Particle-in-Cell Simulation Modules for Laser Induced Air Plasmas with Picosecond Lasers

Novel physical modules for Particle-in-Cell(PIC) simulations of picosecond duration intense lasers (>10¹³ W/cm²) ionising air have been implemented in a modified version of the open source EPOCH code. These modules, such as a custom medium model including PPT[1,2] ionisation, dynamically varying index of refraction and Kerr non-linearity, and the dynamic generation of macroparticles allows for the modelling of up to 40 picosecond pulse lasers of 532nm light in 2D(3v) PIC whilst maintaining sub-femtosecond temporal resolution as required by the explicit finite-difference solver in PIC. Moreover, the medium macroparticle creator routine allows an exponential range of electron densities to be simulated (from 10²¹m^-3 to 10²⁵m^-3) without requiring billions of macroparticles by leveraging a custom macroparticle merger to conserve memory. These new modules, along with code for modelling of condensed matter photonic interactions in PIC[3] constitute an advanced tool for sophisticated time-domain simulations of longer pulse lasers in a ioniseable, self-focusing medium such as air.

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2. Perelemov A M and Popov V S 1967 Soviet Phys.JETP, 25 336

3. Gregory K. Ngirmang, Hue T. B. Do, Guangxin Liu, Michel Bosman, Lin Wu, arXiv:2501.07465