Miniature solar flares made in lab offer insight into high-speed energetic particles

The coronal loop snaps, resulting in a powerful burst of solar flares accompanied by energetic particles and X-rays. These solar flares have the potential to damage satellites and other communication systems in orbit. However, the Earth's magnetic field shields life on the planet from these harmful energetic bursts.

However, scientists aren't sure how the sun generates such high-speed energetic particles and X-rays during a solar flare.

"Solar observations detect energetic particles and hard X-rays but cannot reveal the generating mechanism because the particle acceleration happens at a scale smaller than the observation resolution. Thus, details of the cross-scale physics that explain the generation of energetic particles and hard X-rays remain a mystery," reveals the paper. 

Creating tiny solar flares in the lab

Because it is difficult to study such intricate details in the Sun, scientists have turned to laboratories to mimic it. With this experiment, scientists tried to unravel the reason behind the generation of highly energetic particles that stream through space. 

Led by Caltech's Paul Bellan, the team created a vacuum chamber equipped with twin electrodes to simulate the coronal loop phenomenon.

The apparatus was equipped with a capacitor to store an excessive amount of energy. It was then able to discharge the energy through the electrodes, resulting in the creation of a miniature solar corona loop.

Each lab-made loop lasted about 10 microseconds and measured eight inches (20 centimeters) in length and nearly 0.3 inches (one cm) in diameter. Each of the discharged loops was captured in a specialized, high-speed camera, allowing scientists to process microsecond by microsecond.

They were able to decode some of the mystery as a result of this.

Recent findings indicate that solar loops may be braided structures, similar to large ropes, rather than single strands. “Like an elastic band stretched too tight, the loop gets longer and skinnier until the strands just snap," said Seth Pree, the co-author of this study, in a statement.

This suggests that this type of structure could play a key role in the generation of energetic particles and X-ray bursts associated with solar flares. Using this device, scientists will continue to investigate plasma loops and unlock the dynamics of the majestic Sun.

The study has been published in the journal Nature Astronomy.

Study Abstract:

Solar flares are intense bursts of electromagnetic radiation accompanied by energetic particles and hard X-rays. They occur when magnetic flux loops erupt in the solar atmosphere. Solar observations detect energetic particles and hard X-rays but cannot reveal the generating mechanism because the particle acceleration happens at a scale smaller than the observation resolution. Thus, details of the cross-scale physics that explain the generation of energetic particles and hard X-rays remain a mystery. Here, we present observations from a laboratory experiment that simulates solar coronal loop physics. Transient, localized 7.6-keV X-ray bursts and a several-kilovolt voltage spike are observed in braided magnetic flux ropes of a 2-eV plasma when the braid strand radius is choked down to be at the kinetic scale by either magnetohydrodynamic (MHD) kink or magnetic Rayleigh–Taylor instabilities. This sequence of observations reveals a cross-scale coupling from MHD to non-MHD physics that is likely responsible for generating solar energetic particles and X-ray bursts. All the essential components of this mechanism have been separately observed in the solar corona.