Year: 1993

Nuclear Testing and the 1992 Moratorium

Distributed by the Strategy and Policy Division (N51) of the Office of the Chief of Naval Operations.

This report continues to have relevance in today’s world. Among other issues, it discusses the “robustness” of existing nuclear weapons. There is also an appendix on the seismic verification of underground nuclear explosions.


Reliable Replacement Warhead (RRW) Correspondence: Nature 462, 158 (12 November 2009).

(Nature 12Nov09-Warheads)

Helicity, Topology, and Force-Free Magnetic Fields

Phys. Rev. E Vol. 47, p. 3607 (1993) (PDF)

Concepts from topology are increasingly finding utility in magnetohydrodynamics. This paper gives an example of how the connectivity of the domain and the gauge freedom of the vector potential can play an important role in computing the helicity of twisted magnetic fields used in several areas of astrophysics, particularly solar physics. By computing the relative helicity of a simple magnetic field configuration used to model solar prominences, it is shown that helicity can have a non-local character. This necessitates a reexamination of its conventional physical interpretation. The magnetic energy is also discussed.

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