This guiding center code can simulate test ions in a maxwellian plasma composed of electrons and a single species of ions subject to an external model magnetic field corresponding to a tokamak.
Some contents in the source files are the following:
- main.cpp Contains the particle and time loop of the simulation.
- shared.h Contains the shared constants and variables among subroutines.
- define.h Contains definitions.
- initial.cpp Initializes simulation variables.
- step.cpp Contains the equations of motion that evolve particle variables.
- collisions.cpp Contains the Boozer and Kuo-Petravic collision operators.
- read.cpp Contains subroutines that read user defined parameters.
- record.cpp Contains subroutines that record data and write the .plt files.
- functions.cpp Contains functions used among subroutines.
- field.cpp Contains the analytic magnetic field and the field perturbation.
You need gcc and Python3
You can install gcafpp with the command
make && make install
This will produce an executable file that can be run from the command-line if you include ~/.local/bin in your $PATH.
A sample input file is
# SWITCHES
simulation traj traj/ense/poin
device tkmk tkmk/stell
collisions off on/off
perturbation off on/off
# SIMULATION
number_of_particles 200
time 80 in on-axis toroidal transits
step_delta 2000 toroidal transits/N
step_fix off on/off
max_error 1e-8 maximum energy error in each step
trajectory_points 4000 number of points in traj.plt
moment_points 4000 number of points in dips.plt
distribution_points 4 number of distribution snapshots
poincare_lower_bound 0.1 in r/rmin
poincare_upper_bound 0.9 in r/rmin
# FIELD
field_magnitude 2 in 10kG
major_radius 150 in cm
minor_radius 50 in cm
perturbation_amplitude 1e-4
perturbation_frequency 0 in Hz
perturbation_phase 0 in grades
m_mode 2
n_mode 1
electrostatic_potential 0 in keV
potential_profile cons pres/cons
# PLASMA
ions_mass 1 in proton units
ions_charge 1 in electron charge units
ions_temperature 1 in keV
electrons_temperature 1 in keV
temperature_profile flat flat/gaus
density 2e15 in cm^-3
density_profile flat flat/para
# PARTICLE
particle_type ion ion/ele
mass 1 in proton units
charge 1 in electron charge units
pitch_angle 0 pitch angle in grades
energy 1.0 in keV
energy_distribution mon mon/max
radius 25 in cm
theta 45 in grades
zeta 0 in grades
One can run a simulation as gcafpp -i input_directory/data.in -o output_directory/.
Some command-line flags that can be used are:
-sim Type of simulation traj/poin/ense
-npr Number of particles
-prt Field Perturbation on/off
-amp Field perturbation amplitude
-col Collisions on/off
-den Plasma density in cm^-3
-pch Initial pitch angle (in degrees)
-eng Initial energy in keV
-pot Electrostatic potential in keV
The output .plt data files produced in a simulation can be postprocessed using Python. Various postprocessing programs can be found in the folder pys. These can be run as ./file.py -i input_directory -o output_directory.
- traj.py Plot particle trajectories and the time evolution of particle variables obtained in a trajectory simulation.
- dist.py Plot a snapshot of the particle, energy and pitch angle distribution function obtained in an ensemble simulation.
- mome.py Plot of the time evolution of the statistical moments obtained in an ensemble simulation.
- poin.py Plot a Poincaré section.
- surf.py Postprocess a given particle Poincaré surface. The output data is needed for a flux calculation.