[ad_1]
A space scientist from the Southwest Research Institute has shed new light on the prediction of the thermodynamics of solar flares and other "space weather" events involving hot and fast-moving plasmas, such as those illustrated in this illustration. Image provided by NASA
Recently published results by a space scientist from the Southwest Research Institute (SwRI) shed new light on the prediction of the thermodynamics of solar flares and other "space weather" events involving hot plasmas and fast moving.
The science of statistical mechanics is one of the pillars of understanding the thermodynamic behavior of phenomena involving a large number of particles, such as gases. Conventional statistical methods have stood the test of time to describe Earth-related systems, such as the relatively dense mixture of gases that make up our air, "said Dr. George Livadiotis, Principal Investigator, Space Science and Technology Division. from SwRI.
At thermal equilibrium, where heat energy is transferred evenly between the gas particles, their distribution falls in a predictable ratio – a lot of low-speed particles for only a few fast particles. The particles move in a chaotic manner, frequently bumping into each other. A statistical equation, known as the Maxwell-Boltzmann or Maxwell distribution, accurately characterizes how this mixture of particles of different velocities will be distributed on Earth.
However, says Livadiotis, things are different in space, which is actually not empty, but filled with plasma, the fourth state of matter. Plasma is made up of electrically charged particles – it is neither a gas nor a liquid, although it often behaves like a gas.
Spatial plasma, like the solar wind coming out of the Sun, has a higher rate of fast-moving particles. Unlike gases on Earth, they are "correlated" and generally move in the same direction, reducing the risk of collision. In this set of circumstances, the Maxwellian distribution model no longer works well. Livadiotis confirmed that a separate statistical equation, called "Kappa", is more applicable for spatial phenomena.
Kappa is the mathematical equation that describes the distribution of particle velocities at thermal equilibrium when there are correlations between particle velocities, as is typical for collisionless space particle systems.
"The Kappa equation calculates the particle velocity distribution at thermal equilibrium as fast-moving particle streams move en masse, "he said." It's the typical situation of particle systems such as space plasmas. "
Kappa predicts not only a better distribution of spatial plasma particle distribution, but also characterizes their thermodynamic behavior better than the Maxwellian model, Livadiotis explains. This is what happens when an extremely hot solar wind plasma crashes into the Earth's protective layer of magnetically charged particles called the magnetosphere.
"Kappa distributions have allowed scientists to make the first temperature measurements of the outer heliosphere," says Livadiotis. "With Kappa, we can dramatically improve our understanding of the nature and properties of space matter, be it solar wind, coronal mass eruptions and ejections, or rare and more extreme phenomena such as cosmic rays. "
His article, "The Thermodynamic Origin of Kappa Distributions," is published in the June 18, 2018 edition of EPL, a journal of letters exploring the boundaries of physics.
Source link
