Partners with Energy

PSC collaborations with the Department of Energy

Improved Actions for Staggered Quarks

Magnetism in the Solar Dynamo:
University of Chicago

Rocket Science:
University of Illinois Urbana-Champaign

Shock Waves in Gas:
California Institute of Technology

Turbines and Turbulence:
Stanford University

A New Picture of How Metals Deform

The Edge of Reality

Magnetism in the Solar Dynamo

Distribution of magnetic energy. This frame from a video animation (produced by PSC visualization artist Greg Foss) shows positive (orange) and negative (blue) magnetic field intensities. Download a larger version of this image (144KB).

Temperature fluctuation. This panel, a horizontal plane near the upper boundary of the volume, shows hot (red) and cold (black) fluid regions. The granular structure is typical of convection. Download a larger version of this image (1,195KB).

What happens on the surface of the Sun as the fusion cooker at its core converts matter to energy at the rate of four-million tons per second? An array of complex phenomena occurs in stars like the Sun — nuclear burning, turbulence and convection at extremes of temperature and pressure, magnetic-field generation, star expansion, star death and many more. How can we understand this physics, which simply isn't subject to experiments in the normal sense? You can't build a laboratory model of a star.

The answer, say scientists at the Center for Astrophysical Thermonuclear Flashes at the University of Chicago, is large-scale numerical simulation. Through the ASCI program, this group of researchers has harnessed PSC's CRAY T3E to simulate various stellar phenomena, including x-ray bursts from neutron stars and, recently, a large-scale study of how stars like the Sun generate magnetic fields.

In a series of computations, physicist Fausto Cattaneo simulated the "dynamo action" of the Sun. His question — what is the structure of magnetic fields generated by overturning turbulent layers of ionized gas (convection) at the Sun's surface? Large-scale solar magnetic fields result from rotation patterns in so-called active regions of the Sun, but recent theory has suggested that smaller-scale magnetic fields may also be generated by convection at the Sun's surface.

Essentially, Cattaneo created a box of solar fluid at high temperature inside the computer, and — because of the capability of the CRAY T3E — his box of fluid simulated the physics of the solar dynamo with much greater realism than previously possible. "This calculation," says Cattaneo, "was 1,000 to 10,000 times more ambitious than previous studies." The results — from a series of 512-processor runs — confirm recent theory and indicate that turbulent convection can be an efficient generator of small-scale magnetic fields.

"The T3E is a wonderful machine," says Cattaneo, "and PSC has it set up very well — with the least amount of headache to get it to work. And when it works it's like a dream. The mass-storage system is easy to use. You can migrate data place-to-place without getting stuck. Of all the places I've computed, PSC has been outstanding."

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