Author: George VayakisPublisher:
ISBN:
Category : Nuclear fusion
Languages : en
Pages : 182
Book Description
Anomalous Transport in the Tokamak Edge
Author: George VayakisPublisher:
ISBN:
Category : Nuclear fusion
Languages : en
Pages : 182
Book Description
Anomalous Radial Transport in Tokamak Edge Plasma
Author: Vasudeva Raghavendra Kowsik BodiPublisher:
ISBN:
Category :
Languages : en
Pages : 72
Book Description
Energy from nuclear fusion of Hydrogen isotopes is a possible alternative to fossil fuels. For this to be of practical utility, confinement of Hydrogen in a plasma state for a minimum duration is necessary. Since confinement is strongly affected by radial transport processes, understanding the observed modes of radial transport in confined plasma is of vital importance for progress towards fusion energy. The present dissertation is aimed at studying radial (cross-field) transport in the tokamak edge plasma. The present thesis is divided into three parts : In the first part, we present a model of generation of intermittent convective meso-scale structures (blobs) based on the synergy of the interchange drive and nonlinear effects associated with drift-wave turbulence. In the second part, we attempt to explain the preferential propagation of blobs radially outward as a consequence of the radially decreasing density of a confined plasma. In the third part, we present a model for simulating anomalous radial transport in kinetic codes for tokamak edge plasma.
Observations of Anomalous Transport in Tokamak Plasmas with No Momentum Input
Author: William Davis LeePublisher:
ISBN:
Category :
Languages : en
Pages : 16
Book Description
Anomalous momentum transport has been observed in Alcator C-Mod tokamak plasmas. The time evolution of core impurity toroidal rotation velocity profiles has been measured with a crystal x-ray spectrometer array. Following the L-mode to EDA (enhanced D[/sub/ alpha]) H-mode transition in both Ohmic and ICRF heated discharges, the ensuing co-current toroidal rotation velocity, which is generated in the absence of any external momentum source, is observed to propagate in from the edge plasma to the core with a time scale of order of the observed energy confinement time, but much less than the neo-classical momentum confinement time. The steady state toroidal rotation velocity profiles in EDA H-mode plasmas are relatively flat and the momentum transport can be simulated with a simple diffusion model. Assuming the L-H transition produces an instantaneous edge velocity source (which disappears at the H- to L-mode transition), the momentum transport may be characterized by a diffusivity, with values of 0.07 m2/s during EDA H-mode and 0.2 m2/s in L-mode. These values are large compared to the calculated neo-classical momentum diffusivities. Velocity profiles during ELM-free H-modes are centrally peaked, which suggests inward momentum convection; the observed profiles are matched with simulations including an inward convection velocity of 10 m/s. In EDA H-mode discharges which develop internal transport barriers, the velocity profiles become hollow in the center indicating the presence of a negative radial electric field well in the vicinity of the barrier foot.
Anomalous Perturbative Transport in Tokamaks Due to Drift-wave Turbulence
Author: Anne A. ThoulEdge Gradient and Safety Factor Effects on Electrostatic Turbulent Transport in Tokamaks
Author: Ing Hwie TanModels of Coupled Transport to Investigate Anomalous Transport in Tokamaks
Author: Renato GattoAnomalous Transport Modelling of Tokamak Plasmas
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 23
Book Description
Theory based transport simulations of DIII-D, JET, ITER are compared to experimental data using a combination of anamolous transport models. The Multiple-mode Transport Model is calibrated to a give set of L-mode and H-mode discharges with an emphasis on testing the adequacy of anomalous flux contributions from drift/[eta]{sub i} and resistive ballooning mode theories. A survey of possible additions and/or alternatives to the model from recent theories on neoclassical MHD effects, hot ion modes, circulating electron modes, and high-m tearing modes is also included.
Anomalous Transport and Confinement Scaling Studies in Tokamaks
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
In addressing the general issue of anomalous energy transport, this paper reports on results of theoretical studies concerning: (1) the characteristics and relative strength of the dominant kinetic instabilities likely to be present under realistic tokamak operating conditions; (2) specific nonlinear processes relevant to the saturation and transport properties of drift-type instabilities; (3) the construction of semiempirical models for electron thermal transport and the scaling trends inferred from them; and (4) the application of specific anomalous transport models to simulate recent large-scale confinement experiments (TFTR and JET) and current drive experiments.
Turbulent Correlations and Anomalous Transport in Tokamaks
Author: A. ThyagarajaPublisher:
ISBN: 9780853111702
Category : Plasma turbulence
Languages : en
Pages : 74
Book Description
Author: F. A. Haas