Numerical simulation of collision-free plasma is of great importance in the fields of space physics, solar and radio physics, and in confined plasmas used in nuclear fusion. This work describes a novel completely general and highly efficient algorithm for the numerical simulation of collision-free plasma. The algorithm is termed Vlasov Hybrid Simulation (VHS) and uses simulation particles to construct particle distribution function in the region of phase (r,v) space of interest. The algorithm is extremely efficient and far superior to the classic particle in cell method. A fully vectorised and parallelised VHS code has been developed, and has been successfully applied to the problem of the generation of VLF triggered emissions and VLF ‘dawn chorus’, due to the nonlinear interaction of cyclotron resonant electrons with narrow band VLF band waves (~kHz) in the earth’s magnetosphere.