Mr
Mickey R. Wade
(USA)
10/10/2012, 14:00
Poster
Recent experiments on DIII-D have increased confidence in the ability to suppress edge localized modes (ELMs) using edge-resonant magnetic perturbations (RMPs) in ITER, including an improved physics basis of the edge response to RMPs as well as expansion of RMP ELM suppression to more ITER-like conditions. Experiments aimed at an improved physics understanding have revealed a complex plasma...
Mr
Andrew Kirk
(UK)
10/10/2012, 14:00
Poster
MAST is equipped with 18 coils (6 in the upper row and 12 in the lower row) for use in Resonant Magnetic Perturbation (RMP) ELM control experiments. These coils give considerable flexibility since they allow a range of toroidal mode numbers (up to n=6) but also allow improved alignment of the magnetic perturbations with the plasma equilibrium by allowing the phase of the applied field to be...
Mr
Young Mu Jeon
(Republic of Korea)
10/10/2012, 14:00
Poster
In 2011 KSTAR campaign, we successfully demonstrated an ELM suppression by applying small non-axisymmetric magnetic perturbations, which is the first achievement by using n=1 magnetic perturbations (MPs) [1] while DIII-D did by using n=3 MPs [2]. The ELM-suppressed MP discharges show several unique features such as two step ELM responses (intensification and then suppression) and a gradual...
Mr
Wolfgang Suttrop
(Germany)
10/10/2012, 14:00
Poster
The ASDEX Upgrade tokamak is currently being enhanced with a set of in-vessel saddle coils to study the effects of non-axisymmetric magnetic perturbations. One of the most pronounced phenomena is the mitigation of Edge Localised Modes (ELMs) when n=2 perturbation fields are applied in High-confinement mode. In addition, the effects on the H-mode transition threshold, pellet injection,...
Mr
Peter Thomas Lang
(Germany)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
Magnetic perturbations (MP) with n=2 have been found in ASDEX Upgrade to result in reproducible and robust ELM mitigation in a wide heating power and safety factor range. ELM mitigation is established for peripheral densities above a critical threshold. Pellets injected into mitigation phases do not trigger type-I ELM like events unlike when launched into unmitigated type-I ELMy plasmas. The...
Mr
Philip A. Schneider
(Max-Planck-Institiut für Plasmaphysik)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
A pedestal database was built using data from type-I ELMy H-modes of ASDEX Upgrade, DIII-D and JET. Edge data from high resolution diagnostics was analysed directly before an ELM crash. In this phase reproducible conditions are expected which lead to the type-I ELM crash. The pedestal is characterized in terms of pedestal top, width and gradient. These parameters are determined with the same...
Mr
Francois Ryter
(Germany)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
Investigations of the L-H transition in situations with a high power threshold, such as low density, unfavorable ion gradB drift or application of magnetic perturbations widen the knowledge on transition and pedestal physics. At ASDEX Upgrade, such studies yield the following results.
H-modes achieved with ECRH at low density allowed to decouple the electron and ion channels. The analysis...
Mr
Ahmed Diallo
(USA)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
Characterizations of the pedestal parameter dynamics and microturbulence in the pedestal region throughout the edge localized modes (ELM) cycles are performed on the National Spherical Torus Experiment (NSTX). First, a clear buildup of the pedestal height is observed between ELMs for three different plasma currents, and this buildup tends to saturate prior to the onset of ELM at low and medium...
Mr
Liang Wang
(China)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
In far scrape-off layer (SOL), alternating negative and positive burst structures in ion saturation current were detected at the onset of each type-III edge localized mode (ELM) on EAST. Different from the fast streaming phenomenon reported previously, one subsequent positive burst structure appears every time in the early phase of ELM. It seems like a quick transitional stage between edge...
Mr
Guosheng Xu
(China)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
The EAST tokamak has achieved, for the first time, the ELMy H mode at a confinement improvement factor HITER89-P~1.7, with dominant RF heating and active wall conditioning by lithium evaporation and real-time injection of Li powder. During the H-mode phase, a new small-ELM regime has been observed with the power threshold of the L-H transition close to the prediction by the international...
Mr
Ivo Classen
(Netherlands)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
The application of a 2D temperature diagnostic, ECE-Imaging, at ASDEX Upgrade revealed a variety of temperature fluctuations associated with type-I and type-II edge localized modes (ELMs). The characteristics and dynamics of the various modes, and their role in the ELM cycle, are presented.
During type-I ELMs, different phases of distinct mode activity have been identified. Prior to the onset...
Mr
Keith H. Burrell
(USA)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
Recent DIII-D results demonstrate that quiescent H-mode (QH-mode) sustained by magnetic torque is a promising operating mode for future burning plasmas. We have produced steady, edge localized mode (ELM)-free, QH-mode plasmas with co-I_p neutral beam torque at reactor relevant levels. This was achieved by replacing the counter-I_p torque from neutral beam injection (NBI) with the torque due to...
Mr
Holger Reimerdes
(Switzerland)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
Experiments on DIII-D confirm that the tritium breeding test blanket modules (TBMs) in ITER will lead to a decrease of the plasma rotation in H-modes [1]. Moreover, they suggest that long-wavelength correction fields applied with non-axisymmetric saddle coils will only be able to ameliorate a fraction of such a rotation reduction. The new finding obtained in rotating H-modes contrasts previous...
Mr
Kazuo Toi
(Japan)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
The Large Helical Device (LHD) produces H-mode plasmas with large amplitude edge-localized-modes (ELMs). The ELMs are induced by interchange modes destabilized at the iota=1 rational surface in the stochastic field region just outside the last closed flux surface. These large amplitude ELMs expel large amount of plasma stored energy from the edge transport barrier (ETB) region, that is, up to...
Mr
Deliang Yu
(China)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
Features of high fuelling efficiency of supersonic molecular beam injection (SMBI) have been studied on HL-2A tokamak. Normalized by fuel inventory, the D_alpha emission induced by SMBI is about 50% higher than that of gas puffing (GP), indicating that SMBI can send the fuel to the plasma edge more efficiently. And strong particle convection (inward pinch) is observed both by hydrogen cyanide...
Mr
Jun-Gyo BAK
(Republic of Korea)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
The ELM and pedestal structure are studied in Korea Superconducting Tokamak Advanced Research (KSTAR) ELMy H-mode plasmas. KSTAR H-mode plasmas have three distinctive types of ELMs ; large type-I ELMs with low ELM frequency (f_ELM = 10 - 50 Hz) and good confinement (H_98(y,2) = 0.9 - 1), intermediated, possibly type-III, ELMs with high ELM frequency (f_ELM = 50 - 250 Hz) at a reduced...
Mr
Marcin Jakubowski
(Germany)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
Resonant Magnetic Perturbations (RMPs) recently became a very popular tool to control plasma exhaust in tokamaks following the results obtained on DIII-D. So called pump-out results from a pitch resonant coupling of the external field to the internal magnetic field. Large Helical Device (LHD) due to three-dimensional nature of the magnetic equilibrium a stochastic region is formed at the...
Mr
Luis F. Delgado-Aparicio
(USA)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
A suite of novel spectroscopic imaging diagnostics have facilitated the determination of the perturbed radiated power and impurity density inside the (1,1) ‘snakes’ with unprecedented temporal and spatial resolution, and made it possible to infer, for the first time, the perturbed profiles of the impurity density, plasma pressure, Zeff, and resistivity at the center of these helical modes. The...
Mr
Jerry Hughes
(MIT PSFC)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
New experimental data on the Alcator C-Mod tokamak are used to benchmark predictive modeling of the edge pedestal in various high-confinement regimes, contributing to a greater confidence in projection of pedestal height and width in ITER and reactors. Measurements in conventional Type I ELMy H-mode have been used to test the theory of peeling-ballooning (PB) stability and pedestal structure...
Mr
Shinsuke OHSHIMA
(Japan)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
Nonlinear behavior of broad-band fluctuation and dynamical potential change, associated with beam-driven MHD phenomenon, are observed around edge region in a medium-sized helical device, Heliotron J. Nonlinear phase relationship between the MHD and broad-band fluctuation is demonstrated as a result of bicoherence and envelope analyses applied to floating potential signals measured with...
Mr
Daniel López-Bruna
(Spain)
10/10/2012, 14:00
EXC - Magnetic Confinement Experiments: Confinement
Poster
The physics of hot plasmas in toroidal sheared magnetic fields is common to tokamaks and stellarators and there are good reasons to believe that so is the physics of spontaneous formation of transport barriers. Both types of device have found relationships between the presence of magnetic resonances and the onset of transport barriers. In particular, the TJ-II stellarator, a Heliac device that...
Mr
Jeffrey Levesque
(USA)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
We report high-resolution detection of the time-evolving, three-dimensional (3D) plasma magnetic structure of wall-stabilized tokamak discharges in the HBT-EP device. Measurements and control experiments are conducted using a newly-installed adjustable conducting wall made up of 20 independent, movable, wall segments that have been precision located and equipped with 120 modular control coils...
Ms
Silvana Nowak
(Italy)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
The neoclassical tearing modes (NTMs) are resistive instabilities degrading the high beta plasma confinement with loss of plasma energy. As the NTMs can be triggered by long sawteeth crashes, the control of the sawteeth periods (tau_ST) is a key physics issue in fusion devices: the tau_ST shortening can avoid the NTMs onset allowing to achieve high plasma performances. A powerful tool for the...
Mr
Lorenzo Frassinetti
(KTH, Royal Institute of Technology)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
The EXTRAP T2R resistive wall mode feedback control system, along with new control algorithms has enabled experimental studies of the interaction of external magnetic perturbations with the plasma. Application of low amplitude transient, broad-spectrum magnetic perturbations in parallel with feedback stabilization enables non-destructive measurement of RWM growth rates. It is found that the...
Mr
Yijun Lin
(USA)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
Neo-classical tearing modes (NTMs) have been observed definitely for the first time on Alcator C-Mod. The NTMs occur in high performance I-mode plasmas that are heated by a combination of ICRF D(H) minority heating at 80 MHz and D(He3) mode conversion (MC) heating at 50 MHz. I-mode plasmas have confinement as good as H-mode but lower collisionality [1]. Due to the stabilizing effect by the...
Mr
Yunfeng Liang
(Germany)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
Recently, strong mitigation of Type-I Edge Localized Modes (ELMs) has been observed with application of the n = 2 field in high collisionality (nu^*_e=2.0) H-mode plasma on JET tokamak with ITER-like wall. In this experiment, the EFCC power supply system has been enhanced with a coil current up to 88kAt (twice than before). With an n = 2 field, the large type-I ELMs with frequency of ~ 45 Hz...
Mr
Sadao Masamune
(Japan)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
An equilibrium analysis has shown that the aspect ratio A (=R/a) is an important parameter for optimization of the RFP configuration because the q profile is closely connected to A in the self-organized state. Furthermore, some theories show that the pressure-driven bootstrap current increases as A is lowered to less than 2. RELAX is a RFP machine (R=0.5m/a=0.25m: A=R/a=2) to explore the...
Mr
Xiaoquan JI
(China)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
The onset of neoclassical tearing modes (NTMs) for previous theories requires a seed island, whose width need exceed the critical value. Such seed islands are often provided by sawtooth activities, fishbones, or edge localized modes (ELMs). However, the mechanism for seed island formation is not well undertood up to now. In this paper, NTMs triggered by two mode toroidal coupling and...
Mr
Chijin Xiao
(Canada)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
Flow measurements using ion Doppler spectroscopy (IDS) have been recently used to study toroidal flow velocities of impurity ions. By selecting ion species, such as a CIII line (464.7 nm) with emisiion intensity peaking at the radial location near r=7 cm, an OV line (650.0 nm) at, and CVI line (529.0 nm) near the plasma core, an estimated radial resolution of flow velocities can be achieved...
Mr
Jeremy M. Hanson
(USA)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
DIII-D experiments with off-axis neutral beam injection (NBI) yield evidence of modifications to resistive wall mode (RWM) stability. Measurements of the plasma response to slowly rotating, applied n=1 perturbations decrease in amplitude as the fractional mix of off-axis NBI power is increased at constant normalized beta. This reduction of the plasma response amplitude due to the off-axis...
Mr
Egemen Kolemen
(USA)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
This paper studies the vertical stability of NSTX and NSTX-U, and explains some of the upgrades to the control capabilities that have been implemented and under investigation for NSTX-U that can stabilize Vertical Displacement Events (VDEs). In this study we use NSTX experimental data and n=0 stability simulations via gspert, a nonrigid plasma response model based on the linearized...
Mr
Yuan Huang
(China)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
The H-mode discharge is generally accompanied by quasiperiodic edge localized mode (ELM) events. Many efforts have been spent worldwide on the understanding, mitigation and control of the ELMs, in order to eventually suppress the most destructive ELMs to meet the lifetime requirements on ITER target plates. The pellet pacing ELM mitigation concept is being tested in many tokamaks, but the...
Mr
Satoru Sakakibara
(Japan)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
Penetration of a Resonant Magnetic Perturbation (RMP) and its effect on MHD stability have been investigated in the Large Helical Device (LHD). The existence of an error field is one of the common problems in magnetic confinement systems because it may degrade plasma confinement and trigger MHD instabilities. The RMP experiments have been done in many tokamaks and RFPs to identify the...
Mr
Richard J. Buttery
(USA)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
The correction of error fields in ITER is found to be far more challenging than previously thought due to the effects of a multi-component response to such fields at multiple surfaces in the plasma. This situation is exacerbated by an amplification of error fields in H-modes, where a developing resistive response is observed, with fields found to brake plasma rotation and destabilize intrinsic...
Mr
Enzo Lazzaro
(Italy)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
Plasma rotation affects significantly the performance and stability of tokamak plasmas and is a major object of research both for first principles physics and applications.In the TCV tokamak spontaneous plasma toroidal rotation in absence of external momentum is observed and it is found experimentally that central electron cyclotron heating (ECH) and current drive (ECCD) can modify the...
Mr
Jong-Kyu Park
(USA)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
Edge localized modes (ELMs) can generate unacceptable heat loads to plasma facing components in a reactor scale tokamak or spherical torus, and therefore ELM control is a critical issue in ITER. ELM control using non-axisymmetric (3D) fields is a promising concept, but the 3D coil requirements are demanding in cost and engineering. An alternative means may be to use internally driven 3D field...
Mr
Petr Savrukhin
(Russian Federation)
10/10/2012, 14:00
EXS - Magnetic Confinement Experiments: Stability
Poster
Avoidance of the plasma disruptions is an ultimate goal of a reliable future thermonuclear reactor. Present studies in the T-10 tokamak are clarifying trigger conditions of the fast transition to energy quench from moderate growth of the MHD perturbations at the initial stage of the disruption. New magnetic probe system is installed on the T-10 tokamak to investigate fast-scale magnetic...
Mr
Jesús Antonio Romero
(Spain)
10/10/2012, 14:00
EXW - Magnetic Confinement Experiments: Wave–plasma interactions; current drive; heating; energetic particles
Poster
The economy of future tokamaks may have to rely on having large bootstrap current fractions and/or pulsed operation, with limited power available from non inductive current drive actuators. The transformer primary coil can assist in reducing the power requirements of the non inductive current drive sources needed for current profile control, since the general shape of the current profile can...
Mr
Aaron Redd
(USA)
10/10/2012, 14:00
EXW - Magnetic Confinement Experiments: Wave–plasma interactions; current drive; heating; energetic particles
Poster
Studies on the Pegasus ultralow aspect ratio tokamak are exploring: nonsolenoidal startup using localized helicity injection via edge current injection; and edge peeling mode stability and dynamics. The helicity injection operating space is constrained by helicity injection and dissipation rates and a geometric limit on plasma current. Extrapolation of this technique to other devices requires...
716.
TH/2-1: Non-linear MHD Modelling of Rotating Plasma Response to Resonant Magnetic Perturbations
Ms
Marina Becoulet
(France)
10/10/2012, 14:00
Poster
The application of Resonant Magnetic Perturbations (RMPs) demonstrated the possibility of total Type I ELM suppression or strong mitigation of the ELM size in many experiments motivating to use this method on ITER, where Type I ELMs represent a particular danger for Plasma Facing Components (PFC) and divertor materials. In the present work the rotating plasma response to RMPs was studied using...
Mr
Michael Leconte
(NFRI)
10/10/2012, 14:00
THC - Magnetic Confinement Theory and Modelling: Confinement
Poster
We study the effects of Resonant Magnetic Perturbations (RMPs) on turbulence, flows and confinement in the framework of resistive drift-wave turbulence. This work was motivated by experiments reported at IAEA 2010 conference [1] that showed a decrease of long-range correlations during the application of RMPs. To elucidate the effect of the RMPs on zonal structures in drift-wave turbulence, we...
Mr
Patrick Diamond
(USA)
10/10/2012, 14:00
THC - Magnetic Confinement Theory and Modelling: Confinement
Poster
Understanding the L-H and H-L transitions is crucial to successful ITER operation. In this paper, we present novel theoretical results on: a.) the spatio-temporal dynamics of the L-H and H-L transitions; b.) the physics origin of the grad-B-drift asymmetry in the power threshold. Special emphasis is given to the role of zonal flows (ZFs). We have significantly extended earlier transition...
Mr
Mikhail Dorf
(USA)
10/10/2012, 14:00
THC - Magnetic Confinement Theory and Modelling: Confinement
Poster
The edge of a tokamak in a high confinement (H mode) regime is characterized by steep density gradients, and a large radial electric field. Recent analytical studies demonstrated that the presence of a strong radial electric field consistent with a subsonic pedestal equilibrium modifies the conventional results of the neoclassical formalism developed for the core region. In the present work we...
Mr
Kerchung C. Shaing
(USA)
10/10/2012, 14:00
THC - Magnetic Confinement Theory and Modelling: Confinement
Poster
Real tokamaks have error fields that break toroidal symmetry and lead to enhanced particle, energy and momentum transport. The comprehensive theory for the error field induced transport fluxes consists of several collisionality regimes resulting from the asymptotic analysis of the drift kinetic equation. An analytic theory for the superbanana plateau resonance at the phase space boundary has...
Mr
Gergely Papp
(Hungary)
10/10/2012, 14:00
THW - Magnetic Confinement Theory and Modelling: Wave–plasma interactions; current drive; heating; energetic particles
Poster
Disruptions in large tokamaks can lead to the generation of a relativistic runaway (RE) electron beam that may cause serious damage to the first wall. To suppress the RE beam the application of resonant magnetic perturbations (RMP) has been suggested. In this work we investigate the effect of resonant magnetic perturbations on the spatial distribution of the RE wall loads by simulating the RE...
Ms
Emily A. Belli
(USA)
10/10/2012, 14:00
THC - Magnetic Confinement Theory and Modelling: Confinement
Poster
The delta f code NEO is used to study the neoclassical transport for parameters relevant in the plasma edge and outer core. NEO includes multiple ion species, general geometry, and rapid toroidal rotation. It has recently been upgraded to include the full linearized Fokker-Planck collision operator, using novel numerical schemes which can accurately treat the disparate scales that arise in the...
Mr
Alexei Pankin
(USA)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
The accurate prediction of Edge Localized Modes (ELMs) and their mitigation are critical for sustainable discharge operation. Two main research questions are elucidated in this study: (1) What are the effects of uncertainties in the bootstrap current computations on the ELM stability predictions? (2) How do the resonant magnetic perturbations (RMPs) that are introduced to mitigate ELMs...
Mr
Youwen Sun
(Institute of Plasma Physics, Chinese Academy of Sciences)
10/10/2012, 14:00
THC - Magnetic Confinement Theory and Modelling: Confinement
Poster
Spontaneous rotation has been observed in LHCD H-mode plasmas with type III ELMs (edge localized modes) on EAST, and it revealed that type III ELMs can induce the loss of both core and edge toroidal rotation. Here we work on the breaking mechanism during the ELMs. Several large tokamaks have discovered ELMs’ filamentary structures. It revealed that the ELMs are filamentary perturbations of...
Mr
Guillaume Fuhr
(France)
10/10/2012, 14:00
THS - Magnetic Confinement Theory and Modelling: Stability
Poster
In the context of edge localized mode (ELM) control by resonant magnetic perturbations (RMPs), the impact of micro-turbulence on the RMP penetration process and effectiveness is an important issue. Indeed, on the one hand, theoretical investigations as well as quasi-linear and non-linear MHD modeling reveal that the magnetic perturbation is strongly screened by plasma rotation. On the other...
Mr
Ammar Hakim
(Princeton Plasma Physics Laboratory)
10/10/2012, 14:00
THC - Magnetic Confinement Theory and Modelling: Confinement
Poster
We present integrated fusion simulations that couple the core-edge-wall transport into a self-consistent advance for the state of the plasma on transport time-scales. We accomplish this using the Framework Application for Core Edge Transport Simulation (FACETS), a recently developed parallel fusion simulation package incorporating the best models for each region of the tokamak. An overview of...
Mr
Klaus Schoepf
(Austria)
10/10/2012, 14:00
THC - Magnetic Confinement Theory and Modelling: Confinement
Poster
Resonant magnetic perturbations (RMPs) have become a powerful tool for modifying dge transport properties and for plasma stability control in present day tokamaks. The transport behaviour of charged fusion products as altered by these perturbations can be regarded as a crucial point for approving the application of RMPs in future tokamak reactors. Our present study focuses on fusion alpha...
Mr
Choong Seock Chang
(Republic of Korea)
10/10/2012, 14:00
THC - Magnetic Confinement Theory and Modelling: Confinement
Poster
Previous formulas on the plasma bootstrap current have been developed for the core plasma. However, the edge plasma has an unconventional and difficult neoclassical property compared to the core plasma. There have been prevailing suspicions that the existing bootstrap current formula may not be accurate enough for pedestal physics study. Kinetic simulation based upon first-principles...
Mr
Ahmet Aydemir
(USA)
10/10/2012, 14:00
THC - Magnetic Confinement Theory and Modelling: Confinement
Poster
In the collisional tokamak edge plasmas just inside the separatrix, a radial electric field can be associated with the Pfirsch-Schl\"uter currents, and poloidal density and temperature gradients. Building upon our previous works, this mechanism is further clarified and quantified here. Dependence of the resulting electric fields on magnetic topology, geometric factors like the upper/lower...
Mr
Paolo Ricci
(Switzerland)
10/10/2012, 14:00
THC - Magnetic Confinement Theory and Modelling: Confinement
Poster
Simulations of edge turbulence are particularly challenging due to the presence of large amplitude fluctuations and to the coupling of equilibrium and fluctuating scales. While validating edge simulations is necessary to assess the accuracy of our understanding, difficulties in experimental diagnostics and the lack of a precise validation methodology have, to date, severely limited the...
Mr
Raghvendra Singh
(India)
10/10/2012, 14:00
THC - Magnetic Confinement Theory and Modelling: Confinement
Poster
A theory based on a turbulent particle pinch is proposed to explain the rapid formation of sharp density gradients in tokamak edge plasmas, in particular the pedestal region. The inward radial particle flux in the pedestal results from the interaction between small scale electron temperature gradient driven (ETG) turbulence and self-consistently formed "electron geodesic acoustic modes"...
Mr
Xianzhu Tang
(USA)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
Reduction of wall recycling by, for example, a flowing liquid surface at the divertor and first wall, holds the promise of accessing the distinct tokamak reactor operational mode with boundary plasmas of high temperature and low density. Earlier work has indicated that such a boundary plasma would reduce the temperature gradient across the entire plasma and hence remove the primary...
Mr
Roman Zagorski
(Poland)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
The reduction of divertor target power load due to radiation of sputtered and externally seeded impurities in fusion reactor is investigated in this paper. The approach is based on integrated numerical modelling of DEMO discharges using the COREDIV code, which self-consistently solves 1D radial transport equations of plasma and impurities in the core region and 2D multifluid transport in the...
Mr
Dmitri Ryutov
(USA)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
This paper is concerned with the use of a snowflake (SF) divertor for the control and mitigation of edge localized modes (ELMs). Our research is focused on the following three issues: 1) Effect of the SF geometry on neoclassical ion orbits near the separatrix, including prompt ion losses and the related control mechanism for the electric field and plasma flow in the pedestal; 2) Influence of...
Mr
Robert Goldston
(Princeton Plasma Physics Laboratory)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
A heuristic model for the plasma scrape-off width in low-gas-puff tokamak H-mode plasmas is introduced. Grad B and curvature drifts into the scrape-off layer (SOL) are balanced against near-sonic parallel flows out of the SOL, to the divertor plates. These assumptions result in an estimated SOL width of order the poloidal gyroradius. It is next assumed that anomalous perpendicular electron...
Mr
James D. Callen
(USA)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
Plasma toroidal rotation can prevent or limit reconnection of externally applied resonant magnetic perturbation (RMP) fields delta B on rational magnetic flux surfaces. Hence, it causes the induced radial perturbations to vanish or be small there, and thereby inhibits magnetic island formation and stochasticity in the edge of high (H-mode) confinement tokamak plasmas. However, the radial...
Mr
Nathaniel M. Ferraro
(USA)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
The application of non-axisymmetric fields is found to have significant effects on the transport and stability of H-mode tokamak plasmas. These effects include dramatic changes in rotation and particle transport, and may lead to the partial or complete suppression of edge-localized modes (ELMs) under some circumstances [1]. The physical mechanism underlying these effects is presently not well...
Mr
Yannick Marandet
(France)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
Edge plasmas of magnetic fusion devices exhibit strong intermittent turbulence, which governs perpendicular transport of particles and heat. Turbulent fluxes result from the coarse graining procedure used to derive the transport equation, which entails time averaging of the underlying equations governing the turbulent evolution of the electron and ion fluids. In previous works, we have pointed...
Mr
James Myra
(USA)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
A study of sheared flows in the edge and scrape-off layer (SOL) and their interaction with blob-filaments is presented. Edge sheared flows are believed to be important for the L-H, and H-L transitions. Blob generation and dynamics impacts both the (near-separatrix) scrape-off-layer (SOL) width critical for power handling in the divertor, and the interaction of plasma in the far SOL with...
Mr
Li Jiquan
(Japan)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
Blob/hole dynamics near tokamak separatrix is of striking importance in determining the boundary transport. Based on simulations using an extended 2-region (edge/SOL) fluid model, we found that blob/hole dynamics are sensitively influenced by the plasma collisionality, i.e., ion-electron and ion-neutral collisions. Namely, the holes are enhanced in highly collisional edge whereas the blobs are...
Mr
Umur Daybelge
(Turkey)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
Toroidal and poloidal rotations of plasma at the edge region of tokamak devices have long been known to play an important role, such as enhancing the confinement properties by suppressing turbulent behaviour, improving tolerance to error fields and increasing stability to neoclassical tearing modes. Hence, understanding of creation and evolution of rotation is important, since external...
Mr
Philippe Ghendrih
(France)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
The role of divertors in present device operation is to control particle sources and sinks and consequently the energy flux channels in the boundary region of magnetically confined plasmas. The ESPOIR effort is based on a set of fluid codes from 1-D parallel to 3-D micro-turbulence modelling. Due to the long range particle transport into the SOL governed by intermittent turbulent bursts, the...
Mr
Pavel Cahyna
(Czech Republic)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
Resonant magnetic perturbations (RMPs) for edge localized mode (ELM) mitigation in tokamaks can be modified by the plasma response and indeed strong screening of the applied perturbation is in some cases predicted by simulations. In this contribution we investigate what effect would such screening have on the spiralling patterns (footprints) which may appear at the divertor when RMPs are...
Mr
Gunyoung Park
(NFRI)
10/10/2012, 14:00
THD - Magnetic Confinement Theory and Modelling: Plasma–material interactions; divertors, limiters, scrape-off layer (SOL)
Poster
Control of the edge localized modes (ELMs) is one of the most critical issues for a more successful operation of ITER and the future tokamak fusion reactors. This paper reports ITER relevant simulation results from the XGC0 drift-kinetic code, with respect to the collisionality, plasma density, and rotation dependence of the RMP penetration and the RMP-driven transport in diverted DIII-D...
