Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 1
Compiled by Arne Kallenbach
Report from IPP Garching on work related to the EU PWI Task Force: Oct 2005- Oct 2006
Max-Planck-Institut für Plasmaphysik
With contributions from W. Bohmeyer, A. Chankin, D. Coster, R. Dux, T. Eich, A. Herrmann, C. Hopf, W. Jacob, A. Kallenbach, C. Linsmeier, M. Mayer, H.-W. Müller, R. Neu, R. Pugno,V. Rohde, J. Roth, K.Schmid,T. Schwarz-Selinger
*
* + Berlin +JET+ PISCES-B
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 2
• Chemical erosion (see also talk S. Brezinsek) • Tungsten tokamak (see also talk R. Neu)• Decay and migration of carbon in ASDEX Upgrade• ELM power deposition characteristics in outer midplane• ELM in-out divertor asymmetry• He retention in W-coated surfaces• Chemical erosion by N ions and simultaneous neutral impact (non-scavenging)• Be-W alloying• PISCES-B measurements on D retention and pulsed power with Be seeding• Edge modelling with B2.5 (AUG) and DIVIMP (ITER)• SOL transport and parallel flow
Topics investigated in IPP from Nov 2005 – Oct 2006
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 3
Tungsten erosion at LFS limiters on ASDEX UpgradeR. Dux
ICRH: strongest W erosion by sheath acceleration
NBI: Loss of ripple trapped fast ions identified as dominant W sputtering mechanism by Monte Carlo simulations of pitch angle dependence
for both ICRH and NI, W limiter source dominated by ELMsabout 70 % of time-averaged sputtered W during ELMs
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 4
Tungsten erosion at LFS limiters on ASDEX Upgrade:ICRH sheath potential from measured W yield
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 5
Tungsten erosion at LFS limiters on ASDEX Upgrade:pitch angle dependence form ripple loss of fast NBI ions
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 6
Tungsten erosion at LFS limiters on ASDEX UpgradeEffect of type-I ELMs
x 4
x 9
x 5
x 40
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 7
Structure and radial decay of ELM filaments in the ompA. Herrmann, A. Schmid
energy carried predominantly by ions
dedicated diagnostic setup
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 8
Decay of carbon concentration with increasing W PFC coatingFraction in ASDEX Upgrade A. Kallenbach
slow decay of the carbon concentration with increasing W surface fraction net divertor source becomes important with diminishing C PFC area
scatter due to boronisations,Exp.imerfections, calibrations,…
experiment migration modelling
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 9
Divertor becomes important net carbon source with W PFCsrecovery of C after boronisation allows to estimate net source
net outer divertorC source:1.5e19 ions/s
LFS limiter fluxes and C concentration closely coupled heat shield lags behind (1 ML C on heat shield 30 plasma C content)
C part of divertornot coated by boron
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 10
Erosion of tungsten in the outer divertor of JET• Tungsten erosion was determined with a marker stripe from 2001-2004• Large erosion at outer strike point, outer baffle and apron• Erosion at strike point >> 2.4 µm• Inhomogeneous erosion due to surface roughness
Erosion of Be, C, Ni and W at the inner vessel wall of JET• Erosion was determined with long term samples from 2001-2004• Whole inner vessel wall is erosion dominated, erosion of C is about 10 times larger than erosion of Be
Erosion of carbon and tungsten in the outer divertor of ASDEX Upgrade• Carbon and tungsten erosion were determined with marker stripes from 2004-5 • Largest erosion at strike points, both for carbon and tungsten• Erosion of carbon 10-20 times larger than erosion of tungsten• 2.8 g C eroded during the campaign
Erosion measurements with markers and long term samplesMatej Mayer
factor 3 larger than migration modeluncertainties, direct losses to inner div
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 11
Deposition in inner divertorMatej Mayer
2002 – 20034800 s
2004 – 20053050 s
2005 – 20062900 s
6A
6B
5
4
9C
• Decrease of C-deposition on divertor tiles by factor 7
from 2004/2005 to 2005/2006
• Decrease of C-deposition below roof baffle by factor 10
from 2004/2005 to 2005/2006
Outboard limiters are main carbon source
0 200 400 6000
2
4
6
s-coordinate [mm]
B + C C
9C456B6A
Dep
osi
tio
n o
f B
+C
[10
19 a
t./c
m2]
0 200 400 6000
2
4
6
s-coordinate [mm]
B + C C
9C456B6A
Dep
osi
tio
n o
f B
+C
[10
19 a
t./c
m2]
0 200 400 6000
2
4
6
s-coordinate [mm]
B + C C
9C456B6A
Dep
osi
tio
n o
f B
+C
[10
19 a
t./c
m2]
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 12
SOL plasma flow in upper-SN H-mode at outer midplaneHans-Werner Müller
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 13
Statements on plasma flowH.-W.Müller
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 14
Shot resolved gas balance in ASDEX UpgradeVolker Rohde
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 15
High He plasma concentrations encountered in AUG since the transition from a C to a W first wall
He plasma concentration linked to He glow duration and number of discharges since last boronization
Dedicated laboratory experiments show:
W retains ~10 times more He compared to C or boronization layers
He release due to plasma load similar for W and C
Thermal release starts at 400K for both C and W
High He plasma concentrations in AUG are due to higher retention of He in W compared to C – effect expected to vanish at higher wall temp.
Retained He in different C and W materials (NRA)
1016 1017 1018 10191013
1014
1015
1016
1017
1018
600eV 3He FG PVD-W
Pyro-Perp Pyro-Par Boronization
Ret
ain
ed 3
He
(cm
-2)
3He Fluence (cm-2)
200eV 3He FG PVD-W W-Solid
Implications of Tungsten on Helium Gas RecyclingKlaus Schmid
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 16
0 -50 -100 -150 -200-0.3
-0.2
-0.1
0.0
0.1
0.2
30%
depo
sitio
n /
eros
ion
rate
(nm
/s)
bias voltage (V)
CH4
N2 / H2
N2 / CH4
H2
30%
increase of erosion rate with bias for H2/N2 and changeover from deposition to erosion for CH4/N2
plasmas at higher ion energies can only be explained by surface effects
evidence for chemical sputtering
Because of the increased erosion due to chemical sputtering the present data base does not allow to recommend N2 admixture to divertor plasmas with carbon PFC’s.
Work performed under the EFDA Task TW3-TPP-SCAVOPFinal Report available upon request ([email protected])
But, the high chemical sputtering yield of carbon films in N2/H2 mixtures make them interesting for removal of redeposited layers.
Planned work: investigation of possible scavenging action of N in laboratory plasmas using cavity probes
NITROGEN PUFFING into the DIVERTOR: RESULTS from LABORATORY EXPERIMENTS with remote ECR in H2, CH4, N2 mixtures
© Thomas Schwarz-Selinger, October 2006
T. Schwarz-Selinger, W. Jacob
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 17
Mixed materials formation: Be-W alloying
W on Be • stable Be12W above 1000 K
Tm < 2000 K no W in surface zone
Be on W (ITER divertor!)< 800 K• Be metal layer deposition
Tm ~1560 K
> 1000 K• Be2W surface alloy only (~nm)
• no bulk diffusion, sublimation faster Tm ~2500 K
Future work• Reactivity of Be/W alloys with carbon• Formation of ternary surface layers• Reactivity of different surface layers
with atomic oxygen
Ch. Linsmeier, A. Wiltner, F. Kost
depth profile
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 18
Power pulsing experiments in PISCES-BR. Pugno, PISCES-B team under EFDA contract TW5-TPP-CARWBER
• A transitory positive voltage biasing system has been installed on PISCES-B to simulate the heat pulses associated with ELMs.
• A new infra-red diagnostic system has been installed to measure the target surface temperature during the heat pulses.
• From visible spectroscopy and mass loss measurements, the formation time of the Be2C protective coating on graphite samples exposed to beryllium-seeded deuterium plasmas, is reduced in presence of power transients.
• The deuterium retention is increased in presence of power transients for both pure deuterium (+30%) and Be-seeded plasmas (+60%).
• The infra-red measurements evidence a change in emitting area due to a surface morphology modification during plasma exposure (both for pure carbon and Be2C surfaces) in agreement with previous observations by SEM electron micrographs.
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 19
R. Pugno, PISCES-B team
• Saturation of the surface is observed in CFC target for fluences higher than 1e26 ion/m2 and target temperature of 1100 K.
• No change in deuterium retention in CFC is observed between pure deuterium plasmas and Be seeded plasmas in that conditions.
• Earlier onset of thermal desorption is observed for mixed material surface i.e. after exposure to Be seeded plasmas as already observed in PISCES-B
• The scaling law for the suppression time of chemical erosion in Be seeded plasmas obtained with FGG target seems to be valid also for CFC target.
Work done at PISCES-B in the frame of the EFDA contract TW5-TPP-CARWBER
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 20
• In addition to other activities, the members of the edge group took part in the Edge Modelling Campaign at JET
– Coster
• Edge transport Code-Code Verification/Validation/Benchmarking – Chankin
• EDGE2D runs: adding drifts to JET H-mode pulses
– Konz
• Simulation of disruption thermal quenches with B2 SOLPS – Wischmeier
• SOLPS5 modelling of ohmic plasmas with C13 injection at the top of the
machine
SOLPS work, development and benchmarking D. Coster, A.Chankin, C. Konz, M. Wischmeier
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 21
Detailed comparison between B2.5-EIRENE (SOLPS) edge modelling and experiment shows that the code overestimates plasma density and underestimated electron temperature in the divertor, especially near the strike point position.
The example shown above demonstrates a large discrepancy between simulated and experimental Ha radiation profiles, which is the consequence of the overestimate of the plasma density in the divertor.
Dicrepancy in code-experiment comparisons
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 22
code-code comparison• Phase I: pure D, no drifts• Phase II: pure D, drifts• Phase III: D+C, no drifts• Phase IV: D+C, drifts
– SOLPS-EDGE2D/NIMBUS • Phase I completed successfully (reported on at PSI
2004)• Phases II and III in progress
– SOLPS-UEDGE• Phase I underway• Phase II expected to start soon
• Additional code-experiment– JET: SOLPS-EDGE2D/NIMBUS– AUG/D3D: SOLPS-UEDGE
EDGE2D D+C
EDGE2D D
SOLPSD+C
SOLPS
EDGE2D
Edge code benchmarking / ITPA activity
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 23
• 2D background (ne, Te, Ti, …) written as MDSplus tree by SOLPS (IPP-Garching) [modelled by Chankin]
• provides input to ASCOT Due to open field lines, special care must be taken with the Monte Carlo collisions
• Planned: output of ASCOT to be saved to a MDSplus tree
• ITPA standard pedestal MDSplus tree created based on AUG shot 17151 (provides the equilibrium data)
• ASCOT:
• T. Kurki-Suonio, L. Aho-Mantila, J. Heikkinen, V. Hynönen, T. Kiviniemi, A. Salmi, S. Sipilä, V. Tulkki
Distribution of electrons reaching outer target
AssociationEuratom–Tekes
Using MDSplus for SOLPS to ASCOT
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 24
Divertor in-out power asymmetry during ELMs dependson ion grad-B drift direction T. Eich
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 25
In-out power asymmetry connected to charge flow asymmetrycharge sign suggests ions to carry excess power
AUG upper SN
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 26
TW4-TPP-TRIDEP
Beginning of the project 08/2004intermediate report 12/2004
(end 12/2005) prolongated 06 / 2006 *Main topics:1. Analysis of Cx Hy mixture produced by chemical erosion2. Study of the influence of the target temperature 3. Influence of impurities on chemical erosion IR absorption, QMS, cavities
4. Determination of the balance between deposition and erosion for areas not exposed directly to the plasma ( ITER pumping duct). Experiments and ERO-Modelling
density of atomic hydrogenimprovement of experimental data for modelling (spectroscopic data, cavities,...)
* delayed start of the experiments (reason: no permission to use hydrogen)-
Humboldt Universität zu Berlin W. Bohmeyer
Report IPP Garching @ EU Task Force PWI Meeting, Arne Kallenbach, Ljubljana Nov 13-15 2006 27
Humboldt Uinversität zu Berlin
Ne=3*1017 m-3 Ne=2*1018 m-3Ne=1017 m-3
1.Clear shift from global to local decomposition with increasing el.-density2.Decomposition and excitation length is not in agreement with atomic data
2D-CH-emission at 430 nm
CH4 injection into a He-Plasma
7 cm
nozzle