Imagine the explosive turbulence caused by a supersonic jet. A similar shock wave occurs when subatomic particles known as the “solar wind” escape from the Sun and collide with Earth’s magnetic field. Now scientists have used a newly developed technique to improve estimates of the timing and intensity of solar wind bursts that sometimes disrupt telecommunications satellites and damage power grids.

A research team led by James Juneau, a physicist at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), used something called “field-particle correlation” (FPC) to visualize in detail how shock waves form from plasma. The hot, charged state of matter, which makes up 99% of the visible universe, can be heated by clumps of plasma in space.

FPC is an algorithm that processes data generated by spacecraft or computers and determines how the energy of magnetic fields and moving plasma particles changes. The process gives precise information about the positions and velocities of particles as changes occur.

“Heat transfer has never been studied in this way before, although much of what we found is already well known,” said James Juneau, lead author and staff physicist at the US Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL). about the results of the report Astrophysical Journal. “The fact that this technique also works shows us that there are new ways of looking at old problems.”

PPPL scientists study the plasma that drives fusion reactions in donut-shaped devices known as tokamaks and winding machines known as starlingers. Plasma is a mixture of atomic nuclei or ions, electrons and neutral atoms that together conduct an electric current. This flow allows the plasma to respond to the magnetic fields that scientists use to drive the plasma into fusion reactors. Researchers are trying to use the fusion that powers the sun and stars to generate electricity without producing greenhouse gases and long-lived radioactive waste.

The FPC technique reveals previously unobserved behavior of the plasma, including which parts of the plasma are heated and what physical processes are responsible for it. Ancient techniques can only create general pictures of where and how the plasma is heated.

“One of our key findings is that different regions of the plasma may respond differently to the shock wave,” Juno said. Said. “We now have a more complete picture of what happens when shock waves interact.” “This means we can detect the energy of a particular particle at a particular location, and the shock wave transfers the energy to a particular region of the plasma,” Juno said. she said. “Previous methods cannot discern the wide variety of processes that occur.”

Juno and colleagues applied the FPC technique developed by Gregory House of the University of Iowa to data produced by a plasma simulation program known as Gkeyll (pronounced Dr. Jekyll from Robert Louis Stevenson). PPPL has developed a code to simulate the rotation of plasma particles around magnetic field lines at the plasma edge in fusion tokamaks. Scientists are constantly updating the program to expand its capabilities.

“Gkeyll has many components that apply to a range of plasma problems, from space plasma to laboratory fusion experiments,” said Ammar Hakim, deputy director of the PPPL Computational Science Laboratory. “With the National Science Foundation’s new investment in the Cyber ​​Infrastructure for Sustainable Science Innovation program, we are developing Gkeyll into a national resource for plasma simulations.”

Scientists can use FPCs to gather information from current space missions, such as NASA’s Magnetospheric Multi-Scale (MMS) mission, which uses four satellites flying in formation in a space region affected by Earth’s magnetic field. “The MMS mission provides an incredible opportunity to study cosmic plasma using the FPC technique,” says Colleen Brown, a researcher at the University of Iowa and co-author of the paper. “This greatly expands our ability to study the three-dimensional nature of energy transfer.”

“At most, it’s one thing to use a supercomputer to reproduce a plasma shock wave,” Juno said. “But the FPC technique can actually help you learn something new about the world. And it’s exciting.” Source