EMC3-EIRENEによる
周辺プラズマ・不純物輸送モデリング
河村学思、小林政弘、庄司主、森崎友宏、増崎貴、田中宏彦、桑原竜弥1)、裏川杜彦2)、大野哲靖2)、
Yuhe Feng3)
核融合科学研究所
1) 名古屋大学エコトピア研究所
2) 名古屋大学大学院工学研究科
3) Max-Planck-Institut für Plasmaphysik, Greifswald Germany

1目次
 EMC3-EIRENEによる周辺プラズマモデリング LHDにおける周辺プラズマ解析
 タングステンダイバータ損耗再堆積解析
 直線装置プラズマモデリング2

Transport simulation of LHD peripheral plasmas
 Background and Motivations
 Understandings of plasma-neutralimpurity interactions and realizationof predictive simulation.
 Evaluation of different divertor
configuration; open and closed.

 Realization of three-dimensionaltransport simulation in ergodic andleg regions in the realistic geometry.
 Development of a three-dimensionaltransport code for LHD; EMC3peripheral
EIRENE
plamsa Validation by measurements.
(ergodic&leg)
 Comparisons of results for open/closed
divertor configurations.

connection length [m] Approachcore
regionf=0
3

EMC3-EIRENE code
 EMC3 solves fluid equations of flux tube plasma in SOL:
||  nv||       D  n   S p
||  mi nv || v||  || || v ||       mi v || D  n    v||   || p  S m

55||     i ||Ti  nTi v||         i n Ti  Ti D  n   k Te  Ti   S ei
22
55
||     e||Te  nTe v||         e n Te  Te D  n   k Te  Ti   S ee22 EMC3 can simulate plasma with ergodic magnetic field in LHDby solving them with the aid of Monte Carlo method.
leg plasma

particle transportenergy transport
impurity transport
neutral transport (EIRENE)[G. Kawamura et al., Contr. Plasma Phys. 54 (2014) 437]

vacuum region
Rax=3.6m

4Simulation box
 18-section (1/20 of the torus) is realized in simulation by using
the periodicity and assumption of up-down symmetry.
 Meshes are generated on poloidal planes every 0.25.

f=0

f=18
up-downsymmetry

up-downsymmetry

f=9

f=9
37planes

37 planes

mapping5

目次 EMC3-EIRENEによる周辺プラズマモデリング LHDにおける周辺プラズマ解析 タングステンダイバータ損耗再堆積解析
 直線装置プラズマモデリング6

Simulation conditions and examples
 Conditions and Assumptions
 Input power: 8MW
 Electron density: 21013/cm3 at LCFS Bohm condition is assumed at divertor plates Magnetic configuration: Rax=3.6m
 Perpendicular transport coefficient: Dperp=1 m2/s, perp=3 m2/s
 No neutral-pumping (100% recycled)

electron density[1017 – 21019 /m3]

parallel particle flux[a.u]

H2 molecule density[1017 – 1019 /m3]

7

Neutral gas transport Influence of the closed configuration on neutral-gas pressure Compression of hydrogen gas
 Simulation gives 17 times higher density under the dome structure.
 It agrees with experimental measurement (10~20 times)

openclosed

6 mPa

100 mPa
large recycling& compression

8

Scaling of neutral pressure with electron density
 A series of simulation were carried out.
 Constant input power: 8MW, ne at LCFS: 1, 2, 4,6, 81013/cm3.

 Dependence of neutral pressure on electron density.
 Simulation results has the same scaling law as the experimental
measurements independently of configurations.

Comparison of neutralpressure; measurementsof two discharges andsimulation results (solidlines: 500K H2 gas)

Te,div~35eV

closedopen
Te,div~45eV

Te,div~10eV
9Hydrogen recycling Recycling in open/closed configuration
 Closed configuration causes large particle source, i.e. large recycling.
 Large ionization leads to large energy loss.

 Contribution of divertor legs on recycling
 Major contribution in low-density
discharges, 1~41013/cm3
 Minor contribution in high-density
discharges, 6~81013/cm3nearly detachedf=9

Mean Te on divertor platesparticle
sourcelow-nehigh-ne10Impurity transport
 Impurity screening [M. Kobayashi et al., JNM 390 (2009) 325]
Friction force  v||  divertor platesThermal force  ||Te  coreLow-density discharge:ne(LCFS)=1x1013/cm3

accumulation

Hight-density discharge:ne(LCFS)=6x1013/cm3

screening11Force balance on impurity ions Friction force
vs. thermal force
thermal force dominant
toward the upstreamne(LCFS)=1x1013/cm3ne(LCFS)=2x1013/cm3ne(LCFS)=4x1013/cm3

friction force dominant
toward the downstreamne(LCFS)=6x1013/cm3ne(LCFS)=8x1013/cm3

12

Erosion rate of the divertor plates Assumptions for qualitative comparison
 Sputtering yield is fixed to 1%.
 Self sputtering is not included.
 Sputtered carbon is treated as an atom.

 Large recycling flux leads to large erosion.
 Modification to the closed configuration causes large erosion.
 Amount of the generation  Accumulation in the plasma

erosion due to ion flux
onto the surface

13Impurity retention in the plasma Total carbon amount, i.e. [C+]+[C2+]+…+[C6+] Leg regions

 Impurity retention increase according to the electron density.

 Ergodic region

 Screening effect of the plasma flow significantly reduces the retention in theergodic region.
 No influence of configurations is observed in the case of high-densitydischarges. ––– Why?

screeningeffect
Why they increase?
Why no difference?

14

目次
 EMC3-EIRENEによる周辺プラズマモデリング LHDにおける周辺プラズマ解析
 タングステンダイバータ損耗再堆積解析
 直線装置プラズマモデリング15

ERO code Monte Carlo simulation code of erosion and redeposition
 Background plasma distribution is fixed in simulation.
 Code modification to use EMC3-EIRENE results is on going.

16

Heat load pattern
 EMC3-EIRENE results of heat load on divertor tiles.
 Global estimation of erosion.
 Influence of plasma parameters on the pattern.

verticallyelongatedplane

horizontallyelongatedplaneverticallyelongated
plane

17

ERO simulation modeling Background plasma from EMC3-EIRENE How poloidal/toroidal plasma-distribution affects
deposition/erosion of W.
zz

yx

xz

W tilesx
electron density [1019 /m3]

simulation box of ERO18

W measurement in LHD
 A W-coated tile is installed.
 Other tiles are made of CFC.

W-deposition only inthe private sideerosion
dominant

W-coatedtiles
wetted areawide deposition
distribution[M. Tokitani]

19目次
 EMC3-EIRENEによる周辺プラズマモデリング LHDにおける周辺プラズマ解析
 タングステンダイバータ損耗再堆積解析
 直線装置プラズマモデリング20

Simulation modeling of linear device
 Linear devices for divertor
simulation and PWI

H. Tanaka, M. Kobayashi, G. Kawamura (NIFS)
N. Ohno, T. Kuwabara, M. Urakawa (Nagoya Univ.)
Y. Feng (Max-Planck IPP) GAMMA10, NAGDIS-II, MAGNUM-PSI, PISCES-B, PILOT-PSI, PSI-2,JULE-PSI etc.

 Divertor-plasma codes have been developed fortokamak/helical devices.
 2D: B2-EIRENE (SOLPS), EDGE2D-NIMBUS, UEDGE-DEGAS2
 3D: EMC3-EIRENE Simulation of linear device has been reported
but relatively new and challenging issue.
 B2-EIRENE Cylindrical plasma and device

B Advantage of EMC3-EIRNE code 3D geometry of plasma and walls can be simulated.
 Realistic geometry without cylindrical assumption.
21

NAGDIS-II in Nagoya University
 Linear Device for PSI and detachment
uniform magnetic field(< 0.25 T)
steady state DC discharge(hours)plasma parameterne<1020m-3, Te<10eVplasma
sourceN. Ohno, et al., Nucl.
Fusion 41 (2001) 1055.

22

Modeling of linear plasma Development is in progress.
18cm
5cm

main plasma region
B
VacuumTarget platesource region

Plasmavolume source

100cm

10cm

 Cylindrical mesh system.
 Wall and target plates with 3D shape V-shaped target in future Detachment studies
 NAGDIS-II PWI studies

 NAGDIS-II, GAMMA1023

Summary of the recent progress EMC3-EIRENE code and calculation mesh have beenextended to LHD with the closed divertor configuration.
 A validation by neutral gas pressure
 Influence of dome structure in closed configuration was analyzed.
 The scaling of neutral pressure to ne(LCFS) is in good agreement.

 Impurity screening effect in the open/closed configuration.
 Screening effect due to the flow is recovered in the ergodic region.
 Increase of impurity generation in the closed configuration.

 Application to ERO simulation
 Modeling of a linear device

24Future plans Neutral particles
 Pumping under the dome, wall pumping, gas-puffing
 Penetration to the core (TASK3D)

 Impurities Divertor configuration
 Transport related to screening

 PWI
 Local simulation at LHD W tile (ERO) Global erosion estimation

 Measurements
 Transport coefficient modeling from Thomson scattering 2D imaging of impurity radiation

 Detachment
 LHD (impurity seeding, RMP)
 NAGDIS-II (1D)25