  A new method that solves concurrently the multi-fluid and Maxwell's equations
has been developed for plasma simulations. By calculating the stress tensor in
the multi-fluid momentum equation by means of computational particles moving in
a self-consistent electromagnetic field, the kinetic effects are retained while
solving the multi-fluid equations. The Maxwell's and multi-fluid equations are
discretized implicitly in time enabling kinetic simulations over time scales
typical of the fluid simulations. The fluid-kinetic Particle-in-Cell solver has
been implemented in a three-dimensional electromagnetic code, and tested
against the ion cyclotron resonance and magnetic reconnection problems. The new
method is a promising approach for coupling fluid and kinetic methods in a
unified framework.
