EU PWI Task Force

V. Philipps, SEWG mixed materials, 21.6.06

JET ITER-like Wall Project : Material choice, issues to investigate and role of new SEWG ITER-like Material Mix

V. Philipps , J. Roth

1700 solid Be tiles machined from 4t of Be

Be blanks orderedBe blanks ordered

W coated CFC tiles on high power areas, but 3 cm recessed

Be coated Inconel at inner wall cladding

NBI Shinethrough protection

Inner wall cladding

Inner wall guard limiters

Upper Dump plates

Mushrooms

Saddle coil protection

Saddle coil protection

Outer and inner poloidal limiters

LH + ICRH protection

KC1 coil covers

B&C tiles

Guideline: no carbon in contact with plasma

Be first wall

Beam shinetrough tiles

EU PWI Task Force

V. Philipps, SEWG mixed materials, 21.6.06

V.Philipps, Seminar IPP, 30_03_06

2. Be melting behaviour: melt layer stability and motion, analysis of molten Be, influence of melting on plasma operation

post mortem analysispost mortem analysis and wide angle IR and wide angle IR

3. Fuel retention in (bulk) Be tiles (surface and bulk) post mortem tile analysispost mortem tile analysis

4. Oxidation of Be (leaks, ventings, normal operation), effect on fuel retention, plasma conditioning

post mortem analysispost mortem analysis, spectroscopy, plasma performance, spectroscopy, plasma performance

5. Be erosion & redeposition on first wall : characterisation of redeposited Be (mainly on recessed areas of poloidal limiters)

post mortem analysispost mortem analysis

Full first wall Be : topics to investigate

1. Main Wall plasma wall interaction: Be first wall

JET Divertor

Option 1

20 MJ

Option 2Option 1

A full W divertor will be procured, but JET will preserve 2 options: full W or ITER-like divertor , decision ( or change) can be done on short time schedule

1

3

4 6

7

8

LBSRP

Louvers Louvers

B&CHFGC

5

5a

200μm Plasma sprayed W coating on CFC (tile 1-8)

W bulk on tile 5 (LBSRP)

High power and ITER-like high triangularity shots

→ outer divertor leg on solid W tiles

EU PWI Task Force

V. Philipps, SEWG mixed materials, 21.6.06

Divertor

Option 1

20 MJ

Toroidally isolated

EU PWI Task Force

V. Philipps, SEWG mixed materials, 21.6.06

W bulk concept (FZ Juelich )

-minimises EM forces and optimise mechanical stability

-6mm W-lamellas, poloidal stacks, toroidally isolated

V.Philipps, Seminar IPP, 30_03_06

A key question will be:

Alloying of Be with W (with possibly some remaining C and O) and consequences for W- erosion

With W- bulk lamellas additional key topics can be investigated

•W-mechanical stability (cracking, fatigue) under repetitive power loads

•W melt behaviour: melt layer flow, melt layer loss and stability

•Migration of Be (& C) in W gaps

Need coordinated research in EU PWI Need coordinated research in EU PWI

Tritium retention and material mixings Tritium retention and material mixings

Analysis of fuel retention under new wall conditions is a main goal of the ITER like wall project

1 2• Characteristics of first wall and divertor erosion

• long and short range material migration (Be versus C)• influence of residual C sources and oxygen

Should be addressed in both divertor configurations

V.Philipps, Seminar IPP, 30_03_06

Retention and material mixings (2)Retention and material mixings (2)

1. Fuel retention in Be/C/W/O redeposited mixed layers

influence of :

composition (in particular C&O )

temperature etc..

2. Fuel retention in bulk Be (surface and bulk, including oxidation effects)

V.Philipps, Seminar IPP, 30_03_06

CONCENTRATION RATIO: BERYLLIUM - TO - CARBON

1

2

3

45 6

78 9 10

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

DIVERTOR TILE (POLOIDAL DIRECTION)

Be

/ C

Inner

Outer

Plasma facing sides: Plasma facing sides: stable Be-C mix (stable Be-C mix (~~Be carbide ??)Be carbide ??)D content : D content : 0.1-0.20.1-0.2

Shadowed areas: Shadowed areas: more “pure“ C layersmore “pure“ C layersD content: D content: 0.4- 1 0.4- 1

more information on chemical state of deposits needed& influence of oxygen

1

3

2

64

5

10

7

9

8

MKIIA

V.Philipps, Seminar IPP, 30_03_06

M. Rubel et al

Present JET conditions

10C 1Be

Becarbide (?)

C layer

C

Further C- transport by carbon chemistry (?)

1C(?) 10 Be

Be2 W ??

WC

??

New conditions (?)

Present conditions

Further transport of Be?? (recent PISCES data )

V.Philipps, Seminar IPP, 30_03_06

a-C:H layer

MKIIA 67000 sec

1 kg (850 g on divertor floor)

EU-PWI-Task Force

MKIIGB 58000 sec

600 gC

60 g

116g

170g

100g

480g

8g

~ 1 kg (present estimate, analysis ongoing)

MKIISRP 83000 sec, present estimates by myself!

T retention is due to large amounts of C- erosion, migration and codeposition

??

(150)

erosion

Not analysed

“Massive” C sources are needed to produce thick C-deposits leading to large T retention by codeposition

1 kg C = 5 x1019 C/ 100m2 = 10 μm on 100 m2 area

Under the new wall conditions, some C source will remain probably originating from:

remote areas by H-atom impact, not fully cleaned from C

failure of W coatings

C impurities in metallic components

The residual C can produce C-layers on remote areas in competition with exhaust in form of volatile hydrocarbons

estimate of C- exhaust in from of CxHy C5-C14

injected D- atoms: 1800g = 4.8 1026 D

assumed fraction CxHy/D = 1% → 4.8 1024 CxHy ~ 10g C

Summary

main important open questions , need coordinated research in SEWG

- characterise fuel retention in bulk Be tiles (erosion areas)

- characterisation of Be redeposition on first wall components (composition and fuel retention)

- oxidation/erosion behaviour of large areas of bulk Be and influence on fuel retention

- characterisation of Be/W/C/O containing deposits on plasma facing areas, shadowed areas and gaps (divertor region )

- alloying behaviour of Be with W and importance for W erosion behaviour

For these topics we should develop physics based understanding to have a solid basis to extrapolate to ITER conditions

Needs coordinated work on post mortem analysis of JET tiles , plasma experiments in Pisces and dedicated lab experiments