Simulation of Neoclassical Plasma Transport

                   

Principal Investigator

Robert Dewar

Department of Theoretical Physics and Plasma Research Laboratory,

Research School of Physical Sciences and Engineering

The computation of the physical properties of a plasma (of some 1020 charged particles) and its
self-consistent interactions with magnetic and electric fields is a grand-challenge of modern science - particularly when a detailed comparison with experiment is needed. In paricular, the diffusive loss of charged particles from magnetic fusion experiments (such as the H-1NF Heliac, at the Plasma Research Laboratory, RSPhysSE) has been found to depend sensitively on the magnitude of radial electric fields which are set up by the plasma. The goal of this project has been to build a self-consistent computer simulation of this phenomenon based on the Drift Kinetic Equation of neoclassical transport theory to determine what radial electric field is consistent with the observed transport of plasma particles in fusion experiments.
 

Henry Gardner

Department of Computer Science,

Faculty of Engineering and Information Technology

       
                 

   

Co-Investigators

             

Sean Dettrick

Sally Lloyd

Department of Theoretical Physics and Plasma Research Laboratory,

Research School of Physical Sciences and Engineering

What are the results to date and the future of the work?

A parallel implementation of a Monte Carlo transport code has been developed using the Message Passing Interface and Fortran 90. The transport code has been used to self-consistently calculate the radial electric field in the plasma column of the H-1NF Heliac and electric fields and diffusion coefficients have been compared with experiment. The simulation has been applied to conditions surrounding the so-called "Improved Confinement Mode" transition in the H-1NF Heliac and it has been found that this transition is not inconsistent with neoclassical theory. The code has also predicted that positive electric fields may be obtained in the H-1NF which would signify a different experimental regime from that observed to date.

         

Projects

r21 - VPP, PC

   
                   

A PhD thesis was submitted by S. Dettrick in September 1997.

Future work in 1998 will necessitate a comparison of the "bank queue" and "dynamic queue" parallel versions of the code in order to critically evaluate the effectiveness of each.

                   
Appendix A -
                   

                   
       

What computational techniques are used?

Test particle Monte Carlo simulations of the electron and ion distribution functions in the H-1NF Heliac are run for fixed radial electric fields. The electric fields are then updated to minimise the radial current. Measurements of the fluxes are calculated from the diffusion coefficient and thermal diffusivity in the case of the electrons and from the ion test particle fluxes in the case of the ions.

Publications

S. A. Dettrick, H. J. Gardner, R. L. Dewar, Drift Surface Geometry, Trapped Populations and Radial Electric Fields in the H-1 Heliac, 2nd Asia Pacific Plasma Theory Conference, National Institute for Fusion, Science, Toki, Japan, 24-26 Sept 1997.

S.A. Dettrick, H. J. Gardner, R. L. Dewar, Ambipolar Radial Electric Fields and Confinement in the H-1 Heliac, to appear in Journal of Plasma and Fusion Research (JPFR Series Vol.1).

S. A. Dettrick, S. S. Lloyd, H. J. Gardner, and R. L. Dewar, Particle Orbits and Drift Surfaces in a Heliac, submitted to Nuclear Fusion (1997).

S. A. Dettrick, Drift Orbits and Neoclassical Transport in the H-1NF Heliac, PhD thesis Australian National University (1997).

       
- Appendix A