  A selfconsistent 1D theoretical framework for plasma assisted ignition and
combustion is reviewed. In this framework, a frozen electric field modeling
approach is applied to take advantage of the quasiperiodic behaviors of the
electrical characteristics to avoid the recalculation of electric field for
each pulse. The correlated dynamic adaptive chemistry (CoDAC) method is
employed to accelerate the calculation of large and stiff chemical mechanisms.
The timestep is updated dynamically during the simulation through a three-stage
multitimescale modeling strategy, which takes advantage of the large separation
of timescales in nanosecond pulsed plasma discharges. A general theory of
plasma assisted ignition and combustion is then proposed. Nanosecond pulsed
plasma discharges for ignition and combustion can be divided into four stages.
Stage I is the discharge pulse, with timescales of O(1 to 10 ns). In this
stage, most input energy is coupled into electron impact excitation and
dissociation reactions to generate charged or excited species and radicals.
Stage II is the afterglow during the gap between two adjacent pulses, with
timescales of O(100 ns). In this stage, quenching of excited species not only
further dissociates O2 and fuel molecules, but also provides fast gas heating.
Stage III is the remaining gap between pulses, with timescales of O(1 to 100
microsec). The radicals generated during Stages I and II significantly enhance
the exothermic reactions in this stage. Stage IV is the accumulative effects of
multiple pulses, with timescales of O(1 ms to 1 sec), which include preheated
gas temperatures and a large pool of radicals and fuel fragments to trigger
ignition. For plasma assisted flames, plasma significantly enhances the radical
generation and gas heating in the preheat zone, which could trigger upstream
autoignition.
