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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The ARIES reactor study group has found an economically attractive ST-based reactor configuration with: A= 1.6, [kappa]= 3.4, [delta]= 0.65, [beta]= 50%, [beta][sub N]= 7.3, f[sub BS]= 0.95, R[sub 0]= 3.2 meters, B[sub t0]= 2.08 Tesla, and I[sub P]= 28.5 MA which yields a cost of electricity of approximately 80mils/kWh. MHD stability analysis finds that a broad pressure profile is optimal for wall-stabilizing the pressure driven kink modes typical of such configurations, and that wall stabilization is crucial to achieving the high[beta] needed for an economical power plant. The 6MW high-harmonic fast wave system presently being installed on NSTX should allow real-time control of the plasma[beta], and in combination with NBI may permit experimental investigations of the effect of pressure profile peaking on MHD stability in the near-term. In the longer term, ejection of ions through resonant interaction with HHFW might be used to induce a controllable edge radial electric field with potentially interesting effects on edge MHD and confinement.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The ARIES reactor study group has found an economically attractive ST-based reactor configuration with: A= 1.6, [kappa]= 3.4, [delta]= 0.65, [beta]= 50%, [beta][sub N]= 7.3, f[sub BS]= 0.95, R[sub 0]= 3.2 meters, B[sub t0]= 2.08 Tesla, and I[sub P]= 28.5 MA which yields a cost of electricity of approximately 80mils/kWh. MHD stability analysis finds that a broad pressure profile is optimal for wall-stabilizing the pressure driven kink modes typical of such configurations, and that wall stabilization is crucial to achieving the high[beta] needed for an economical power plant. The 6MW high-harmonic fast wave system presently being installed on NSTX should allow real-time control of the plasma[beta], and in combination with NBI may permit experimental investigations of the effect of pressure profile peaking on MHD stability in the near-term. In the longer term, ejection of ions through resonant interaction with HHFW might be used to induce a controllable edge radial electric field with potentially interesting effects on edge MHD and confinement.
Author: Jeffrey P. Freidberg Publisher: Cambridge University Press ISBN: 1139991809 Category : Science Languages : en Pages : 743
Book Description
Comprehensive, self-contained, and clearly written, this successor to Ideal Magnetohydrodynamics (1987) describes the macroscopic equilibrium and stability of high temperature plasmas - the basic fuel for the development of fusion power. Now fully updated, this book discusses the underlying physical assumptions for three basic MHD models: ideal, kinetic, and double-adiabatic MHD. Included are detailed analyses of MHD equilibrium and stability, with a particular focus on three key configurations at the cutting-edge of fusion research: the tokamak, stellarator, and reversed field pinch. Other new topics include continuum damping, MHD stability comparison theorems, neoclassical transport in stellarators, and how quasi-omnigeneity, quasi-symmetry, and quasi-isodynamic constraints impact the design of optimized stellarators. Including full derivations of almost every important result, in-depth physical explanations throughout, and a large number of problem sets to help master the material, this is an exceptional resource for graduate students and researchers in plasma and fusion physics.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Global magnetohydrodynamic stability limits in the National Spherical Torus Experiment (NSTX) have increased significantly recently due to a combination of device and operational improvements. First, more routine H-mode operation with broadened pressure profiles allows access to higher normalized beta and lower internal inductance. Second, the correction of a poloidal field coil induced error-field has largely eliminated locked tearing modes during normal operation and increased the maximum achievable beta. As a result of these improvements, peak beta values have reached (not simultaneously)[beta][sub t]= 35%, [beta][sub N]= 6.4, [beta][sub N]= 4.5, [beta][sub N]/l[sub i]= 10, and[beta][sub P]= 1.4. High[beta][sub P] operation with reduced tearing activity has allowed a doubling of discharge pulse-length to just over 1 second with sustained periods of[beta][sub N][approx] 6 above the ideal no-wall limit and near the with-wall limit. Details of the[beta] limit scalings and[beta]-limiting instabilities in various operating regimes are described.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The role of shear in determining the ideal MHD stability properties of tokamaks is discussed. In particular, we assess the effects of low shear within the plasma upon pressure-driven modes. The standard ballooning theory is shown to break down, as the shear is reduced and the growth rate is shown to be an oscillatory function of n, the toroidal mode number, treated as a continuous parameter. The oscillations are shown to depend on both the pressure and safety-factor profiles. When the shear is sufficiently weak, the oscillations can result in bands of unstable n values which are present even when the standard ballooning theory predicts complete stability. These instabilities are named ''infernal modes.'' The occurrence of these instabilities at integer n is shown to be a sensitive function of q-axis, raising the possibility of a sharp onset as plasma parameters evolve. 20 refs., 31 figs.
Author: Antoine Julien Cerfon Publisher: ISBN: Category : Languages : en Pages : 250
Book Description
In this work, two separate aspects of ideal MHD theory are considered. In the first part, analytic solutions to the Grad-Shafranov equation (GSE) are presented, for two families of source functions: functions which are linear in the flux function T , and functions which are quadratic in T. The solutions are both simple and very versatile, since they describe equilibria in standard tokamaks, spherical tokamaks, spheromaks, and field reversed configurations. They allow arbitrary aspect ratio, elongation, and triangularity as well as a plasma surface that can be smooth or possess a double or single null divertor X-point. The solutions can also be used to evaluate the equilibrium beta limit in a tokamak and spherical tokamak in which a separatrix moves onto the inner surface of the plasma. In the second part, the reliability of the ideal MHD energy principle in fusion grade plasmas is assessed. Six models are introduced, which are constructed to better describe plasma collisonality regimes for which the approximations of ideal MHD are not justified. General 3-D quadratic energy relations are derived for each of these six models, and compared with the ideal MHD energy principle. Stability comparison theorems are presented. The main conclusion can be summarized in two points. (1) In systems with ergodic magnetic field lines, ideal MHD accurately predicts marginal stability, even in fusion grade plasmas. (2) In closed field line geometries, however, the ideal MHD predictions must be modified. Indeed, it is found that in collisionless plasmas, the marginal stability condition for MHD modes is inherently incompressible for ion distribution functions that depend only on total energy. The absence of compressibility stabilization is then due to wave particle resonances. An illustration of the vanishing of plasma compressibility stabilization in closed line systems is given by studying the particular case of the hard-core Z-pinch.
Author: Publisher: ISBN: Category : Languages : en Pages : 10
Book Description
This paper will give an overview of the some of the methods which are used to simulate the ideal MHD properties of tokamak plasmas. A great deal of the research in this field is necessarily numerical and the substantial progress made during the past several years has roughly paralleled the continuing availability of more advanced supercomputers. These have become essential to accurately model the complex configurations necessary for achieving MHD stable reactor grade conditions. Appropriate tokamak MHD equilibria will be described. Then the stability properties is discussed in some detail, emphasizing the difficulties of obtaining stable high [beta] discharges in plasmas in which the current is mainly ohmically driven and thus demonstrating the need for tailoring the current and pressure profiles of the plasma away from the ohmic state. The outline of this paper will roughly follow the physics development to attain the second region of stability in the PBX-M device at The Princeton Plasmas Physics Laboratory.
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Author: Jonathan Edward Menard
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Author: Jeffrey P. Freidberg
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Author: Jonathan Edward Menard
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Author: Antoine Julien Cerfon
Author: A. Ardelea
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