# spectral_density_liteļ

- plasmapy.diagnostics.thomson.spectral_density_lite(
*wavelengths*,*probe_wavelength: float*,*n: float*,*T_e: ndarray*,*T_i: ndarray*,*efract: ndarray*,*ifract: ndarray*,*ion_z: ndarray*,*ion_mass: ndarray*,*electron_vel: ndarray*,*ion_vel: ndarray*,*probe_vec: ndarray*,*scatter_vec: ndarray*,*instr_func_arr: ndarray | None = None*,*notch: ndarray | None = None*,The lite-function version of

`spectral_density`

. Performs the same thermal speed calculations as`spectral_density`

, but is intended for computational use and thus has data conditioning safeguards removed.- Parameters:
**wavelengths**((NĪ»,)`ndarray`

) ā The wavelengths in meters over which the spectral density function will be calculated.**probe_wavelength**(*real number*) ā Wavelength of the probe laser in meters.**n**(`ndarray`

) ā Total combined number density of all electron populations in m^{-3}.**T_e**((Ne,)`ndarray`

) ā Temperature of each electron population in kelvin, where Ne is the number of electron populations.**T_i**((Ni,)`ndarray`

) ā Temperature of each ion population in kelvin, where Ni is the number of ion populations.**efract**((Ne,)`ndarray`

) ā An`ndarray`

where each element represents the fraction (or ratio) of the electron population number density to the total electron number density. Must sum to 1.0. Default is a single electron population.**ifract**((Ni,)`ndarray`

) ā An`ndarray`

object where each element represents the fraction (or ratio) of the ion population number density to the total ion number density. Must sum to 1.0. Default is a single ion species.**ion_z**((Ni,)`ndarray`

) ā An`ndarray`

of the charge number \(Z\) of each ion species.**ion_mass**((Ni,)`ndarray`

) ā An`ndarray`

of the mass number of each ion species in kg.**electron_vel**((Ne, 3)`ndarray`

) ā Velocity of each electron population in the rest frame (in m/s). If set, overrides`electron_vdir`

and`electron_speed`

. Defaults to a stationary plasma`[0, 0, 0]`

m/s.**ion_vel**((Ni, 3)`ndarray`

) ā Velocity vectors for each electron population in the rest frame (in m/s). If set, overrides`ion_vdir`

and`ion_speed`

. Defaults to zero drift for all specified ion species.**probe_vec**((3,) float`ndarray`

) ā Unit vector in the direction of the probe laser. Defaults to`[1, 0, 0]`

.**scatter_vec**((3,) float`ndarray`

) ā Unit vector pointing from the scattering volume to the detector. Defaults to [0, 1, 0] which, along with the default`probe_vec`

, corresponds to a 90 degree scattering angle geometry.**instr_func_arr**(`ndarray`

, shape (Nwavelengths,) optional) āThe instrument function evaluated at a linearly spaced range of wavelengths ranging from \(-W\) to \(W\), where

\[W = 0.5*(\max{Ī»} - \min{Ī»})\]Here \(Ī»\) is the

`wavelengths`

array. This array will be convolved with the spectral density function before it is returned.**notch**((2,) or (N, 2)`ndarray`

, keyword-only, optional) ā A pair of wavelengths in meters which are the endpoints of a notch over which the output Skw is set to 0. Can also be input as a 2D array which contains many such pairs if multiple notches are needed. Defaults to no notch.

- Returns:
**alpha**(*float*) ā Mean scattering parameter, where`alpha`

> 1 corresponds to collective scattering and`alpha`

< 1 indicates non-collective scattering. The scattering parameter is calculated based on the total plasma density \(n\).**Skw**(`ndarray`

) ā Computed spectral density function over the input`wavelengths`

array with units of s/rad.