Source file p3d-hybrid.F90

• perform initialization tasks (e.g. call to subroutine init_pe_env, source file modules.F90), load start-up file (call to subroutine input, source file inout.F90), enforce div B = 0 (call to subroutine divergence, source file hybrid.M)
• main time stepping loop
1. calculate total energy: call to subroutine energy (source file misc.M)
2. advance electron pressure and magnetic field from t to t+dt/2 using electron fluid equations: call to subroutine stephybrid (source file hybrid.M); loop since stephybrid allows for a reduced time step controlled by the switch substeps
3. step particle location from t to t+dt/2: call to subroutine stepx (source file particles.F90)
4. sort particles in particle buffer to increase performance due to better usage of the memory cache: call to subroutine partsort (source file particles.F90)
5. calculate and smooth ion density n (for compatibility with the particle code the density is stored in the variable rho): call to subroutines calc_rho (source file particles.F90) and smooth_rho (source file boundary.F90); add base density to avoid numerical instabilities at very low particle density: call to subroutine add_base_density (source file hybrid.M)
6. calculate and smooth ion current density j (required to calculate electric field): call to subroutines calc_j (source file particles.F90) and smooth_j (source file boundary.F90)
7. calculate electric field (required for ion equation of motion): call to subroutine calc_e (source file hybrid.M)
8. step particle velocity form t to t+dt: call to subroutine stepv (source file particles.F90)
9. step particle location from t+dt/2 to t+dt: call to subroutine stepx (source file particles.F90)
10. calculate and smooth ion density n: call to subroutines calc_rho (source file particles.F90) and smooth_rho (source file boundary.F90); add base density: call to subroutine add_base_density (source file hybrid.M)
11. calculate and smooth ion current density j: call to subroutines calc_j (source file particles.F90) and smooth_j  (source file boundary.F90)
12. advance electron pressure and magnetic field from t to t+dt/2 using electron fluid equations: call to subroutine stephybrid (source file hybrid.M)
13. write movie frames on request (controlled by special header files, e.g. movie2dhybrid.h): calls to subroutines in source file movie.F90
• several scenarios for finishing execution: maximum number of time steps reached, maximum execution time reached, stop on operator's request (only on T3E in Garching): call to subroutine output (source file inout.F90)

• maxruntime: After maxruntime minutes of operation the code starts termination and stores the data. maxruntime should be sufficiently smaller than the time limit of the batch queue, since storing the data can require a significant amount of time. Example:  #define maxruntime 180
• substeps: The code allows substepping of the fluid part, the time step in the routine stephybrid is dt(2*substeps). Only at the last substep in the substepping loop the multigrid is called in full version leading to convergence, whereas during the other cycles multigrid iterations with a fixed number of iterations are performed (compare discussion for the source file multigrid.M)