Boosted Oblique Particle Simulation
BOPS is a one and three halves (1 spatial, 3 velocity coordinates: 1D3V) particle-in-cell code originally created by Paul Gibbon and Tony Bell in the Plasma Physics Group of Imperial College, London. It employs a Lorentz transformation, or 'boost' along the target surface to mimic the standard 2D, periodic-in-y geometry common to much of the early PIC work on resonance absorption in high-power laser-plasma interactions.
The technique was presented at the ECLIM conference in 1990, and later applied to absorption of femtosecond laser pulses on solid targets in PRL 68, 1535 (1992). A longer description of the method including the transformation subtleties can be found in Phys. Plasmas 6, 947 (1999).
While restricting the simulations to a special class of problems - in which the light and all its harmonics are reflected in the specular direction only - the reduction from 2D -> 1D brings huge savings in computational effort and/or increased spatial and temporal resolution. This type of code has become a 'workhorse' for high-intensity laser-matter interaction studies, giving relatively easy access to some extremely nonlinear, kinetic plasma phenomena, such as hot electron generation, ion acceleration and high-harmonic generation from solid surfaces.