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by Trinity College Dublin
https://phys.org/news/2019-05-scientists-uncover-exotic-sun-atmosphere.html
Scientists from Ireland and France today announced a major new finding about how matter behaves in the extreme conditions of the Sun’s atmosphere.
The scientists used large radio telescopes and ultraviolet cameras on a NASA spacecraft to better understand the exotic but poorly understood “fourth state of matter”. Known as plasma, this matter could hold the key to developing safe, clean and efficient nuclear energy generators on Earth. The scientists published their findings in the leading international journal Nature Communications.Most of the matter we encounter in our everyday lives comes in the form of solid, liquid or gas, but the majority of the Universe is composed of plasma—a highly unstable and electrically charged fluid. The Sun is also made up of this plasma.
Despite being the most common form of matter in the Universe plasma remains a mystery, mainly due to its scarcity in natural conditions on Earth, which makes it difficult to study. Special laboratories on Earth recreate the extreme conditions of space for this purpose, but the Sun represents an all-natural laboratory to study how plasma behaves in conditions that are often too extreme for the manually constructed Earth-based laboratories.
Postdoctoral Researcher at Trinity College Dublin and the Dublin Institute of Advanced Studies (DIAS), Dr. Eoin Carley, led the international collaboration. He said: “The solar atmosphere is a hotbed of extreme activity, with plasma temperatures in excess of 1 million degrees Celsius and particles that travel close to light-speed. The light-speed particles shine bright at radio wavelengths, so we’re able to monitor exactly how plasmas behave with large radio telescopes.”
“We worked closely with scientists at the Paris Observatory and performed observations of the Sun with a large radio telescope located in Nançay in central France. We combined the radio observations with ultraviolet cameras on NASA’s space-based Solar Dynamics Observatory spacecraft to show that plasma on the sun can often emit radio light that pulses like a light-house. We have known about this activity for decades, but our use of space and ground-based equipment allowed us to image the radio pulses for the first time and see exactly how plasmas become unstable in the solar atmosphere.”
Studying the behaviour of plasmas on the Sun allows for a comparison of how they behave on Earth, where much effort is now under way to build magnetic confinement fusion reactors. These are nuclear energy generators that are much safer, cleaner and more efficient than their fission reactor cousins that we currently use for energy today.
Professor at DIAS and collaborator on the project, Peter Gallagher, said: “Nuclear fusion is a different type of nuclear energy generation that fuses plasma atoms together, as opposed to breaking them apart like fission does. Fusion is more stable and safer, and it doesn’t require highly radioactive fuel; in fact, much of the waste material from fusion is inert helium.”
“The only problem is that nuclear fusion plasmas are highly unstable. As soon as the plasma starts generating energy, some natural process switches off the reaction. While this switch-off behaviour is like an inherent safety switch—fusion reactors cannot form runaway reactions—it also means the plasma is difficult to maintain in a stable state for energy generation. By studying how plasmas become unstable on the Sun, we can learn about how to control them on Earth.”
The success of this research was made possible by the close ties between researchers at Trinity, DIAS, and their French collaborators.
Dr. Nicole Vilmer, lead collaborator on the project in Paris, said: “The Paris Observatory has a long history of making radio observations of the Sun, dating back to the 1950s. By teaming up with other radio astronomy groups around Europe we are able to make groundbreaking discoveries such as this one and continue the success we have in solar radio astronomy in France. It also further strengthens scientific collaboration between France and Ireland, which I hope continues in the future.”
Dr. Carley previously worked at the Paris Observatory, funded by a fellowship awarded by the Irish Research Council and the European Commission. He continues to work closely with his French colleagues today, and hopes to soon study the same phenomena using both French instruments and newly built, state-of-the-art equipment in Ireland.
Dr. Carley added: “The collaboration with French scientists is ongoing and we’re already making progress with newly built radio telescopes in Ireland, such as the Irish Low Frequency Array (I-LOFAR). I-LOFAR can be used to uncover new plasma physics on the Sun in far greater detail than before, teaching us about how matter behaves in both plasmas on the Sun, here on Earth and throughout the Universe in general.”
More information: Eoin P. Carley et al, Loss-cone instability modulation due to a magnetohydrodynamic sausage mode oscillation in the solar corona, Nature Communications (2019). DOI: 10.1038/s41467-019-10204-1
Journal information: Nature Communications-https://en.wikipedia.org/wiki/Plasma_globe-
A plasma globe or plasma lamp (also called plasma ball, dome, sphere, tube or orb, depending on shape) is a clear glass container filled with a mixture of various noble gases with a high-voltage electrode in the center of the container.
Physicists create stable, strongly magnetized plasma jet in laboratory
by Raphael Rosen, Princeton Plasma Physics Laboratory
https://phys.org/news/2019-05-physicists-stable-strongly-magnetized-plasma.html
When you peer into the night sky, much of what you see is plasma, a soupy amalgam of ultra-hot atomic particles. Studying plasma in the stars and various forms in outer space requires a telescope, but scientists can recreate it in the laboratory to examine it more closely.
Now, a team of scientists led by physicists Lan Gao of the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) and Edison Liang of Rice University, has for the first time created a particular form of coherent and magnetized plasma jet that could deepen the understanding of the workings of much larger jets that stream from newborn stars and possibly black holes—stellar objects so massive that they trap light and warp both space and time.
“We are now creating stable, supersonic, and strongly magnetized plasma jets in a laboratory that might allow us to study astrophysical objects light years away,” said astrophysicist Liang, co-author of the paper reporting the results in the Astrophysical Journal Letters.
The team created the jets using the OMEGA Laser Facility at the University of Rochester’s Laboratory for Laser Energetics (LLE). The researchers aimed 20 of OMEGA’s individual laser beams into a ring-shaped area on a plastic target. Each laser created a tiny puff of plasma; as the puffs expanded, they put pressure on the inner region of the ring. That pressure then squeezed out a plasma jet reaching over four millimeters in length and created a magnetic field that had a strength of over 100 tesla.
“This is the first step in studying plasma jets in a laboratory,” said Gao, who was the primary author of the paper. “I’m excited because we not only created a jet. We also successfully used advanced diagnostics on OMEGA to confirm the jet’s formation and characterize its properties.”
The diagnostic tools, developed with teams from LLE and the Massachusetts Institute of Technology (MIT), measured the jet’s density, temperature, length, how well it stayed together as it grew through space, and the shape of the magnetic field around it. The measurements help scientists determine how the laboratory phenomena compare to jets in outer space. They also provide a baseline that scientists can tinker with to observe how the plasma behaves under different conditions.
“This is groundbreaking research because no other team has successfully launched a supersonic, narrowly beamed jet that carries such a strong magnetic field, extending to significant distances,” said Liang. “This is the first time that scientists have demonstrated that the magnetic field does not just wrap around the jet, but also extends parallel to the jet’s axis,” he said.
The researchers hope to expand their research with larger laser facilities and investigate other types of phenomena. “The next step involves seeing whether an external magnetic field could make the jet longer and more collimated,” Gao said.
“We would also like to replicate the experiment using the National Ignition Facility at Lawrence Livermore National Laboratory, which has 192 laser beams, half of which could be used to create our plasma ring. It would have a larger radius and thus produce a longer jet than that produced using OMEGA. This process would help us figure out under which conditions the plasma jet is strongest.”
More information: L. Gao et al, Mega-Gauss Plasma Jet Creation Using a Ring of Laser Beams, The Astrophysical Journal (2019). DOI: 10.3847/2041-8213/ab07bdJournal information: Astrophysical Journal , Astrophysical Journal Letters
Provided by Princeton Plasma Physics Laboratory
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