Researchers at the Laboratory for Laser Energetics are the first to experimentally measure the mechanism responsible for generating astrophysical magnetic fields.
An international research collaboration, co-led by researchers at the 鈥檚 (LLE) and the University of Oxford, has captured for the first time in a laboratory setting the process thought to be responsible for generating and sustaining astrophysical magnetic fields.
Publishing their results in the聽, the team reports the findings could help explain the origin of large-scale magnetic fields that have been observed but didn鈥檛 match theoretical calculations.
The work is the latest to refine further scientists鈥� understanding of a once-elusive phenomenon known as a 鈥渢urbulent dynamo,鈥� an astrophysical process that amplifies magnetic fields. By creating experimental conditions that mimic most hot, diffuse plasmas in the universe鈥攃onditions in which the turbulent dynamo mechanism is thought to operate鈥攖he team was able to quantify the rate at which a turbulent dynamo amplifies magnetic fields. Up until now, the rate had only been predicted theoretically and via numerical simulations.
鈥淭he rapid amplification we found exceeds theoretical expectations and could help explain the origin of the present-day large-scale fields that are observed in galaxy clusters,鈥� says , an associate professor of physics and astronomy at Rochester and a senior scientist at the LLE.
The researchers鈥攑art of the Turbulent Dynamo (TDYNO) team鈥攃onducted their experimental research at the LLE鈥檚 Omega Laser Facility, where they had previously . That breakthrough earned the team the 2019 from the American Physical Society.
Using laser beams whose total power is equivalent to that of 10,000 nuclear reactors, the researchers were able to study plasma at energy levels that previous liquid-metal and laser-driven experiments could not.
鈥淯nderstanding how and at what rates magnetic fields are amplified at macroscopic scales in astrophysical turbulence is key for explaining the magnetic fields seen in galaxy clusters, the largest structures in the universe,鈥� says , a postdoctoral research associate in the Department of Astrophysical Sciences at Princeton and lead author of the study. 鈥淲hile numerical models and theory predict fast turbulent dynamo amplification at very small scales compared to turbulent motions, it had remained uncertain as to whether the mechanism operates rapidly enough to account for dynamically significantly fields on the largest scales.鈥�
The experiments demonstrated that turbulent dynamo鈥攚hen operating in a realistic plasma鈥攃an generate large-scale magnetic fields much more rapidly than currently expected by theorists.
鈥淥ur theoretical understanding of the workings of turbulent dynamo has grown continuously for over half a century,鈥� says , professor of physics at the University of Oxford and the experimental lead of the project. 鈥淥ur recent laser-driven experiments were able to address for the first time how turbulent dynamo evolves in time, enabling us to experimentally measure its actual growth rate.鈥�
The experiments were designed using numerical simulations performed with the FLASH code, a publicly available simulation code that can accurately model laser-driven experiments of laboratory plasmas. FLASH is developed by the , which recently moved from the University of Chicago to the 人妻少妇专区.
鈥淭he ability to do high-fidelity, predictive modeling with FLASH, and the state-of-the art diagnostic capabilities of the Omega Laser Facility at the LLE, have put our team in a unique position to decisively advance our understanding of how cosmic magnetic fields come to be,鈥� says Tzeferacos, who also serves as director of the Flash Center at Rochester.
The project was funded by the US Department of Energy, the National Science Foundation, the European Research Council, the Engineering and Physical Sciences Research Council, the National Laser Users鈥� Facility of DOE鈥檚 National Nuclear Security Administration, and the ASCR Leadership Computing Challenge of the DOE Office of Science.
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