Physicists at the University of West Virginia have made a breakthrough on an age-old limitation of the first law of thermodynamics.
Paul Cassak, professor and associate director of the Center for KINETIC Plasma Physics, and graduate research assistant Hasan Barbhuiya, both from the Department of Physics and Astronomy, study how energy is converted in superheated plasmas in space . Their findings, funded by a grant from the National Science Foundation and published in the Physical examination letters journal, will revamp scientists’ understanding of how plasmas in space and laboratories heat up, and might have a wide variety of other applications in physics and other sciences.
The first law of thermodynamics states that energy cannot be created or destroyed, but can be converted into different forms.
“Suppose you are heating a balloon,” Cassak said. “The first law of thermodynamics tells you how much the balloon expands and how much hotter the gas inside the balloon gets. The key is that the total amount of energy causing the balloon to expand and the gas to heat up is the same as the amount of heat you put into the balloon. The First Law has been used to describe many things, including how refrigerators and car engines work. It is one of the pillars of physics. »
Developed in the 1850s, the first law of thermodynamics is only valid for systems in which a temperature can be properly defined, a state known as equilibrium. For example, when combined, a cup of cold water and a cup of hot water will eventually reach a hot temperature between them. This warm temperature is equilibrium. However, when the hot water and the cold water have not yet reached this end point, the water is out of balance.
Likewise, in many areas of modern science, the systems are not in equilibrium. For more than 100 years, researchers have tried to extend the first law to common materials not in equilibrium, but such theories only work when the system is almost there – when hot and cold water are almost mixed. . The theories don’t work, for example, in space plasmas, which are far from equilibrium.
The work of Cassak and Barbhuiya fills the gaps in this limitation.
“We generalized the first law of thermodynamics for systems that are not in equilibrium,” Cassak said. “We did a pencil-and-paper calculation to find the amount of energy associated with matter not being in equilibrium, and it works whether the system is near or far from equilibrium. »
Their research has many potential applications. The theory will help scientists understand plasmas in space, which is important for preparing for space weather. Space weather occurs when huge flares in the solar atmosphere shoot superheated plasma into space. This can lead to problems such as power outages, disruptions in satellite communications, and aircraft rerouting.
“The result represents a very big step in our understanding,” Cassak said. “Until now, the state of the art in our field of research has been to account for the energy conversion only associated with expansion and heating, but our theory provides a way to calculate all the energy not to be in balance. »
“Because the first law of thermodynamics is so widely used,” Barbhuiya said, “we hope that scientists from a wide range of fields will be able to use our results.”
For example, it can be useful for studying low-temperature plasmas — which are important for etching in the semiconductor and circuit industry — as well as other fields like chemistry and quantum computing. It might also help astronomers study the evolution of galaxies over time.
Groundbreaking research related to Cassak and Barbhuiya is being conducted in PHASMA, the PHAse Space MApping experiment, at the WVU Center for Experimental, Theoretical, and Integrated Computational Plasma Physics KINetic.
“PHASMA performs spatial measurements of energy conversion in plasmas that are not in equilibrium. These measures are totally unique in the world,” Cassak said.
Likewise, the breakthrough he and Barbhuiya have made will change the landscape of plasma and space physics, a feat that doesn’t happen often.
“There aren’t many laws of physics – Newton’s laws, the laws of electricity and magnetism, the three laws of thermodynamics and the laws of quantum mechanics,” said Duncan Lorimer, professor and Acting Director of the Department of Physics and Astronomy. . “Taking one of these laws that has been around for over 150 years and improving it is a major achievement.
“This new first-principles result in non-equilibrium statistical mechanics applied to plasmas is an excellent example of academic research made possible by NSF’s mission ‘to promote the advancement of science,'” said Vyacheslav Lukin, director of the plasma physics program in the Physics Division of the NSF.
Haoming Liang of the University of Alabama at Huntsville and Matthew Argall of the University of New Hampshire joined WVU researchers on the project.
