.. _absorption-label:
Absorption
==========

.. include:: ../shared.rst

File Column Reference
---------------------

The energy absorption data is written to the :file:`absorbedEnergy.dat` file.


**#time,s**
  
  Time elapsed since the beginning of the simulation, in seconds.

The following fields show energy gained during the set period of time. 
The period of time is defined by the ``config.IterationSubstepsRate`` field in the JSON file.
The values are units of energy are `Watts * IterationSubstepsRate`. 


**EmissionTotalPower**
  
  Total power emitted by the energy source. For example, if the beam power :math:`P` is constant, and is defined in the 
  ``ScanStrategy.Beam.Power`` parameter (W) in the JSON file, the **EmissionTotalPower** is equal to :math:`PT`, where `T` is ``config.IterationSubstepsRate``: the number of time steps between simulation outputs.

**TotalPowerFluid**

  Power absorbed in the fluid phase.

**TotalPowerSolid**

  Power absorbed in the solid phase. 

**BeamPowerFluid**

  Beam power absorbed in the fluid phase.

**BeamPowerSolid**

  Beam power absorbed in the fluid phase.


The following fields show energy lost during the set period of time. 
The values are negative, to show that the energy is lost. 

**EvaporationPower**

  Energy lost through evaporation.

**RadiationPower**

  Energy lost through black-body radiation.

**ConvectionPower**

  Energy lost through gas convection in the chamber.

**PowerLostBottom**

  Energy which is not caught by the material.

The energy balance treats the `PowerLostBottom` as the energy absorbed by the material:

.. math::

  &\texttt{TotalPowerFluid}
  +
  \texttt{TotalPowerSolid}
  \approx \\
  \texttt{BeamPowerFluid}
  +
  &\texttt{BeamPowerSolid}
  +
  \texttt{EvaporationPower}
  +
  \texttt{RadiationPower}
  +
  \texttt{ConvectionPower}




Energy Absorption Percentage
----------------------------

.. absdf['A'] = (absdf['BeamPowerFluid']+absdf['BeamPowerSolid'])/P/T


To find the ratio of the absorbed energy, 
take the sum of the ``BeamPowerFluid`` and ``BeamPowerSolid`` columns,
divide by the total laser power :math:`P` (the ``ScanStrategy.Beam.Power`` parameter in the JSON file), 
and divide by the time the power was being recorded :math:`T` (the ``config.IterationSubstepsRate`` field in the JSON file). 

.. math::

  \frac{\texttt{BeamPowerFluid}+\texttt{BeamPowerSolid}} {TP}

If the beam power is variable, which  can be set by using the `XYpositions` scanning strategy, the expression should use the **EmissionTotalPower** column of the :file:`absorbedEnergy.dat` file:

.. math::

  \frac{\texttt{BeamPowerFluid}+\texttt{BeamPowerSolid}} {\texttt{EmissionTotalPower}}