laboratorio nacional de fusión asociación euratom-ciemat chemical erosion research at ciemat...

Laboratorio Nacional de FusiónAsociación EURATOM-CIEMAT

Chemical Erosion Research at CIEMAT Chemical Erosion Research at CIEMAT

(Madrid)(Madrid)

presented by F. Tabarpresented by F. Tabarésés

Laboratorio Nacional de Fusión por Confinamiento Laboratorio Nacional de Fusión por Confinamiento

MagnéticoMagnético

Asociación EURATOM/CIEMAT. Madrid.Spain Asociación EURATOM/CIEMAT. Madrid.Spain

SEWG Meeting JET 23March. 2007SEWG Meeting JET 23March. 2007


OUTLINOUTLINEE

Carbon contamination studies in TJ-II

Photon yields

Material erosion

Laboratory studies of Chemical Erosion

Carbon contamination studies in TJ-II

Photon yields

Material erosion

Laboratory studies of Chemical Erosion



PFC in TJ-IIPFC in TJ-II

-TJ-II Stellarator (R=1.5 m, a <0.23 m, B=1T)-Boronisation at beginning of the exp. campaign 4 gr o-carborane in He GD --> B/C ~ 50nm+ He/Ne GD 30 min at beginning of experimental day.-Two Graphite Limiters, movable, instrumented.-ECRH plasmas (up 600 kW): good impurity control (Z~1) and acceptable density control.-NBI plasmas (400 kW): loss of density control.

In progress:- Lithium coating in 2007 campaign- Upgrade of heating systems (2 NBI)

-TJ-II Stellarator (R=1.5 m, a <0.23 m, B=1T)-Boronisation at beginning of the exp. campaign 4 gr o-carborane in He GD --> B/C ~ 50nm+ He/Ne GD 30 min at beginning of experimental day.-Two Graphite Limiters, movable, instrumented.-ECRH plasmas (up 600 kW): good impurity control (Z~1) and acceptable density control.-NBI plasmas (400 kW): loss of density control.

In progress:- Lithium coating in 2007 campaign- Upgrade of heating systems (2 NBI)



Edge Edge DiagnosticsDiagnostics

0

5 1017

1 1018

1.5 1018

2 1018

2.5 1018

31 32 33 34 35 36

13576 (fondo:13577)

densidaddensidaddensidaddensidaddensidad

dens

idad

z (cm)

1050 ms1100 ms1150 ms1200 ms1250 ms

100_44_64LIMC:-0.362

0

20

40

60

80

100

120

0,6 0,7 0,8 0,9 1 1,1

#11413

Te_corrected

Te

(eV

)

Li BeamLi Beam Supersonic He BeamSupersonic He Beam

+Reflectrometer, Langmuir Probes Limiter, Press gauges, RGA….+Reflectrometer, Langmuir Probes Limiter, Press gauges, RGA….



CH4 and C2H4 have been injected at the plasma edge using a mobile, instrumented limiter, producing local C-films.Identical(reference)limiter at 180 deg. (PSI-2006 to appear J. Nucl. Mat, PSI 04, EPS 05….)

CH4 and C2H4 have been injected at the plasma edge using a mobile, instrumented limiter, producing local C-films.Identical(reference)limiter at 180 deg. (PSI-2006 to appear J. Nucl. Mat, PSI 04, EPS 05….)

C2H4 presents lower fuellingefficiency than H2

C2H4 presents lower fuellingefficiency than H2

C:H film formation and C:H film formation and erosionerosion


- C2H4 injection producedC-layers with high H content

(from particle balance)

-No difference between erosion ofmethane/ethylene layers

- Physical sputtering dominant for carbon erosion in TJ-II

- C2H4 injection producedC-layers with high H content

(from particle balance)

-No difference between erosion ofmethane/ethylene layers

- Physical sputtering dominant for carbon erosion in TJ-II-0.2 0 0.2

-0.36

-0.24

-0.12

0

0.12

R-R0 (m)

Z (

m)

CH emission

gass-puff hole

H limiter



Limiter insertion (Limiter C)Pulses of 15 ms during radial scanLimiter A at LCFSFrom ρ=1 to ρ ~0.8 (25 mm inside LCFS (<13575)From 13576 to 13582 the reverse. Lim. A was inserted while C remain at the LCFSa) and b) before pulsec) fuelling effect of ethylene


Erosion of local C-layersErosion of local C-layers

Comparison of erosion of the deposited films by plasmasfed by local puffing or by distant puffingComparison of erosion of the deposited films by plasmasfed by local puffing or by distant puffing

Global contamination ofthe full wallGlobal contamination ofthe full wall

Higher erosion by plasmasfeed away for the limiterHigher erosion by plasmasfeed away for the limiter

0

1

2

3

4

5Summary of ethylene injection/erosion

CHC

Inte

ns

ity

(a

.u)

Clean limiterz=-10 Puff z=-10 Plasma z=-15 Puff z=-15Plasma

CHinject.

Reference: z=-10Puff. H2 in cleanlimiter

0

2

4

6

8

10

15280 15285 15290 15295 15300 15305 15310 15315

Inte

nsi

ty (

a.u

)

Shot#

CH/ne

CV/ne



ethylene methane hydrogen Electron /molecule 16 10 2 Molec /pulse 1.21018 1.2 1018 5 1018 Density increase /pulse (total electrons)

1.5 1018 1.4.1018 1.8 1018

H /molecule 4 4 2 H.increase/ pulse(a.u.)

1.4 2.2 2.6

CH/ H (a.u.) 1.8 0.6 1.0 (limiter)


8 eV14 eV20 eV

For one electron collisional process:

CH4 + e CH3+prod (Eth1) CH*+prod (Eth 2)

-D/XB = A. exp(-Eth/kT)

For one electron collisional process:

CH4 + e CH3+prod (Eth1) CH*+prod (Eth 2)

-D/XB = A. exp(-Eth/kT)

EthEth


EIRENE data BasisEIRENE data Basis

Constant D/XB ??Constant D/XB ??


Verification of data basis required!Verification of data basis required!


Afterglow Afterglow EmissionEmission

EthyleneEthylene

MethaneMethane HydrogenHydrogen

- Fast decay of Te( 1ms)- Detrapping of injected hydrocarbon ??

- Fast decay of Te( 1ms)- Detrapping of injected hydrocarbon ??

Te dep. of D/XB at low Te??Te dep. of D/XB at low Te??NeCHHaECE

NeCHHaECE


Doped-C studies Doped-C studies (2007)(2007)

CD,CCD,C22, He beam, He beamemissionemission

-Chemical sputtering of doped graphite (metal carbides)

(in collaboration C. Garcia-Rosales)

TJ-II NBI Plasma

C dopedC

Methane/He injectionHolder:rotable, radial displacement


: Nanometric carbides, Ti, Si,.. : Nanometric carbides, Ti, Si,..


Cryogenic Trap Assisted Mass Spectrometry (CTAMS)Cryogenic Trap Assisted Mass Spectrometry (CTAMS)

0

0.2

0.4

0.6

0.8

1

100 150 200 250

Vapour Pressures at Low T

P CNHP NH3P H2OP C2H2

P v

ap. (

Pa)

T (K)

1-pumping system 7-diaphragm2-B-A manometer 8-mass spectr.3-Cap. Manometer 9-optic port4-cutting valve 10-manipulator5-gas inlet 11-cryogenic trap6-anode 12-float V measure

1-pumping system 7-diaphragm2-B-A manometer 8-mass spectr.3-Cap. Manometer 9-optic port4-cutting valve 10-manipulator5-gas inlet 11-cryogenic trap6-anode 12-float V measure

Vapor pressure vs. T for different species

Vapor pressure vs. T for different species

J.A. Ferreira et al.PFMC-11. Griefswald 200621 IAEA. Chengdu 2006Submitted: J.Vac.Sci.Tech.Chem Vap. Dep.

J.A. Ferreira et al.PFMC-11. Griefswald 200621 IAEA. Chengdu 2006Submitted: J.Vac.Sci.Tech.Chem Vap. Dep.

CTAMSCTAMS


HH22:CH:CH44 plasma plasma

500 600 700 800 900 1000 1100 1200 1300 1400 15000

0.5

1

1.5

2

2.5

3x 10

-7

2151618252627282930

Liquid N2

Minor masses during DC plasma glow discharge

Conditions:Conditions:

Total Pressure

8 mTorr

%CH4 ~20%

I=100 mA

V=560 V

C2H2ΔM25/ ΔM26=0,2

Other hydrocarbons?? C2 & C3


Detection of trace C3,C4… hydrocarbons in the 10 ppm range!

Detection of trace C3,C4… hydrocarbons in the 10 ppm range!

Warming up of the trap (~30mK/s)Warming up of the trap (~30mK/s)

Information presently available for several systems, e.g. Ar, N2,H2 sputtering on C:H films

Information presently available for several systems, e.g. Ar, N2,H2 sputtering on C:H films

Implementation in fusion devices? Implementation in fusion devices?

Release of condensateRelease of condensate


Equilibrium pressures, C1-C4 Equilibrium pressures, C1-C4 HCsHCs

SpeciesSpecies T (K)P=133Pa

T (K)P=133Pa

T (K)P=0.1Pa

T (K)P=0.1Pa

SpeciesSpecies T (K)P=133.3Pa

T (K)P=133.3Pa

T (K)P=0.1Pa

T (K)P=0.1Pa

MethaneMethane 65,0265,02 44,8444,84 1,3-Butadiene (C4H6)1,3-Butadiene (C4H6) 170,3170,3 126,9126,9

Ethylene (C2H4)Ethylene (C2H4) 104,8104,8 77,577,5 n-Butane (C4H10)

n-Butane (C4H10) 171,6171,6 125,1125,1

Ethane (C2H6)

Ethane (C2H6)

113,6113,6 81,781,7 trans-Butene (C4H8)trans-Butene (C4H8) 173,7173,7 128,6128,6

Acetylene (C2H2)Acetylene (C2H2) 130,2130,2 90,190,1 2-Methyl-1-Propene

(C4H8)

2-Methyl-1-Propene (C4H8)

168,0168,0 129,4129,4

Propylene (C3H6)Propylene (C3H6) 141,2141,2 104,7104,7 cis-Butene (C4H8)

cis-Butene (C4H8) 176,7176,7 132,3132,3

Carbon dioxide(CO2)

Carbon dioxide(CO2)

138,8138,8 106,1106,1 1-Butyne (C4H6)1-Butyne (C4H6) 180,6180,6 136,2136,2

Propane (C3H8)Propane (C3H8) 144,2144,2 106,1106,1 Butenyne (C4H4)

Butenyne (C4H4) 179,9179,9 136,9136,9

Propyne (C3H4)Propyne (C3H4) 162,1162,1 113,9113,9 1,2-Butadiene (C4H6)

1,2-Butadiene (C4H6) 184,1184,1 138,8138,8

1-Butene (C4H8)1-Butene (C4H8) 168,3168,3 115,5115,5 2-Butyne (C4H6)

2-Butyne (C4H6) 200,1200,1 138,9* 138,9*

Propadiene (C3H4)Propadiene (C3H4) 152,5152,5 116,2116,2 Butadiyne (C4H2)

Butadiyne (C4H2) 190,6190,6 158,3158,3

Isobutane (C4H10)Isobutane (C4H10) 163,9163,9 121,5121,5 Water (H2O)Water (H2O) 255,8255,8 199199


CTAMS resultsCTAMS results

Ar/H2 (20:80) plasmaAr/H2 (20:80) plasma

N2/H2 (20:80) plasmaN2/H2 (20:80) plasma

condensationcondensation releaserelease

Main product:acetylene

Main product:acetylene

Main product:HCN

Main product:HCN


300 400 500 600 700 800 900 10000

0.5

1

1.5x 10

-7

Time (s)

Partia

l pre

ssure

(A

.U.)

H2/Ar plasma

1516252627282918

0 500 1000 1500 2000 2500 3000 3500

1

2

3

4

5

6

7

8

9

x 10-6

Time (s)

Partia

l pre

ssure

(A.U

.)

H2/Ar on a-C:H desorption

252627282918


Future PlansFuture Plans


a) Redeposited layers by CxHy injection: - Erosion yield by H/He plasmas b) Photon yields -Afterglow experiments -Supersonic beam injection: He seedingc) Doped Graphites - Effect of H content and dopingd) Mechanism studies - CTAMS studies in technical plasmas

a) Redeposited layers by CxHy injection: - Erosion yield by H/He plasmas b) Photon yields -Afterglow experiments -Supersonic beam injection: He seedingc) Doped Graphites - Effect of H content and dopingd) Mechanism studies - CTAMS studies in technical plasmas

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