Download or read book Mitigating Edge localized Modes on the Mega ampere Spherical Tokamak Using Resonant Magnetic Perturbations written by Peter John Denner and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mitigating Edge localized Modes on the Mega Ampere Spherical Tokamak Using Resonant Magnetic Perturbations written by Peter Denner and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Type-I ELMy H-mode is planned to be the reference inductive operational scenario for ITER. However, unmitigated type-I ELMs would cause unacceptable damage to ITER's divertor, so a way of mitigating their effect must be found. This thesis focuses on the ergodization of the plasma edge using RMPs as a means of ELM control, and on related topics relevant to ergodic magnetic fields in MAST. Chapter 1 provides an introduction to nuclear fusion and chapter 2 provides an overview of ELMs. In chapter 3, the effect of ergodic fields on L-mode temperature profiles is calculated. It is found that no flattening of the temperature profile should be expected in MAST plasmas, which is in agreement with experimental results. In chapter 4, various metrics characterizing the degree of ergodicity in both L- and H-mode plasmas are calculated using vacuum modelling and compared with the amount of density pump-out observed experimentally in the those plasmas during the application of RMPs. The only parameter to show a correlation with the amount of density pump-out is the width of the laminar region. However, plasma response modelling provides a robust criterion for the occurrence of density pump-out that applies both to L- and H-mode plasmas. In chapter 5, the results of lower single-null H-mode ELM mitigation experiments using n=4 and n=6 RMPs are presented. ELM mitigation is achieved and refuelling of plasmas that had begun to undergo pump-out is successfully demonstrated. Both ELM frequency and density pump-out are found to increase with ELM coil current above a certain threshold. An analysis of an ergodic magnetic field formed by a current sheet on a rational surface is presented in chapter 6. Various properties of this ergodic field are calculated and compared with experimental effects observed in the plasma. Some agreement is found between the experimental data and the modelling. Finally, a summary of the thesis is given in chapter 7.
Download or read book Particle Exhaust and Neutral Fueling in Spherical Tokamaks with Resonant Magnetic Perturbation Fields written by Ian Jacob Waters and published by . This book was released on 2018 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Resonant Magnetic Perturbations (RMPs) and Advanced Divertors (ADs) are both promising candidates to be utilized to meet the challenges of power exhaust in future fusion devices. A combination of both approaches is a promising avenue in order to achieve a stable, high performance plasma edge in an integrated way that takes into account divertor heat load limits while allowing for density and impurity control. The latter is of particular importance in spherical tokamaks which feature Edge Localized Mode free high confinement H-mode regimes prone to density rises and core impurity accumulation. The capability to control core densities and particle exhaust in spherical tokamaks needs to be assessed to determine their viability for compact fusion nuclear science facilities. The experimentally observed, density pump-out effect induced by the application of small amplitude RMPs is an important phenomena with respect to density control but its underlying cause is not well understood. One proposed mechanism for this density pump-out is that the opening of formerly confined field lines from the plasma edge enables enhanced parallel exhaust from the core plasma into the scrape-off-layer and to the divertor targets. Further, regions of stochasticity inside the separatrix can lead to enhanced perpendicular transport, even if these field lines do not themselves escape to the wall. Based on magneto-hydrodynamic (MHD) modeling, it has been previously proposed that a particular resonant response to the applied RMP fields--the so called "Edge-Peeling" response--enhances these geometric changes and thus drives enhanced exhaust. How much these mechanisms contribute to the overall pump-out is an open question. Further, how these RMPs impact the fundamental coupling between the plasma core, edge, and scrape-off-layer, through changes to particle fueling and particle exhaust, is the subject of this thesis. The EMC3-EIRENE code is utilized to assess these scenarios on the Mega-Ampere Spherical Tokamak (MAST) and it's upgrade (MAST-U). Initially, work was carried out to validate the theoretical mechanism for enhanced exhaust: that pressure gradients drive flows along open field lines in the plasma edge. Modeling showed that flows generated by local gas puffing are robust to changes in plasma parameters, and ultimately are a fundamental feature that can be experimentally validated. The underlying mechanism of static pressure driven flows was resolved with a 1D model. Modeling was then used to study the impact of RMP fields specifically. The inclusion of plasma response (from a resistive single fluid MHD model) in the RMP fields shows a more moderate response of density and temperature to the RMPs than does a vacuum field approach in MAST lower single null discharges. In this scenario, enhanced exhaust is shown to contribute to the density pump-out, but the modeled confinement changes underpredict the impact expected from analysis of experiments. Applying this same approach in MAST double null discharges--a second test case from experiment--shows that the addition of RMPs with the single fluid Edge-Peeling response does not cause a consistent pump-out signature in the modeling. This numerical finding of no density pump-out is in contrast to experimental observations for such configurations. This is found in spite of the fact that field lines are escaping the confined region, pressure driven flows are formed, and characteristic lobe structures appear in the plasma edge. This study has shown in a consistent manner that pressure driven flows along field lines are a viable mechanism to govern the plasma particle exhaust from the edge reservoir. If 3D magnetic flux bundles generated by RMP fields connect to regions deep inside of the separatrix, the parallel pressure gradient towards divertor targets will drive enhanced particle flux out of the formerly confined region of the plasma. If the length scale of connection is too long such that the parallel pressure gradient can not be maintained, the flow vanishes, and in spite of the nominal 3D structures in the magnetic field, no impact on particle exhaust is seen. This finding is important for the efforts to understand plasma exhaust with RMP fields. The mere existence of the 3D lobes of the separatrix, formed by the RMP fields, is not sufficient to explain the plasma density pump out alone. But for plasma scenarios with short connection length, and magnetic fields characterized by steep radial gradients they are a viable contributor.
Download or read book Edge Localized Mode Control by Resonant Magnetic Perturbations in Tokamak Plasmas written by Francois Orain and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The growth of plasma instabilities called Edge Localized Modes (ELMs) in tokamaks results in the quasi-periodic relaxations of the edge plasma, potentially harmful for the divertor in ITER. One of the promising ELM control methods planned in ITER is the application of external resonant magnetic perturbations (RMPs), already efficient for ELM mitigation/suppression in current tokamak experiments. However a better understanding of the interaction between ELMs, RMPs and plasma flows is needed to make reliable predictions for ITER. In this perspective, non-linear modeling of ELMs and RMPs is done with the reduced MHD code JOREK, in realisitic geometry including the X-point and the Scrape-Off Layer. The two-fluid diamagnetic drifts, the neoclassical friction, a source of parallel rotation and RMPs have been implemented to simulate the RMP penetration consistently with the plasma response. As a first step, the plasma response to RMPs (without ELMs) is studied for JET, MAST and ITER realistic plasma parameters and geometry. Then the cyclic dynamics of the ELMs (without RMPs) is modeled for the first time in realistic geometry. After an ELM crash, the diamagnetic rotation is found to be instrumental to stabilize the plasma and to model the cyclic reconstruction and collapse of the plasma pressure profile. Last the ELM mitigation and suppression by RMPs is observed for the first time in modeling. The non-linear coupling of the RMPs with unstable modes is found to induce a continuous MHD activity in place of a large ELM crash, resulting in the mitigation of the ELMs. Over a threshold in magnetic perturbation, the full ELM suppression is also observed.
Download or read book The Effects of Resonant Magnetic Perturbations on Fast Ion Confinement in the Mega Amp Spherical Tokamak written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Toroidal Phasing of Resonant Magnetic Perturbation Effect on Edge Pedestal Transport in the DIII D Tokamak written by Theresa M. Wilks and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Resonant Magnetic Perturbation (RMP) fields produced by external control coils are considered a viable option for the suppression of Edge Localized Modes (ELMs) in present and future tokamaks. Repeated reversals of the toroidal phase of the I-coil magnetic field in RMP shot 147170 on DIII-D has generated uniquely different edge pedestal profiles, implying different edge transport phenomena. The causes, trends, and implications of RMP toroidal phase reversal on edge transport is analyzed by comparing various parameters at 0 and 60 degree toroidal phases, with an I-coil mode number of n=3. An analysis of diffusive and non-diffusive transport effects of these magnetic perturbations it the plasma edge pedestal for this RMP shot is characterized by interpreting the ion and electron heat diffusivities, angular momentum transport frequencies, ion diffusion coefficients, and pinch velocities for both phases.
Download or read book Edge Turbulence in the Mega amp Spherical Tokamak written by Benjamin D. Dudson and published by . This book was released on 2007 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Plasma Response to Magnetic Perturbations Relevant to Edge Localised Modes in Tokamaks written by and published by . This book was released on 2013 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Edge localized Mode Control and Transport Generated by Externally Applied Magnetic Perturbations written by and published by . This book was released on 2011 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Nuclear Fusion written by Edward Morse and published by Springer. This book was released on 2018-10-15 with total page 527 pages. Available in PDF, EPUB and Kindle. Book excerpt: The pursuit of nuclear fusion as an energy source requires a broad knowledge of several disciplines. These include plasma physics, atomic physics, electromagnetics, materials science, computational modeling, superconducting magnet technology, accelerators, lasers, and health physics. Nuclear Fusion distills and combines these disparate subjects to create a concise and coherent foundation to both fusion science and technology. It examines all aspects of physics and technology underlying the major magnetic and inertial confinement approaches to developing nuclear fusion energy. It further chronicles latest developments in the field, and reflects the multi-faceted nature of fusion research, preparing advanced undergraduate and graduate students in physics and engineering to launch into successful and diverse fusion-related research. Nuclear Fusion reflects Dr. Morse’s research in both magnetic and inertial confinement fusion, working with the world’s top laboratories, and embodies his extensive thirty-five year career in teaching three courses in fusion plasma physics and fusion technology at University of California, Berkeley.
Download or read book Plasma Science written by National Academies of Sciences Engineering and Medicine and published by . This book was released on 2021-02-28 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma Science and Engineering transforms fundamental scientific research into powerful societal applications, from materials processing and healthcare to forecasting space weather. Plasma Science: Enabling Technology, Sustainability, Security and Exploration discusses the importance of plasma research, identifies important grand challenges for the next decade, and makes recommendations on funding and workforce. This publication will help federal agencies, policymakers, and academic leadership understand the importance of plasma research and make informed decisions about plasma science funding, workforce, and research directions.
Download or read book Iter Physics written by C Wendell Horton, Jr and published by World Scientific. This book was released on 2015-06-25 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: The promise of a vast and clean source of thermal power drove physics research for over fifty years and has finally come to collimation with the international consortium led by the European Union and Japan, with an agreement from seven countries to build a definitive test of fusion power in ITER. It happened because scientists since the Manhattan project have envisioned controlled nuclear fusion in obtaining energy with no carbon dioxide emissions and no toxic nuclear waste products.This large toroidal magnetic confinement ITER machine is described from confinement process to advanced physics of plasma-wall interactions, where pulses erupt from core plasma blistering the machine walls. Emissions from the walls reduce the core temperature which must remain ten times hotter than the 15 million degree core solar temperature to maintain ITER fusion power. The huge temperature gradient from core to wall that drives intense plasma turbulence is described in detail.Also explained are the methods designed to limit the growth of small magnetic islands, the growth of edge localized plasma plumes and the solid state physics limits of the stainless steel walls of the confinement vessel from the burning plasma. Designs of the wall coatings and the special 'exhaust pipe' for spent hot plasma are provided in two chapters. And the issues associated with high-energy neutrons — about 10 times higher than in fission reactions — and how they are managed in ITER, are detailed.
Download or read book Fundamentals of Magnetic Thermonuclear Reactor Design written by Vasilij A. Glukhikh and published by Woodhead Publishing. This book was released on 2018-05-21 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals of Magnetic Thermonuclear Reactor Design is a comprehensive resource on fusion technology and energy systems written by renowned scientists and engineers from the Russian nuclear industry. It brings together a wealth of invaluable experience and knowledge on controlled thermonuclear fusion (CTF) facilities with magnetic plasma confinement – from the first semi-commercial tokamak T-3, to the multi-billion international experimental thermonuclear reactor ITER, now in construction in France. As the INTOR and ITER projects have made an immense contribution in the past few decades, this book focuses on its practical engineering aspects and the basics of technical physics and electrical engineering. Users will gain an understanding of the key ratios between plasma and technical parameters, design streamlining algorithms and engineering solutions. Written by a team of qualified experts who have been involved in the design of thermonuclear reactors for over 50 years Outlines the most important features of the ITER project in France which is building the largest tokamak, including the design, material selection, safety and economic considerations Includes data on how to design magnetic fusion reactors using CAD tools, along with relevant regulatory documents
Download or read book Physics of High Density Z Pinch Plasmas written by Michael A. Liberman and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt: A "z pinch" is a deceptively simple plasma configuration in which a longitudinal current produces a magnetic field that confines the plasma. Z-pinch research is currently one of the fastest growing areas of plasma physics, with revived interest in z-pinch controlled fusion reactors along with investigations of new z-pinch applications, such as very high power x-ray sources, high-energy neutrons sources, and ultra-high magnetic fields generators. This book provides a comprehensive review of the physics of dense z pinches and includes many recent experimental results.
Download or read book Electromagnetic Waves For Thermonuclear Fusion Research written by Ernesto Mazzucato and published by World Scientific. This book was released on 2014-04-02 with total page 223 pages. Available in PDF, EPUB and Kindle. Book excerpt: The science of magnetically confined plasmas covers the entire spectrum of physics from classical and relativistic electrodynamics to quantum mechanics. During the last sixty years of research, our initial primitive understanding of plasma physics has made impressive progress thanks to a variety of experiments — from tabletop devices with plasma temperatures of a few thousands of degrees and confinement times of less than 100 microseconds, to large tokamaks with plasma temperatures of up to five hundred million degrees and confinement times approaching one second. We discovered that plasma confinement is impaired by a variety of instabilities leading to turbulent processes with scales ranging from the plasma size to a few millimeters. Understanding these phenomena, which have slowed down progress towards a fusion reactor, requires the use of very sophisticated diagnostic tools, many of which employ electromagnetic waves.The primary objective of this book is to discuss the fundamental physics upon which the application of electromagnetic waves to the study of magnetically confined plasmas is based.
Download or read book Star Power written by Alain Bécoulet and published by MIT Press. This book was released on 2023-09-19 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: A concise and accessible explanation of the science and technology behind the domestication of nuclear fusion energy. Nuclear fusion research tells us that the Sun uses one gram of hydrogen to make as much energy as can be obtained by burning eight tons of petroleum. If nuclear fusion—the process that makes the stars shine—could be domesticated for commercial energy production, the world would gain an inexhaustible source of energy that neither depletes natural resources nor produces greenhouse gases. In Star Power, Alan Bécoulet offers a concise and accessible primer on fusion energy, explaining the science and technology of nuclear fusion and describing the massive international scientific effort to achieve commercially viable fusion energy. Bécoulet draws on his work as Head of Engineering at ITER (International Thermonuclear Experimental Reactor) to explain how scientists are trying to “put the sun in a box.” He surveys the history of nuclear power, beginning with post–World War II efforts to use atoms for peaceful purposes and describes how energy is derived from fusion, explaining that the essential principle of fusion is based on the capacity of nucleons (protons and neutrons) to assemble and form structures (atomic nuclei) in spite of electrical repulsion between protons, which all have a positive charge. He traces the evolution of fusion research and development, mapping the generation of electric current though fusion. The ITER project marks a giant step in the development of fusion energy, with the potential to demonstrate the feasibility of a nuclear fusion reactor. Star Power offers an introduction to what may be the future of energy production.
