![]() This issue... Plants with Backbone: A Promising Mystery Laboratory Plasmas Shed Light on the Sun Eureka! California Discovers Plutonium...Again! This issue... Plants with Backbone: A Promising Mystery Laboratory Plasmas Shed Light on the Sun |
Laboratory Plasmas Shed Light on the Sunby Terri Gilbride Laboratory research on plasmas is cutting across the fields of solar physics and fusion science to provide new tools for solar researchers and new answers for fusion physicists attempting to understand the activity of plasma in fusion reactors. Paul Bellan and Freddy Hansen at the California Institute of Technology (CalTech) are using advanced laboratory equipment to zap a puff of hydrogen gas with hundreds of megawatts of electricity transforming it into plasmaa super hot electrically conducting gas of charged particles. The intense power pulse drives many tens of kiloamperes of electric current through the plasma creating strong magnetic fields that mold the plasma's shape. Cameras with shutter speeds as fast as 10 billionths of a second show that the magnetized plasma forms twisting arches that replicate gigantic arches called solar prominences that protrude from the sun's surface. The sun's arches are up to 100,000 kilometers high; the miniature replicas produced in Bellan's lab reach heights of several inches but have similar shape and dynamics. (See photo animation of Bellan and Hansen's experiments from Scientific American online.) This research has led to the development of a new model to explain S-shaped features on the solar surface that are believed to be the precursor for prominence eruptions. These eruptions spew enormous clouds of plasma into space and have been known to destroy satellites and even cause electricity blackouts on earth. Stewart Prager and colleagues at the University of Wisconsin are studying another solar phenomenonthe dynamo effecta huge river of current deep in the sun's interior that creates its magnetic field. Prager and his team have recreated the dynamo effect in a 5-meter-wide, magnetic-sensor-studded, doughnut-shaped vessel in their lab. They are hoping to determine why the plasma exhibits spontaneous tumultuous magnetic fluctuations and how it produces an orderly electric flow. This knowledge could ultimately help fusion researchers control the dynamo effect in reactors where it diverts energy that could otherwise sustain fusion reactions. The new availability of detailed data from laboratory plasma experiments, together with satellite observations, theoretical analysis, and computer simulations has raised interest in magnetic reconnection to new heights among communities in solar physics, magnetospheric physics, and general plasma physics. In magnetic reconnection experiments, a group led by Masaaki Yamada of the Princeton Plasma Physics Laboratory is focusing on the diverse and intriguing physics of magnetic reconnection. ![]() The charged particles that create the aurora are thought to be accelerated through magnetic reconnection. Magnetic reconnection is the breaking and reattaching of magnetic field lines that have snapped after twisting, stretching or crossing other lines. Reconnection is recreated in the lab by slamming together pairs of doughnut-shaped plasma clouds known as spheromaks. These reconnections are thought to be accompanied by powerful energy conversions. Researchers suspect they may energize solar flares, which reach tens of millions of degrees, and they may even account for the mysteriously high temperature of the sun's corona, which is over a million degrees and 200 times hotter than the sun's surface. Fusion researchers see magnetic reconnection's potential for creating plasmas with reactor temperatures. This work is supported by SC's Office of Fusion Energy Sciences Program. Contacts: Related Information: "The Sun also Writhes," Science News, Vol. 155, pp. 200-02, March 27, 1999. "Magnetic Reconnection, Solar Flares, and You," Energy Research News, March/April 1998, Vol. 8, Num. 3. "The Fusion Program Has Changed Direction," Energy Research News, March/April 1999, Volume 9, Number 3. |
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www.pnl.gov/energyscience/ |