Plasma is an essential element in science fiction, most notably in the Star Wars franchise as a critical component of the Stormtroopers’ guns. At UW-Madison, Cary Forest, a professor of physics, is studying plasma that’s anything but fictional. Forest is recreating plasma solar flares right here on campus.
“I build devices in the lab that mimic processes that we think are taking place in stars and galaxies so we can study them here … in a way that is impossible to do with telescopes,” said Forest.
Forest is interested in learning more about the sun and what he calls “space weather.” This is the cosmic interaction of plasma, the fourth state of matter, in the sun and solar flares, with Earth and the surrounding universe. Solar flares are electromagnetic plasma pulses from the core of the sun ejecting toward the surface.
Plasma is just an energized gas. Introducing large amounts of energy to a gas frees the electrons, turning it into plasma.
Why does the plasma sit there stably without exploding? How is it building up enough energy? What triggers the explosion? These questions are what Forest and other astrophysicists are trying to answer.
“Magnetic fields contact plasma in the atmosphere of the sun; those plasmas can sit there for months and months stably and do nothing. Then, spontaneously they will erupt, explode and fire a plasma ball toward the earth that has the mass of a mountain,” said Forest. Understanding this will help scientists understand space weather.
Space weather has broader implications here on Earth. Solar flares can cause communication frequency blackouts and destroy satellites. There was even a solar flare in 1987 that took out most of eastern Canada’s power grid. Learning what triggers a plasma solar flare can help scientists design more durable satellites.
“If we can better understand space weather and better understand our local environment around the earth, when Elon Musk decides to put a base on the moon, then travel to Mars, we’re going to have to understand the plasma environment and how the sun interacts with it,” said Forest. “How do we create a spaceship so the people inside don’t get radiated?”
By recreating plasma solar flares on earth, Forest can study the potential triggers. They call the trigger a magnetic reconnection, because the magnetic waves build up to release the stored plasma.
Exactly how or why this happens is still unknown. Forest’s research is leading the world in studying how magnetic reconnection happens in the lab. “By probing [the plasma] in the lab, we think we can better understand what happens in the sun,” said Forest.
A $12.5 million grant from the U.S. Department of Energy will allow UW-Madison to integrate two existing projects — the Big Red Plasma Ball and the Madison Symmetric Torus — into the Wisconsin Plasma Physics Laboratory. It will also create a degree of collaboration and efficiency never before seen in this area of research.
Forest is still hard at work studying plasma and magnetic reconnection. Forest enters the control room just as Ethan Peterson, a doctorate student, is minutes away from firing energy into a gas to create plasma. The narrow viewing window on the Big Red Plasma Ball, appropriately named for its large, red appearance and ability to generate plasma, flashes for a split second.
There’s more on the horizon when it comes to understanding the sun, plasma and solar flares. Next year, NASA will be launching its first instrument into the sun. It will be the first time researchers can directly measure the sun.
“I can’t imagine being anywhere else right now. [UW-Madison] is the most exciting place to be doing plasma physics.”
