Download or read book Modeling of Far SOL Plasma Transport in NSTX written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For better understanding and characterization of non-diffusive transport occurring in the NSTX tokamak edge plasma, we performed extensive simulations of NSTX edge plasmas with the multi-fluid two-dimensional UEDGE code by using realistic model for impurity sputtering sources and hybrid model for anomalous cross-field transport. Our cross-field transport model incorporates the effects of non-diffusive intermittent transport by introducing anomalous convective velocities whose spatial profile is adjusted for each ion charge state to match available experimental data. The research in 2002-2005 financial years was focused on the following areas: (i) development of capabilities for UEDGE simulation of NSTX spectroscopy data (i.e., the 3D real-geometry postprocessor UEDGE tools for comparison between UEDGE and experimental data), (ii) simulation of multi-diagnostic data from NSTX with UEDGE, (iii) study of anomalous cross-field convective transport of impurity ions, (iv) analysis of divertor plasma opacity to resonance radiation, and (v) study the effects of ballooning-like anomalous cross-field transport and spherical-torus magnetic configuration on parallel plasma flows in the SOL.
Download or read book Multi fluid Code Simulations Including Anomalous Non diffusive Transport of Plasma and Impurities in the Tokamak SOL written by and published by . This book was released on 2003 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fast intermittent transport has been observed in the scrape-off layer (SOL) of major tokamaks including Alcator C-Mod, DIII-D, and NSTX. This kind of transport is not diffusive but rather convective. It strongly increases plasma flux to the chamber walls and enhances the recycling of neutral particles in the main chamber. We discuss anomalous cross-field convection (ACFC) model for impurity and main plasma ions and its relation to intermittent transport events, i.e. plasma density blobs and holes in the SOL. Along with plasma diffusivity coefficients, our transport model introduces time-independent anomalous cross-field convective velocity. In the discharge modelling, diffusivity coefficients and ACFC velocity profiles are adjusted to match a set of representative experimental data. We use this model in the edge plasma physics code UEDGE to simulate the multi-fluid two-dimensional transport for these three tokamaks. We present simulation results suggesting the dominance of anomalous convection in the far SOL transport. These results are consistent with the hypothesis that the chamber wall is an important source of impurities and that different impurity charge states have different directions of anomalous convective velocity.
Download or read book Modeling of Low Frequency MHD Induced Beam Ion Transport in NSTX written by N. N. Gorelenkov and published by . This book was released on 2004 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Edge Sol and Diverter Plasma Turbulence and Macroscopic Transport written by Prof. Sergi Krasheninnikov and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last few years, it was clearly shown that cross-field transport in the far SOL could be significantly faster than previously thought and that this transport exhibited convective rather then diffusive features. As a result, in high density cases the plasma coming into the SOL from the core recycled at the wall of the tokamak main chamber, rather than flowing into the divertor and recycling there, as the conventional picture of edge plasma flows would suggest. It was also shown that coherent structures, often called ''blobs'', played very important roles in the particle and energy transport inside the SOL region for both L and H confinement modes. The blobs seen in the SOL are extended along the magnetic field lines and have a plasma density two to three times higher than the ambient SOL plasma density and poloidal and radial scales of about 1 cm. In experimental measurements, the blobs propagated in radial direction towards the chamber wall with a velocity {approx} 10{sup 5} cm/s, and the contribution of non-diffusive flux associated with transport of blobs to the total particle flux in the far SOL attained 70-90%. In addition, recent assessment of experimental data and theoretical models shows that plasma propagation into the SOL during ELM is somewhat similar to that of blobs.
Download or read book Simulation of Large Parallel Plasma Flows in the Tokamak SOL Driven by Cross Field Transport Asymmetries written by and published by . This book was released on 2006 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large-Mach-number parallel plasma flows in the single-null SOL of different tokamaks are simulated with multi-fluid transport code UEDGE. The key role of poloidal asymmetry of cross-field plasma transport as the driving mechanism for such flows is discussed. The impact of ballooning-like diffusive and convective transport and plasma flows on divertor detachment, material migration, impurity flows, and erosion/deposition profiles is studied. The results on well-balanced double null plasma modeling that are indicative of strong asymmetry of cross-field transport are presented.
Download or read book Plasma Transport Simulation Modeling for Helical Confinement Systems written by K. Yamazaki and published by . This book was released on 1991 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling of Low Frequency MHD Induced Beam Ion Transport In NSTX written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Beam ion transport in the presence of low frequency MHD activity in National Spherical Tokamak Experiment (NSTX) plasma is modeled numerically and analyzed theoretically in order to understand basic underlying physical mechanisms responsible for the observed fast ion redistribution and losses. Numerical modeling of the beam ions flux into the NPA in NSTX shows that after the onset of low frequency MHD activity high energy part of beam ion distribution, E{sub b}> 40keV, is redistributed radially due to stochastic diffusion. Such diffusion is caused by high order harmonics of the transit frequency resonance overlap in the phase space. Large drift orbit radial width induces such high order resonances. Characteristic confinement time is deduced from the measured NPA energy spectrum and is typically H"4msec. Considered MHD activity may induce losses on the order of 10% at the internal magnetic field perturbation [delta]B/B = [Omicron] (10−3), which is comparable to the prompt orbit losses.
Download or read book The Role of Parallel Heat Transport in the Relation Between Upstream Scrape off Layer Widths and Target Heat Flux Width in H mode Plasmas of NSTX written by and published by . This book was released on 2009 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The physics of parallel heat transport was tested in the Scrape-off Layer (SOL) plasma of the National Spherical Torus Experiment (NSTX) [M. Ono, et al., Nucl. Fusion 40, 557 (2000) and S.M. Kaye, et al., Nucl. Fusion 45, S168 (2005)] tokamak by comparing the upstream electron temperature (T{sub e}) and density (n{sub e}) profiles measured by the mid-plane reciprocating probe to the heat flux (q{sub {perpendicular}}) profile at the divertor plate measured by an infrared (IR) camera. It is found that electron conduction explains the near SOL width data reasonably well while the far SOL, which is in the sheath limited regime, requires an ion heat flux profile broader than the electron one to be consistent with the experimental data. The measured plasma parameters indicate that the SOL energy transport should be in the conduction-limited regime for R-R{sub sep} (radial distance from the separatrix location) 2-3 cm. The SOL energy transport should transition to the sheath-limited regime for R-R{sub sep} 2-3cm. The T{sub e}, n{sub e}, and q{sub {perpendicular}} profiles are better described by an offset exponential function instead of a simple exponential. The conventional relation between mid plane electron temperature decay length (?{sub Te}) and target heat flux decay length (?{sub q}) is?{sub Te} = 7/2?{sub q}, whereas the newly-derived relation, assuming offset exponential functional forms, implies?{sub Te} = (2-2.5)?{sub q}. The measured values of?{sub Te}/?{sub q} differ from the new prediction by 25-30%. The measured?{sub q} values in the far SOL (R-R{sub sep}> 2-3cm) are 9-10cm, while the expected values are 2.7
Download or read book Modeling and Control of Plasma Rotation for NSTX Using Neoclassical Toroidal Viscosity and Neutral Beam Injection written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A model-based feedback system is presented to control plasma rotation in a magnetically confined toroidal fusion device, to maintain plasma stability for long-pulse operation. This research uses experimental measurements from the National Spherical Torus Experiment (NSTX) and is aimed at controlling plasma rotation using two different types of actuation: momentum from injected neutral beams and neoclassical toroidal viscosity generated by three-dimensional applied magnetic fields. Based on the data-driven model obtained, a feedback controller is designed, and predictive simulations using the TRANSP plasma transport code show that the controller is able to attain desired plasma rotation profiles given practical constraints on the actuators and the available measurements of rotation.
Download or read book Modeling of Alpha Particle Transport in Tokamak Fusion Plasma written by Junpeng Guo and published by . This book was released on 1994 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Far SOL Transport and Main Wall Plasma Interaction in DIII D written by and published by . This book was released on 2004 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Fusion written by and published by . This book was released on 2006 with total page 1102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Edge of Magnetic Fusion Devices written by Sergei Krasheninnikov and published by Springer. This book was released on 2021-09-09 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews the current state of understanding concerning edge plasma, which bridges hot fusion plasma, with a temperature of roughly one million degrees Kelvin with plasma-facing materials, which have melting points of only a few thousand degrees Kelvin. In a fact, edge plasma is one of the keys to solution for harnessing fusion energy in magnetic fusion devices. The physics governing the processes at work in the edge plasma involves classical and anomalous transport of multispecies plasma, neutral gas dynamics, atomic physics effects, radiation transport, plasma-material interactions, and even the transport of plasma species within the plasma-facing materials. The book starts with simple physical models, then moves on to rigorous theoretical considerations and state-of-the-art simulation tools that are capable of capturing the most important features of the edge plasma phenomena. The authors compare the conclusions arising from the theoretical and computational analysis with the available experimental data. They also discuss the remaining gaps in their models and make projections for phenomena related to edge plasma in magnetic fusion reactors.
Download or read book The Plasma Boundary of Magnetic Fusion Devices written by P.C Stangeby and published by CRC Press. This book was released on 2000-01-01 with total page 738 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Plasma Boundary of Magnetic Fusion Devices introduces the physics of the plasma boundary region, including plasma-surface interactions, with an emphasis on those occurring in magnetically confined fusion plasmas. The book covers plasma-surface interaction, Debye sheaths, sputtering, scrape-off layers, plasma impurities, recycling and control, 1D and 2D fluid and kinetic modeling of particle transport, plasma properties at the edge, diverter and limiter physics, and control of the plasma boundary. Divided into three parts, the book begins with Part 1, an introduction to the plasma boundary. The derivations are heuristic and worked problems help crystallize physical intuition, which is emphasized throughout. Part 2 provides an introduction to methods of modeling the plasma edge region and for interpreting computer code results. Part 3 presents a collection of essays on currently active research hot topics. With an extensive bibliography and index, this book is an invaluable first port-of-call for researchers interested in plasma-surface interactions.
Download or read book Plasma Surface Interactions in Controlled Fusion Devices written by and published by . This book was released on 1978 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory of Fusion Plasmas written by Olivier Sauter and published by American Institute of Physics. This book was released on 2008-12-02 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Joint Varenna-Lausanne International Workshop on Theory of Fusion Plasmas takes place every other year in a place particularly favorable for informal and in depth discussions. Invited and contributed papers present state-of-the art researches in theoretical plasma physics, covering all domains relevant to fusion plasmas. This workshop always allows a fruitful mix of experienced researchers and students, to allow for a better understanding of the key theoretical physics models and applications, such as: Theoretical issues related to burning plasmas; Anomalous Transport (Turbulence, Coherent Structures, Microinstabilities) RF Heating and Current Drive; Macroinstabilities; Plasma-Edge Physics and Divertors; Fast particles instabilities.
Download or read book Tokamak Start Up Problems and Scenarios Related to the Transient Phases of a Thermonuclear Fusion Reactor Ettor Majorana International Science Series written by Heinz Knoepfel and published by Springer. This book was released on 2013-12-19 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the papers presented at the Course on "Tokamak Startup - Problems and Scenarios Related to the Transient Phases of a Thermonuclear Fusion Reactor" which was held in Erice, July 14-20, 1985. The fact that the critical startup and transient phases of a tokamak reactor are now the specific subject of a comprehensive international gathering of fusion specialists seems indicative of the substantial pro gress made in recent years towards attaining controlled ignition of a nuclear fusion fuel, i.e. towards demonstrating the scientific feasibili ty of controlled thermonuclear fusion. In fact, the steady-state burning phase has attracted so far most of the attention of fusion physicists and engineers, as it is conceptually more rewarding, and theoretically easier to handle. However, as for many large engineering systems, - nuclear fis- ... ':1' " . 10 ' ... Entrance to San Rocco's lecturing hall v sion power plants, or aerospace crafts, for example - the major issues of design and operation lie often in the startup, shutdown and power tran sieQt phases, rather than at the full load, or at cruising regimes. In ehoosing the contributions to this 7th Course of Prof. B.
