The world's largest turbulence simulation unmasks the flow of energy in astrophysical plasmas
Reconnecting current sheets and magnetic flux ropes in MHD turbulence. (A) Volume rendering of the current density ∣J∣ in the entire domain at a stage when turbulence is fully developed. Myriad of current sheets is evident in the plane perpendicular to the mean magnetic field Bz0. (B) and (C) depict one reconnecting current sheet and the embedded flux ropes in a small subdomain [within the boundaries ( − 0.45, − 0.4) × (0.45, 0.5) × (0.95, 1.05)]. (B) shows the volume rendering of ∣J∣, while (C) displays magnetic field lines (colored by ∣B∣) associated with the featured current sheet (including magnetic flux ropes) and an x-y slice view of the current density component, Jz, along the mean magnetic field. (D) Out-of-plane current density Jz in an x-y slice (at z = −1) of the 3D turbulence simulation (left) compared with the corresponding result from a 2D simulation (right). Copious formation of magnetic flux ropes/plasmoids occurs in both 3D and 2D simulations despite the different morphology. Zoomed-in subdomains are used to illustrate the increased morphological complexity that characterizes the 3D simulation. Credit: Science Advances (2022). DOI: 10.1126/sciadv.abn7627

The solar corona can be vastly hotter than the sun's surface, thanks to a previously undiscovered heating process.

The ability to predict eruptive space and the origin of large-scale magnetic fields in the universe could be improved by the discovery at the U.S. Department of Energy. Understanding the heating process has implications.

It is the first clear explanation.

"Our direct numerical simulation is the first to provide clear identification of this heating mechanism in 3D space, and it took 200 million hours of computer time to do it," said Chuanfei Dong, a physicist atPPPL. According to the journal Science Advances, current telescope and spacecraft instruments may not have high enough resolution to identify the process happening at small scales.

The solar atmosphere is formed by the soup of electrons and atomic nuclei that form the magnetic field. The simulation showed how the large-scale turbulent energy can be turned into small-sale internal energy. The corona is superheated due to the efficient conversion of the turbulent energy to thermal energy.

He said to put cream in coffee. The drops of cream begin to turn into whorls. Thin sheets of electric current break up due to magnetism. The process facilitates the energy cascade from large-scale to small-scale, making it more efficient in the solar corona.

The transfer of energy can't be affected when the reconnection process is slow. When the reconnection rate surpasses the traditional cascade rate, the cascade can be moved more efficiently.

The plasmoids are created by breaking and rejoining the magnetic field lines. The paper says that the turbulent energy cascade has been accepted for more than 50 years. The energy transfer rate is tied to how fast the plasmoids grow, enhancing the transfer of energy from large to small scales and heating the corona at these scales.

There is a regime with a large magnetic Reynolds number. The large number shows the high energy transfer rate. The more efficient the energy transfer is the higher the magnetic Reynolds number is.

The world's largest turbulence simulation unmasks the flow of energy in astrophysical plasmas
Halo-like solar corona. Credit: NASA

200 million hours worked by humans.

The world's largest turbulence simulation has taken over 200 million computerCPU at the NASA Advanced Supercomputing facility. For the first time, a theoretically predicted mechanism for a previously undiscovered range of turbulent energy cascade has been proven.

His paper in the high impact journal Science Advances completes the computational program he began with his earlier 2D results. The papers form a coda to the work that Chuanfei has done in the center. The NASA High-End Computing program gave us generous allocation of computer time and we are grateful for that.

Current and future satellites and telescopes can be used to explore the impact of this finding. The paper said that packing the energy transfer process across scales will be important to solve the mysteries.

There is more information about the Reconnection-driven energy cascade. There is a book titled "Sci Adv.abn7627."

Journal information: Physical Review Letters , Science Advances