Volume 18: Pages 504-513, 2005

Is a Plasma Diamagnetic?

W. Engelhardt

Max‐Planck‐Institut für Plasmaphysik, IPP‐Euratom Association, Garching, Germany

Classical plasmas in thermodynamic equilibrium should be neither para‐ nor diamagnetic due to the action of the Lorentz force. Magnetic confinement, however, is based on the observed diamagnetism of laboratory plasmas. The apparent paradox is investigated on the basis of the resistive magnetohydrodynamic equations. It is found that, at least in simple plasma configurations, these equations do not permit a solution, i.e., the paradox cannot be resolved. It seems that the Lorentz force is a test‐particle approximation that is not suitable to describe the interaction of moving particles in agreement with the conservation of energy.

Keywords: plasma diamagnetism and paramagnetism, interaction of moving particles, Bohr‐Van Leeuwen theorem, Lorentz force, Maxwell's equations, electrodynamics and energy conservation, magnetohydrodynamics, magnetic plasma confinement, ideal equilibrium, slowly diffusing equilibrium

Received: October 26, 2004; Published online: December 15, 2008