Screening of Reaction Rates
Introduction
Plasma screening is the enhancement of nuclear reaction rates,
where
where
where
Screening Options
The screening enhancement factor can be can be computed using
several different methods, controlled by the make parameter SCREEN_METHOD
.
For example,
make SCREEN_METHOD=screen5
Any of the available screening methods can be used with any reaction network.
The options are:
screen5
:This is the screening routine from the Kepler stellar evolution code and is the default used with the distributed versions of the “aprox” family of reaction networks. In the weak screenng regime,
, it uses screening described in [20]. In the strong screening regime, , it uses screening described in [21], [22], [23]. For the intermediate screening regime, , a weighted blending between the weak and strong screening are used. The overall procedure is described in [24].This is the default screening method.
chugunov2007
:This implements the screening of [25], following [26] to extend to binary mixtures. It is suitable for
.chugunov2009
:This implements the screening of [27]. The main difference is that the 2007 one calculates an effective coupling parameter based on the two ions and then treats it as a one-component plasma, while this version (2009) treats it fully as a multi-component plasma (which is significantly more expensive)
This includes the portion in the appendix that blends in the weak screening limit.
chabrier1998
:This implements the screening of [28] as well as the quantum corrections for strong screening according to screen5, which is suggested in the appendix of [29]. This screening is compatible with NSE calculations unlike
screen5
,chugunov2007
, andchugunov2009
. This screening is valid in the weak screening regime, , and strong screening regime, .
debye_huckel
:This is just the Debye-Hückel weak-screening limit from [27].
While it can be used on its own (by building with
SCREEN_METHOD=debye_huckel
, it is really meant to be used as a test to determine whether a more extensive screening approximation should be used. By settingscreening.enable_debye_huckel_skip
, we first compute this weak-screening approximation and then, if it is larger thanscreening.debye_huckel_skip_threshold
, the full screening factor is computed (using the method specified viaSCREEN_METHOD
).null
:This disables screening by always returning 1 for the screening enhancement factor.
Runtime Options
screening.enable_chabrier1998_quantum_corr = 1
in the input file enables an additional quantum correction term added to the screening factor whenSCREEN_METHOD=chabrier1998
. This is disabled by default sincechabrier1998
is often used along withUSE_NSE_NET=TRUE
, and the NSE solver doesn’t include quantum corrections.