Space weather and sunspots
PICTURE: An artist’s imagination of coronal mass ejections and magnetic reconnection via photos of PPPL physicists from left, view of Masaaki Yamada, Hantao Ji and Jongsoo Yoo More
Photo credit: (Astrophysical inages courtesy of NASA / Headshots and collage courtesy of Elle Starkman)
Scientists at the Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) have received three awards from the National Aeronautics and Space Administration (NASA) totaling over $ 2 million for research that could help Predict the potentially harmful effects of subatomic explosions from particles from the sun.
The three-year awards will fund research into a process known as magnetic reconnection, the meeting and explosive separation of magnetic field lines in plasma that occur throughout the universe. Scientists suspect that the magnetic reconnection causes the explosions that produce large amounts of electrically charged subatomic particles known as plasma. The rush of particles that is part of what is known as space weather can disrupt communications satellites and power grids on Earth.
The awards will also support research into a type of plasma blob that can regularly inflate on the surface of the sun and emit an energetic variety of X-rays.
Two of the awards will help PPPL scientists investigate whether some type of electromagnetic wave can cause magnetic reconnection. “This research will be an extension of my previous experiments with these lower hybrid drift waves,” said PPPL research physicist Jongsoo Yoo, referring to previous research on the strong plasma waves that had received one of the grants. “If we can show that these waves lead to rapid magnetic reconnection, it would be a big breakthrough. In predicting space weather, it is very important to find out what is causing rapid magnetic reconnection to begin.”
Yoo and a researcher from University of Maryland-College Park will analyze data created by NASA’s Magnetospheric Multiscale Mission (MMS), a group of four spacecraft flying in formation, to reconnect in the magnetosphere, the magnetic field that surrounds the earth. The team will use PPPL’s Magnetic Reconnection Experiment (MRX), a device that resembles a giant silver cylinder tilted on its side, to determine what MMS information could be important for laboratory experiments.
With MRX, the team hopes to restore conditions in the magnetosphere that are associated with reconnection and to investigate what phenomena may be responsible. Yoo’s guess is that lower hybrid drift waves could heat electrons in the plasma and cause a rapid magnetic reconnection to begin. “We’d be thrilled if at some point we could say that if you spotted these waves in space, you could reasonably predict that the reconnection will follow.”
This research ties in with experiments from 20 years ago when scientists came to a different conclusion. “We first observed these waves in MRX in 2001 and concluded in 2010 that they weren’t doing much to reconnect,” said senior PPPL physicist Hantao Ji, professor of astrophysical sciences at Princeton University and recipient of a related fellowship Research. “Now, 10 years later, we realized that the waves can actually be important under certain conditions. So we decided to revisit the same topic after a 20-year hiatus, but under new conditions and with new data from MMS and MRX. “
Third prize went to PPPL Principal Physicist Masaaki Yamada, a distinguished researcher and principal researcher at the MRX. He will use the grant to run tests on MRX to see if some type of magnetic configuration could help explain the clumps of plasma that inflate and emit X-rays on the sun’s surface.
Yamada and his research team will use some type of pistol to shoot a smoke ring-shaped burst of plasma with a pattern of magnetic fields known as spheromaks into MRX. They then examine the plasma to see if it is emitting high-energy particles such as X-rays.
The Sphäromak was originally developed for fusion reactors. “I worked on the concept almost 30 years ago,” said Yamada. “We have confirmed that a device based on the Sphäromak idea can lead to fusion. We have built a device called the S-1, but it does not contain the plasma well.”
Now the Sphäromak concept has re-emerged as a possible explanation for solar events. “Dr. Spiro Antiochos of NASA Goddard gave a talk at the PPPL several years ago about giant, dome-shaped torches the size of Earth that appear on the sun and emit X-rays,” said Yamada. “So far, no one has discovered a clear mechanism to explain why these emissions occur. Since the spheromak configuration can occur in nature, I thought that similar configurations on the sun could stimulate these blobs to form.”
After the talk, Yamada, PPPL physicist Elena Belova, and Princeton University student Joshua Latham conducted computer simulations that investigated whether the spheromak’s magnetic configuration could result in X-ray emitting blobs appearing on the Sun and confirmed this . The team will use their grant to run real-world experiments that use MRX to verify simulation results.
Unlike tokamaks, a popular type of donut-shaped fusion reactor used around the world, a spheromak does not have a central hole for a large magnet that creates magnetic fields to confine the plasma. Instead, a spheromak is more like a unitary ball of fire and creates the necessary magnetic fields from the electrical currents that naturally flow through it.
The three awards will expand PPPL’s extensive history in space and astrophysical research related to reconnection. The laboratory, which has been working with the MMS mission since it started in 2015, is now installing the FLARE experiment (Facility for Laboratory Reconnection Experiment), a new and more powerful version of MRX. The $ 4.3 million device will examine facets of magnetic reconnection never before accessible for laboratory experimentation.
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