contamination of the core plasma caused by lithium influx from the plasma boundary, measurements of core lithium concentration, nLi(R), have been performed in diverted H-mode plasmas of...
Mr
Masayuki Yoshikawa
(Japan)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Correlation between the drift type fluctuation and anomalous radial transport was observed in GAMMA 10 and these fluctuations were suppressed by electron cyclotron heating (ECH) driven radial electric field. We have developed new diagnostics to investigate for these studies, which are a simultaneous two points measuring gold neutral beam probe (GNBP) for the radial electric field and potential...
Ms
Lorella Carraro
(Italy)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
High current (I_p up to 2 MA) operations in RFX-mod access the Single Helical Axis (SHAx) regime, during which the magnetic dynamics is dominated by the innermost resonant mode (m=1, n=-7): the magnetic chaos level is reduced and internal magnetic field configuration is close to a pure helix.
The best plasma performances at high Ip with pure SHAx states featuring electron transport barriers...
Ms
Natalia Kirneva
(Russian Federation)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
This paper reports on recent TCV experiments performed to investigate the confinement of electron-heated discharges simulating reactor relevant conditions with dominant electron heating. The dependence of the L-mode confinement properties on the electron heating power density profile width has been analyzed for the first time. Discharges with on-axis peaked ECR heating profiles with half-width...
Mr
Bernardo Zurro
(Spain)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
In TJ-II we have been able to detect suprathermal ions by passive spectroscopy in the plasma interior and by means of a luminescent probe for those escaping from the confinement region. We have measured their temporal evolution in both cases and with several vision cords in the first system. The luminescent probe has very high sensitivity and it was operated in a height pulse analysis regime....
Mr
Tohru MIZUUCHI
(Japan)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
This paper discusses the effects of fueling control on plasma performance in Heliotron J, a helical-axis heliotron device with an L/M = 1/4 helical coil (R_0 = 1.2 m, <a_p> = 0.12-0.17 m, <B_0> < 1.5 T). Here, L and M are the pole number of the helical coil and its helical pitch number, respectively. Based on recent installation/improvement of diagnostics, which give us plasma profile database...
Mr
Weixing Ding
(UCLA)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Magnetic fluctuations have been long observed in various magnetic confinement configurations. These perturbations may arise naturally from plasma instabilities such as tearing modes and energetic particle driven modes, but they can also be externally imposed by error fields or external magnetic coils. It is commonly observed that large MHD modes lead to plasma locking (no rotation) due to...
Mr
Hongjuan Sun
(Republic of Korea)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Resolving the long standing question of whether tokamak transport is local or non-local is crucial for successful predictive modeling of ITER. Though most theoretical and modeling schemes are based on the local Fickian formulation, there are many conspicuous experimental results suggesting otherwise. Most notable of these is the cold pulse nonlocality in which edge cooling produces a central...
Ms
Natalia Kirneva
(Russian Federation)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Investigation aimed at the understanding of a general origin of the thermal and particle transport has been carried out in regimes with the dominant electron heating in the T-10 tokamak. ECR heating with the power of 0.25-3 MW has been used. Two scans have been summarized for the analysis: density scan at the constant EC heating power value, (P_EC=0.9 MW, P_tot=1 MW), and recently obtained EC...
Mr
Marco Valisa
(Italy)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
RFX-mod embodies the characteristics of flexibility of an experiment where cross-configuration studies can be carried out. Such condition has aroused lively interest and has led to important collaborations with laboratories worldwide (JT60-SA, DIII-D, AUG, PPFL, PPPL, Auburn University, ORNL). As a Reversed Field Pinch (RFP), RFX-mod addresses many basic physics issues that are common to both...
Mr
Federico Felici
(Netherlands)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
A new paradigm for real-time plasma profile reconstruction is demonstrated in the TCV tokamak. Predictions based on physics models are merged with available real-time diagnostic data to construct a self-consistent profile state estimate compatible with a time-dependent model of transport processes in the plasma. This is enabled by a new RApid Plasma Transport simulatOR (RAPTOR), implemented in...
Mr
Miklos Porkolab
(USA)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Transport in ohmically heated plasmas in Alcator C-Mod was studied in both the linear (LOC) and saturated (SOC) confinement regimes and the importance of turbulent transport was established with gyrokinetic analysis. The presence of turbulence was measured with an absolutely calibrated phase contrast imaging (PCI) method and was compared with theoretical predictions. While in the SOC regime...
Mr
Andreas Dinklage
(Germany)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Stellarator-Heliotrons (S-H) offer an alternative route to steady-state fusion reactors and one mission of the largest S-H devices is to provide a physics basis for burning S-H plasmas. The S-H devices closest to reactor conditions play key-roles: the Large Helical Device and Wendelstein 7-X (under construction). In contrast to tokamaks, 3D magnetic fields in S-H lead even in the plasma core...
Mr
Thomas Pütterich
(Germany)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
For the ITER-like wall at JET, the screening of the divertor W source is investigated along with possibilities to influence the central metal transport. From visible spectroscopy the erosion fluxes of W are determined at the outer strike line, which intersects the horizontal, solid tungsten target tile. The W-fluxes as determined by visible spectroscopy are related to the W-content in the main...
Mr
Jay K. Anderson
(USA)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Classical behavior of two types of ions (impurity and NBI-born fast bulk) has recently been observed in the MST RFP plasma. Both have positive implications, as NBI-born fast ions (with normalized Larmor radius similar to that of fusion alphas in a reactor-sized plasma) are well confined and transfer their energy to the background plasma. Classical transport of impurities in this specific...
Mr
Daniel Den Hartog
(USA)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Comparison of measurements made in the MST Reversed-Field Pinch (RFP) to the results from extensive single-fluid nonlinear resistive MHD simulations provides two key observations. First, thermal diffusion from parallel streaming in a stochastic magnetic field is reduced by particle trapping in the magnetic mirror associated with the toroidal equilibrium. Second, the structure and evolution...
Mr
Timothy C. Luce
(USA)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Drift wave theories (ion or electron temperature gradient modes) have an onset threshold in gradient beyond which the flux transported is predicted to increase very rapidly. For fixed boundary condition, this type of behavior would manifest itselfg as a strong resistance to change in the temperature profiles or “stiffness”. A new series of experiments exploiting the unique tools available in...
Mr
Brian A. Grierson
(USA)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Recent experimental comparisons of the bulk deuterium ion toroidal rotation to neoclassical theory have revealed a significant discrepancy with neoclassically predicted bulk ion toroidal rotation. Performance of ITER plasmas will depend strongly on the level of main-ion toroidal rotation achieved due to the beneficial effects of rotation for stabilization of MHD as well as the toroidal...
Mr
Wulu Zhong
(China)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
For the first time, a high performance ELM-free H-mode was observed in the HL-2A tokamak.It was realized with Electron Cyclotron Resonance Heating (ECRH) and co-current Neutral Beam Injection (NBI) heating. The H98y2 factor increased by about 40-50% compared with the one before the transition. This regime is triggered by a minor disruption via the edge current change, where the temperature...
Mr
Xuru Duan
(China)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
In next-generation fusion devices reduction of impurity concentration is of great importance for mitigating the radiation losses and the fusion fuel dilution to achieve a high confinement and high density plasma with a high radiation loss fraction at the edge for divertor compatibility. In HL-2A tokamak electron cyclotron resonance heating (ECRH) has been extensively carried out for the...
Mr
Carlos Hidalgo
(Spain)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Understanding the relation between free energy sources and transport is a fundamental issue in systems far from thermal equilibrium that has been debated for years. Instabilities governed by a gradient will typically produce transport events at all scales connecting different regions of plasma. In the case of a critical gradient mechanism, the functional dependence between the transport flux...
Mr
Nathan Howard
(MIT - Plasma Science and Fusion Center)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
For the first time, quantitative comparison of nonlinear gyrokinetic simulation and experiment is found to demonstrate simultaneous agreement in the ion heat and impurity transport channels. Linear and nonlinear simulation was used to interpret changes in measured transport as changes in turbulence drive and suppression terms. Extensive sensitivity analysis of the GYRO predicted impurity...
Mr
Siye Ding
(China)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Inward energy pinch in electron channel is observed in HT-7 superconducting tokamak using off-axis ion cyclotron resonance frequency (ICRF) heating. The experimental results and power balance transport analysis by TRANSP code are presented in this article. With the aids of GLF23 transport model, which predicts energy diffusivity in experimental condition, the estimation of electron pinch...
Mr
Xiang Gao
(China)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
The particle diffusion coefficient and the convection velocity have been studied by means of the density modulation using pulsed deuterium gas puffing on the HT-7 tokamak. It was observed in AC plasmas that the particle transport coefficient and confinement time of the positive current plasma is different from that of the negative current plasma (Gao X et al 2008 Nucl. Fusion 48 035009) on...
Mr
E. J. Doyle
(USA)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Recent GYRO simulations predict that particle flux, as a function purely of collisionality, should show a strong increase at low collisionality, but with little change above a critical value, nu^*~0.01. In an L-mode experiment in which collisionality was varied from nu^*~0.01 to 0.05, little change was observed in the density profile, profile peaking, measured D, V, (obtained using...
Mr
Sumio Kitajima
(Japan)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
The transitions to the improved confinement mode, which were accompanied with bifurcation phenomena characterized by a negative resistance, were clearly observed in various magnetic configurations on the Large Helical Device (LHD) by the electrode biasing. The configuration dependence of the transition condition and the radial resistivity qualitatively agreed with neoclassical theories.
The...
Ms
Catherine Fiore
(USA)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
New results suggest that changes observed in the intrinsic toroidal rotation influence the internal transport barrier (ITB) formation in the Alcator C-Mod tokamak. Detailed plasma rotation and ion temperature profile measurements are combined with linear and non-linear gyrokinetic simulation to examine the effects of the self-generated rotational shear on the transport changes that occur in...
Mr
Aleksandr Burdakov
(Russian Federation)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
The GOL-3 Multiple Mirror Trap is an 11-m-long solenoid with axially-periodical (corrugated) magnetic field. In the basic operation regime the solenoid consists of 52 magnetic corrugation cells with Bmax/Bmin=4.8/3.2 T. Deuterium plasma of 10^20÷10^22 m^-3 density is heated up to ~ 2 keV ion temperatures (at ~10^21 m^-3 density and confinement time ~1 ms) by a high power relativistic electron...
Mr
David Anderson
(USA)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
The Helically Symmetric Experiment (HSX) was designed to have an axis of symmetry in the helical direction, reduced neoclassical transport and small equilibrium currents due to the high effective transform. Unlike other stellarators in which |B| varies in all directions on a flux surface, plasmas in HSX are free to rotate in the direction of quasihelical symmetry. In this paper we will present...
Ms
Maria Filomena Nave
(Portugal)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Intrinsic rotation levels measured in JET plasmas are generally lower than expected from scaling laws that predict that rotation increases with normalised beta. Several factors have been observed to influence intrinsic rotation, such as fast ion losses and toroidal field (TF) ripple, suggesting that different physics mechanisms are at play to drive intrinsic rotation and that these should be...
Mr
Sang Gon Lee
(Republic of Korea)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Investigation of the toroidal rotation is one of the most important topics for the magnetically confined fusion plasma researches since it is essential for the stabilization of resistive wall modes (RWMs) and its shear plays an important role to improve plasma confinement by suppressing turbulent transport. Impurity toroidal rotation has been observed in the core region of KSTAR plasmas from...
Mr
Geert Verdoolaege
(Belgium)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Any measurement is in essence a sample from a latent probability distribution. Hence, measurement uncertainty is an intrinsic property, rather than a side-effect, of the measurement process, and it should be taken advantage of. In this contribution we show that an inherent probabilistic description of fusion confinement data drastically improves the capability to discriminate between...
Mr
Filippo Scotti
(PPPL)
10/10/2012, 08:30
EXC - Magnetic Confinement Experiments: Confinement
Poster
Intrinsic impurity (carbon and lithium) neoclassical transport is analyzed for H-mode discharges in the National Spherical Torus eXperiment (NSTX). The application of lithium coatings on boronized graphite plasma facing components led to high performance H-mode discharges with edge localized modes (ELMs) suppression but affected by core carbon accumulation (core inventory increased by up to...
Mr
Toru Li
(Japan)
10/10/2012, 08:30
ICC - Innovative Confinement Concepts
Poster
The first experimental investigation of tangential neutral beam injection (NBI) application on oblate field-reversed configurations (FRCs) has been conducted in the TS-4 plasma merging device. The low-n modes are responsible for the short discharge duration of the oblate FRCs formed from light gases. The co-NBI with injection power of 0.6 MW largely extended the magnetic energy decay time of...
Mr
Michl Binderbauer
(USA)
10/10/2012, 08:30
ICC - Innovative Confinement Concepts
Poster
Field Reversed Configurations (FRCs) with high confinement are obtained in the C-2 device by combining plasma gun edge biasing and neutral beam injection. The plasma gun inward radial electric field counters the usual FRC spin-up and mitigates the n = 2 rotational instability without applying quadrupole magnetic fields. The FRCs are nearly axisymmetric, which enables fast ion confinement. The...
Mr
Sadayoshi Murakami
(Japan)
10/10/2012, 08:30
Poster
Important role of the plasma flow and its shear in the transport improvement is suggested by many experimental observations. The spontaneous toroidal flow has been observed during ICRF heating with no direct momentum input in many devices. Especially, in the Alcator C-Mod plasma, the spontaneous toroidal flow and ITB formation have been investigated intensively in the ICRF heating plasma and...
Mr
Henry Strauss
(USA)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
A critical issue for the ITER device construction is to evaluate the forces produced on the surrounding conducting structures during plasma disruptions [1]. In this work we extend previous studies of vertical displacement events (VDE) combined with disruptions [2]. The emphasis is on the non axisymmetric "sideways" wall force. The disruptions are simulated using the M3D [3] code, which solves...
Mr
Edward Lazarus
(USA)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The coupling of the internal kink to an external m/n=1/1 perturbation is studied for profiles that are known to result in a saturated internal mode in the limit of a cylindrical tokamak (Rosenbluth, Dagazian & Rutherford [Phys,Fluids 14(1973)1895]). 3D equilibria are calculated with thr VMEC code.
If a small m/n=1/1 perturbation is applied to the boundary, it is found that for aspect ratios...
Mr
Ping Zhu
(University of Wisconsin-Madison)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Resistive MHD computations using the NIMROD code find stabilizing effects of edge current density distribution on the low-n instabilities localized in the edge pedestal region. It is widely accepted that the low-n edge localized modes can be driven unstable by increasing the edge current density. The destabilization of the edge current driven peeling modes is reproduced in our computations for...
Mr
Stephen C. Jardin
(USA)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Recent advances in implicit numerical algorithms for solving the 3D extended magneto-hydrodynamic equations in strongly magnetized plasmas have enabled massively parallel simulations of the internal global dynamics of tokamaks that can use very large time steps which allow one to span the timescales of ideal MHD stability, magnetic reconnection, and particle, energy, and momentum transport . ...
Ms
Sara Moradi
(Sweden)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
In the view of an increasing interest in high beta operation scenarios, such as hybrid scenarios for ITER the question of finite beta effects on the impurity transport is a critical issue due to possible fuel dilution and radiative cooling in the core. Here, electromagnetic effects at finite beta on impurity transport are studied through local linear gyrokinetic simulations with GYRO [J. Candy...
Mr
Ralf Kleiber
(Germany)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Particle-in-cell methods are an efficient way of simulating the gyrokinetic equation especially in complicated three-dimensional configurations such as stellarators because they are relatively easy to implement and show a good scaling behaviour on parallel machines. It is however necessary to employ variance reduction techniques in order to decrease the noise inherent to particle methods....
Mr
Richard Fitzpatrick
(USA)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
A theory is developed in order to predict the error-field penetration threshold in low density, ohmically heated, tokamak plasmas. The novel feature of the theory is that the response of the plasma in the vicinity of the resonant surface to the applied error-field is calculated from nonlinear drift-MHD magnetic island theory, rather than linear layer theory. Error-field penetration, and...
Mr
Carl Sovinec
(University of Wisconsin-Madison)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
We present a computational study of the coupling between dynamo and momentum transport, motivated by findings of two-fluid effects in the Madison Symmetric Torus (MST). Laser polarimetry and magnetic probes measure correlated current-density and magnetic-field fluctuations during sawtooth events [1,2]. With ion skin depths being 0.1-0.2 a, the correlation implies significant Hall dynamo...
Mr
Makoto Hirota
(Japan)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
A mechanism for fast magnetic reconnection in collisionless plasma is studied for understanding sawtooth collapse in tokamak discharges. Nonlinear growth of the tearing mode driven by electron inertia is analytically estimated by invoking the energy principle for the first time. Decrease of potential energy in the nonlinear regime (where the island width exceeds the electron skin depth) is...
Mr
Samuli Saarelma
(UK)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The H-mode pedestal is crucial for the good confinement of a tokamak fusion plasma. In this paper we analyze the stability of the pedestal used in ITER transport simulations and show that a pedestal temperature of 6.1 keV (corresponding to 115 kPa) is at the stability limit of a type I ELMy H-mode pedestal limited by peeling-ballooning modes. We also show that the pedestals assumed in the...
Mr
Scott Kruger
(USA)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
We present integrated feedback simulations of neoclassical tearing modes in tokamak plasmas. The implementation relies on the NIMROD and GENRAY codes, along with new codes for calculating a local quasilinear operator, and for performing the code coupling. The mathematical formulation relies on the formulation of a third-order electron drift-kinetic equation that captures the bootstrap...
Mr
Isao Katanuma
(Japan)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
A flute instability is the most dangerous instability to an open system such as GAMMA10. A line tying is a powerful tool for stabilizing a flute instability because the magnetic field lines terminate at the conducting ends in an open system. Firstly, a particle simulation was performed to investigate a flute instability and the line tying effect on it. Here the particle code takes into account...
Ms
Valerie Izzo
(USA)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Simulations of massive-gas-injection (MGI) in DIII-D have been carried out with the extended MHD code NIMROD in order to study the role of 2D and 3D plasma flows, specifically those associated with the m=1/n=1 instability, in mixing injected impurities into the core. In a simulation with poloidally and toroidally symmetric impurity injection, we find that the impurity distribution does not...
Mr
Katsuji ICHIGUCHI
(Japan)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The mechanism of a partial collapse observed in the experiments with the change of the background magnetic field in the Large Helical Device (LHD) is investigated with a nonlinear MHD simulation by utilizing a multi-scale numerical scheme. It is crucial to predict the MHD stability boundary in the design of future reactors. However, systematic procedure for the prediction has not been...
Mr
Vladimir Pustovitov
(Russian Federation)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The paper is devoted to studying the combined effect of the mode rotation and energy dissipation in the resistive wall on the plasma stability. The problem is analyzed on the basis of the energy approach complementing the standard methods of the traditional MHD theory of plasma stability. The key element that makes our model different from this theory and commonly used thin-wall approaches to...
Mr
Philip B. Snyder
(USA)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The pressure at the top of the edge transport barrier (or “pedestal height”) strongly impacts global confinement and fusion performance, while large ELMs can significantly limit component lifetimes. Hence, accurately predicting the ped¬estal height in ITER, as well as developing a predictive understanding of ELM suppression, are essential. The EPED model predicts the H-mode pedestal height and...
Mr
Junya Shiraishi
(Japan)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
It is shown for the first time that magnetohydrodynamic (MHD) equilibrium change induced by plasma toroidal rotation significantly reduces the growth rates of resistive wall modes (RWMs). Moreover, the equilibrium change can open the stable window even if there is no window under the assumption that the rotation affects only the linear dynamics, which is employed in conventional numerical...
Mr
Abhijit Sen
(India)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
We report on an analytic calculation of Delta_prime, the tearing mode stability index, in a toroidal tokamak geometry with an equilibrium sheared toroidal flow. A flow modified external kink equation is derived and a boundary layer formalism is adopted. The ``outer'' solutions of this equation, obtained analytically using a perturbation theory are matched asymptotically to the analytic ideal...
Mr
Timothée Nicolas
(France)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
In this contribution, the plasma density evolution in sawtooth regime on the Tore Supra tokamak is studied. The density is measured using a novel fast-sweeping X-mode reflectometry technique, which is fast enough to allow tomographic reconstructions. There is strong evidence that temperature and density are governed by different mechanisms. Postcursor oscillations sometimes lead to the...
Mr
Nikolay Ivanov
(Russian Federation)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The modeling of the magnetic island evolution under RMP in rotating plasma from seed island initial generation, through appearance and development of the NTM till its locking and saturation is presented. The effects of plasma resistivity, viscosity, diamagnetic drift and the effect of the currents induced in the resistive vacuum vessel are taken into account. The calculations are carried out...
Mr
Linjin Zheng
(University of Texas at Austin)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Magnetohydrodynamics instabilities of high-mode (H-mode) pedestal are investigated in this paper with the inclusion of bootstrap current for equilibrium and rotation for stability. This may help clarify the physics of edge localized modes (ELMs) and edge hormonic oscillations (EHOs) or outer modes (OMs). The equilibrium of an H-mode discharge at the Jointed European Torus (JET) is...
Mr
Youwen Sun
(China)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Intrinsic steady state plasma rotation is important for plasma confinement in ITER, since the momentum input is expected to be small. It is well known that the intrinsic plasma rotation in stellarators is determined by non-ambipolar diffusion due to helical ripple. The non-ambipolar diffusion due to small 3D magnetic perturbation described by the Neoclassical Toroidal plasma Viscosity (NTV)...
Mr
Masahiko Sato
(Japan)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
In order to understand characteristics of the MHD stability of high beta plasmas obtained in the LHD experiments, full MHD simulations including the chaotic magnetic field region have been performed for the first time. Nonlinear MHD simulation is carried out by using the MIPS code (MHD Infrastructure for Plasma Simulation) which solves the full MHD equations in the cylindrical coordinates (r,...
Mr
Naoki Mizuguchi
(Japan)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
A unique control method which makes use of the self-concentrating nature of the plasma perturbations into a small number of modes has been proposed both experimentally and theoretically in the reversed-field-pinch(RFP) to avoid the degradation of confinement due to the chaotizing of the field lines in the core region. Several types of such states termed QSH or SHAx have been observed. In this...
Mr
Guangzhou Hao
(China)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The stabilization of the resistive wall mode (RWM) is an essential issue for future magnetic fusion reactors (e.g. ITER) aiming at long-duration steady discharges over the no-wall beta limit. The RWM has been extensively investigated during recent years, both theoretically and experimentally. However, so far the physical mechanism of the passive control of the RWM has not been investigated...
Mr
Leonid Zakharov
(USA)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
Plasma disruptions in tokamaks represent a significant obstacle in enhancing performance of the plasma regime, especially in the next step machines, such as ITER. Although, for the global forces due to disruptions on the vacuum vessel there is sufficient certainty because of explicit scalings, e.g., from JET to ITER, many important aspects of plasma interaction with the plasma facing...
Mr
David A. Gates
(USA)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
The onset criterion for radiation driven islands [1] in combination with a simple cylindrical model of tokamak current channel behavior is consistent with the empirical scaling of the tokamak density limit [2]. A number of the unexplained phenomena at the density limit are consistent with this novel physics mechanism. Issues addressed in this work include:
1) The scaling is universal, but...
Mr
Simon Pinches
(UK)
10/10/2012, 08:30
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
A recent focus of the programme at MAST has been upon the development of tools to interpret and understand the fast ion driven instabilities observed with a view to developing a predictive capability for the future: In particular, which modes will be unstable, how will they behave, and what will be the consequences? The drive arises from gradients in the fast ion distribution, and the...
