External Radiation Source Setup

This option is only available for 1-D planar and 1-D spherical geometries.

For 1-D planar geometry, an external source can be specified at one or both boundaries of the plasma. For 1-D spherical geometry an external source can be specified at the sphere's outer boundary.

In SPECT3D, time-dependent external radiation fields are modeled using 4 approaches:

• A 1-T Planckian radiation model, in which the user specifies the radiation temperature T_R(t). Here, T_R(t) is used in setting both the radiation flux at the boundary and the frequency-dependent incident spectrum.
• A 2-T diluted Planckian radiation model, in which the user specifies T_R(t) and the spectral temperature T_Spec(t). Here, T_R(t) is used in setting the radiation flux at the boundary, while T_Spec(t) is used to set the frequency-dependent spectral distribution.
• VISRAD input file. The VISRAD 3-D radiosity code can be used to compute the time- and frequency-dependent radiation field incident on a surface. SPECT3D supports using VISRAD-formatted files to specify the external radiation field incident on a plasma boundary.
• Data written in the hydrocode file. In the case of a hydrocode file produced by HELIOS, the radiation flux at the outer boundaries is written to the file for HELIOS version 4.5.0 and greater.

For the 1-T and 2-T table options, click the Setup button to enter values in a table. See also Entering Table Data.

External source radiation intensities at a given simulation time are interpolated from the tabulated data.

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