September 22, 2017, 1:00 pm - 2:00 pm

Septmeber 22, 1:00 pm - 2:00 pm

Hybrid kinetic models of shocks in astrophysical and laboratory plasmas: PIC vs CPK vs CPK/FMM(SFK) concepts

Alexander S. Lipatov (GPHI-UMBC and NASA GSFC Code 673)

Many macroscopic problems in plasma physics are characterized by ion Larmor radii comparable to the scale lengths of the system. For these problems, and for problems involving micro-instabilities, a fluid description of the ions is inadequate, and the ions must instead be treated in a fully kinetic manner. The phenomena in the astrophysical and laboratory plasmas present a various wave-particle interactions which are responsible for electrostatic and electromagnetic instabilities and particle heating, and acceleration. The most of these effects are controlled by the non-Maxwellian particle Velocity Distributions and Finite Gyroradius. These effects are main features in the formation of the fine structure of the collisionless shocks, the reconnection in plasma systems with reversed magnetic configuration, and plasma beams. Note the such phenomena can not be self-consistently studied by the use of MHD/multi-fluid/Hall-MHD models.

In this talk we shall discuss the current status of the hybrid computational models: standard particle-in-cell (PIC), complex particle kinetic approach (CPK), and combination of the CPK approach and finite mass method (FMM)-- shape function kinetics method (SFK). The CPK method includes the internal dynamics of the probe Maxwellian distributions (time-dependent shape functions in phase space) and fragmentation of macro-particles to probe for emerging features, and refined merging where fine macro-particles are no longer needed. In opposite to CPK the CPK/FMM uses the re-mapping(re-starting) for particle distribution to get fine structures in phase space. Both CPK and CPK/FMM algorithms need much smaller computational resources in compare with a standard PIC method.

We shall also discuss the results of modeling of the shock dynamics and particle acceleration, astrophysical explosion, and non-linear field line resonance triggered by shocks.