Author: Cuma YarımPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Effects of the Non-axisymmetric Perturbations on the Divertor Tokamaks
Importance of Plasma Response to Non-axisymmetric Perturbations in Tokamaks
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Tokamaks are sensitive to deviations from axisymmetry as small as [delta]B=B0 ~ 10-4. These non-axisymmetric perturbations greatly modify plasma confinement and performance by either destroying magnetic surfaces with subsequent locking or deforming magnetic surfaces with associated non-ambipolar transport. The Ideal Perturbed Equilibrium Code (IPEC) calculates ideal perturbed equilibria and provides important basis for understanding the sensitivity of tokamak plasmas to perturbations. IPEC calculations indicate that the ideal plasma response, or equiva- lently the effect by ideally perturbed plasma currents, is essential to explain locking experiments on National Spherical Torus eXperiment (NSTX) and DIII-D. The ideal plasma response is also important for Neoclassical Toroidal Viscosity (NTV) in non-ambipolar transport. The consistency between NTV theory and magnetic braking experiments on NSTX and DIII-D can be improved when the variation in the field strength in IPEC is coupled with generalized NTV theory. These plasma response effects will be compared with the previous vacuum superpositions to illustrate the importance. However, plasma response based on ideal perturbed equilibria is still not suffciently accurate to predict the details of NTV transport, and can be inconsistent when currents associated with a toroidal torque become comparable to ideal perturbed currents.
Effect of Nonaxisymmetric Perturbations on the Structure of a Tokamak Poloidal Divertor
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 45
Book Description
The effects of n = 1 nonaxisymmetric perturbations on a tokamak poloidal divertor are described. Despite the existence of a region of chaotic field line trajectories outside the last closed flux surface, the footprint of the trajectories on the divertor plates is found to be largely coherent, forming a spiral structure. At a fixed toroidal angle, the footprint exhibits a bifurcation similar to that seen experimentally on DIII-D. For field errors of the magnitude that exist in present day tokamaks, the width of the nonaxisymmetric structure in the divertor footprint is comparable to the width of the scrape-off layer.
Effect of Nonaxisymmetric Perturbations on the Structure of a Tokamak Poloidal Divertor
Author: N. PomphreyPublisher:
ISBN:
Category : Magnetic fields
Languages : en
Pages : 44
Book Description
Non-ambipolar Transport by Trapped Particles in Tokamaks
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 587
Book Description
Small non-axisymmetric perturbations of the magnetic field can greatly change the performance of tokamaks through non-ambipolar transport. A number of theories have been developed, but the predictions were not consistent with experimental observations in tokamaks. This Letter provides a resolution, with a generalized analytic treatment of the non-ambipolar transport. It is shown that the discrepancy between theory and experiment can be greatly reduced by two effects: (1) The small fraction of trapped particles for which the bounce and precession rates resonate. (2) The non- axisymmetric variation in the field strength along the perturbed magnetic field lines rather than along the unperturbed magnetic field lines. The expected sensitivity of ITER to non-axisymmetries is also discussed.
Energy Research Abstracts
Author: Effect of Magnetic Perturbations on Divertor Scrape-off Width
Author: Allen H. BoozerOrbit Effects on the Particles and Energy Flow in Thepoloidalnull Region of a Tokamak Axisymmetric Divertor
Author: W. G. F. CoreOrbit Effects on the Particles and Energy Flow in the Poloidal Null Region of a Tokamak Axisymmetric Divertor
Author: W. G. F. CorePublisher:
ISBN:
Category : Plasma heating
Languages : en
Pages : 8
Book Description
Parametric Analysis of the Thermal Effects on the Divertor in Tokamaks During Plasma Disruptions
Author: Michael Lindsay BruhnPublisher:
ISBN:
Category :
Languages : en
Pages : 314
Book Description