Scientists use spacecraft's measurements to study solar wind heating

Feb. 14 (UPI) -- With the help of a NASA spacecraft, astrophysicists have uncovered the process by which energy is transferred between electromagnetic fields and plasma in space.

Most of the visible matter in the universe exists in the form of plasma, an ionized state of matter. Understanding how energy is transferred to and from ionized particles in space can help scientists to better understand a variety of cosmological phenomena.

The transfer of energy from electromagnetic turbulence in space to the electrons in the solar wind is caused by a process known as Landau damping. When electromagnetic waves travel through plasma and the plasma particles themselves are traveling at the same speeds, the plasma particles absorb the wave's energy, reducing -- or damping -- the electromagnetic wave.

Landau damping has only been observed in relatively simple space environments. Until now, scientists weren't sure whether the Landau damping could explain energy transfer among more turbulent electromagnetic fields and complex plasma environs.

To measure the energization of solar wind in space, scientists analyzed the observations of NASA's Magnetospheric Multi-Scale spacecraft. Researchers used a first-of-its-kind data processing technique, known as the field-particle correlation technique, to detail the interactions between electromagnetic fields and plasma particles inside solar wind.

"Plasma is by far the most abundant form of visible matter in the universe, and is often in a highly dynamic and apparently chaotic state known as turbulence," Christopher Chen, astrophysicist at Queen Mary University of London, said in a news release. "This turbulence transfers energy to the particles in the plasma leading to heating and energization, making turbulence and the associated heating very widespread phenomena in nature."

Chen and his colleagues shared their analysis of solar wind energization this week in the journal Nature Communications.

"In this study, we made the first direct measurement of the processes involved in turbulent heating in a naturally occurring astrophysical plasma," Chen said. "We also verified the new analysis technique as a tool that can be used to probe plasma energization and that can be used in a range of follow-up studies on different aspects of plasma behavior."

The new research showed Landau damping is present even among the complex electromagetnic fields and plasma waves found streaming through interstellar space.

"In the process of Landau damping, the electric field associated with waves moving through the plasma can accelerate electrons moving with just the right speed along with the wave, analogous to a surfer catching a wave," said Greg Howes, professor at the University of Iowa. "This first successful observational application of the field-particle correlation technique demonstrates its promise to answer long-standing, fundamental questions about the behavior and evolution of space plasmas, such as the heating of the solar corona."