Variational principle for nonlinear gyrokinetic Vlasov-Maxwell equations

A new variational principle for the nonlinear gyrokinetic Vlasov-Maxwell eq uations is presented. This Eulerian variational principle uses constrained variations for the gyrocenter Vlasov distribution in eight-dimensional exte nded phase space and turns out to be simpler than the Lagrangian variationa l principle recently presented by ii. Sugama [Phys. Plasmas 7, 466 (2000)]. A local energy conservation law is then derived explicitly by the Noether method. In future work, this new variational principle will be used to deri ve self-consistent, nonlinear, low-frequency Vlasov-Maxwell bounce-gyrokine tic equations, in which the fast gyromotion and bounce-motion time scales h ave been eliminated. (C) 2000 American Institute of Physics. [S1070-664X(00 )03412-7].