Findings recently published by a Southwest Research Institute (SwRI) space scientist shed new light on predicting the thermodynamics of solar flares and other "space weather" events involving hot, fast-moving plasmas.

The science of statistical mechanics is one of the pillars of understanding the thermodynamic behavior of phenomena with a large number of particles, such as gases. Classical statistical methods have stood the test of time for describing Earth-bound systems, such as the relatively dense mix of gases that makes up our air, explains Dr. George Livadiotis, a senior research scientist in SwRI's Space Science and Engineering Division.

At thermal equilibrium, where heat energy is transferred equally among gas particles, their distribution falls into a predictable ratio - lots of low-velocity particles to only a few fast ones.

The particles move chaotically, colliding with each other frequently. A statistical equation, known as a Maxwell-Boltzmann or Maxwellian distribution, accurately characterizes how this mix of particles of different speeds will be distributed on Earth.

However, Livadiotis says, things are different in space, which is actually not empty but filled with plasma, the so-called fourth state of matter. Plasma consists of electrically charged particles - it's neither gas, liquid nor solid, although it often behaves like a gas.

Space plasma like the solar wind that flows outward from the Sun has a higher ratio of fast-moving particles. Unlike gases on Earth, they are "correlated," mostly moving in the same direction so they experience fewer collisions with each other.

For this set of circumstances, the Maxwellian distribution model no longer works well. Livadiotis has confirmed that a separate statistical equation, called "Kappa," is more applicable for space phenomena.

Kappa is the mathematical equation that describes the distribution of particle velocities at thermal equilibrium when there are correlations among particle velocities, as is typical for collision-less space particle systems.

"The Kappa equation calculates the distribution of particle velocities at thermal equilibrium when streams of fast-moving particles are moving en masse," he said. "That is the typical situation for particle systems such as space plasmas."

Kappa not only predicts space plasma particle distributions better, but also characterizes their thermodynamic behavior better than the Maxwellian model, Livadiotis says. This relates to what happens when extremely hot solar wind plasma crashes into Earth's protective blanket of magnetically charged particles, known as the magnetosphere.

"Kappa distributions allowed scientists to make the first temperature measurements of the outer heliosphere," Livadiotis says. "With Kappa, we can dramatically improve our understanding of the nature and properties of space matter, whether it is the solar wind, flares and coronal mass ejections, or rare and more extreme phenomena like cosmic rays."

Research Report: "Thermodynamic Origin of Kappa Distributions," George Livadiotis, 2018 July 18, EPL/Europhysics Letters

Related Links
Southwest Research Institute
Solar Science News at SpaceDaily

Tweet

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

School students identify sounds caused by solar storm
London, UK (SPX) Oct 19, 2018
School students have successfully identified sounds caused by a solar storm in the Earth's magnetic shield, as part of a Queen Mary University of London research project. The findings, by a group of year 12 pupils from Eltham Hill School in south east London, have now been published in the scientific journal Space Weather. The project encouraged schools in London to take part in university research and the resulting study presents a novel approach to undertaking scientific research by making ... read more