## Section: Software

### SPIN

Participants : Sébastien Jund, Guillaume Latu [ correspondant ] , Pierre Navaro, Eric Sonnendrücker.

The Scalable Particle-IN-cell (Spin) code is dedicated to the solving of Vlasov-Maxwell equations, using finite elements for the Maxwell solver. This code is designed to be able to scale well on parallel machine. We elaborated different strategies to balance both the computational loads of Vlasov part (Particle In Cell method) and the Maxwell part (Edge finite elements), in order to take into account the number of particles and elements per processor. The proposed load balancing schemes are for example: static, dynamic (several options), eulerian, lagrangian.

This code has run several 2D test cases, and the 3D version will be achieved soon. The 2D Maxwell solver is able to deal with hybrid grid (triangles and quadrangles) and has the capability of using high order elements. We built the numerical scheme in order to achieve a charge conserving property. An other characteristic of the solver concerns parallel work distribution. The computations on quadrangles are highly parallel: there are few communications and nearly no dependencies between computations. On the triangles, we use a sparse solver in order to solve Maxwell equation (all triangles are tightly coupled). The PASTIX solver (INRIA/Scalapplix team) or a classical Conjugate Gradient solver are used in order to perform the sparse computations.