dependent on the magnetic configuration and for the case of double null configuration (which effectively disconnects the inboard and outboard sides of the torus due to
the X-point effects), plasma transport and the magnitude of the turbulent fluctuations
on the inboard side become much weaker than on the outboard one (see Fig. 7.25).
Finally, it was found experimentally that the SOL midplane width, and, therefore,
midplane plasma transport, can also strongly depend on divertor conditions and for
the detached divertor case, the width is about two times larger than for the attached
one (see Fig. 7.26). We note that so far there is no clear theoretical explanation of
such an effect, although there is an indication that neutrals, density of which strongly
increases in the detached divertor regime, can play some role in the modification
[103] and even enhancement of plasma transport, in particular, due to reduction of
the shear of the plasma flow [104].
Thus, taking into account so many different factors which can alter anomalous
edge plasma transport, we can conclude that the only plausible way to estimate
anomalous transport with some confidence is to use 3D edge plasma turbulent codes
such as BOUT++ [105], XGC1 [106], GENE [107], Gkeyll [108], JOREK [109] and
some others. These codes are based on different plasma models (e.g. BOUT++ and
JOREK codes are based, respectively, on the fluid and MHD plasma equations,
eV/m 3
R–R SEP (cm)
10
19
10
3
USN
DN
LSN
δn
10
4
10
5
10
3
δn
10
4
10
5
10
20
10
21
eV/m 3
10
19
10
20
10
21
0.0 0.2 0.4 0.6 0.8 1.0 1.2
R–R SEP (cm)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
R–R SEP (cm)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
R–R SEP (cm)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Inner Midplane Fluctuation Levels
Outer Midplane Fluctuation Levels
Inner Midplane Plasma Pressure
(a)
(b)
(c)
(d)
Outer Midplane Plasma Pressure
Fig. 7.25 Distribution of plasma pressure and fluctuation level at the inner and outer midplanes of
the SOL for upper- and low-single null (USN, LSN) and double-null (DN) magnetic configurations.
(Reproduced with permission from [101], © IAEA 2004)
182
7 Anomalous Cross-Field Transport in Edge Plasma
the X-point effects), plasma transport and the magnitude of the turbulent fluctuations
on the inboard side become much weaker than on the outboard one (see Fig. 7.25).
Finally, it was found experimentally that the SOL midplane width, and, therefore,
midplane plasma transport, can also strongly depend on divertor conditions and for
the detached divertor case, the width is about two times larger than for the attached
one (see Fig. 7.26). We note that so far there is no clear theoretical explanation of
such an effect, although there is an indication that neutrals, density of which strongly
increases in the detached divertor regime, can play some role in the modification
[103] and even enhancement of plasma transport, in particular, due to reduction of
the shear of the plasma flow [104].
Thus, taking into account so many different factors which can alter anomalous
edge plasma transport, we can conclude that the only plausible way to estimate
anomalous transport with some confidence is to use 3D edge plasma turbulent codes
such as BOUT++ [105], XGC1 [106], GENE [107], Gkeyll [108], JOREK [109] and
some others. These codes are based on different plasma models (e.g. BOUT++ and
JOREK codes are based, respectively, on the fluid and MHD plasma equations,
eV/m 3
R–R SEP (cm)
10
19
10
3
USN
DN
LSN
δn
10
4
10
5
10
3
δn
10
4
10
5
10
20
10
21
eV/m 3
10
19
10
20
10
21
0.0 0.2 0.4 0.6 0.8 1.0 1.2
R–R SEP (cm)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
R–R SEP (cm)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
R–R SEP (cm)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Inner Midplane Fluctuation Levels
Outer Midplane Fluctuation Levels
Inner Midplane Plasma Pressure
(a)
(b)
(c)
(d)
Outer Midplane Plasma Pressure
Fig. 7.25 Distribution of plasma pressure and fluctuation level at the inner and outer midplanes of
the SOL for upper- and low-single null (USN, LSN) and double-null (DN) magnetic configurations.
(Reproduced with permission from [101], © IAEA 2004)
182
7 Anomalous Cross-Field Transport in Edge Plasma