In just a few minutes, flares on the sun can release enough energy to power the whole world for 20000 years. These solar flares were triggered by an explosive process called magnetic reconnection, and scientists have been trying to figure out how it works for the past half century.
This is not just out of scientific curiosity. A more comprehensive understanding of magnetic reconnection can enable people to understand nuclear fusion and provide better prediction of particle storms from the sun that may affect earth orbit technology.
Now, scientists from NASA's magnetospheric multiscale mission (MMS) think they have figured it out. Researchers have developed a theory and explained how the most explosive type of Magnetic Reconnection - called rapid Reconnection - occurs and why it occurs at a consistent rate. The new theory uses a common magnetic effect that is used in household devices, such as sensors that time the car's anti lock braking system and know when the flip of a mobile phone closes.
"We finally understand what makes this type of magnetic reconnection so fast. We now have a theory to fully explain it," said Yi Hsin Liu, the lead author of the new study, a professor of physics at Dartmouth College in New Hampshire and deputy head of the MMS theory and modeling team
The fourth state of matter, sometimes referred to as the fourth state of matter, occurs in the plasma. Plasma is formed when a gas is given enough energy to break its atoms and leave impurities with negatively charged electrons and positively charged ions side by side. This energetic, fluid like substance is very sensitive to magnetic fields.
From flares on the sun to near earth space to black holes, the plasma in the whole universe is undergoing magnetic reconnection, which quickly converts magnetic energy into heat and acceleration. Although there are several types of magnetic reconnection, there is a particularly confusing variant called rapid reconnection, which occurs at a predictable rate.
"We already know that rapid reconnection occurs at a certain speed and seems to be quite constant. But until now, the factors that really drive this speed have been a mystery," said Barbara Giles, a MMS project scientist and research scientist at NASA Goddard Space Flight Center in Greenbelt, Maryland
This visualization shows the Hall effect, which occurs when the motion of heavier ions (blue) and lighter electrons (red) enter the region with strong current (Golden region).
The new study, published in nature's communication physics and funded in part by the National Science Foundation, explains how rapid reconnection occurs in collision free plasmas. Where reconnection takes place in space, most plasmas are in this collision free state, including the plasmas in solar flares and the space around the earth.
The new theory shows how and why rapid reconnection can be accelerated by Hall effect. Hall effect is a common magnetic phenomenon, which is used in daily technologies, such as automobile wheel speed sensor and 3D printer. The sensor is responsible for measuring speed, proximity, positioning or current.
During rapid magnetic reconnection, charged particles in the plasma -- ions and electrons -- stop moving as a group. When ions and electrons begin to move alone, they create a Hall effect and create an unstable energy vacuum - where reconnection occurs. The pressure from the magnetic field around the energy vacuum will lead to the vacuum implosion, which will quickly release huge energy at a predictable speed.
This new theory will be tested by MMS in the next few years. It is understood that MMS uses four spacecraft to fly around the earth in the form of a pyramid to study magnetic reconnection in collision free plasma. In this unique space laboratory, MMS can study magnetic reconnection at a higher resolution than on earth.
"Ultimately, if we can understand how magnetic reconnection works, we can better predict events that may affect our earth, such as geomagnetic storms and solar flares. And if we can understand how reconnection starts, it will also help energy research because researchers can better control the magnetic field in fusion devices," Giles said