Processes Leading to Supernova Explosions and Cosmic Radio Bursts Discovered at PPPL



Physicist Kenan Qu with figures from his article. Credit: Qu Photo by Elle Starkman / PPPL Office of Communications. Collage by Kiran Sudarsanan.

A promising method for producing and observing on Earth a process important for black holes, supernova explosions and other extreme cosmic events has been proposed by scientists in the Department of Astrophysical Sciences at Princeton University, National Laboratory of acceleration of SLAC and the US Department of Energy (DOE). Princeton Plasma Physics Laboratory (PPPL). The process, called quantum electrodynamic cascades (QEDs), can lead to supernovas – exploding stars – and rapid radio bursts that are equivalent in milliseconds to the energy the sun emits in three days.

First demonstration

The researchers produced the first theoretical demonstration that the collision of a laboratory laser with a dense electron beam can produce high density QED cascades. “We show that what was thought to be impossible is in fact possible,” said Kenan Qu, lead author of an article in Physical Review Letters (PRL) that describes the groundbreaking demonstration. “This in turn suggests how previously unobserved collective effects can be probed with existing advanced laser and electron beam technologies.”

The process takes place in a simple manner. The collision of a strong laser pulse with a high-energy electron beam splits the vacuum into high-density electron-positron pairs that begin to interact with each other. This interaction creates what are known as collective plasma effects that influence how the pairs collectively respond to electric or magnetic fields.

Plasma, the hot, charged state of matter composed of free electrons and atomic nuclei, represents 99% of the visible universe. Plasma powers the fusion reactions that power the sun and stars, a process PPPL and scientists around the world are looking to develop on Earth. Plasma processes throughout the universe are strongly influenced by electromagnetic fields.

The PRL article focuses on the electromagnetic force of the laser and the energy of the electron beam that the theory brings together to create QED cascades. “We seek to simulate the conditions that create electron-positron pairs with sufficient density to produce measurable collective effects and see how to unambiguously verify these effects,” Qu said.

The tasks consisted of discovering the signature of a successful plasma creation through a QED process. The researchers found the signature in the shift from a laser of moderate intensity to a higher frequency caused by the proposal to send the laser against an electron beam. “This discovery solves the common problem of producing the QED plasma diet the most easily and observing it the most easily,” Qu said. “The amount of shift varies depending on the density of the plasma and the energy of the pairs.”

Beyond current capacities

Theory has previously shown that sufficiently strong lasers or electric or magnetic fields can create QED pairs. But the amplitudes required are so high that they exceed the current capacities of laboratories.

However, “It turns out that current laser and relativistic beam technology [that travel near the speed of light], if co-located, is sufficient to access and observe this regime, ”said physicist Nat Fisch, professor of astrophysical sciences and associate director of academic affairs at PPPL, and co-author of the PRL paper and principal investigator of the project. “A key point is to use the laser to slow down the pairs so that their mass decreases, thereby increasing their contribution to the frequency of the plasma and increasing the collective effects of the plasma,” said Fisch. building super intense lasers, ”he said.

This work was funded by grants from the National Nuclear Security Administration and the Air Force Office of Scientific Research. Researchers are now preparing to test the theoretical findings at SLAC at Stanford University, where a moderately powerful laser is being developed and the source of the electron beams is already there. At the heart of this effort is physicist Sebastian Meuren, co-author of the article and former post-doctoral visitor to PPPL who is now at SLAC.

“Like most basic physics, this research aims to satisfy our curiosity about the universe,” Qu said. “For the community at large, a big impact is that we can save billions of dollars in tax revenue if the theory can be validated.”

Scientists discover how high-energy electrons boost magnetic fields

More information:
Kenan Qu et al, Signature of collective plasma effects in beam-driven QED cascades, Physical examination letters (2021). DOI: 10.1103 / PhysRevLett.127.095001

Provided by Princeton Plasma Physics Laboratory

Quote: Process leading to supernova explosions and cosmic radio bursts discovered at PPPL (2021, October 5) retrieved November 7, 2021 from .html

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