Deriving magnetofluid models from action principles

An algorithmic prescription is described for building action principles for plasma magnetofluid models that are extensions of magnetohydrodynamics. The action principles naturally lead to physically important invariants and Hamiltonian structure. Also, a prescription for obtaining reduced fluid models is given. Examples relevant to laboratory plasma discharges and naturally occurring plasmas will be presented, including models with gyroviscosity and generalizations of Ohm's law.