1 Unitá Tecnica Fusione, C.R. ENEA Frascati, CP65, 00044 Frascati, Italy2 Consorzio RFX, Corso Stati Uniti 4 - 35127 Padova, Italy3 Consorzio CREATE, Università di Napoli Federico II, Via Claudio 21, 80125, Napoli,Italy

Analysis of the SOL plasma in DEMO baseline scenario with EDGE2D/EIRENE code

Introduction

G. Rubino1,2, R. Ambrosino3, G. Calabrò1, V. Pericoli Ridolfini3, B. Viola1

Baseline scenario

One of the most critical point in view of future fusion reactors is the power exhaust issue. This work presents a preliminary scoping study on DEMO by considering the baseline scenario and a pure Deuterium plasma. The numerical simulation has been performed by means of EDGE2D/EIRENE, a numerical tools developed at JET [1]. The results are also compared to the one obtained with a different tool, TECXY [2], and a quite good matching has been observed, especially in the global quantities.

Mesh generation and main simulation parameters

Conclusions and perspectives● This preliminary analysis enphasizes the power exhaust issue in DEMO baseline scenario, which is far away

from the achievement of detachment condition in pure D plasma● Due to the simple geometry adopted a benchmark with previous results obtained with TECXY has been done,

which highlights that the neutral processes play a minor role in the radiation power losses ● A more accurate analysis is needed. First of all, the real geometry should be taken into account.● Subsequently the injection of impurities should be considered evaluating their role in the volume power losses● The effect of a change of the divertor magnetic configuration, as in case of Snowflake or XD divertor, can be

studied to evaluate the possible benefit which could arise from geometrical factor. However EDGE2D is able to handle only Single Null magnetic configurations

● The effect on the volumetric power losses induced by the advanced configuration scenario should be investigate since the mitigation could be larger than expected, as seen in other works [4],[5]

Table 2. Plasma parameters used the EDGE2D simulations.

[1]R. Simonini, et al., Contrib. Plasma Phys. 34 (2/3) (1994) 368-373.[2]R. Zagórski, H. Gerhauser, Phys. Scr. 70 (Part 2/3) (2004) 173[3]Private Communication [4]B. Viola et al., TECXY modelling studies of alternative EAST magnetic configurations, 40th EPS Conference on Plasma Physics[5]V. Pericoli Ridolfini et al., J. Nucl. Mater 438 (2013) S414-S417

Results

EDGE2D and TECXY comparison

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This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commision.

Machine parametersMajor radius (R

0) 8.77 m

Aspect ratio (A) 3.1

Elongation (κ95

) 1.55

Volume (V) 2214 m3

Magnetic field on axis (B0) 5.8 T

Plasma current (IP) 20.3 MA

Plasma parametrsNormalized beta (β

N) 2.6

Temperature on axis/average (T

e0,i0 / <T

e,i>)

27.0 / 13.5 keV

Density on axis/ average(n

e0 / <n

e>)

11 / 8.7 x 1019 m-3

Power fluxesFusion power (P

fus) 2023 MW

α-heating (Pα) 404 MW

Aux. Heating (Paux

) 51 MW

Effective heting power (Pheat,eff

) 301 MW

Line radiation in the core (P

rad,core)

151 MW

Power crossing the separatrix (P

sep)

149 MW

Table 1. Main parameters of the machine, plasma and power fluxes in DEMO baseline scenario [3].

Fig. 1. Computational mesh for the EDGE2D simulation (left), divertor detail (right on the top) and OMP detail (right on the bottom).

● Single null divertor (SD) with tungsten divertor target

● H-mode confinement● Relative low normalized beta● Modest improvement of the

confinement, i.e. H =1.1● Density in the core slightly

beyond the Greenwald limit considering a peaked density profile

● Power load onto the divertotor target should be smaller than 5 MW/ m2

● Operation condition typical of the detachment regime over the full divertor.

● A pure Deuterium plasma has been considered, though a complete description has to consider the impurities injection

● Control mechanism based on the OMP density through a wall puffing, which also take into account the recycle of the ions in the divertor region

● Equal distributed power entering the SOL between ions and electrons

● As a first approximation constant profiles of the diffusion coefficients, has been assumed both for particle (D

perp) and heat

(χi =χ

e)

● A density scan has been performed in order to evaluate the effect of the density itself

● Mesh obtained in GRID2D● The divertor target has been chosen perpendicular to the separatrix due to

numerical noise encountered in the EDGE2D simulations● Spatial resolution of the mesh at the outer midplane, about 1,2 mm, compatible

with the power e-folding length λq,OMP

= 3-5 mm

Fig. 2. EIRENE mesh with the pump (red line) and the puffing (green line) details.

ne,LCMS

Dperp

χi =χ

eP

SEP,iP

SEP,e

2.7-3.0-3.4-3.5 x 1019 m-3 0.32 m2/s 0.12 m2/s 75 MW 75 MW

-200 -150 -100 -50 0 50 100 150 200 250 3000

20

40

60

80

100

120

140

160

180 2,7 10 1̂9 m -̂3

3,0 10 1̂9 m -̂3

3,4 10 1̂9 m -̂3

3,5 10 1̂9 m -̂3

Distance from strike point [mm]

n_

e [1

0^1

9 m

^-3

]

-200 -150 -100 -50 0 50 100 150 200 250 3000

20

40

60

80

100

120

140

3,5 10 1̂9 m -̂3

3,4 10 1̂9 m -̂3

3,0 10 1̂9 m -̂3

2,7 10 1̂9 m -̂3

Distance from strike point [mm]

T_

e [e

V]

-200 -150 -100 -50 0 50 100 150 200 250 3000

20

40

60

80

100

120

3,5 10 1̂9 m -̂3

3,4 10 1̂9 m -̂3

3,0 10 1̂9 m -̂3

2,7 10 1̂9 m -̂3

Distance from strike point [mm]

P [

MW

/m^2

]

0 5 10 15 20 25 30 35 40 45 50 550

0,2

0,4

0,6

0,8

1

1,2

Y =n_e * T_e 1̂.5

3,5 10 1̂9 m -̂3 1/e

R-Rsep (mm)

Y/Y

0

Fig. 4. Profiles of electron density (left on the top), electron temperature (right on the top) and power load on the outer target (left on the bottom) for the different values of the OMP control density. The power load corrected with the poloidal tilt of the target is also shown (right on the bottom).

Fig. 3. Normalized power flow evaluated at the OMP considering P

flow∝ n

eT

e

3/2.

-600 -400 -200 0 200 400 600 8000

102030405060708090

100

n_e_LCMS = 3,5x10 1̂9 m -̂3

Psin(θ)

PERP.

Distance from strike point [mm]

P [

MW

/m^2

]

0 50 100 150 200 250 300 350 4000

20

40

60

80

100

120

n_e_LCMS = 2.7 10 1̂9 m -̂3

EDGE2D TECXY

Distance from strike point [mm]

P [

MW

/m^2

]

2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5 3.60

20

40

60

80

100

120

140

TECXY EDGE2D

n_e_LCMS [10^19 m^-3]

P_

tot

[MW

]

2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5 3.60

20

40

60

80

100

120

EDGE2D TECXY

n_e_LCMS [10^19 m^-3]

P_

peak

[M

W/m

^2]

Fig. 5. Power load onto the outer target obtained with EDGE2D (blue line) and TECXY (red line).

● TECXY is a simpler and fatser code compared to EDGE2D

● Much simpler model for the neutral description (analytical) [2]

● It does not take into account the real geometry (always a perpendicular target, similar to our calculation) and the private region [2]

● The power load profiles match very well and the higher peak in TECXY can be explained considering the absence of the Private region

● The gloabal quantities are very close in terms of total power deposited. The differences can be explained considering the different hypotesis used for the neutral particle description

● Also the peaks power are very simlar● The coherence of the results highlights the small effect of the neutral Dueterium physics processes.● The fraction of dissipated power is not high enough to macth the desired divertor condition (less

than 1/3 of the power is radiated within the SOL volume)

giulio.rubino@igi.cnr.it Joint Doctorate and Network in Fusion Science and Engineering