xrays Command Line Arguments

Table of Contents

• Introduction
• Command Options
• Example commandline
  • Ray intialization.
  • Ray Models.

Command Line Arguments for the xrays RF Ray tracing code.

Introduction

This page documents the commandline arguments or the RF ray tracing code xrays. All arguments take the form of

xrays [--options] [--options=with_value]

Command Options

Command	Values	Discription
General Options
--help		Display help text
--verbose		Show verbose output about kernel information.
--print_expressions		Render ray equations as \(\LaTeX\) expressions.
--print		Display a sample of ray progress to the screen.
--seed		Use a fixed random seed.
Control Options
--num_times	Positive Integer	Total number of time steps to run.
--sub_steps	Positive Integer	Number of steps to run between outputs.
--num_rays	Positive Integer	Total number rays to run.
--endtime	Positive Number	Total time to trace the ray to.
Ray Initialization Options
--init_w_dist	uniform normal	Distribution function for wave frequency.
--init_w_mean	Positive Number	Mean value for the wave frequency distribution function.
--init_w_sigma	Positive Number	Standard deviation of for the wave frequency distribution function.
--init_kx_dist	uniform normal	Distribution function for wave number in the x direction.
--init_kx		Solve for initial wave number in the x direction position.
--init_kx_mean	Positive Number	Mean value for the wave number in the x direction distribution function.
--init_kx_sigma	Positive Number	Standard deviation of for the wave number in the y direction distribution function.
--init_ky_dist	uniform normal	Distribution function for wave number in the y direction.
--init_ky		Solve for initial wave number in the y direction position.
--init_ky_mean	Positive Number	Mean value for the wave number in the y direction distribution function.
--init_ky_sigma	Positive Number	Standard deviation of for the wave number in the y direction distribution function.
--init_kz_dist	uniform normal	Distribution function for wave number in the z direction.
--init_kz		Solve for initial wave number in the z direction position.
--init_kz_mean	Positive Number	Mean value for the wave number in the z direction distribution function.
--init_kz_sigma	Positive Number	Standard deviation of for the wave number in the z direction distribution function.
--init_x_dist	uniform normal	Distribution function for ray x position.
--init_x_mean	Positive Number	Mean value for the ray x position distribution function.
--init_x_sigma	Positive Number	Standard deviation of for the ray x position distribution function.
--init_y_dist	uniform normal	Distribution function for ray y position.
--init_y_mean	Positive Number	Mean value for the ray y position distribution function.
--init_y_sigma	Positive Number	Standard deviation of for the ray y position distribution function.
--init_z_dist	uniform normal	Distribution function for ray z position.
--init_z_mean	Positive Number	Mean value for the ray z position distribution function.
--init_z_sigma	Positive Number	Standard deviation of for the ray z position distribution function.
--use_cyl_xy		Use cylindical coordinates for x and y.
Ray Tracing Physics Options
--equilibrium	efit vmec	Equilibrium to use.
--equilibrium_file	Path to equilibrium file	Equilibrium file path.
--dispersion	simple bohm_gross ordinary_wave extra_ordinary_wave code_plasma	Wave disperion function to trace rays from.
--absorption_model	root_find weak_damping	Power absoption model to use.
--solver	split_simplextic rk2 rk4 adaptive_rk4	Method used to solve the equation.

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Example commandline

Take the example command line

./graph_driver/xrays --absorption_model=weak_damping --dispersion=ordinary_wave --endtime=2.0 --equilibrium=efit --equilibrium_file=../graph_tests/efit.nc --init_kx --init_kx_mean=-700.0 --init_ky_dist=normal --init_ky_mean=-100.0 --init_ky_sigma=10.0 --init_kz_dist=normal --init_kz_mean=0.0 --init_kz_sigma=10.0 --init_w_dist=normal --init_w_mean=700 --init_w_sigma=10.0 --init_x_mean=2.5 --init_y_dist=normal --init_y_mean=0.0 --init_y_sigma=0.05 --init_z_dist=normal --init_z_mean=0.0 --init_z_sigma=0.05 --num_rays=100000 --num_times=100000 --solver=rk4 --sub_steps=100 --use_cyl_xy --verbose

This example should be run from the build directory.

The options

--num_rays=100000 --num_times=100000 --sub_steps=100 --verbose

In this example, we will run a 100000 rays for 100000 steps and output every 100th step. This is also the provides verbose output of the kernel information.

--endtime=2.0 --init_w_mean=700

Time and frequency are input in modified units.

Conversion between input and real units.

Value	Input Value	Real Unit
\(\omega \)	700	\(\frac{700}{c}\) \(\frac{rad}{s}\)
\(t \)	2.0	\(2.0c \) \(s \)

Ray intialization.

--init_x_mean=2.5 --init_y_dist=normal --init_y_mean=0.0 --init_y_sigma=0.05 --init_z_dist=normal --init_z_mean=0.0 --init_z_sigma=0.05 --use_cyl_xy

Inital values for the position for \(y \) and \(z \) will be sampled from a normal distribution fuction. Both values have a mean of zero and as standard devation of 0.05. \(x \) is initalized with a uniform value of 2.5. We also set the command to use cylindical coordinates. So \(xyz\rightarrow r\phi z \).

--init_w_dist=normal --init_w_mean=700 --init_w_sigma=10.0

Frequency uses a normal distribution with a mean of 700 and a standard deviation of 10.

--init_kx --init_kx_mean=-700.0 --init_ky_dist=normal --init_ky_mean=-100.0 --init_ky_sigma=10.0 --init_kz_dist=normal --init_kz_mean=0.0 --init_kz_sigma=10.0

Inital values for \(k_{y}\) and \(k_{z}\) will be sampled from a normal distribution fuction. Both of them have a standard deviation of 10. \(k_{y}\) has a mean of -100 and \(k_{z}\) has zero mean. \(k_{x}\) uses the default uniform value of -700.0. However, it is configured to solve for \(k_{x}\) which satisfies the dispersion function given the values of \(\omega,k_{y},k_{z},\vec{x}\).

Ray Models.

--equilibrium=efit --equilibrium_file=../graph_tests/efit.nc

We are using a EFIT equilibirum with values initalized from ../graph_tests/efit.nc.

--absorption_model=weak_damping --dispersion=ordinary_wave --solver=rk4

It uses the o-mode dispersion function. Rays are integrated using a 4th Order Runge Kutta integrator. Power absorption uses the Weak Damping Model.