Diamagnetism in a plasma

• Published in: Physics of plasmas 1997-06, Vol.4 (6), p.2072-2080
• Main Author: Cole, K. D.
• Format: Article
• Language: English
• Subjects: Boundary layers; Polarization; Q1
• ISSN: 1070-664X; 1089-7674
• DOI: 10.1063/1.872373

This is an extension of a study of electric currents and force balance orthogonal to a unidirectional magnetic field of induction (B) in a collisionless plasma [K. D. Cole, Phys. Plasmas 3, 2717 (1996)]. All quantities are assumed to vary only in one direction orthogonal to B. Two new concepts are introduced, which are not in conventional plasma physics. First a magnetic polarization effect corresponding to electric polarization is found. This defines a contribution to the magnetic moment per unit volume of −ρ m c 2 E 2 /B 3 . Second the conduction current is defined in terms of the curl of the magnetic field intensity H, in accordance with Maxwell. In this scheme, when there is no electric field, (1/4π)(∂H/∂z)B+(∂p ⊥ /∂z)=0, instead of the conventional equation with B/μ 0 in place of H. In both schemes, j×B−∇p ⊥ =0. Though this makes no difference to the electric current intensity calculated in the two schemes, and no difference to the force balance equation, it makes a significant difference to the relationship between B and p ⊥ in many plasma conditions of interest. When the electric field is nonzero, the situation is more complex. It is shown that the new diamagnetism of this paper and the dielectric current of the earlier one are consistent with special relativity. Some applications of the theory are discussed.