  Hybrid-VPIC is an extension of the open-source high-performance
particle-in-cell (PIC) code VPIC incorporating hybrid kinetic ion/fluid
electron solvers. This paper describes the models that are available in the
code and gives an overview of applications of the code to space and laboratory
plasma physics problems. Particular choices in how the hybrid solvers were
implemented are documented for reference by users. A few solutions for handling
numerical complications particular to hybrid codes are also described. Special
emphasis is given to the computationally taxing problem of modeling mix in
collisional high-energy-density regimes, for which more accurate electron fluid
transport coefficients have been implemented for the first time in a hybrid PIC
code.
