Calculations for the Practical Applications of Quadratic Helicity in MHD

Petr Akhmet'ev, Simon Candelaresi, Alexander Yu Smirnov

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)
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For the quadratic helicity χ(2) we present a generalization of the Arnol’d inequality which relates the magnetic energy to the quadratic helicity, which poses a lower bound. We then introduce the quadratic helicity density using the classical magnetic helicity density and its derivatives along magnetic field lines. For practical purposes we also compute the flow of the quadratic helicity and show that for an α2-dynamo setting it coincides with the flow of the square of the classical helicity. We then show how the quadratic helicity can be extended to obtain an invariant even under compressible deformations. Finally, we conclude with the numerical computation of χ(2) which show cases the practical usage of this higher order topological invariant.
Original languageEnglish
Article number102128
JournalPhysics of Plasmas
Publication statusPublished - Oct 2017


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