High Heat Flux Facility GLADIS at IPP Garching

High Heat Flux Facility GLADIS at IPP Garching
Outline:
H. Greuner, Ch. Linsmeier, H. Maier
Max-Planck-Institut für Plasmaphysik, Euratom Association, Garching
1. Introduction & loading conditions in GLADIS
2. Component oriented investigations
3. Material investigations, surface modification of W under H / He beam loading
4. Further facility improvement & summary
Max-Planck-Institut für Plasmaphysik
EURATOM Association
Facility designed to evaluate plasma facing components as well as metallic and non-metallic
materials (W, CFC,…) under fusion relevant heat & particle fluxes
High heat flux test of large actively water-cooled components as well as small samples
PMI: Investigation of surface and bulk morphology modifications of W-PFCs under H/ He loading
H. Greuner, IPP Garching PMTS Workshop, Aug.31 –Sep.2 2010
Oak Ridge, TN, USA
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“Where we are”: Experimental activities in the US and Japan
GLADIS, high heat load & long pulses
600 – 2500 K neutrals
Source: S. Sharafat, UCLA, IAE W‐Satellite ICFRM-14 Sapporo, Sept. 9, 2009
H. Greuner, IPP Garching PMTS Workshop, Aug.31 –Sep.2 2010
Oak Ridge, TN, USA
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d
Investigation of Plasma Facing Components in GLADIS
Heat load resulting from H, He,… particles
plasma facing material
externally heating/ cooling
Lab experiments
Lab experiments,
accelerators, plasma
devices
material, gas
from component
interface
heat sink
coolant
actively cooled
T(d) = const.
T(d)
surface
No temperature gradient
surface
strong temperature gradient
compressive
tensile
d
compressive
tensile
Surface processes
• depending on T surf (time)
• evaporation, melting, mixed materials,
alloys, morphology changes, formation
of deposited layers, ….
Gas transport into bulk is driven by
• concentration gradient
• temperature gradient
• stress gradient, gas accumulation in
regions of tensile stress
thermal stress =0
thermal stress
• Component behavior affects the PWI processes and lifetime of component
• Unique investigations in GLADIS, complementary to linear plasma experiments
H. Greuner, IPP Garching PMTS Workshop, Aug.31 –Sep.2 2010
Oak Ridge, TN, USA
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1. Introduction GLADIS (Garching LArge DIvertor Sample test facility)
Neutral beams offer a homogeneous heating of metallic and non-metallic surfaces (W,
CFC,…) under hydrogen/ helium loading conditions.
• 2010: start of operation of 2nd beam line, completely independent operation
Free superposition of the two beams possible!
Unique capability for operation with H, He or mixed H/He neutral beams and thermal loads
• Power 2 x 1 MW ion source, H 2
• U ex 15 – 55 KV
• Heat flux 3 - 45 MW/m²
• Loaded area 300 cm²
• Pulse length 1 ms - 45 s
• Cycle rate 80 - 100 /h
• Target dim. up to 2 m
using vacuum lock)
• Target cooling: (currently)
(0.6 m
„high purity water“ fulfils ITER requirements
flow rate: ≤ 8.5 l/s (T‘=20 °C)
1 MW ion
sources
~ 3700
H. Greuner, IPP Garching PMTS Workshop, Aug.31 –Sep.2 2010
Oak Ridge, TN, USA
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1800
target plane

Physical parameters and loading conditions
Heat flux distribution at target position
(examples)
corresponding H/ He particle flux:
Heat load H: φ Η , [m -2 s -1 ] He: φ He , [m -2 s -1 ]
2 MW/m² 0.7 · 10 21 0.75 · 10 21
10 MW/m² 2.5 · 10 21 2 · 10 21
Calculated penetration depth of particles
H. Greuner, IPP Garching PMTS Workshop, Aug.31 –Sep.2 2010
Oak Ridge, TN, USA
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Current programme: Main achievements of component tests
W7-X: highly loaded divertor plates: (production ongoing)
• 15 m² target area, 900 actively cooled CuCrZr
elements,CFC NB31 covered, Σ 18,000 CFC tiles
60 prototypes tested, focused on reliability of CFC/Cu
interlayer, finally 99.4% of tested tiles w/o defects
• up to 10,000 cycles 10 MW/m², 10 s
• screening 32 MW/m², 30 s, and CHF tests 31 MW/m²
JET ILW: W Coatings on CFC (fibre-reinforced carbon)
• R&D and quality assurance for 50 m² inner wall
• Evaluation tests mainly performed in GLADIS
– Upscaling of VPS process to real size failed
– PVD W/Re multilayer caused problems
beam dump
target length 600 mm
W7-X Manufactured target test by (view PLANSEE from the (Austria) ion source)
10 µm thin W magnetron sputter coating on Mo interlayer,
150 mm
was finally selected
W-PVD coating on CFC during heat loading
• further physical investigation, carbide formation & brittleness, life-time…
H. Greuner, IPP Garching PMTS Workshop, Aug.31 –Sep.2 2010
Oak Ridge, TN, USA
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Investigation of W Plasma Facing Components for DEMO
Physics topics:
• Investigation of surface and bulk morphology modifications of W PFCs which have both,
high heat and simultaneous high particle loading similar to the expected ITER /DEMO
loading conditions primary H, He (5 – 100%), impurities N, Ar,..
Collaborations:
• EFDA topical group materials: investigation of W and W alloys
• KIT - He cooled W divertor: investigation of erosion, micro-cracks
Example of performed investigations in 2010:
focussed on He loading under divertor conditions
test of different manufactured W materials provided by IPP & FZJ
study of temperature and fluence dependence
Loading conditions: Φ= 1·10 24 – 3·10 25 He/m²
heat flux: 10 - 15 MW/m²
T surf = 600 - 1550°C (depending on height of sample)
H. Greuner, IPP Garching PMTS Workshop, Aug.31 –Sep.2 2010
Oak Ridge, TN, USA
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He beam loading of actively cooled component
Heat load distribution and resulting surface temperatures
Rolled plate
Rod Ø12 mm
Forged plate Rod Ø30 mm
Rod Ø80 1 2 3 mm 4 Rod Ø30 mm (POLEMA)
Rod Ø60 mm
cooling water
15 mm: 1550 °C
10 Height: mm: 1000 5 -15 °C mm
Temperature distribution:
15 mm W tile with 10 MW/m²,
12 m/s cooling water, 20°C,16bar
applied particle fluences:
tile 1, 4: loaded with 1· 10 24 He/m²
tile 2,3: loaded with 1· 10 25 He/m²
H. Greuner, IPP Garching PMTS Workshop, Aug.31 –Sep.2 2010
Oak Ridge, TN, USA
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Tsurf=200°C
Results: influence of surface temperature on erosion (1)
high fluence 1·10 25 He/m²
1 µm
note: 70 nm penetration depth
Tsurf=1000°C
calculated erosion: 5 µm
Low temperature: no bubble formation was observed
Tsurf ≥ 1000°C: strong bubble formation dominates erosion pattern
Tsurf=1450°C
Further investigation: confirmation of results, determination of “bubble start temperature”
H. Greuner, IPP Garching PMTS Workshop, Aug.31 –Sep.2 2010
Oak Ridge, TN, USA
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1 µm
1 µm
FIB cross-sections M.Balden

Results: influence of particle fluence on erosion (2)
constant surface temperature 1000°C
1·10 24 He/m²
calculated erosion: 0.5 µm
1 µm
No pronounced dependence on fluence
Surface degradation occurred after very low fluence
Balance between bubble formation and erosion rate
1·10 25 He/m²
H. Greuner, IPP Garching PMTS Workshop, Aug.31 –Sep.2 2010
Oak Ridge, TN, USA
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1 µm
calculated erosion: 5 µm
FIB cross-sections M.Balden

Summary He loading
Helium loading:
Morphology dominated by physical sputtering due to He.
For lower temperatures the erosion patterns depend on the local orientation of each individual grain.
T surf < 850°C Cone and wave structures for long pulses and high fluence, loss of micro particles
T surf 1000 – 1500°C Formation of sharp cone like structures; nano-sized bubbles inside cones
no pronounced dependence on fluence or surface temperature
T surf > 2000°C Formation of coral-like structures with depth of several µm
Conclusions:
• He bombardment modifies the surface stronger as expected
• results in higher erosion rate and possible dust production
• but: no catastrophic effects expected concerning lifetime of plasma facing material
• at present no consistent explanation of formation mechanism of all observed structures available.
Further investigations are necessary, especially effects of mixed H/He loading (in progress)
H. Greuner, IPP Garching PMTS Workshop, Aug.31 –Sep.2 2010
Oak Ridge, TN, USA
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Future technical capabilities
KIT: strong interest in cooperation for PF material investigations in the frame of
DEMO divertor development
• Advanced W based alloys developed by KIT,
• Armour material optimization of divertor modules
Proposed Upgrade to meet DEMO cooling conditions:
• Under discussion ~2011-2013
Hot He coolant loop:
• He loop: 130 g/s He flow, p=80 bar, 400-430°C
• vessel modifications, auxiliary equipment
He-cooled modular divertor
P.Norajitra, ICFRM 14
H. Greuner, IPP Garching PMTS Workshop, Aug.31 –Sep.2 2010
Oak Ridge, TN, USA
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Summary
• GLADIS is a well-characterized and reliable NB facility
• Sensitive diagnostics for both beams and samples during loading
• Operation with 2 independent beams allows superposition of various heat and
particle loading
• Investigation of small material samples as well as full-scale water-cooled
components complementary to linear plasma devices
• GLADIS embedded in IPP Materials Research division
• Additional material characterization expertise and equipment available
H. Greuner, IPP Garching PMTS Workshop, Aug.31 –Sep.2 2010
Oak Ridge, TN, USA
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