In the realm of energy research, understanding magnetic fields and their behavior is crucial, particularly when it comes to harnessing energy from sources like the sun. Researchers Anthony R. Yeates from Northumbria University and Gunnar Hornig from the University of Glasgow have delved into the complexities of magnetic helicity, a property that describes the twist and interlinkage of magnetic field lines. Their work, published in the journal Physical Review Letters, offers new insights that could have practical applications in the energy sector, particularly in fusion energy and solar power.
Magnetic helicity is a valuable tool in solar physics because it helps avoid ambiguities that arise in open magnetic domains. However, its physical interpretation can be challenging due to the need for a reference field. Yeates and Hornig have found a way to express relative magnetic helicity intrinsically, using only the magnetic field, without the need for a reference field or its vector potential. This is particularly useful for spherical shell domains, like those found in the sun’s corona.
The researchers used this intrinsic expression to prove that non-zero relative helicity implies lower bounds for both magnetic energy and free magnetic energy. This generalizes the Arnol’d inequality, a well-known concept in the study of closed-field magnetic helicity. By decomposing the relative helicity spatially over a magnetic partition of the domain, they derived a new ideal invariant called unsigned helicity, which provides a stronger energy bound.
To illustrate these bounds, Yeates and Hornig used analytical linear force-free fields that maximize relative helicity for given boundary conditions, as well as a non-potential data-driven model of the solar corona. Their findings confirm that both relative helicity and unsigned helicity can influence the dynamics in the solar corona, which could have implications for understanding and predicting solar flares and other energetic events.
In the energy industry, these findings could contribute to the development of more efficient and stable fusion reactors, which rely on understanding and controlling magnetic fields. Additionally, improved models of solar activity could enhance our ability to predict and manage the impact of solar events on power grids and other energy infrastructure. The research was published in Physical Review Letters, a prestigious journal in the field of physics.
This article is based on research available at arXiv.