The turbulence features of the large-scale solar flare current sheet (CS)were explored by researchers from the Chinese Academy of Sciences’ Yunnan Observatories. They measured the magnetic reconnection rate, diffusivity, dissipation scale, turbulence amplitude, and other parameters when tearing instabilities created turbulence. Turbulence, they discovered, can effectively extend the CS width and add to the CS’s dissipation effect. On May 31, the findings were published in the journal Research in Astronomy and Astrophysics.
A solar flare is one of the most powerful phenomena in the solar system, with magnetic reconnection releasing up to 1032 ergs of energy. The magnetic reconnection process takes place mostly on this large-scale current sheet that connects to the flare and the erupting flux rope. Classical theories predict a CS width of tens or hundreds of metres corresponding to the ion inertial scale, whereas multiple observations have revealed a breadth of 104 to 105 kilometres.
The massive disparity can be attributed to turbulence in the CS. As a result, a precise estimate of the energy dissipation caused by turbulence is critical to comprehending the solar flare’s rapid energy release. The researchers used 2D high-resolution magnetohydrodynamic numerical simulations in the gravitationally stratified solar atmosphere, based on the classic flare model. Due to the advent of tearing instabilities, the magnetic reconnection rate appeared to increase.
They discovered that the advent of turbulence was comparable to adding an extra dissipation component to the induction equations, resulting in a dramatic increase in the CS’s local diffusivity. “We computed a related dissipation scale of 100–200 km based on the spectrum analysis, which was substantially higher than the ion inertial scale. The breadth of the secondary reconnection CS between merging plasmoids corresponded to this value “Zhang Yining, the study’s first author, stated.
In addition, they calculated the present sheet’s general breadth to be 1500–2500 km, which matched the observational observations. Indeed, the Taylor scale from Biskamp’s theory has been shown to be relevant with the CS breadth typically encountered in data. “The flare loop top termination shock can somewhat boost the turbulence magnitude. The amplification factor is connected to the termination shock’s local geometry, and it has been proven that the termination shock has a higher heating efficiency than the kinetic energy transfer “Dr. Ye Jing, the study’s corresponding author, stated.
This research delves into the mechanics of magnetic reconnection dissipation in the presence of turbulence in a solar flare.