Dr
Silvana Nowak
(CNR)
14/10/2014, 14:00
Poster
The onset of both the conventional and neoclassical tearing modes (N)TMs remains an important issue for the fusion plasma operations. The understanding of the (N)TM onset driven by on-axis EC action, far from the mode locations, is a field still not well understood for the MHD instability control. Comparison of the responses from different devices with comparable size and operation parameters...
Dr
Tongnyeol Rhee
(NFRI, Daejeon, South Korea)
14/10/2014, 14:00
Poster
The importance and urgency of ELM control for ITER urge to develop tractable reduced model to understand ELM mitigation experiments because first principle models of ELMs have not been developed due to terrific complexities of ELM-related physics. In this work, we present such an effort particularly focused on ELM mitigation experiment by supersonic molecular beam injection (SMBI) and pellet...
Dr
C. Craig Petty
(General Atomics)
14/10/2014, 14:00
Poster
The natural attributes of the hybrid scenario, especially the anomalously broad current profile that suppresses sawteeth by maintaining the safety factor minimum (qmin) above unity, allows steady-state conditions with zero surface loop voltage to be achieved in 1 MA discharges in DIII-D with efficient central current drive and simultaneous high beta and high confinement. Steady-state hybrid...
Mr
A. M. Garofalo
(USA)
14/10/2014, 14:00
Poster
Recent experiments on DIII-D have overcome a long-standing limitation in accessing quiescent H-mode (QH-mode), a high confinement state of the plasma that does not exhibit the explosive instabilities associated with edge localized modes (ELMs). In the past, QH-mode was associated with low density operation, but has now been extended to high normalized densities compatible with operation...
Dr
Thomas W. Petrie
(General Atomics)
14/10/2014, 14:00
Poster
Results are reported and interpretation made of recent experiments on DIII-D that assess the effectiveness of three innovative tokamak divertor concepts under radiating divertor (RD) conditions: (1) high performance standard double-null divertor (DND) plasmas, (2) high performance double-null “snowflake” (SF-DN) plasmas, and (3) single-null H-mode plasmas with different parallel connection...
Dr
Lionello Marrelli
(Italy)
14/10/2014, 14:00
Poster
Disruptions caused by tearing modes (TM) are considered to be one of the most critical roadblocks to achieving safe steady state operation of tokamak fusion reactors. Here, a new scheme to avoid such disruptions is proposed by utilizing the electro-magnetic (EM) torque produced with 3D coils that are available in many present tokamaks. In this scheme, the EM torque to the modes is created by a...
Prof.
Frank Jenko
(IPP Garching)
14/10/2014, 14:00
Poster
The common view in fusion theory is that nonlinear gyrokinetics constitutes a reliable first-principles approach to describe turbulent transport in MCF devices. Surprisingly, however, two recent findings challenged this notion. First, the experimental ion heat fluxes in the outer core of certain DIII-D L-mode discharges were underpredicted by GK simulations by almost an order of magnitude....
Dr
Federica Causa
(ENEA C. R. Frascati)
14/10/2014, 14:00
Poster
In the 2013 experimental campaign a novel optical diagnostic system, based on the Cherenkov effect, was installed on FTU, in collaboration with the NCBJ group (IPPLM Association) to study the dynamics of non-thermal electrons in the presence of magnetic islands.
Data from the Cherenkov probe was correlated with data from several other diagnostics, including ECE, neutron and gamma detector,...
Mr
Andrea M. Garofalo
(General Atomics)
14/10/2014, 14:00
Poster
A high bootstrap current fraction plasma regime is desirable for steady-state tokamak operation because it reduces the demands on external non-inductive current drive. Typically, this regime is characterized by high βN and an internal transport barrier (ITB), leading to concerns about stability limits and profile control with reduced external input (power). Recent DIII-D research has increased...
Prof.
Xianzu Gong
(Insititute of Plasma Physics, Chinese Academy Sciences)
14/10/2014, 14:00
Poster
A main goal for EAST is to investigate an approach to fully noninductive long-pulse operation based on high bootstrap fraction under fusion relevant conditions. Building on results of previous DIII-D experiments , first joint experiments on DIII-D have developed a fully noninductive plasma scenario with EAST-similar plasma cross section shape, plasma current formation consistent with the...
Dr
Sterling Smith
(General Atomics)
14/10/2014, 14:00
Poster
In a continuing effort to validate turbulent transport models, the electron heat flux has been probed as a function of electron temperature gradient on the DIII-D tokamak. In the scan of gradient, a critical electron temperature gradient has been found in the electron heat fluxes and stiffness at various radii in L-mode plasmas. The TGLF reduced turbulent transport model [G.M. Staebler, J.E....
Dr
Ahmet Y. Aydemir
(National Fusion Research Institute, Daejeon, Korea)
14/10/2014, 14:00
Poster
Although ELM control by RMP's has been successfully demonstrated on a number of tokamaks, whether this method will be successful in all anticipated ITER operational scenarios is not clear. Thus, there is a recognized need to investigate other approaches to reducing transient heat and particles loads due to ELM's on PFC's in ITER. A low-cost technique that may not require dedicated equipment...
Dr
Timothy C. Luce
(General Atomics)
14/10/2014, 14:00
Poster
Results obtained recently in DIII-D provide critical information for ITER baseline scenario operation. Much of the physics basis for ITER baseline scenario operation has been obtained in plasmas with significant fueling and applied torque from neutral beam injection (NBI). DIII-D has unique capabilities to extend this physics basis toward ITER conditions by applying neutral beam injection...
Dr
Egemen Kolemen
(USA)
14/10/2014, 14:00
Poster
A new approach has been developed to control fusion power by applying a non-axisymmetric magnetic field (n=3) using the DIII-D in-vessel coils (I-coils) to modify the energy confinement time. This has potential advantages for a power plant due to the reduced power requirements relative to auxiliary heating and that it may enable the control of the plasma response more rapidly than with fueling...
Dr
GUSTAVO GRANUCCI
(ISTITUTO DI FISICA DEL PLASMA - CNR)
14/10/2014, 14:00
Poster
The intrinsic limited toroidal electric field (0.3 V/m for ITER) in devices with superconducting poloidal coils (ITER, JT-60SA, DEMO) requires an additional heating, like Electron Cyclotron (EC) waves, to initiate plasma current and to sustain it during the burn-through phase. The circular full metallic FTU tokamak, equipped with an ECRH system (140 GHz, 0.5 s, up to 1.6 MW), has contributed...
Dr
Carlo Sozzi
(Istituto di Fisica del Plasma CNR, Associazione EURATOM-ENEA)
14/10/2014, 14:00
Poster
Experiments of magneto-hydrodynamics (MHD) instabilities control using injection of Electron Cyclotron Waves (ECW) are being performed in the FTU tokamak at toroidal field of 5.3T, plasma current of 0.5MA, line averaged density of 0.6 10^20 m^-3. The control system is based on only three real time key items: an equilibrium estimator (EQUIFAST) based on a statistical regression, a MHD...
Prof.
Piero Martin
(Consorzio RFX)
14/10/2014, 14:00
Poster
High current, stable tokamak plasmas with edge safety factor below or around 2 are attractive for magnetic fusion due to favourable high fusion gain and higher confinement. But they have long been considered inaccessible in modern devices owing to the unforgiving MHD instabilities. Even in tokamaks with a resistive wall, the onset of an n=1 resistive wall mode leads to a disruptive limit at...
Dr
Hongda He
(Southwestern institute of physics)
14/10/2014, 14:00
Poster
Neutral beam injection (NBI) is one of the important methods to heat plasmas in current tokamaks. However, fishbone instability induced by fast ions during NBI experiment is the main source for resulting in fast ion loss. Generally speaking, the density gradient of fast ions is the primary driving force to destabilize the fishbone modes. Therefore, it is possible to reduce the instability by...
Dr
Tianyang XIa
(Institute of Plasma Physics, Chinese Academy of Sciences)
14/10/2014, 14:00
Poster
In this paper we report the simulations of the evolution of the particle and heat flux during the burst of ELMs in realistic discharges on DIIID and EAST tokamaks. A set of six-field two-fluid equations based on the Braginskii equations with non-ideal physics effects is found to simulate pedestal collapse under the BOUT++ framework [1]. In general studies with shifted-circular geometry, the...
Prof.
Zhe Gao
(Tsinghua University)
14/10/2014, 14:00
Poster
The frequency and damping rate are two most fundamental properties of the GAM. The collisional effect could be important in the plasma edge. In our work [1], where a number conservation Krook collisional operator was used in the gyrokinetic model, it was found that the damping rate of the GAM is non-monotonic as the collision rate increases. At low ion collision rate the damping rate increases...
Dr
Sterling Smith
(USA)
14/10/2014, 14:00
Poster
Optimization and control of the H-mode pedestal and scrape-off layer (SOL) for burning plasma devices such as ITER requires a predictive model for the transport of particles, energy and momentum from the top of the pedestal to the first wall. The transport simulation code XGC0 leverages high-performance computing to rigorously compute the full-f multi-species (D+, C6+, e-) flux-driven...
Mr
Zhiyong Qiu
(Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou, China)
14/10/2014, 14:00
Poster
The new capabilities in the gyrokinetic simulation code GTC enable it to simulate the turbulent transport in real tokamak experiments. We apply these capabilities to simulate one ITG turbulence case for DIII-D tokamak and one TEM turbulence case for EAST tokamak with real experimental profiles and equilibrium magnetic field. For DIII-D case, the radial heat diffusivity profile simulated by GTC...
Mrs
Ksenia Razumova
(NRC Kurchatov Institute)
14/10/2014, 14:00
Poster
Based on hypotheses about self-organization and pressure profile shape conservation in tokamak plasma, the turbulent heat transport processes are analyzed. The mechanism of internal transport barriers formation in regions without low number rational magnetic surfaces is suggested. The stronger pressure profile distortions from the self-consistent profile bring to the lower mode number...
Dr
John Ferron
(General Atomics)
14/10/2014, 14:00
Poster
Increased confinement and ideal stability limits at relatively high values of the internal inductance (l_i) have enabled an attractive scenario for steady-state tokamak operation to be demonstrated in DIII-D. The potential of the scenario was shown in high elongation and triangularity double-null divertor discharges in which β_N>4.5 was achieved at l_i≈1.3. This high value of β_N just reached...
Dr
Francesca Turco
(Columbia University)
14/10/2014, 14:00
Poster
Modeling results, obtained with the full kinetic MARS-K code [1] for a set of DIII-D experimental equilibria, predict that the absence of fast beam generated ions in ITER will lead to a plasma response ~40% higher than in the present NBI-sustained H-mode plasmas. It has been postulated that the presence of fast ions may have a stabilizing effect on the RWM that would account for its observed...
Dr
Vladimir Pastukhov
(NRC Kurchatov Institute)
14/10/2014, 14:00
Poster
Temporal evolution of anomalous transport and global plasma energy confinement time is studied in simulations of plasma turbulence in tokamaks with additional plasma heating. The simulations have shown that external boundary conditions with the specially chosen power dependence of heat fluxes on the local time-dependent values of plasma density and temperatures at the boundary of plasma core...
Dr
Nicholas Eidietis
(General Atomics)
14/10/2014, 14:00
Poster
Experiments have been undertaken on the DIII-D tokamak to examine the magnitude and causes of radiated power asymmetries during disruption mitigation. In order to mitigate the most deleterious effects of disruptions, massive quantities of radiating impurities can be injected into the pre-disruptive plasma to pre-emptively radiate away the stored thermal and magnetic energy. However, toroidal...
Dr
NOBUYUKI AIBA
(Japan Atomic Energy Agency)
14/10/2014, 14:00
Poster
A mechanism exciting magnetohydrodinamic (MHD) instabilities in rotating tokamak plasmas is found numerically for the first time. This mechanism is the interplay between a resistive wall mode (RWM) and a stable MHD mode. When a plasma has a discrete stable MHD eigenmode, the RWM can be destabilized when the plasma rotation frequency is close to the real frequency of the stable eigenmode. In a...
Dr
Saskia Mordijck
(College of William and Mary)
14/10/2014, 14:00
Poster
Turbulent particle transport and momentum transport have been shown to be closely connected theoretically as well as experimentally. In DIII-D H-mode plasmas we study the changes in particle and momentum transport across the linear ITG-TEM stability regime as well as studying the changes in particle transport as a function of the rotation profile. Counter to previous experimental [1], we do...
Dr
Animesh Kuley
(University of California Irvine)
14/10/2014, 14:00
Poster
Nonlinear global particle in cell simulation model in toroidal geometry has been developed for the first time to provide a first principle tool to study the radio frequency (RF) nonlinear interactions with plasmas. In this model, ions are considered as fully kinetic ion (FKi) particles using the Vlasov equation and electrons are treated as guiding centers using the drift kinetic (DKe)...
Dr
Naoaki Miyato
(Japan Atomic Energy Agency)
14/10/2014, 14:00
Poster
A nonlocal response of plasma to edge density sources, which has been sometimes observed in toroidally magnetic confinement plasmas, is found in global fluid simulations. In the 4-field reduced MHD model, a toroidally-elongated particle source is applied in the edge region after saturation of the resistive ballooning mode turbulence is attained. The nonlocal transport appears at the location...
Dr
Robert Pinsker
(General Atomics)
14/10/2014, 14:00
Poster
Modeling shows that fast waves at very high ion cyclotron harmonics (also called “whistlers” or “helicons”) can drive current efficiently in the mid-radius region of a high beta tokamak plasma, as is required to sustain steady-state high performance discharges in a DEMO-like configuration. DIII-D has developed discharges with high electron beta and high electron temperature so that full...
Mr
Basilio Esposito
(ENEA)
14/10/2014, 14:00
Poster
The determination of the threshold density value to be achieved by means of massive gas injection for runaway electron (RE) suppression in ITER relies on the relativistic collisional theory of RE generation which predicts that, below a critical electric field (E_R), no runaway electrons can be generated. No account of additional loss mechanisms, that may reduce the critical density, is usually...
Mrs
Cristina Mazzotta
(ENEA)
14/10/2014, 14:00
Poster
The density profile peaking produced by Ne-gas puffing was studied in in different L-mode plasma scenarios during recent experimental campaigns on FTU. In fact an stable radiative edge seeded with light impurities has beneficial effects and provokes density peaking without any undesirable central impurity accumulation [1,2]; on the other hand, a too large amount of impurities can lead to a...
Mr
Justin E. Barton
(Lehigh University)
14/10/2014, 14:00
Poster
DIII-D experiment results are presented to demonstrate the potential of integrated physics-model-based q-profile and βN control for the systematic development and sustainment of advanced scenarios. Both simulations and experiments demonstrate improved control performance relative to unoptimized preprogrammed control, by utilizing a combined feedforward+feedback scheme. At the core of the...
Dr
Yusuke Kosuga
(Institute for Advanced Study, Kyushu University)
14/10/2014, 14:00
Poster
Predictive modeling of turbulent transport is essential to the success of ITER and DEMO. Due to the collisionless nature of fusion plasmas, turbulence with strong wave-particle interaction – such as collisionless trapped electron or ion modes (CTEM/CTIM) or energetic particle (EP) modes – can develop in fusion plasmas. However, transport caused by these turbulence cannot be described by the...
Mr
Dmitry L. Rudakov
(University of California San Diego)
14/10/2014, 14:00
Poster
We report a substantial reduction of net compared to gross erosion of a tungsten PFC surface observed in DIII-D divertor in good agreement with modeling, and suppression of molybdenum erosion by a local gas injection. A sample featuring a 1 mm and a 1 cm diameter 15-24 nm thick W films deposited on a Si substrate over a carbon inter-layer was exposed in the lower divertor of DIII-D using the...
Dr
daniele carnevale
(Universita' Roma Tor Vergata, Dipartimento di Ing. Civile ed Ing. Informatica)
14/10/2014, 14:00
Poster
Runaway electrons (RE) are highly energetic electrons that might gain energy up to 20-30MeV (FTU). Runway electron beam can be harmful for plasma facing components: its low pitch angle allows the deposition of a high amount of energy on small areas yielding serious and deep damages of the vessel structure. For Tokamakas such as ITER, RE beams current should be around 11-13 MA and an impact...
Dr
Mirjam Schneller
(Max-Planck-Institut für Plasmaphysik)
14/10/2014, 14:00
Poster
A nonlinear hybrid model is used to study energetic particle transport and losses in realistic TOKAMAK – particularly ASDEX Upgrade – multi-mode scenarios. The model consists of the vacuum-extended version of the drift kinetic HAGIS code. As crucial new elements of a realistic scenario, the perturbation structures, frequencies and damping rates are taken as obtained from the gyrokinetic...
Dr
Dmitri Orlov
(University of California San Diego)
14/10/2014, 14:00
Poster
Recent experiments on DIII-D have demonstrated the ability to suppress edge localized modes (ELMs) using edge-resonant magnetic perturbations (RMPs) produced by an incomplete I-coil set in ITER similar shape plasmas with low pedestal electron collisionality. Robust ELM suppression has been reproducibly obtained on DIII-D using a wide range of toroidal RMP modes during experiments in which...
Chengkang Pan
(China)
14/10/2014, 14:00
Poster
Plasma rotation in tokamaks driven by the lower-hybrid-waves (LHW) was firstly reported by the Alcator C-Mod team and also observed in the EAST tokamaks. The LHW injection can induce both co- and counter-current directed changes in toroidal rotation. The direct momentum absorption of the LHW induces the impurity ions to rotate in the counter-current direction. The inductive electric field...
Dr
Carlos Paz-Soldan
(Oak Ridge Institute for Science Education)
14/10/2014, 14:00
Poster
Experiments at DIII-D have demonstrated that several key 3D field sensitivities are directly related to their coupling to the least-stable kink mode of the plasma, and concomitantly that the plasma is remarkably insensitive to fields which have no net coupling to this single dominant (kink) mode. Specifically, plasma rotation and error field (EF) penetration thresholds are nearly unchanged...
Dr
Giuseppe Mazzitelli
(ENEA - Unità Tecnica Fusione)
14/10/2014, 14:00
Poster
Power load on the divertor is one of the main problems to be solved for steady state operation on the future reactors and liquid metals (Li, Ga, Sn) could be a viable solution for the target materials. Since 2006 experiments by using a Capillary Porous System (CPS) Liquid Lithium Limiter (LLL) were successfully performed on FTU indicating a good capability of the system to sustain power loads....
Dr
Henry R. Strauss
(HRS Fusion)
14/10/2014, 14:00
Poster
In several experiments, including JET [1], Alcator C-Mod [2], and NSTX [3], it was observed that disruptions were accompanied by toroidal rotation. There is a concern that there may be a resonance between rotating toroidal perturbations and the resonant frequencies of the ITER vacuum vessel, causing enhanced damage. We present MHD simulations with M3D [4] of ITER, JET, and DIII-D, as well as...