(code)¶

The numerical tool CODE (for COllisional Distribution of Electrons) [1] [2] [3], solves the spatially homogeneous Fokker–Planck equation for electrons. The code includes many effects important to runaway electron dynamics, including electric field acceleration, time-dependent plasma parameters, avalanche multiplication, bremsstrahlung and synchrotron radiation losses, as well as partial plasma ionization. SOFT provides support for loading distribution functions calculated with CODE directly through the present module.

[1]	Landreman et al., 2014 “Numerical calculation of the runaway electron distribution function and associated synchrotron emission”. Computer Physics Communications 185 (3), 847-855 doi:10.1016/j.cpc.2013.12.004.

[2]	Stahl et al., 2016 “Kinetic modelling of runaway electrons in dynamic scenarios”, Nuclear Fusion 56 (11), 112009 doi:10.1088/0029-5515/56/11/112009.

[3]	http://ft.nephy.chalmers.se/retools/code/

Summary of options¶

Option	Description
`code interptype`	Interpolation method to use when interpolating in the distribution function.
`code name`	Name of file containing distribution function.
`code radprof`	Name of configuration block defining the radial profile to use.
`code time`	Index of distribution function time slice to use for simulation.

Example configuration¶

The following example shows how to load a CODE distribution function and use the final time step of the CODE simulation. The configuration also sets a radial profile to use with the CODE momentum-space distribution function. If code radprof is not explicitly set, a uniform radial profile is used:

distribution_function = ourDistribution;

@DistributionFunction ourDistribution (code) {
    name    = "/path/to/code/distribution.mat";
    radprof = ourRadProf;
    time    = -1;         # -1 = last time step
}

@RadialProfile ourRadProf (linear) {}

File layout¶

The file containing the CODE distribution function must contain the variables listed in the table below. They are all contained in the CODE output struct.

Variable	Description
`delta`	Normalization of momentum. Defined such that \(p = y\delta\), where \(p\) is momentum normalized to the electron rest mass \(m_e c\).
`f`	Distribution function matrix. Must be of size \(n_t\times n_y n_\xi\).
`Nxi`	Number of Legendre modes used in the CODE calculation to resolve the angular dependence.
`nref`	Reference density (used for un-normalising the distribution function).
`Tref`	Reference temperature (used for un-normalising the distribution function).
`y`	Momentum grid, given in thermal units.

All options¶

interptype¶

Default value:	`cspline`
Allowed values:	`akima`, `akima_periodic`, `cspline`, `cspline_periodic`, `linear`, `polynomial`, `steffen`

Determines which interpolation method to use for interpolating in the momentum dimension.

name¶

Default value:	None
Allowed values:	String

Specifies the name of the file containing the CODE distribution function to load.

radprof¶

Default value:	Uniform radial profile
Allowed values:	Name of any defined @RadialProfile

Specifies the radial profile object to use to generate a radial profile.

time¶

Default value:	`-1` (last timestep)
Allowed values:	Any integer with absolute value less than the number of time points in the distribution function

Selects the index of the time step to take the distribution function from. Negative indices count from the back of the array, so that -1 corresponds to the last timestep, -2 to the next-to-last etc.