PPPL scientists bring mysterious magnetic process down to earth

Scientists believe that magnetic reconnection is behind the extraordinary bursts of radiation that have emerged from the center of the Crab nebula, the remains of an exploded star. 

Astrophysicists from Princeton and other institutions are paying close attention to the efforts of the MRX research team, hoping to better understand some of the mysteries surrounding the phenomenon. 

(Image courtesy of NASA; the European Space Agency; and Jeff Hester and Allison Loll, Arizona State University)

With the click of a computer mouse, a scientist at the U.S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL) sends 10,000 volts of electricity into a chamber filled with hydrogen gas. The charge heats the gas to 100,000 degrees Celsius.

In an instant - one-thousandth of a second, to be precise - a process called "magnetic reconnection," a powerful force that can light up the skies, takes place in a device roughly the size of a sport utility vehicle.

PPPL researchers have run this and similar carefully controlled experiments - called "shots" - more than 100,000 times since 1995, and amassed volumes of data and numerous scientific papers.

The shots recreate one of the most common but least understood phenomena in the universe - one that gives rise to the northern lights, solar flares and geomagnetic storms, and that can disrupt cell phone service, black out power grids and damage orbiting satellites.

Researchers at PPPL have brought this basic process down to earth in miniature to be studied under laboratory conditions in the Magnetic Reconnection Experiment (MRX), the leading project of its kind in the world in terms of the quantity and quality of the data it has collected.

"Here we can actually recreate reconnection," said Masaaki Yamada, a PPPL physicist and principal investigator for MRX, "This is not theory or a computer simulation." Hantao Ji, principal research physicist at PPPL for MRX, concurred: "This provides a chance to see what's really going on in reconnection."

The experiments seek to unravel the secrets of magnetic reconnection and ultimately provide benefits including improved prediction of solar outbursts and dangerous geomagnetic storms; increased understanding of the formation of the sun and stars; and greater control of the nuclear fusion reactions that PPPL researchers are studying as a clean fuel for generating electric power.

Magnetic reconnection takes place when magnetic lines of force - or field lines - break apart and reconnect with a violent burst of energy that, in huge bodies such as the sun and stars, has the explosive power of millions of tons of TNT.

This occurs when superheated and electrically charged gases called plasmas converge.