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| -rw-r--r-- | Docs/source/running_cpp/parameters.rst | 31 |
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diff --git a/Docs/source/running_cpp/parameters.rst b/Docs/source/running_cpp/parameters.rst index 5e2c3a575..592ea1b0b 100644 --- a/Docs/source/running_cpp/parameters.rst +++ b/Docs/source/running_cpp/parameters.rst @@ -266,6 +266,37 @@ Particle initialization well as standard deviations along each direction ``<species_name>.ux_th``, ``<species_name>.uy_th`` and ``<species_name>.uz_th``. + * ``maxwell_boltzmann``: Maxwell-Boltzmann distribution that takes a dimensionless + temperature parameter ``<species_name>.theta`` as an input, where theta is kb*T/(m*c^2), + kb is the Boltzmann constant, c is the speed of light, and m is the mass of the species. + It also includes the optional parameter ``<species_name>.beta`` where beta is equal to v/c. + The plasma will be initialized to move at drift velocity beta*c in the positive + ``<species_name>.direction = 'x', 'y', 'z'`` direction. The MB distribution is initialized + in the drifting frame by sampling three Gaussian distributions in each dimension using, + the Box Mueller method, and then the distribution is transformed to the simulation frame + using the flipping method. The flipping method can be found in Zenitani 2015 + section III. B. (Phys. Plasmas 22, 042116). + + Note that though the particles may move at relativistic speeds in the simulation frame, + they are not relativistic in the drift frame. This is as opposed to the Maxwell Juttner + setting, which initializes particles with relativistc momentums in their drifting frame. + + * ``maxwell_juttner``: Maxwell-Juttner distribution for high temperature plasma. This mode + requires a dimensionless temperature parameter ``<species_name>.theta``, where theta is equal + to kb*T/(m*c^2), where kb is the Boltzmann constant, and m is the mass of the species. It also + includes the optional parameter ``<species_name>.beta`` where beta is equal to v/c. The plasma + will be initialized to move at velocity beta*c in the positive + ``<species_name>.direction = 'x', 'y', 'z'`` direction. The MJ distribution will be initialized + in the moving frame using the Sobol method, and then the distribution will be transformed to the + simulation frame using the flipping method. Both the Sobol and the flipping method can be found + in Zenitani 2015 (Phys. Plasmas 22, 042116). + + Please take notice that particles initialized with this setting can be relativistic in two ways. + In the simulation frame, they can drift with a relativistic speed beta. Then, in the drifting + frame they are still moving with relativistic speeds due to high temperature. This is as opposed + to the Maxwell Boltzmann setting, which initializes non-relativistic plasma in their relativistic + drifting frame. + * ``radial_expansion``: momentum depends on the radial coordinate linearly. This requires additional parameter ``u_over_r`` which is the slope. |