“We’re not re-creating the sun, because that’s impossible,” says plasma physicist Ethan Peterson of the University of Wisconsin–Madison, who reports the new work July 29 in Nature Physics. “But we’re re-creating some of the fundamental physics that happens near the sun.”
The sun spews a constant stream of charged particles, called the solar wind, out into space — though scientists aren’t sure exactly how (SN Online: 8/18/17). As the sun rotates, its magnetic field twists the wind into a helical shape called the Parker spiral, named after solar physicist Eugene Parker, who predicted the existence of the solar wind in 1958.
NASA last year launched its Parker Solar Probe to directly investigate the source of the solar wind (SN: 7/21/18, p. 12). But Peterson and colleagues found a way to mimic the Parker spiral much closer to home.
The team used a 3-meter-wide aluminum vacuum chamber called the Big Red Ball at the Wisconsin Plasma Physics Laboratory to confine a ball of plasma heated to 100,000° Celsius. A magnet in the center of the ball mimics the sun’s magnetic field, and carefully applied electric currents send the plasma spinning and a wind streaming.
There are some unavoidable differences between the Big Red Ball and the sun, including size, gravity and temperature. Even so, the wind organized itself into a clear Parker spiral, as expected. The wind also occasionally ejected little blobs of plasma, each about 10 centimeters across. The sun ejects similar blobs, called plasmoids, but no one is sure why. The Big Red Ball could help provide an answer, Peterson says.