  Electromagnetic particle simulation model has been formulated and verified
for nonlinear processes of lower hybrid (LH) waves in fusion plasmas. Electron
dynamics is described by the drift kinetic equation using either kinetic
momentum or canonical momentum. Ion dynamics is treated as the fluid system or
by the Vlasov equation. Compressible magnetic perturbation is retained to
simulate both the fast and slow LH waves. Numerical properties are greatly
improved by using electron continuity equation to enforce consistency between
electrostatic potential and vector potential, and by using the importance
sampling technique. The simulation model has been implemented in the
gyrokinetic toroidal code (GTC), and verified for the dispersion relation and
nonlinear particle trapping of the electromagnetic LH waves.
