Making the infeasible feasible: creating pair plasmas without ultra-strong lasers
Making the infeasible feasible: creating pair plasmas without ultra-strong lasers lead image
Emerging science, such as magnetars producing fast radio bursts and the multi-messenger nature of neutron star mergers, depends on understanding the foundations of extreme plasmas. In the quantum electrodynamics (QED) regime, pair plasmas combine strong-field quantum and collective plasma effects and provide a paradigm for probing harsh astrophysical environments.
Unfortunately, reaching and observing the QED pair plasma regime is thought to require collisions of two laser pulses with ultra-high intensities. This would require a 100 PW laser system costing upwards of a billion dollars.
As a far cheaper alternative, Qu et al. suggest current technology in lasers and relativistic electron beams, if co-located, can access the QED pair plasma regime. The team found a dense electron beam and 5-10 PW optical laser were sufficient in their simulations, and the combination costs much less compared to previous concepts.
“The laser cannot only create high density pairs, but also slow them down so that their mass decreases,” said author Kenan Qu. “It greatly increases their contribution to the plasma frequency, making the collective plasma effects observable. Furthermore, creation of the pair plasma causes a measurable frequency upshift of the laser, which serves as an unambiguous signal of the collective plasma effects.”
While this work demonstrated the concept theoretically, author Sebastian Meuren, together with other scientists, is working towards experimental testing at the SLAC National Accelerator Laboratory.
“By identifying the intersection of what can be produced with what can be observed, we show that what was thought infeasible is in fact feasible,” said author Nathaniel Fisch. “The validity of this suggestion should influence current funding decisions for next-generation high-intensity laser facilities.”
Source: “Collective plasma effects of electron-positron pairs in beam-driven QED cascades,” by Kenan Qu, Sebastian Meuren, and Nathaniel J. Fisch, Physics of Plasmas (2022). The article can be accessed at https://doi.org/10.1063/5.0078969 .
