1/18 TORE SUPRA Association Euratom-Cea B. Pégourié – SEWG Gaz Balance & Fuel Retention - JET – July 22-23, 2008 Tore Supra – repetitive long discharges.

1/18

TORE SUPRA

AssociationEuratom-Cea

B. Pégourié – SEWG “Gaz Balance & Fuel Retention” - JET – July 22-23, 2008

Tore Supra – repetitive long discharges.Tore Supra – repetitive long discharges.

B. Pégourié, C. Brosset, E. Tsitrone, A. Beauté, S. Brémond, J. Bucalossi, S. Carpentier,Y. Corre, E. Delchambre, C. Desgranges, P. Devynck, D. Douai, G. Dunand, A. Ekedahl,

aA. Escarguel, E. Gauthier, J. P. Gunn, P. Hertout, S.-H. Hong, F. Kazarian, M. Kocan, F. Linez, aY. Marandet, A. Martinez, bM. Mayer, O. Meyer, P. Monier-Garbet, P. Moreau, P. Oddon, J.-Y. Pascal, F. Rimini, bJ. Roth, F. Saint-Laurent, F. Samaille, S. Vartanian,

aC. Arnas, E. Aréou, C. Gil, J. Lasalle, L. Manenc, aC. Martin, aM. Richou, aP. Roubin, R. Sabot

Association Euratom-CEA, CEA/DSM/DRFC, CEA Cadarache, F-13108 Saint-Paul-lès-Durancea PIIM, CNRS/Université de Provence, F-13397 Marseille

bMPI für PlasmaPhysik, Euratom Association, Boltzmannstr. 2, D-85748 Garching

Motivation:

Fuel retention issue

Reconcile the 2 determinations of D-retention : gas balance post-mortem analysis

Bring information on the retention mechanism : co-deposition deep migration in bulk CFC

2/18

TORE SUPRA



A dedicated experiment

Deuterium Inventory in Tore Supra

Load the wall in D for good knowledge of the wall inventorygoal: 12g of D, i.e. 5× pre-campaign estimation

May 23th - June 7th, 2007

Dismantle one sector (20°) of the Toroidal Pumped LimiterExtract a number of tiles (~40) for analysis + deposits…for indentifying the retention mechanisms and close the particle balance

2007/

2008

Up to now, 10 tiles analysed

outline

OPERATIONINCREASE of IN-VESSEL D-INVENTORY INTEGRATED PARTICLE BALANCE PHYSICS of RETENTIONDetailed results on sample analysis (E. Tsitrone)Diagnostic of plasma-surface interaction (E. Delchambre)

3/18

TORE SUPRA



OPERATION

4/18

TORE SUPRA



OP

ER

AT

ION

100

10-1

10-2

10-3

10-4

10-5

Pre

ssu

re in

th

e to

rus

(Pa)

0 50 100 150 200 250 300 350 400 Time (h) since the beginning of the campaign

10 days of operation in 3 weeks160 « identical » long discharges (between 1 and 2 minutes)5h of plasma (about a normal year of operation)

Carbonization 13C + boronization

Time schedule of the campaign

nl ~ 2.5x1019 m-2

PLH ~ ramp up 1.31.8 MWPlasma duration 80 s

nl ~ 2.5x1019 m-2

PLH ~ 2 MWPlasma duration 120 s

Plasma scenario: retention >> post-discharge recovery

5/18

TORE SUPRA



Disruptions due to UFOs limit plasma durationO

PE

RA

TIO

N

UFO : Increase in Prad > 20%Scenario 1 Scenario 2

39750 Discharge number 40060

6/18

TORE SUPRA



OP

ER

AT

ION

~85% of disruptions associated to flake ejection

from the limiter surface

from the LH-launchers

Hot spot outgassing (impurity) MARFE & flake ejection Prad increases swith-off PLH by security disruption

No change in core & edge parameters(moderate increase in impurity content)

7/18

TORE SUPRA



OP

ER

AT

ION

Deposit pattern evolves during experiment

Beginning End of 1st phase

Deposits are thermally poorly attached to CFCIncrease of deposit thickness seen as increase of surface temperature

T-TrefT-Tref

Thick deposits : private flux regionsNo plasma , but radiation + CX atoms

Competition growth / erosionPattern characteristic to each scenario

8/18

TORE SUPRA



BUILDING D-INVENTORY

9/18

TORE SUPRA



D-I

NV

EN

TO

RY

WI = Inj.Gas – Exh.Gas – Post.Rec

Constant D-retention rate during campaign

60x1021

50

40

30

20

10

0

QIn

j (D

)

40.1x103

40.039.939.839.7

Discharge number

6x1021

4

2

0

QP

ost (

D)

40.0x103

39.939.839.7

Discharge number

25x1021

20

15

10

5

0

QE

xh (

D)

40.1x103

40.039.939.839.7

Discharge number

Exh

Normal dischargeDisruption

30x1021

20

10

0

-10

WI (

D)

140120100806040200

Discharge duration (s)

Trapping

Outgassing

Normal discharges Disruption

Retention rate ~ 2 g/h

Total increase of in-vessel inventory ~ 11 g deuterium

10/18

TORE SUPRA



During plasma operation, C is 0.01× D in the pumped gas

[H]/[D] decreases from 20% to 2% during the campaign

D-I

NV

EN

TO

RY

Global wall inventory (1)

Total correction ~ 0.4g D

11/18

TORE SUPRA



Background chamber pressure 6×10-5 Pa ( 50% D2)

Total exhausted ~ 0.6g D

GlobalWI ~ 10g D (3.0×1024 atoms)

Global wall inventory (2)

Global WI = WI during plasmas – exhaust during nights & week-ends

D-I

NV

EN

TO

RY

12/18

TORE SUPRA



PARTICLE BALANCE - RETENTION

13/18

TORE SUPRA



Tile selection for analysisP

AR

TIC

LE

BA

LA

NC

E -

RE

TE

NT

ION 40 tiles to be extracted for sampling and analysis

10 tiles selected out of 40• 5 erosion zone• 2 thin deposits• 3 thick deposits

DITS CFC structure PFCs IR Detritiation

14/18

TORE SUPRA



0.30

0.25

0.20

0.15

0.10

0.05

0.00

[D]/

[C]

403020100

depth (m)

Thick deposits Thin deposits Erosion zone

0.30

0.25

0.20

0.15

0.10

0.05

0.00

[D]/

[C]

403020100

depth (m)

Thick deposits Thin deposits Erosion zone

Thick deposits 500-600°C(up to 1000°C close to the tangency point)

Thin deposits 120°C

Erosion zone 200°C

Top of the tiles Poloidal gaps

Tile analysis : NRA – average [D]/[C] profilesP

AR

TIC

LE

BA

LA

NC

E -

RE

TE

NT

ION

Gaps < 400°C

15/18

TORE SUPRA



PA

RT

ICL

E B

AL

AN

CE

- R

ET

EN

TIO

NTile analysis : Thermodesorption

Integrated over Toroidal Limiter surface

Total 4g Deuterium : 40% of D-loaded

Erosion zone

Thin deposits

Thick deposits

D a

tom

s d

eso

rbed

/ s

amp

le

Integrated measurement / whole D-content

Medium samples (2mm from surface) : < 5% of D-content

Results for the first 10 tiles analysed

Top samples (first 2mm)2g/m2

0.4g/m2

16/18

TORE SUPRA



Integrated D-inventory

Erosion zones (3.5 m²) 2.1 g 37 % in gaps (275m)

Thin deposits (3.0 m²) 1.5 g 1 % in gaps (235 m)

Thick deposits (0.5 m²) 1.1 g 8 % in gaps ( 39 m)

Total 4.7 g (18 % in gaps)to be compared with 10 g from gas balance measurements

Erosion zones 0.4 g in tiles 0.8 g in gaps

Thin deposits 1.95 g in tiles 0.05g in gaps

Thick deposits 0.6 g 0.1 g in gaps

Trapped in bulk CFC 0.4 g (~10 % total retention)Co-deposition 3.5 g (~90 % total retention)

NRA(top +lateral faces)

TDS (top)NRA (lateral)

PA

RT

ICL

E B

AL

AN

CE

- R

ET

EN

TIO

N

17/18

TORE SUPRA



0 2000 4000 6000 8000 100000

2

4

6

8

10

12

14

20 mm19 mm

D r

etai

ned

[1021

D/m

2 ]

Air exposure time [h]

QD = 1.97x1021 exp(-t/442.2)+ 8.16x1021 exp(-t/22517)

where QD is the D amount (0-16 m) expressed in D/m2,

t is the storage time expressed in h

200 eV D ions CFC NB31, Tirr = 323 K, = 4x1024 D/m2

NRA (0-16 m)

20 mm

21 mm

20 mm

20 mm19 mm

6 months

~ 65 %

PA

RT

ICL

E B

AL

AN

CE

- R

ET

EN

TIO

ND-inventory : effect of time

Decrease of the D-content between end of operation and analysis

Estimated TPL D-inventory at the end of plasma operation~7.2 g if CFC and deposits concerned (70 % of total)~5.4 g if only CFC concerned (55 % of total)

total

presentlyfound

with D-losseswith time

tiles

gaps

erosion thin deposits

thick deposits

TPL ~ 7 m² (of ~ 15 m² in Tore Supra)Possible total D-inventory > 10 g of the dedicated D-inventory campaign

Contribution to previous campaigns

18/18

TORE SUPRA



Summary

PARTICLE BALANCE & PHYSICS of RETENTION

First results : ~ 50% of wall D-inventory found in Toroidal Limiter(up to 70 % if D-losses with time taken into account)

Retention on limiter: ~ 10% in CFC, ~90 % in deposits

Constant retention rate for the whole campaign, no saturation2g/h D, i.e. 60% of injected flux

Increase of wall D-inventory ~10g (~3×1024 D)

PLASMA-WALL INTERACTION & D-INVENTORY

5h of plasma in long pulse (>1min) operationScenario modified due to increasing number of UFOs and disruptionsNo change in the main plasma parameters

Largest flakes probably the consequence of repetitive discharges(constant wetting and constant deposition at exactly the same location)

OPERATION

19/18

TORE SUPRA



Additional viewgraphs

20/18

TORE SUPRA



Previous TS results (C. Brosset et al., JNM 2005)

All deposits far from LCFS but significant plasma flux (~ to B)Deposits on TPL surface, close to LCFS but no direct plasma flux not collected

Collection after campaign with high power discharges (high temperature of deposits)

0.3g D found (2.6g estimated Wall Inventory)

Extrapolated to present Wall Inventory (10g) 1.2g

21/18

TORE SUPRA



Attempt for global C-balance (from J.Hogan et al., IAEA 2006)

750m

D-load exp. 2002-2007

230g 2200g

Gross erosion (scaling law)

Net redeposition : cleaning of whole vacuum chamber ~800g deposits scrapped from PFCs

Net erosion ~ net redeposition(neglects erosion due to glows)

D-load exp. 2002-2007

100g 1000g

Net erosion

agrees with erosion from confocal scopy ~1000g eroded from TPL surface

Only ~55-65% of local C-redeposition

UFO ~0.2mg C (3mm×3mm×3m)500 UFOs during D-loading experiment ~0.12g C (5×10-4 of gross erosion)

22/18

TORE SUPRA



Extrapolation fuel retention to ITER

From D-loading experiment:5h of plasmas 10g of increase of wall D-inventory 4g D found in TPL

1.3g in erosion zones 2.7g in deposits

TPL = main source of C other PFCs likely deposited areas 8.7g in deposits

Extrapolation to ITER speculative becauseNot the same geometryNot the same edge parametersNot the same surface temperatures…

With respect to flux on PFCs (2 orders of magnitude)150g/h 700g T after ~40 nominal discharges (400s)

In erosion zones, with respect to integrated flux (2 orders of magnitude) : 20g/hwith respect to loaded surface (~1order of magnitude) : 2g/h

In deposited zones, with respect to net erosion (Redep = 0.55 in TS; 46g/h eroded C) (Redep = 0.99 in ITER; 27g/h): 1.5g/h(22-4)g/h 700g T after ~300-1600 nominal discharges (400s)

23/18

TORE SUPRA



Particle recovery after disruptions

Recovery after disruption : up to 5 1022 D

• Large scatter at given Ip : machine history dependent ?composition of gas ?

• Threshold in Ip :

• Ip < 0.8 MA : ~ after shot recovery• Ip > 0.8 MA : increase with Ip dissipated energy high enough for significant outgassing

0.2 0.4 0.6 0.8 1 1.2 1.4 1.60

20

40

60

80

100

120

Plasma current before disruption (MA)

Par

ticle

exh

aust

(P

a.m

3)

Tore Supra - Disruptions 2002-2004

0.2 0.4 0.6 0.8 1 1.2 1.4 1.60.2 0.4 0.6 0.8 1 1.2 1.4 1.60

20

40

60

80

100

120

0

20

40

60

80

100

120

Plasma current before disruption (MA)

Par

ticle

exh

aust

(P

a.m

3)

Tore Supra - Disruptions 2002-2004

Qinj-Qexh

24/18

TORE SUPRA



6 anodes toroidally distributed Itot=6A applied potential : ~600 V

Tokamak walls = cathode

Station de gaz

6 gas injection points toroidally distributed

Pumping speed 2200 l.s-1

Gas injection and glow electrodes system

6 anodes toroidally distributed Itot=6A applied potential : ~600 V

Tokamak walls = cathode

Station de gaz

6 gas injection points toroidally distributed

Pumping speed 2200 l.s-1

Gas injection and glow electrodes system

0

50

100

150

200

4:48 7:12 9:36 12:00 14:24 16:48 19:12

Temp (°C)

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

Pressure (Pa)

D2 GDC He GDC He:15%B2D6 He:15%13CH4

SequenceD2-GDC : remove oxyde p=0,35 Pa duration : 180 min.

He-GDC : desorb implanted D2

p=0,4 Pa duration : 30 min.

Carbonisation : 15 bar.l 13CH4 p=0,45 Pa duration : 210 min. He:20%13CH4 80 monolayers a-13C:H

Boronisation : 7,5 bar.l B2D6

p=0,45 Pa duration : 100 min. He:15% B2D6 80 monolayers a-B:D

[D. Douai]

CONDITIONNING INITIAL SURFACE IDENTIFICATION

25/18

TORE SUPRA



<ne> = 1.5×1019m-3

Ip = 0.6 MA

PLH = 1.8 MW max

Prad = 0.7 MW

<ne> = 1.5×1019m-3

Ip = 0.6 MA

PLH ~ 2 MW

Prad = 0.7 MW

2nd scenario1st scenario

125 s 85 s

Plasma scenarios

Magnetic field = 3.8 T

26/18

TORE SUPRA



MARFE causes PLH switched off by security

PLH switced off if radiation increases above fixed limitLine of sight of the security system located in midplane

With increasing impurity content, MARFEs are triggered by smaller perturbations

27/18

TORE SUPRA



Time schedule of the radiative instability

DPrad

C IV

MARFE

Flakeejection

Hot spot outgassing (impurity) MARFE & flake ejection Prad increases swith-off PLH by security density limit

28/18

TORE SUPRA



Deposit pattern evolves during experiment

Deposits are thermally poorly attached to CFCIncrease of deposit thickness seen as increase of surface temperature

Movie of the TTPL during the 1st phase of the experiment

Thick deposits : private flux regions on TPLNo plasma , but radiation + CX atoms

Competition growth / erosionDeposit pattern characteristic to each scenario

29/18

TORE SUPRA



Plasma-wall interaction & Carbon erosion

CII 515nm

CII emission on net erosion zones + gaps

CD on net erosion zones + leading edge

CD 431nm

Carbon erosion estimated in both erosion and deposition regionsTotal erosion from CII/D ratio: Ytot ~1%

Chemical erosion from CD/D ratio:low S/N, data consistent with Ychem1%

Gross erosion estimated from Ytot + BBQ simulations (J.Hogan et al., IAEA 2006)

For the whole campaign ~ 230 g

30/18

TORE SUPRA



Constant plasma edge parameters

[J. Lasalle, L. Manenc]

Temperature :3.97 3.975 3.98 3.985 3.99 3.995

x 104

0

5

10

15

20

25

30

shot

Te [e

V]

r - rLCFS

~ 2 cm

r - rLCFS

~ 7 cm

[M. Kocan, J. Gunn, J.-Y. Pascal]

Edge density and temperature :

0

20

40

60

80

100

tem

pe

ratu

re [

eV

]

Ti

Te

T

i,e

0.06m

= Ti / T

e 3.5

0.02 0.04 0.06 0.08 0.1 0

0 0.02 0.04 0.06 0.08 0.1 0.1210

17

1018

distance from the LCFS [m]

De

nsi

ty [

m-3]

ne(T

i = 3.5T

e)

ne(T

i = T

e)

n

e

0.07m

n

e

0.04m

31/18

TORE SUPRA



Constant plasma core parameters

[J. Lasalle, L. Manenc]

Temperature :

Density : feed-back controlled <ne> = 1.5×1019 m-3

No uncontrolled increase during the whole campaign No significant change in the profile

[C. Gil, R. Sabot]

Scenario 1# 39777# 39930

Scenario 2# 39990# 40030

32/18

TORE SUPRA



Moderate increase of impurity content

Constant core and edge plasma parameters ne(0)~2.7×1019m-3 ; Te(0)~3.5keV ; ne(a)~2×1018m-3 ; Te(a)~25eV

Moderate increase of impurity content

33/18

TORE SUPRA



Toroidal gaps

Poloidal gaps Top (plasma)

Bottom (copper)

Sample analysis

Toroidal gaps

Poloidal gaps

34/18

TORE SUPRA



depth (m)

[D]/[

C]

Poloidal gaps, erosion zone

Répartition du D dans les parties latérales toroïdales des tuiles en zone d'érosion.

0

5000

10000

15000

20000

25000

1 2 3 4 5 6 7

Profondeur en mm du plasma au Cu

No

mb

re d

e D

en

1E

15

D/c

m²

F1T3Q4L1

F4T2Q4L1

F26T9Q4L1

F26T11Q4L1

F27T8Q4L1

Top (plasma) Bottom (copper)

35/18

TORE SUPRA



depth (m)

[D]/[

C]

Poloidal gaps, thin deposits

Dépôts fins Gap

0

50

100

150

200

250

300

350

400

450

500

1 2 3 4 5 6 7

F17T7Q4L1

F27T20Q4L1


36/18

TORE SUPRA



depth (m)

[D]/[

C]

Poloidal gaps, thick deposits

Répartition GAP dépôts épais

0

5000

10000

15000

20000

25000

1 2 3 4 5 6 7

profondeur en mm

no

mb

re d

e D

en

1E

15D

/cm

²

F4T9Q4L1

F26T3Q4L1

F27T4Q4L1


37/18

TORE SUPRA



PA

RT

ICL

E B

AL

AN

CE

- R

ET

EN

TIO

NErosion zones : Mechanism for D-retention

Erosion zone : D-content ~100× that expected from implantation

5 µm

100 µm

Porosity probably involved in retention process

Filling up of pores by hydrocarbonsOn a layer of 15m thickness(average depth of D in erosion zone)

2g of D for the Limiter

(compared with 1.3g already found)

CFC = porous material ~20% of voids

1/18 TORE SUPRA Association Euratom-Cea B. Pégourié – SEWG Gaz Balance & Fuel Retention - JET – July 22-23, 2008 Tore Supra – repetitive long discharges.

Documents

euratom association

fuel retention issue

retention mechanisms

sabot association euratomcea

gas balance

g d slide

operation slide

g of d