Impurities and Radiation
The impurity radiation model in PROCESS uses a multi-impurity model which integrates the radiation contributions over an arbitrary choice of density and temperature profiles1
The impurity number density fractions relative to the electron density are constant and are set
using input array fimp(1,...,14). The available species are as follows:
fimp |
Species |
|---|---|
| 1 | Hydrogen isotopes (fraction calculated by code) |
| 2 | Helium (fraction calculated by code) |
| 3 | Beryllium |
| 4 | Carbon |
| 5 | Nitrogen |
| 6 | Oxygen |
| 7 | Neon |
| 8 | Silicon |
| 9 | Argon |
| 10 | Iron |
| 11 | Nickel |
| 12 | Krypton |
| 13 | Xenon |
| 14 | Tungsten |
As stated above, the number density fractions for hydrogen (all isotopes) and
helium need not be set, as they are calculated by the code to ensure
plasma quasi-neutrality taking into account the fuel ratios
fdeut, ftrit and fhe3, and the alpha particle fraction ralpne which may
be input by the user or selected as an iteration variable.
The impurity fraction of any one of the elements listed in array fimp (other than hydrogen
isotopes and helium) may be used as an iteration variable.
The impurity fraction to be varied can be set simply with fimp(i) = <value>, where i is the corresponding number value for the desired impurity in the table above.
The synchrotron radiation power2 3 is assumed to originate from the
plasma core. The wall reflection factor ssync may be set by the user.
By changing the input parameter coreradius, the user may set the normalised
radius defining the 'core' region. Only the impurity and synchrotron radiation
from this affects the confinement scaling. Figure 1 below shows the
radiation power contributions.
Figure 1: Schematic diagram of the radiation power contributions and how they are split between core and edge radiation
Constraint equation no. 17 with iteration variable no. 28 (fradpwr)
ensures that the calculated total radiation power does not exceed the total
power available that can be converted to radiation (i.e. the sum of the fusion
alpha power, other charged particle fusion power, auxiliary injected power and
the ohmic power). This constraint should always be turned on.