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V.Philipps, SEWG Gas balance and fuel removal, JET, 22.7.08, Association EURATOM – FZJ Effect of disruptions on fuel release from JET walls V. Philipps,

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Presentation on theme: "V.Philipps, SEWG Gas balance and fuel removal, JET, 22.7.08, Association EURATOM – FZJ Effect of disruptions on fuel release from JET walls V. Philipps,"— Presentation transcript:

1 V.Philipps, SEWG Gas balance and fuel removal, JET, , Association EURATOM – FZJ Effect of disruptions on fuel release from JET walls V. Philipps, M. Freisinger, A.Huber, T. Loarer and JET EFDA contributors Motivation Disruptions affect gas balance measurements by additional particle release proposed as a possible T-removal method in ITER (controlled mitigated disruptions) This work Long term study of particle injection and release in between discharges for disruptive and non disruptive shots in C5-C14 JET campaigns ( )

2 V.Philipps, SEWG Gas balance and fuel removal, JET, , Association EURATOM – FZJ Experimental method Long term data ( 700sec ) of main chamber penning gauges routinely check of calibration using dry gas injections restriction of data base to all shots with - long term penning data - pumping by - divertor cryopump (125m 3 /sec) - main vessel turbopumps (8m 3 /sec) - and 2 NBI beam crypopumps(40m 3 /sec each)

3 V.Philipps, SEWG Gas balance and fuel removal, JET, , Association EURATOM – FZJ Number of shots Number of disruptions Average injection/shot (atoms) Integrated injection (atoms) Overall campaign (9.7% )7.12 x x Database (10% )9.7 x x Database

4 V.Philipps, SEWG Gas balance and fuel removal, JET, , Association EURATOM – FZJ current Pressure < mbar Particle release after non disruptive shots

5 V.Philipps, SEWG Gas balance and fuel removal, JET, , Association EURATOM – FZJ Q (t) t n, n = -0.6 Shot JET TEXTOR 1h 12h

6 V.Philipps, SEWG Gas balance and fuel removal, JET, , Association EURATOM – FZJ Long tail of particle release after non disruptive shots Pumping of neutrals by plasma until very end of discharge Release just after the shot recycling flux at plasma end Consistent total release for all nondisruptive shots, average value atoms, does not correlate directly with amount of fuelling (quasi- saturation of dynamic wall inventory) Represents dynamic wall inventory in C- walls at 200C (10 16 /cm 2, 10% of saturation value for erosion areas)

7 V.Philipps, SEWG Gas balance and fuel removal, JET, , Association EURATOM – FZJ Absolute particle release up to 700sec for all non disruptive shots (1091 shots) Mean release: 1.8 x /shot

8 V.Philipps, SEWG Gas balance and fuel removal, JET, , Association EURATOM – FZJ release up to 50sec/release up to 10sec for all nondisruptive and disruptive shots

9 V.Philipps, SEWG Gas balance and fuel removal, JET, , Association EURATOM – FZJ Mean value of non disruptive shots

10 V.Philipps, SEWG Gas balance and fuel removal, JET, , Association EURATOM – FZJ

11 Summary All disruptive shots show a larger particle release Release increases with stored energy Temporal characteristic consistent with an instantaneous particle release during disruption ( similar a sin gas injection) Consistent with thermal outgassing from disruptive heated areas Additional release: 2x10 22/ dis = 40g D/campaign (7000shots, 10% disruptions), but effect on long term retention only possible for release from deposition dominated areas Disruptive release contribute to reduce fuel inventory on plasmaetted areas ( D/C) but not on remote areas (D/C 0.5-1)

12 V.Philipps, SEWG Gas balance and fuel removal, JET, , Association EURATOM – FZJ surface concentration D/m 2 Erosion area: released fuel will be refilled Deposition area: new layer deposited on top of existing disruptive release can reduce inventory 1 m C layer 3 x D/m 2

13 V.Philipps, SEWG Gas balance and fuel removal, JET, , Association EURATOM – FZJ Pressure in main chamber Shot x mbar9 x mbar shot After shot


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