Summary
Objectives
The Second International Atomic Energy Agency Technical Meeting (IAEA-TM) on
Theory of Plasma Instabilities is to provide a forum for open discussion on the
physics issue of linear and non-linear theory in large and small scale plasma
instabilities, integrated modelling, turbulence and magneto-hydrodynamic (MHD)
effects. Special attention is to be paid to the modelling and prediction of instabilities
generated by fast alpha particles and their role in the plasma confinement in burning
plasmas. This subject is of significant importance in view of the International Thermonuclear Experimental Reactor (ITER) project and future fusion power plants performance.
Relevance for the IAEA activities
The relevance of this meeting for the IAEA activities is directly linked with the
objectives stated in the Agency’s Subprogramme D.4. – Nuclear Fusion Research: to
strengthen cooperation amongst major institutions and world wide commitment for
plasma physics and nuclear fusion in order to create a viable source of nuclear
energy through support to new and alternative fusion confinement concepts.
Scientific Summary
The meeting gave the opportunity for 49 scientists from 21 countries actively
involved in this research field to present their latest work and discuss their results
since the last meeting of this series held in 2002 in Kloster Seon.
New ideas for explaining and modeling the new different types of plasma instabilities
and turbulence that have been found in plasma devices have recently emerged such as
the interplay between different types of instabilities, cascades of instabilities and their
interaction with plasma turbulence, etc. Plasma turbulence results in cross-field
transport of one or two orders of magnitude larger than transport arising from
neoclassical transport due to the binary collisions. The consequent reduction in
plasma performance has implications on the development of fusion energy as an
economic alternative power source. Thus a comprehensive understanding of plasma
turbulence remains an important scientific objective.
In the turbulence topic, there were two common themes emphasized in many
presentations.The first one consisted of examples of subtle
nonlinear physics which are better understood in configuration space than in k-space, such as scale dependent
anisotropy in MHD turbulence and turbulence spreading in tokamak plasmas. The second one was detailed studies of turbulent eddy shearing by zonal flows and zonal
flow generation, which are two different manifestations of the same phenomenon.
In the transport area, recent advances in implementing more realistic and sophisticated
physics models in various gyrokinetic simulation codes were highly visible.
Addressing the reactor relevant issues, there were continuous efforts in understanding
collisional and turbulence induced toroidal momentum transport, and external control
of turbulence via RF heating.
In the energetic particle physics area, there was a recurring message from all the
speakers as to how well they understand the general features of toroidal Alfven
eigenmodes. It was pointed out that, for ITER, it is important to understand the effects
of two classes of fast particles (isotropic alpha particles and anisotropic fast ions due
to auxiliary heating).
In the MHD area, mechanisms for the threshold island width for neoclassical tearing
mode excitation were discussed in detail, including ion sound effects, finite orbit size
effects, and effects of flows. A code was developed to address the interaction of small
scale turbulence and large scale MHD phenomena. The status of mean field dynamo
theory was reviewed as well.
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