Deuterium retention in tore supra long discharges
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Deuterium retention in Tore Supra long discharges. E. Tsitrone, C. Brosset, J. Bucalossi, B. Pégourié, T. Loarer, P. Roubin 2 , Y. Corre, E. Dufour, A. Géraud, C. Grisolia , A. Grosman, J. Gunn , J. Hogan 3 , C. Lowry, R. Mitteau , V. Philips 4 ,

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Deuterium retention in Tore Supra long discharges

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Deuterium retention in tore supra long discharges

Deuterium retention in Tore Supra long discharges

E. Tsitrone, C. Brosset, J. Bucalossi, B. Pégourié, T. Loarer, P. Roubin2, Y. Corre, E. Dufour,

A. Géraud, C. Grisolia , A. Grosman, J. Gunn, J. Hogan3 , C. Lowry, R. Mitteau , V. Philips4,

D. Reiter4, J. Roth5, M. Rubel6, R. Schneider7, M. Warrier7

Association Euratom-CEA, CEA Cadarache, CEA-DSM-DRFC, F-13108 Saint Paul-lez-Durance, France

2 : LPIIM, UMR 6633, Université de Provence, Centre Saint-Jérôme13 397 Marseille cedex 20

3 : Fusion Energy Division, ORNL, Oak Ridge, TN 37831-8072 USA

4 : Institut für Plasmaphysik, FZ Jülich, Euratom Association, D-52425 Jülich, Germany

5 : Max Planck Institute für Plasmaphysik, Euratom Association, Boltzmannstr. 2, D-85748 Garching Germany

6 : Alfven Laboratory, Royal Institute of Technology, Association Euratom VR, 100 44 Stockholm, Sweden

7 : Max Planck Institute für Plasmaphysik, Euratom Association, Teilinst. Greifswald, Wendelsteinstrasse 1, D-17491 Greifswald Germany

  • Experimental results

  • Particle retention during long discharges

  • Particle recovery (after shot, glows, disruptions)

  • Interpreting the particle balance


Tore supra the ciel configuration

Outboard movable limiter

Bumpers

Shadowed zones

Toroidal pump limiter (TPL)

CCD imaging of the TPL

Plasma loaded zones

  • 15 m2 of carbon plasma facing components

  • Active cooling : stationary PFC temperature

from 120°C (cooling loop) up to 250°C on the limiter for long pulses

  • Active pumping : neutralisers below TPL

Tore Supra : the CIEL configuration

  • Long pulse : LH driven discharge at Vloop~ 0, low plasma current/density

  •  low density hot edge plasma (Te ~ 100 eV at the LCFS)


Deuterium retention in tore supra long discharges

Particle retention in long discharges

Phase 2

Phase 1

  • Phase 1 (~ 100 s)

  • Decreasing retention rate

  • Phase 2

  • Constant retention rate (= 50% of injected flux)

  • No saturation after 6 minutes

  • In vessel inventory

  • shot duration in phase 2

    (Imax = 8 1022 D for 6 minutes)

  • Identical shot to shot behaviour

No saturation of in vessel retention after 15 minutes of cumulated plasma time


Deuterium retention in tore supra long discharges

Particle recovery after shot

Retention phase 1

~ 100 s

Phase 1

Phase 2

x 1022

x 1021

  • Small fraction recovered after shot

  • Recovery correlated to retention in phase 1 : transient retention mechanism

  • Recovery > plasma content :

  • the wall releases particles


Deuterium retention in tore supra long discharges

Recovery after disruption :

up to 5 1022 D < Imax

  • Large scatter at given Ip : machine history dependent ?

  • (highest exhaust in start up phase)

Particle recovery

after glow discharge and disruptions

  • Recovery after He glow discharge (6 hours): 1.5 - 2 1022 D < Imax

  • Independent of the quantity trapped during the day of experiment

  • Threshold in Ip :

    • Ip < 0.8 MA : ~ after shot recovery

    • Ip > 0.8 MA : increase with Ip  dissipated energy high enough to heat D rich deposited layers

    • [D. Whyte, PSI 2004]


Deuterium retention in tore supra long discharges

Sample analysis : D content

Net deposition zone

Shadowed

Plasma facing

Net erosion zone

(main plasma interaction area)

Carbon deposits

Several mms

TPL

< 1 mm

Several mms

Net deposition zones

Outboard limiter

Neutraliser finger

Cold deposits (~ 120 °C)

D/C ~ 10 %

ND~ 1022 at /m2 / mm * S * d

Hot deposits (> 500°C)

D/C ~ 1 %

ND~ 1021 at/m2 * S

[C. Brosset, PSI 2004]

TPL deposits analysis still in progress

Cold deposits in shadowed areas

 D reservoir


Deuterium retention in tore supra long discharges

  • Implantation D  C

D+, D0

Progressive saturation of bombarded surfaces (D+, D0) until CDmax reached

Carbon

dimp< 0.1 mm

D0

D2

D2+

Phase 1

Bumpers

D+

TPL

[E. Tsitrone, PSI 2004]

Interpreting the particle balance

Saturation time :

from ~ 1s (TPL)

to ~ 100 s (bumpers)

BUT : does not explain shot to shot behaviour unless very strong diffusion takes place


Deuterium retention in tore supra long discharges

Interpreting the particle balance

  • Filling the CFC porosity

D2, D0

5 1021 D

Phase 1

  • Extrapolation from lab exp (77 K) :

  • 1022 D/g deposits  0.5 g enough to account for phase 1

Adsorption

M. Warrier et al., Contrib. Plasma

Phys. 44, No. 1-3, (2004)

  • TS deposited layers : 100 times more porous than original CFC

  • [P. Roubin, PSI 2004]

  • Adsorption : weak bond (  chemical bond)

  •  ok for transient mechanism

  • Outgassing after shot ~ phase 1 duration ( ~ 100s) :

  • ok with filling / emptying the porosity reservoir

Good candidate for phase 1 BUT : extrapolation from lab to tokamak environment (temperature)


Deuterium retention in tore supra long discharges

Interpreting the particle balance

  • Codeposition :

physical sputtering

chemical sputtering

Phase 1 + 2

Distant redeposition (TPL shadowed areas, neutralisers, outboard limiter …)

C, D

Carbon deposits

5 1020 C6+/s

Erosion

CxDy

6 1020 C/s (phys. + self)

  • 1.5 1020 CD4/s (chem.)

1020 C/s

Local redeposition

1.5 1020 CD4/s

  • Preliminary estimates of carbon erosion sources

  • physical + chemical sputtering by D+ and D0

  • self sputtering by Cn+ (assumed 5% C in D+ flux)

  • ok with Zeff, ok with low net erosion on TPL (high local redeposition), ok with layers growing rate

 carbon balance roughly coherent


Deuterium retention in tore supra long discharges

Interpreting the particle balance

  • Codeposition : D balance

2 1020 D/s

Phase 1 + 2

  • 1/3 of produced CD4 trapped :

  • but high D/C ratio film : not observed

Distant redeposition (TPL shadowed areas, neutralisers, outboard limiter …)

Erosion

6 1020 C/s

5 1020 C6+/s

  • 1.5 1020 CD4/s

1020 C/s

1.5 1020 CD4/s

Local redeposition

  • If D/C = 0.1 : need 2 1021 C/s of net redeposition : high erosion/redeposition on TPL ( > 100 mm on 4 m2):not observed

  • No coherence between D retention rate / D/C ratio / C erosion/redeposition

D rich film created during the discharge subsequently depleted in D

(glows, disruptions) ?

Hard to explain the retention rate in phase 2 with codeposition alone


Deuterium retention in tore supra long discharges

Summary

Transient retention : recovered after shot

Permanent retention : NOT recovered after shot

Phase 1

Phase 2

  • D retention : no wall saturation after 15 minutes in high Te / low ne edge plasma

  • D recovery (He glow discharge, disruptions) < in vessel inventory accumulated in a single long discharge

  • Codeposition of D and C :

  • Can hardly explain the retention rate in phase 2

  • D implantation in C :

  • progressive saturation but not transient

  • D content sample analysis :

  • D mainly in cold deposits in shadowed areas (120 °C)

  • D adsorption in porosity :

  • good candidate, but to be assessed in tokamak environment

Missing D not found yet but still a lot to investigate

(TPL deposits, pumping ducts …)


Deuterium retention in tore supra long discharges

D+

to pumps

Tore Supra : well equipped

for particle balance

dNp/dt = Finj – Fpump –F in vessel

  • Gas injection : manometers

  • Active pumping : 10 neutralisers with turbo-molecular pumps equipped with 20 pressure gauges (1 in vertical port, 1 at the pump) + 2 Penning gauges (D2/He) + mass spectrometer

  • 2 pressure gauges in the chamber (equatorial ports)

  • pressure gauges in primary exhaust system

  • Systematic calibration procedure : calibrated gas injection in the chamber with/without pumps activated


Deuterium retention in tore supra long discharges

Effect of active pumping

Shifted gas injection

Pumping on

Pumping off

Active pumping on Tore Supra : no effect on dynamic wall retention but offset on gas injection

Same wall inventory


Deuterium retention in tore supra long discharges

Particle balance sensitive

to LH power loss

LH power (MW)

Shot 32299

Injected flux (Pa.m3/s)

Extracted Flux (Pa.m3/s)

Gas Puffing

Inventories (Pa.m3)

Vessel Inventory

TPL exhaust

Plasma Content x100

Vessel Exhaust

s

Time (s)

dNp/dt = Finj – Fpump –F in vessel


Deuterium retention in tore supra long discharges

Disruption heats deposited layers

Plasma loaded zones

DT (°C) before/after disruption (20 ms)

Net erosion zone (main plasma interaction area)

Shot 33067

CCD imaging of the TPL

DT > 220 °C

Shadowed zones

Thickest deposition zone (shadowed/plasma area)

Moderate deposition zone (plasma interaction area)


Deuterium retention in tore supra long discharges

IR shows cold deposits

T°C #33067 (t-20ms)

T #33067 (disruption)


Deuterium retention in tore supra long discharges

D inventory in the machine

Estimated D inventory in the machine :

From analysed samples : ~ 5 1022 D (80% in cold deposits)

From non analysed samples (TPL surface) : ~ 4 1022 D (most of it in TPL shadowed zones)

Total : ~ 9 1022 D

BUT : surface/depth of layers difficult to assess, samples still to be analysed

Estimated D inventory from particle balance integrated over a campaign:

From averaged net retention rates : ~ 1.5 1024 D

Glow discharge : ~ 4 1023 D

Disruptions : ~ 3 1023 D

Total : ~ 8 1023 D

BUT : retention rate scenario dependent, not all disruptions recorded, glow D2 not accounted, cleaning discharges …

 No firm conclusion can be drawn on D balance


Deuterium retention in tore supra long discharges1

Deuterium retention in Tore Supra long discharges

E. Tsitrone, C. Brosset, J. Bucalossi, B. Pégourié, T. Loarer, P. Roubin2, Y. Corre, E. Dufour,

A. Géraud, C. Grisolia , A. Grosman, J. Gunn, J. Hogan3 , C. Lowry, R. Mitteau , V. Philips4,

D. Reiter4, J. Roth5, M. Rubel6, R. Schneider7, M. Warrier7

Association Euratom-CEA, CEA Cadarache, CEA-DSM-DRFC, F-13108 Saint Paul-lez-Durance, France

2 : LPIIM, UMR 6633, Université de Provence, Centre Saint-Jérôme13 397 Marseille cedex 20

3 : Fusion Energy Division, ORNL, Oak Ridge, TN 37831-8072 USA

4 : Institut für Plasmaphysik, FZ Jülich, Euratom Association, D-52425 Jülich, Germany

5 : Max Planck Institute für Plasmaphysik, Euratom Association, Boltzmannstr. 2, D-85748 Garching Germany

6 : Alfven Laboratory, Royal Institute of Technology, Association Euratom VR, 100 44 Stockholm, Sweden

7 : Max Planck Institute für Plasmaphysik, Euratom Association, Teilinst. Greifswald, Wendelsteinstrasse 1, D-17491 Greifswald Germany

ITER in vessel T inventory limit :

 (retention rate - recovery rate) dt < 350 g

  • minimize the retention rate

  • optimize the recovery techniques

  • Experimental results

  • Particle retention during long discharges

  • Particle recovery (after shot, glows, disruptions)

  • Interpreting the particle balance


Deuterium retention in tore supra long discharges

Particle retention in long discharges

Phase 2

Phase 1

dNp/dt = Finj – Fpump –F in vessel

  • Phase 1 (~ 100 s)

  • Decreasing retention rate

  • Phase 2

  • Constant retention rate (= 50% of injected flux)

  • No saturation after 6 minutes

  • In vessel inventory

  • shot duration in phase 2

    (Imax = 81022 D for 6 minutes)

  • Identical shot to shot behaviour

No saturation of in vessel retention after 15 minutes of cumulated plasma time


Deuterium retention in tore supra long discharges

Sample analysis : D content

Net erosion zone (main plasma interaction area)

Net deposition zone

Shadowed

Plasma facing

Carbon deposits

Several mms

TPL

< 1 mm

Several mms

Moderate deposition zone (plasma interaction area)

Outboard limiter

Thickest deposition zone (shadowed area)

Neutraliser finger

Cold deposits (~ 120 °C)

D/C ~ 10 %

ND~ 1022 at /m2 / mm * S * d

Hot deposits (> 500°C)

D/C ~ 1 %

ND~ 1021 at/m2 * S

[C. Brosset, PSI 2004]

TPL deposits analysis still in progress

Cold deposits in shadowed areas

 D reservoir

D content in analysed samples < D inventory over campaign


Deuterium retention in tore supra long discharges

Interpreting the particle balance

  • Codeposition :

Estimates of carbon

erosion sources

Phase 1 + 2

Distant redeposition (TPL shadowed areas, neutralisers, outboard limiter …)

C, D

Carbon deposits

Erosion

CxDy

6 1020 C/s

5 1020 C6+/s

  • 1.5 1020 CD4/s

1020 C/s

1.5 1020 CD4/s

Local redeposition

  • C source underestimated : no synergy D+/D0, no localised hot Tsurf, no LH accelerated e-

  • ok with Zeff, ok with high redeposition (low net erosion on TPL), ok with layers growing rate

  •  carbon balance roughly coherent


Deuterium retention in tore supra long discharges

Sample analysis : D content

Net erosion zone

Net deposition zone

Plasma facing

Shadowed

Plasma facing

Carbon substrate

Carbon deposits

Several mms

< 1 mm

< 1 mm

cold deposits

Several mms

hot deposits

TPL

Neutraliser finger

TPL deposits analysis still in progress

Cold deposits in shadowed areas

Outboard limiter

Hot deposits (> 500°C)

D/C ~ 1 %

ND~ 1021 at/m2 * S

[C. Brosset, PSI 2004]

Cold deposits (~ 120 °C)

D/C ~ 10 %

ND~ 1022 at /m2 / mm * S * d


Deuterium retention in tore supra long discharges

Interpreting the particle balance

  • Filling the CFC porosity

D2, D0

  • TS deposited layers : 100 times more porous than virgin CFC

  • [P. Roubin, PSI 2004]

5 1021 D

  • Extrapolation from lab exp :

  • 1022 D/g deposits  0.5 g enough to account for phase 1

Phase 1

Adsorption

dpvessel/dt = Soutgas – Seff pvessel

M. Warrier et al., Contrib. Plasma

Phys. 44, No. 1-3, (2004)

pvessel

  • Recovery ~ phase 1 duration : ok with filling / emptying the porosity reservoir

Soutgas

  • Adsorption : weak bond

  • (  chemical bond)

  •  ok for transient mechanism

Good candidate for phase 1 BUT : extrapolation from lab to tokamak environment

(temperature, pressure, incident particles)


Deuterium retention in tore supra long discharges2

Deuterium retention in Tore Supra long discharges

E. Tsitrone, C. Brosset, J. Bucalossi, B. Pégourié, T. Loarer, P. Roubin2, Y. Corre, E. Dufour,

A. Géraud, C. Grisolia , A. Grosman, J. Gunn, J. Hogan3 , C. Lowry, R. Mitteau , V. Philips4,

D. Reiter4, J. Roth5, M. Rubel6, R. Schneider7, M. Warrier7

Association Euratom-CEA, CEA Cadarache, CEA-DSM-DRFC, F-13108 Saint Paul-lez-Durance, France

2 : LPIIM, UMR 6633, Université de Provence, Centre Saint-Jérôme13 397 Marseille cedex 20

3 : Fusion Energy Division, ORNL, Oak Ridge, TN 37831-8072 USA

4 : Institut für Plasmaphysik, FZ Jülich, Euratom Association, D-52425 Jülich, Germany

5 : Max Planck Institute für Plasmaphysik, Euratom Association, Boltzmannstr. 2, D-85748 Garching Germany

6 : Alfven Laboratory, Royal Institute of Technology, Association Euratom VR, 100 44 Stockholm, Sweden

7 : Max Planck Institute für Plasmaphysik, Euratom Association, Teilinst. Greifswald, Wendelsteinstrasse 1, D-17491 Greifswald Germany

ITER in vessel T inventory limit :

 (retention rate - recovery rate) dt < 360 g

  • minimize the retention rate

  • optimize the recovery techniques

  • Experimental results

  • Particle retention during long discharges

  • Particle recovery (after shot, glows, disruptions)

  • Interpreting the particle balance


Deuterium retention in tore supra long discharges

Recovery after disruption :

up to 5 1022 D < Imax

  • Large scatter at given Ip : machine history dependent ?

  • (highest exhaust in start up phase)

Particle recovery

after glow discharge and disruptions

  • Recovery after He glow discharge (6 hours): 1.5 - 2 1022 D < Imax

  • Independent of the quantity trapped during the day of experiment

  • ~ desaturation of 15 m2 of carbon implanted with D for 300 eV incident He

  • Threshold in Ip :

    • Ip < 0.8 MA : ~ after shot recovery

    • Ip > 0.8 MA : increase with Ip  dissipated energy high enough to outgas deposited layers

    • [D. Whyte, PSI 2004]


Deuterium retention in tore supra long discharges

  • Implantation D  C

D+, D0

Progressive saturation of bombarded surfaces (D+, D0) at CDmax = f(Einc, Tsurf )

Carbon

Saturation time :

from ~ 1s (TPL) to ~ 100 s (bumpers)

dimp< 0.1 mm

D0

D2

D2+

Phase 1

Implantation of D0 in bumpers

Bumpers

D+

TPL

[E. Tsitrone, PSI 2004]

Interpreting the particle balance

BUT : does not explain shot to shot behaviour unless very strong diffusion takes place


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