BLOGS

A researcher holds the scaffolding with tiny copper foils attached. These copper pieces will be struck with lasers, heating them to thousands of degrees Fahrenheit.

Credit: Hiroshi Sawada

Topics: Applied Physics, Lasers, Materials Science, Plasma, Radiation, Thermodynamics

For the first time, researchers monitor the heat progression in laser-created plasma that occurs in only a few trillionths of a second.

A team of researchers supported by the U.S. National Science Foundation has developed a new method of tracking the ultra-fast heat progression in warm, dense matter plasmas — the type of matter created when metals are struck with high-powered lasers. Published in Nature Communications, the results of this study will help researchers better understand not only how plasma forms when metal is heated by high-powered lasers but also what's happening within the cores of giant planets and even aid in the development of fast ignition laser fusion with energy-generating potential here on Earth.

The research team aimed a high-powered laser at very thin strips of copper, which heated to 200,000 degrees Fahrenheit and momentarily shifted to a warm, dense matter plasma state before exploding. At the same time, the researchers used ultrashort-duration X-ray pulses from an X-ray free-electron laser to capture images of the copper's transformation down to a few picoseconds or trillionths of a second. By doing so, the researchers were able to observe the ultra-fast and microscopic transformation of matter.

"These findings shed new light on fundamental properties of plasmas in the warm dense matter state," says Vyacheslav Lukin, NSF program director for Plasma Physics. "The new methods to probe the plasma developed by this international team of researchers may also inform future experiments at extremely high-powered lasers, such as the NSF ZEUS Laser Facility."

Researchers track plasma creation using a novel ultra-fast laser method, National Science Foundation

FIG. 1. Schematic of the motivation and the method for this paper.

Topics: Applied Physics, Chemistry, Physics, Plasma, Research

ABSTRACT

Cold atmospheric plasmas have great application potential due to their production of diverse types of reactive species, so understanding the production mechanism and then improving the production efficiency of the key reactive species are very important. However, plasma chemistry typically comprises a complex network of chemical species and reactions, which greatly hinders the identification of the main production/reduction reactions of the reactive species. Previous studies have identified the main reactions of some plasmas via human experience, but since plasma chemistry is sensitive to discharge conditions, which are much different for different plasmas, widespread application of the experience-dependent method is difficult. In this paper, a method based on graph theory, namely, vital nodes identification, is used for the simplification of plasma chemistry in two ways: (1) holistically identifying the main reactions for all the key reactive species and (2) extracting the main reactions relevant to one key reactive species of interest. This simplification is applied to He + air plasma as a representative, chemically complex plasma, which contains 59 species and 866 chemical reactions, as reported previously. Simplified global models are then developed with the key reactive species and main reactions, and the simulation results are compared with those of the full global model, in which all species and reactions are incorporated. It was found that this simplification reduces the number of reactions by a factor of 8–20 while providing simulation results of the simplified global models, i.e., densities of the key reactive species, which are within a factor of two of the full global model. This finding suggests that the vital nodes identification method can capture the main chemical profile from a chemically complex plasma while greatly reducing the computational load for simulation.

Simplification of plasma chemistry by means of vital nodes identification

Bowen Sun, Dingxin Liu, Yifan Liu, Santu Luo, Mingyan Zhang, Jishen Zhang, Aijun Yang, Xiaohua Wang, and Mingzhe Rong, Journal of Applied Physics

Image source: Link below ("ride the lightning")

Topics: Aerodynamics, Futurism, Plasma, Propulsion, Spaceflight

Personal note: I've been offline prepping for my preliminary exam presentation, and grieving the loss of a friend I had known for 40 years since our freshman year at NC A&T. I was his best man. He did not die of COVID, but a heart attack. As such, my remarks were read at the funeral in Indiana, as the pandemic and social distancing concerns did not allow me to give my eulogy in-person. I hope you will forgive my absence.

This past autumn, a professor at Wuhan University named Jau Tang was hard at work piecing together a thruster prototype that, at first, sounds too good to be true.

The basic idea, he said in an interview, is that his device turns electricity directly into thrust — no fossil fuels required — by using microwaves to energize compressed air into a plasma state and shooting it out like a jet. Tang suggested, without a hint of self-aggrandizement, that it could likely be scaled up enough to fly large commercial passenger planes. Eventually, he says, it might even power spaceships.

Needless to say, these are grandiose claims. A thruster that doesn’t require tanks of fuel sounds suspiciously like science fiction — like the jets on Iron Man’s suit in the Marvel movies, for instance, or the thrusters that allow Doc Brown’s DeLorean to fly in “Back to the Future.”

But in Tang’s telling, his invention — let’s just call it a Tang Jet, which he worked on with Wuhan University collaborators Dan Ye and Jun Li — could have civilization-shifting potential here in the non-fictional world.

This Scientist Says He’s Built a Jet Engine That Turns Electricity Directly Into Thrust, Dan Robitzski, Futurism

Image Source: Link Below

Topics: Astrophysics, Interstellar, Plasma, Supernovae, Radiation

Scientists have found new evidence that Earth has been moving through the remains of exploded stars for at least the last 33,000 years.

In a new study published in the journal Proceedings of the National Academy of Sciences, a team of Australian researchers describes how they extracted a special isotope of iron called iron-60 from five deep-sea sediment samples using mass spectrometry.

That’s illuminating because as the researchers wrote in their paper, the isotope is “predominantly produced in massive stars and ejected in supernova explosions.” In other words, iron-60 is left over after a star explodes.

And because iron-60 is radioactive and decays in 15 million years, the theory is that our planet is continuously being dusted with the stuff as it’s moving through the “Local Interstellar Cloud,” a region of unclear origins made up of gas, dust, and plasma.

Scientists: Earth Moving Through Radioactive Debris of Exploded Stars, Victor Tangermann, Futurism

Lasers are used to create an indestructible optical fiber out of plasma.

Credit: Intense Laser-Matter Interactions Lab, University of Maryland

Topics: Lasers, Optics, Plasma, Research, Star Trek, Star Wars

In science fiction, firing powerful lasers looks easy — the Death Star can just send destructive power hurtling through space as a tight beam. But in reality, once a powerful laser has been fired, care must be taken to ensure it doesn’t get spread too thin.

If you’ve ever pointed a flashlight at a wall, you’ve observed an example of the diffusion of light. The farther you are from the wall, the more the beam spreads, resulting in a larger and dimmer spot of light. Lasers generally expand much more slowly than the beams from flashlights, but the effect of diffusion is important when the laser travels a long way or must maintain a high intensity.

Whether your goal is to achieve galactic domination or, more realistically, to accelerate electrons to incredible speeds for physics research, you’ll want as tight and powerful a beam as possible to maximize the intensity.

In their experiments, researchers can use devices called waveguides, like the optical fibers that might be carrying the internet throughout your neighborhood, to transport lasers while keeping them contained to narrow beams.

Plasma guides maintain focus of lasers, National Science Foundation Public Affairs