1 TORE SUPRA Association Euratom-Cea A. Ekedahl et al Progress Report DITS project : 13 July 2007...

Progress Report DITS project : 13 July 2007 1

TORE SUPRA

AssociationEuratom-Cea

A. Ekedahl et al

Operational Limits during the TPL Deuterium Loading Experiment

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Operational Limits during the TPL Deuterium Loading Experiment

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F. Saint-Laurent, F. Rimini, A. Ekedahl, E. Tsitrone, A. Triay-Alcouffe, P. Monier-Garbet et al

Overview of the 10 days experiment (talk E. Tsitrone)

Main Limitation: Disruptions Revised scenario

Probability of UFOs and Disruptions

Appearance of UFOs

Origin of UFOs Analysis of IR and CCD films

Conclusions


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A. Ekedahl et al

0

20

40

60

80

100

120

140

1 2 3 4 5 6 7 8 9 10

nb of disruption shot > 120 s

60< shot < 120 s percentage disruption

nb of UFOs

Performance evolution over 10 daysPerformance evolution over 10 days

[F. Saint-Laurent, F. Rimini]

Day

Number of UFOs

% Disruptions

Scenario 2

Scenario 1: Ip = 0.6MA, PLH = 2MW, 120 s pulse duration

Scenario 2: PLH reduced, ~80 s duration


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A. Ekedahl et al

Probability of UFOs and disruptionsProbability of UFOs and disruptions

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

1 2 3 4 5 6 7 8 9 10

# of UFOs per 100s Disruption per 100s (*5)

Day

Disruption probability follows the number of UFOs. 10-20% of UFOs lead to disruption

Definition of UFO: Increase in Prad > 20%

34 34.5 350

0.5

1

1.5

2TS #39928

Prad (MW)

Time (s)

threshold

# of UFOs per 100s of plasma# of disruption per 100s of plasma


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A. Ekedahl et al

23/05/07 (Day 3) : clean pulses

Appearance of UFOs: Scenario 1Appearance of UFOs: Scenario 1

[E. Tsitrone]


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A. Ekedahl et al

23/05/07 (day 3) : almost no UFOs …01/06/07 (Day 7): lots of UFOs, and disruptions.UFOs appear when PLH is first applied, then more sporadic

Appearance of UFOs: Scenario 1Appearance of UFOs: Scenario 1

[E. Tsitrone]

LH power is switched off by the safety system when UFOs appear


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A. Ekedahl et al

Day 10 : Search of power limit Day 10 : Search of power limit

Scenario 2: PLH limited to 1.6-1.8 MW

[E. Tsitrone]

Reduced PLH No UFOs


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A. Ekedahl et al

Time distribution of UFOsTime distribution of UFOs

29 shots with LH power 117 UFOs

24 shots with LH power 33 UFOs

Day 7

Day 3

3 disruptions

19 disruptions


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A. Ekedahl et al

IR analysis of disruptionsIR analysis of disruptions

Number of disruptions 62Disruptions with IR data available 59

1st originArcs in front of launcher prior to disruption 18 30%Carbon flakes from side protections prior to arcing 10

2nd originHot spot on TPL prior to disruption (Q6 and Q5) 14Hot spot on TPL prior to disruption (Q6 => 1/6 of TPL) 10 17%

Both origins simultaneously 0

IR cameras to monitor : both LH launchers 1/6 of the TPL (Q6) ~1/18 of the TPL with high resolution (Q5)

[A. Ekedahl]


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A. Ekedahl et al

Disruption precursor: ArcsDisruption precursor: Arcs

IR camera observation of LH launchers

Flaking of co-deposited layer from launcher side protections Induce arcing in front of launchers

C2

• Impurity safety system detects Cu in the plasma.• IR safety system detects arcing.LH power is switched off.

Impurity safety system was later modified to act on all impurities (C, Cu,Fe, …) to try to avoid disruptions due to UFOs.

Increase of electron density and radiated power

30% of the disruptions were preceded by arcs in front of launchers.70% of disruptions can NOT be attributed to arcing.

LH launcher safety:

Plasma safety:


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A. Ekedahl et al

IR camera observation : localized at vertical port in Q6

Overheating of co-deposited layers prior to disruption

Disruption precursor: TPL Disruption precursor: TPL

Pulse 39918, t = 4.16-4.34s

Localised hot spot on TPL appears around 4.0s. Followed by overheating of the co-deposited layer.

PRad and CIV increase at 4.2s. PLH is switched off at 4.25s (plasma safety).No arcs in front of launchers.


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A. Ekedahl et al

Overheating of TPL starts ~100ms before increase in PRad and ne .

Increase in PRad is associated with carbon release.

Disruption precursor: TPL Disruption precursor: TPL

39868, t=5.0s 39868, t=6.0s 39868, t=6.4s39868, t=5.56s

Heating on high field side on TPL prior to disruption

Overheating of co-deposited layers prior to disruption


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A. Ekedahl et al

bolo3/bolo14

HFSLFS

314

PLH

Zeff-2

Ip

b3/b14

nl

0-100ms before LH is cut off

steady phase

TS39868

A MARFE is triggered before the disruption

A MARFE is triggered before the disruption

[P. Monier-Garbet]The ratio of the signals from two bolometer sight-lines indicate the roll-over of the radiation towards the HFS (MARFE)


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A. Ekedahl et al

Appearance of UFO (IR camera)Appearance of UFO (IR camera)

Overheating of CFC tile on TPL => UFO

Hot spot on TPL appears at ~48.3s. Increase of electron density and radiated power (UFO). Then the tile remains overheated, but ne and Prad are recovered until the plasma disrupts ~50s later.

39922, t = 48.5s

Q6A


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A. Ekedahl et al

Appearance of UFOs (visible CCD camera)

Appearance of UFOs (visible CCD camera)

T1T2

T3T4

T5 T6

OriginUnknown : 30 %From TPL : 70 %

Localisation of UFOs from TPL for 2 days1/3rd of TPL is observed

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25

30

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50

0 1 2 3 4 5 6 7

ovni010607 ovni070607

Number of UFOs :01/06/07 (day 7) : 598 (CCD) [117 from Prad]07/06/07 (day 10) : 325 (CCD) [80 from Prad]

1/18th = if equal repartition

T1 T2 T3 T4 T5 T6

Per

cen

tag

e

[A. Triay-Alcouffe]


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A. Ekedahl et al

ConclusionsConclusions

The TPL loading campaign was limited by disruptions, induced by UFOs.

Two strategies were applied :- Modified impurity safety system (fast switch-off of LH power) PLH reduced for all impurity influx (C, Cu, Fe, …) not enough.

- Reduced PLH in beginning of pulse, followed by slow PLH ramp-up 80s pulse duration OK until end of campaign.

LH power limit : ~1.6 MW at the end of the campaign.

- Statistical limit : associated with the probability of UFOs to appear. 10-20% of the UFOs lead to disruption.- Dynamical limit : the power threshold seemed to decreased with time.

Analysis of CCD and IR films indicate that most UFOs seem to originate from the TPL.

Day 8

Day 4


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A. Ekedahl et al

Appearance of UFOsAppearance of UFOs

Shot number [F. Rimini]

UFO : Increase in Prad > 20%

Data averaged over 5 shots

Scenario 2Scenario 1

1 TORE SUPRA Association Euratom-Cea A. Ekedahl et al Progress Report DITS project : 13 July 2007...

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