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Market: Scientists and students involved in thermonuclear fusion research. Thermonuclear fusion research using the confinement device tokamak represents one of the most prominent science projects in the second half of the 20th century. International Tokamak Community is now committing significant effort and funds to experiments with burning plasma, hot and dense enough to produce significant nuclear fusion reactions. The methods used to enhance tokamak performance have a profound and immediate effect on machine design. This book provides an up-to-date account of research in tokamak fusion and puts forward innovative ideas in confinement physics.
The lectures given in the Summer School covered most of the important topics in controlled nuclear fusion and high temperature plasma physics. The topics are as follows: tokamak research, stellarator physics, transport and confinement of high temperature plasma, plasma-wall interaction and edge plasma physics, heating and current drive, diagnostics and general plasma theory.
This book reviews recent progress in our understanding of tokamak physics related to steady state operation, and addresses the scientific feasibility of a steady state tokamak fusion power system. It covers the physical principles behind continuous tokamak operation and details the challenges remaining and new lines of research towards the realization of such a system. Following a short introduction to tokamak physics and the fundamentals of steady state operation, later chapters cover parallel and perpendicular transport in tokamaks, MHD instabilities in advanced tokamak regimes, control issues, and SOL and divertor plasmas. A final chapter reviews key enabling technologies for steady state reactors, including negative ion source and NBI systems, Gyrotron and ECRF systems, superconductor and magnet systems, and structural materials for reactors. The tokamak has demonstrated an excellent plasma confinement capability with its symmetry, but has an intrinsic drawback with its pulsed operation with inductive operation. Efforts have been made over the last 20 years to realize steady state operation, most promisingly utilizing bootstrap current. Frontiers in Fusion Research II: Introduction to Modern Tokamak Physics will be of interest to graduate students and researchers involved in all aspects of tokamak science and technology.
We present the global analysis of a recent survey of the H-mode power threshold in DIII-D using D{sup o} --> D NBI after boronization of the vacuum vessel. Single parameter scans of B{sub T}, I{sub p}, density, and plasma shape have been carried out on the DIII-D tokamak for neutral beam heated single-null and double-null diverted plasmas. In single-null discharges, the power threshold is found to increase approximately linearly with B{sub T} and n{sub e} but remains independent of I{sub p}. In double-null discharges, the power threshold is found to be approximately independent of both B{sub T} and n{sub e}. Various shape parameters such as plasma-wall gaps had only a weak effect on the power threshold. Imbalancing the double null configuration resulted in a large increase in the threshold power.
The exact nature of the physics governing the L-H transition seen in tokamak magnetic confinement experiments has eluded fusion researchers for several decades. To date, a first principles model for the transition does not exist. The improved particle and energy confinement realized by the suppression of turbulence in the post-transition H-mode motivates an understanding of the transition and the empirically known conditions necessary for its initiation, generically an input power threshold with key sensitivities to the edge electron density, main ion mass and charge, plasma configuration, divertor conditions, ∇B drift direction, etc. Modern consensus that an increase in the E x B shear at the plasma edge is responsible for the turbulence suppression and formation of a transport barrier invigorates research into possible driving mechanisms. The loss of thermal ions from the imperfectly confining magnetic field of a tokamak manifests as a steady-state radial current in the edge and has long been suspected to play a role in the generation of the E x B shear and hence the L-H transition.The body of this thesis presents the development of a model for the steady-state thermal orbit loss based on the identification of the phase-space loss cone. The presented model boasts several improvements over other loss cone models found in the literature, largely rooted in the careful consideration of local pitch angle scattering on ions within and near the velocity-space boundaries of projections of the phase-space loss cone to observation points in configuration-space. The probability that ions within the loss cone will be lost on a first orbit is estimated by comparing the rates of collisionally scattering out of the loss cone to the periods of orbit loss. The steady-state is determined by the rates of collisional loss cone refueling modified by the statistical chance of first orbit loss. A competition arises between the sufficiently large temperatures necessary for appreciable parts of the distribution to interact with the loss cone and the reduced rate of collisional refueling of high energy ions. The steady-state orbit loss current calculated by the model exhibits several features of the experimentally measured L-H transition power threshold not present in other models. The orbit loss current displays branching behaviors in the edge density, peaking at densities similar to those minimizing the required transition power on ASDEX Upgrade. Additionally, the loss current features the suspected strong ∇B drift direction asymmetry of the orbit loss. The unfavorable drift configuration requires about a factor of two greater input power to produce a similar orbit loss current seen in the favorable drift, again echoing a known behavior of the power threshold. Other explored features that suggest a promising connection between the thermal orbit losses and the transition are the main ion mass and the horizontal position of the X-point. The orbit loss current has been implemented into the edge fluid transport code SOLPS. The first order plasma response to the current is studied over the high-density branch of the loss current. The leading order effect is an increase in the magnitude of the edge Er well and the associated E x B shear. Over the explored parameter space, the input power necessary to reach some threshold Er magnitude lessens on the order of ∼ 10-20% in the presence of the loss current. Thermal ion orbit loss appears capable of influencing the onset of the L-H transition.
The tokamak is the principal tool in controlled fusion research. This book acts as an introduction to the subject and a basic reference for theory, definitions, equations, and experimental results. The fourth edition has been completely revised, describing their development of tokamaks to the point of producing significant fusion power.
Proceedings of the Sixteenth International Conference, formerly called the International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Montreal, 7-11 October 1996. The papers presented reflect the excellent progress achieved since the last conference in Seville 1994. Among many other achievements, the Tokamak Fusion Test Reactor has produced over 10 MW of fusion power, the JT-60U experiment has demonstrated plasma conditions equivalent to breakeven, the reversed shear mode has been demonstrated, low aspect ratio tokamaks have produced promising results and plans have been drawn up for powerful new inertial confinement fusion experiments.