Articles | Volume 29, issue 6
25 Jun 2011
 | 25 Jun 2011

Flux quanta, magnetic field lines, merging – some sub-microscale relations of interest in space plasma physics

R. A. Treumann, R. Nakamura, and W. Baumjohann

Abstract. We clarify the notion of magnetic field lines in plasma by referring to sub-microscale (quantum mechanical) particle dynamics. It is demonstrated that magnetic field lines in a field of strength B carry single magnetic flux quanta Φ0=h/e. The radius of a field line in the given magnetic field B is calculated. It is shown that such field lines can merge and annihilate only over the length ℓ of their strictly anti-parallel sections, for which case we estimate the power generated. The length ℓ becomes a function of the inclination angle θ of the two merging magnetic flux tubes (field lines). Merging is possible only in the interval 12πθ≤π. This provides a sub-microscopic basis for "component reconnection" in classical macro-scale reconnection. We also find that the magnetic diffusion coefficient in plasma appears in quanta D0m=eΦ0/me=h/me. This lets us conclude that the bulk perpendicular plasma resistivity is limited and cannot be less than η0⊥0eΦ0/me0h/me~10−9 Ohm m. This resistance is an invariant.