.. _physics-atomicRecombinationRateRadiativeCooling:

Atomic Recombination Cooling
============================

Class providing recombination cooling rate coefficients (in cm\ :math:`^3` s\ :math:`^{-1}`) for ions of given atomic number and ionization state at a specified electron temperature. When a free electron recombines radiatively with an ion it releases energy both in the emitted photon and in the kinetic energy difference; the cooling rate coefficient quantifies this energy loss from the gas per recombination event. Case A (all recombinations) and case B (excluding direct recombinations to the ground state) coefficients are supported, consistent with the corresponding radiative recombination rate classes.

**Default implementation:** ``atomicRecombinationRateRadiativeCoolingHummer``

Methods
-------

``rate`` → ``double precision``
   Returns the recombination cooling rate coefficient in units of cm\ :math:`^3` s\ :math:`^{-1}`.

   * ``integer , intent(in ) :: atomicNumber, ionizationState``

   * ``double precision , intent(in ) :: temperature``

   * ``type (enumerationRecombinationCaseType), intent(in ), optional :: level``

.. _physics-atomicRecombinationRateRadiativeCoolingComputed:

``atomicRecombinationRateRadiativeCoolingComputed``
---------------------------------------------------

Atomic radiative cooling rates computed from the corresponding photoionization cross section using detailed balance (i.e. the Milne relation---see for example "Astrophysics of the Diffuse Universe" by Dopita & Sutherland, 2004, Springer Science & Business Media, section 5.3.3).

.. _physics-atomicRecombinationRateRadiativeCoolingFixed:

``atomicRecombinationRateRadiativeCoolingFixed``
------------------------------------------------

Atomic radiative cooling rates which are a fixed multiple of the recombination rate,  :math:`\beta = \gamma \alpha` where :math:`\alpha` is the corresponding radiative recombination coefficient and :math:`\gamma` is a parameter.

**Parameters**

* ``[gamma]`` (real; default ``0.67d0``) — The multiplicative factor, :math:`\gamma`, used to compute the cooling coefficient.

.. _physics-atomicRecombinationRateRadiativeCoolingHummer:

``atomicRecombinationRateRadiativeCoolingHummer``
-------------------------------------------------

Atomic radiative cooling rates based on the tabulated results of :cite:t:`hummer_total_1994` and :cite:t:`hummer_recombination_1998`. For non-hydrogenic or helium-like ions an optional default of :math:`\beta = \gamma \alpha` can be returned where :math:`\alpha` is the corresponding radiative recombination coefficient and :math:`\gamma` is a parameter.

**(Default implementation)**

**Parameters**

* ``[gamma]`` (real; default ``0.67d0``) — The multiplicative factor, :math:`\gamma`, used to compute the cooling coefficient in cases of non-hydrogenic or helium-like ions.