The simulations were run using hybrid particle-In-Cell (PIC) code HYPSI. The code simulates a collisionless shock with a desired geometry. In this model, protons are modelled as macroparticles and advanced using the standard PIC method. Electrons are modelled as a massless, charge-neutralising fluid with an adiabatic equation of state. A shock is created using the so-called injection method, in which the plasma is injected at the left-hand, open boundary simulation side (x = 0) with a superalfvènic velocity. The right-hand side of the simulation acts as a reflecting wall. Therefore, a shock is generated due to the interaction between the reflected plasma and the superalfvènic inflow. In the simulation frame, the shock is propagating in the negative x-direction. The simulation domain is periodic along the y and z directions, and is of 240×240×80 gridpoints. The number of particles per cell is always greater than 100 (upstream).
Distances are normalised to the ion inertial length c/ωpi≡di, time to the inverse cyclotron frequency Ωci-1 , velocity to the Alfvén speed vA (all referred to the upstream state), and the magnetic field and density to their upstream values, B0 and n0, respectively. The spatial resolution used is Δx=Δy=Δz=di/4.
The angle between the upstream magnetic field and the mean shock normal, θBn, is 870, with the upstream magnetic field in the x - y plane. The shock has an Alfvénic Mach number MA of 6.6 and is, therefore, supercritical, as it can be seen from the rippled structure of the magnetic field at the shock front.
The Figure above shows the magnetic field magnitude for snapshot uploaded in Aidadb, that is taken when the shock is well-developed. Superimposed to the magnetic field rendering are four virtual spacecraft trajectories, that can be found in the high-level data directory.