Joachim Roth: SEWG Gas balance, JET, July, 2008 Recent analysis of Tritium retention in ITER Report from the joint EU-US meeting at MIT combining the ITPA

Joachim Roth: SEWG Gas balance, JET, July, 2008

Recent analysis of Tritium retention in ITER

Report from the joint EU-US meeting at MIT combining the ITPA SOL/DIV, EFDA PWI TF and ITER PWI Team

B. Lipschultz, J. Roth,

A.Loarte, V. Philipps, A. Kallenbach, K. Schmid,

R. Doerner, D. Whyte, G. Wright, A. Haasz, J. Davis, R. Kolasinski, B. Wampler


Meeting held at MIT on June,23-24, 2008Evaluation of retention in different materials in ITERMonday (start 8:30 AM)

Session 0 – 08:30 – 09:00 Introduction and discussion of goals (Roth and Lipschultz)Session 1 (chair, Roth) – Goal: Agree on wall fluxes and temperatures over the entire vessel for use in empirical and code models of erosion, re-deposition and retention (09:00 - 10:30) Kallenbach – Review scaling from ASDEX-Upgrade and application to ITER

(10 minutes)Lipschultz – Review multiple machine scaling and application to ITER

(10 minutes)Discussion - till 10:10Break 10:10-10:30

Agenda:


Session 2 (chair – Kallenbach) – Goal: Be and C erosion sources and resultant flow paths for C and Be.

Schmid – Model calculations of C, Be sources and resultant paths for impurity transport and final deposition - should cover modelling of Be wall flux for Doerner (20 minutes)Philipps – ERO code calculations (Kirschner) for CFC divertor erosion including Be influxes and resultant deposition and retention.

(20 minutes)Philipps – empirical scaling of Be and C erosion and co-deposition based

on JET (10 minutes)Whyte – empirical scaling of multiple C-wall tokamaks for both Be and C

(10 minutes)Discussion till lunch Lunch 12:30-14:00Discussion continued till 15:00

Agenda:


Session 3 (Chair – Doerner) Goal – Review the current lab and tokamak data for D retention in C, Be and W.

(15:30-18:00) Doerner – Data on concentration in co-deposited layers vs temperature and flux

for Be, C and W (10 minutes)Haasz – Data basis for W from ion beams and linear plasma devices

(10 minutes)Kallenbach – Retention measurements in all-W AUG and extrapolation to ITER

(10 minutes)Lipschultz/Whyte – Retention measurements in C-mod and extrapolation to ITER

(10 minutes) Discussion till end of day

Agenda:


Tuesday (start 8:30)

Session 4 (chair – Philipps) - Goal: Review of assumptions in codes modeling retention in W, on ranges of recombination, neutron damage and its conversion to trap sites (08:30-10:10)Whyte – Parameters for modeling of DIONISOS and C-Mod (15 minutes)Kolasinski – DIFFUSE and TMAP7 modeling of TPE results(15 minutes)Roth/Schmid for Ogorodnikova – Modeling of data from ion beams and linear

devices (15 minutes)Wampler – Assessment of n-induced damage and hydrogen trap site characteristics (15 minutes)Whyte – Assessment of n-induced damage and hydrogen trap site characteristics (15 minutes)Break 10:10-10:30Discussion continued until 12:00

12:00-13:30 – LunchSession 5 (Chair – Lipschultz) – Goal: Finalize calculations and figures based on earlier sessions (13:30 - end of day)Schmid, Whyte, Kolasinski, empirical estimates – final calculation if different

Agenda:


•Wall and divertor fluxes from B2/EIRENE (Kukushkin)

•Wall erosion/deposition from DIVIMP

•Divertor erosion/deposition using ERO

•Co-depostion from exp. data

•Retention in W from exp. data extrapolated by diffusion codes

Recent EU evaluation:e.g. review PPCF, PSI Toledo


High Flux Low Flux

Wall Flux 1E24 /s 1E23 /s

Carbon yield 0.02

Be yield 0.01

Wall deposition 50% 0

Outer divertor deposition

1/4 1/4

Inner divertor deposition

3/4 3/4

D/C Regression equation from PISCES

D/Be Regression equation from PISCES

Retention in W Fit to data base at 500 KTemp. dependence for different fluxes

Effect of n damage Maximum amount between 370g and 2 kg,to be settled by Bill and Dennis

Different approach:An plasma experimentalist view:


Area (m2)

Tsurf (K)

Flux atoms

(/m2s)

Eatoms

(eV)

Flux ions

(/m2s)

Eions

(eV)

Fluxions

(1/s)

outer divertor 1 1,21 325 9E22 1,5 6E22 3 7,2E22

2 2,39 593 1,1E24 4,65 4E23 9,8 9,5E23

3 7,67 520 3,2E22 29 6,1E22 126 4,7E23

4 22,1 318 2,2E21 33 3E21 94 6,6E22

Inner divertor 1 1,15 322 3,3E22 0,9 2E22 1,9 2,3E22

2 4,4 466 4,8E23 3,37 1,7E23 7,5 7,3E23

3 4,9 382 3,9E22 9 5,6E22 20 2,7E23

4 6,1 324 3,2E21 11,2 5,8E21 25 3,5E22

dome 1 62 320 2,8E22 1,4

wall high flux 1 50 500 7E21 100 3,5E23

ELMs 50 500 3E21 200 1,5E23

wall low flux 1 200 450 1,75E21 100 3,5E23

wall atoms 1 250 450 1,5E21 20

upper divertor 1 35 450 2E22 20 1,5E22 100 5,2E23

ELMs 35 450 9E20 1000 3,15E22

Sum wall 450 12 1,4E24

Sum divertor 2,6E24

Flux conditions:e.g. High flux limit, 1E24 /s (Bruce)


D/Beyield

D/C yield

Chemyield

Eroded C

Depos C

T in C Eroded Be

Depos Be

T in Be

T in W ITER Mix

T in W/Be

outer divertor 0 0 1E-3 7,3E19 5E20 3,4E21 0 1E21 1,6E18 1,8E20 1,6E18 1,5E18

0 0 0,002 1,9E21 4E21 7,0E20 0 8E21 1,0E19 2,3E20 1,0E19 1,0E19

0,06 0,02 0,01 1,4E22 5E20 5E19 2,8E22 1E21 5,2E19 4E20 1,4E21 5,2E19

0,06 0,02 0,01 1,9E21 4E21 6,6E20

Inner divertor 0 0 1E-3 2,3E19 1E20 1,3E21 0 3E20 2,7E17 9,5E19 2,7E17 2,7E17

0 0 1E-4 7,5E19 1E21 5,8E20 0 2E22 3,3E19 5,4E20 3,3E19 3,3E19

0,01 0 0,01 2,7E21 3E20 3,2E20 2,7E21 6E20 6,6E18 5,1E20 6,6E18 6,6E18

0,01 0 0,02 7,1E20 3,5E20 2,5E20

wall high flux 0,05 0,02 0 7E21 2E22 2,8E21 1,7E22 8,9E20 2,6E20 2,6E20

0,07 0,02 0 3E21 1,0E22 5,6E20 5,6E20 5,6E20

wall low flux 0,05 0,02 0 7E21 1,7E22 2,2E21 2,2E21 2,2E21

wall atoms 0,01 0 0,02 1,5E22 7,5E21 4E22 2,6E20 2,5E21 2,5E21 2,5E21

upper divertor 0,05 0,02 0 1,0E22 2,6E22 1,2E21 1,2E21 1,2E21

0,05 0,02 0 6,3E20 1,6E21 2,6E20 2,6E20 2,6E20

Sum wall 4,3E22 8,1E22 7,6E21

Sum divertor 2,2E22 3,5E22 2,8E21

total 6,5E22 9,2E21 1,2E23 3,7E20 1,0E22 9,8E21 8,5E21

Erosion data from literature

Co-deposition from Russ

D in W from data base

Numbers before

correcting the

temperature by

100 K


1 10 100 100010-4

10-3

10-2

10-1

100

Ar->W

Sputtering theory Experimental data MD Simulations Trim Simulations

D->C

D->W

D->BeS

PU

TT

ER

ING

YIE

LD

(at

/io

n)

ENERGY (eV)

Erosion yields:Comparison with YC=0.02, YBe=0.01

1% Be

2% C


For beryllium:

Tdi erE

Be

D 18013061.059.015.034.1510*94.2

From De Temmerman et al.,Nucl. Fusion 48 (2008)075008

Co-deposition with Be:Regression formula from PISCES


• Von Keudell determined retention below 200C behaved differently than above 200C

• For ITER we can ignore everything below 200C

• Impact of deposition rate on D/C is still unknown (so I ignore it, which is saying it’s saturated)

• Temperature scales as exp(2268/T) similar to metal codeposits (between 473 < T < 973K)

• D/C scales with incident D energy as E(-0.43) different from metal codeposits (15 < E <100 eV)

0.001

0.01

0.1

1

0 200 400 600 800 1000

D/C = 0.0204*E^(-0.43)*exp(2268/T)

Balden [J. Nucl. Mater. 1999]Alimov [Phys. Scripta 2004]Von Keudell [Appl. Phys. Lett. 1993]C model E=68eV (compare to Alimov)C model E=15eV (compare to Von Kuedell)

Temperature (C)

Co-deposition with C:Regression formula from PISCES (Russ)


Data base for retention in W:e.g. fluence dependence at 500 K


Assumed temperature dependence is the envelope of the maxima. In most cases it overestimates the inventory.

With better knowledge of temperatures and fluxes better estimates can be achieved.

Normalised to 2x1024/m2

300 400 500 600 700 800 900 10000

2

4

6

8

10 polycrystalline W

200 eV D ion beam

3x1019 D/m2s, 1024D/m2

200 eV D plasma

1x1021 D/m2s, 1024D/m2

98 eV D plasma

1x1022 D/m2s, 1025D/m2

100 eV D+T plasma

1x1022 D/m2s, 1025D/m2

100 eV D plasma

1x1022 D/m2s, 1025D/m2

38 eV D plasma

1x1022 D/m2s, 1026D/m2

38 eV D plasma

1x1022 D/m2s, 1027D/m2

Hyd

roge

n is

otop

e re

tent

ion

[1020

(D

+T

)/m

2 ]

Exposure temperature [K]

Ogorodnikova et al. (2007) TDSAlimov et al. (2007) NRALuo et al. (2006) TDSCausey et al. (1999-2001) TDSTokunaga et al. (2005) TDS Alimov, Shu (2007/08) TDS

Data base for retention in W:e.g. temperature dependence at 2x1024/m2

y = 56.88*exp(-x/185)


New EU-US evaluation:Retained tritium vs. discharge duration


Recent EU evaluation:e.g. review PPCF, PSI Toledo


Reasonable agreement, but stillopen questions:

• What is the reason for uncertainty of factor of 10 in wall flux?Can this uncertainty be reduced?

• What is the re-deposition fraction in the main vessel.Is it reducing net erosion?Does it lead to co-deposition at cool vessel walls?

• Why is divertor erosion not important for erosion and co-deposition? Does the divertor material matter for tritium retention?

• Deposition and co-deposition is known to occur not only on divertor targets. This is not taken into account. How can we include this effect?

• ERO and DIVIMP code with grid extended to the walls must support the present rough assumptions.

Documents

Joachim Roth: SEWG Gas balance, JET, July, 2008 Recent analysis of Tritium retention in ITER Report from the joint EU-US meeting at MIT combining the ITPA