(power)¶

This module provides a radial profile the decays according to a power-law from a radius \(r_{\rm min}\) to a radius \(r_{\rm max}\) and is zero outside of that radial interval. More precisely, on the interval \(r_{\rm min}\leq r \leq r_{\rm max}\) the radial profile is

(1)¶\[f_r(r) = 1 - \left( \frac{r - r_{\rm min}}{r_{\rm max} - r_{\rm min}} \right)^b,\]

and it is identically zero everywhere else. The parameter \(b\) must be specified by the user.

Summary of options¶

The following parameters can be set on a power radial profile.

Option	Description
`radprof-power exponent`	Exponent in radial profile.
`radprof-power amax`	Normalized minor radius of the outer edge of the electron beam.
`radprof-power amin`	Normalized minor radius of the inner edge of the electron beam.
`radprof-power rhomax`	Major radius of the outer edge of the electron beam.
`radprof-power rhomin`	Major radius of the inner edge of the electron beam.
`radprof-power rmax`	Minor radius of the outer edge of the electron beam.
`radprof-power rmin`	Minor radius of the inner edge of the electron beam.

Example configuration¶

This example illustrates how a power radial profile can be defined and used together with the (avalanche) distribution function in SOFT2 simulations:

# Global parameter specifying which distribution function to use
distribution_function = analytical_avalanche;

@DistributionFunction analytical_avalanche (avalanche) {
    EHat     = 10;            # Electric field strength (normalized to
                              # the Connor-Hastie critical electric field)
    lnLambda = 17;            # Coulomb logarithm
    Zeff      = 4;             # Effective plasma charge

    # Set the radial profile
    radprof   = ourradprof;
}

@RadialProfile ourradprof (power) {
    # Set normalized minor radius
    # These settings creates a beam with radius
    # 2/3 of the device minor radius.
    amin = 0;
    amax = 0.67;

    # Create quadratically decreasing profile
    exponent = 2;
}

All options¶

exponent¶

Default value:	None (i.e. must be defined)
Allowed values:	Any real value.

Specifies the exponent \(b\) in (1).

amax¶

amin¶

rhomax¶

rhomin¶

rmax¶

rmin¶

Default value:	`amin = 0` and `amax = 1`.
Allowed values:	Any radial position that is inside the plasma and on the outboard side.

Specifies the inner and outer edges of the electron beam. The prefix (a*, r*, rho*) specifies whether the edge is given in normalized minor radius, regular minor radius or major radius coordinates.