NERSC 1999 Annual Report

J. M. Dawson, V. K. Decyk, M. W. Kissick, J. N. Leboeuf, and T. L. Rhodes,
University of California, Los Angeles
R. D. Sydora, University of Alberta, Edmonton

Research Objectives

(1) Investigate the possible application of free surface liquid magnetohydrodynamic (MHD) flows for liquid walls to both magnetic and inertial fusion plasma chambers. This involves the modeling of turbulent liquid free surface flows in the presence of strong magnetic fields in some cases. (2) Extend the capabilities of the three-dimensional global toroidal gyrokinetic particle model of ion temperature gradient driven turbulence in magnetically confined plasmas beyond adiabatic electrons and in the longer term beyond electrostatics.

Computational Approach

(1) The standard formulation for incompressible liquid flow is the so-called projection or fractional step method. This solution methodology can be applied to the magnetic vector potential equations as well. Message passing will be used to partition this among multiple processors in the massively parallel implementation. (2) Gyrokinetic particle code techniques currently applied to the ions will be duplicated for the now mobile electrons by calling the particle manager routines in the PLIB library once for each mobile species. This simplifies the coding enormously and insures symmetry in the massively parallel treatment of the multi-particle species.

Accomplishments

(1) The parallel work is still in the developmental stages. (2) Production calculations have enabled us to investigate the effects of impurities and externally imposed poloidal flows on ion temperature gradient driven turbulence. Both of these additions to the standard description of ion temperature gradient driven instabilities have a stabilizing influence on the growth rates, and lead to a reduction of the saturation level and of the heat flux.

Significance

(1) The interaction of turbulence with both free surface interfaces and magnetic fields is of interest in many scientific disciplines, including atmospheric sciences (missing CO₂ sink in oceans) and metallurgy (casting of metal components). We are interested in the application to free liquid walls in fusion reactors as a possible new paradigm for plasma containment structures. (2) Including electrons in the gyrokinetic description of ion temperature gradient driven instabilities extends the applicability of the model to describe particle transport as well as heat transport. It also provides a more relevant description of the physics of ion temperature gradient driven modes, since trapped electrons are known to enhance the growth rate of the underlying instability.


Turbulence mitigation by externally imposed local and global flows in UCLA's Electric Tokamak, as simulated by massively parallel 3D full torus gyrokinetic particle-in-cell calculations. Localized flow suppresses fluctuations where flow shear is largest.

Publications

R. D. Sydora, V. K. Decyk, J. M. Dawson, J. Ongena, A. Messiaen, P. E. Vandenplas, and J. Boedo, "3D global gyrokinetic particle simulation study of turbulence suppression in neon impurity-seeded tokamak plasmas," Bull. Am. Phys. Soc. 44, 357 (1999).

A. Ying, N. Morley, M. Abdou, and M. Youssef, "Description and thermalhydraulic analysis of liquid surface FW/blankets concepts for high power density reactors," Fusion Technology 34, 1035 (1998).

A. M. Dimits, M. A. Beer, G. W. Hammett, C. Kim, S. E. Parker, D. E. Shumaker, R. Sydora, A. J. Redd, J. Weiland, M. T. Kotschenreuther, W. M. Nevins, G. Bateman, C. Bolton, B. I. Cohen, W. D. Dorland, A. H. Kritz, J. E. Kinsey, L. L. Lao, and J. Mandrekas, "Comparisons and physics basis of tokamak transport models and turbulence simulations," Phys. Plasmas (submitted).

http://exodus.physics.ucla.edu
http://www.fusion.ucla.edu/apex


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