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Trilateral Euregio Cluster
TEC
Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich
Development of in situ diagnostic for fuel retention, material deposition and dust detection
in ITER
A. Huber (project leader), B. Schweer, F. Irrek S. Brezinsek, V. Philipps, G. Sergienko,
Ph. Mertens, W. Biel
Trilateral Euregio Cluster
TEC
Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich
Urgent need to develop in situ diagnostic for fuel retention, material deposition and dust production generation, recognised by ITER (design change request Nr: )
Proper gas balance should be a main method to measure fuel retention in a global way
No further information from post mortem tile analysis
Development of in situ laser based methods for fuel retention, material deposition and dust production to
• support gas balance and enable (some) space resolution
• determine amount and composition of material deposition (correlation with gas balance)
• allow dust detection near deposition dominated areas
Idea: develop a single laser and mirror based system for all 4 methods which can scan some part of inner
wall/divertor area in ITER
Methods
During discharges
Smooth (≈ 1 ms) laser desorption with spectroscopy to measure fuel retention
Laser ablation with spectroscopy to measure material deposition
Rayleigh / Mie scattering for dust monitoring
In-between discharges
Laser-induced breakdown spectroscopy (LIBS) for material deposition and composition
TEC
Strategy: a Nd:YAG laser operating with/without Q-switch
Operating modes
Laser-induced desorption
(LID):
Laser without Q-switch
at 1064 or 532 nm;
Pulse duration: up to 3 ms;
Total energy: up to 120 J.
Rayleigh/Mie scattering:Laser without Q-switch
at 1064 or 532 nmPulse duration:
up to 10 ms
Total energy: up to 120 J.
Laser-induced Ablation (LIA):
Laser with Q-switch at 532 nm;
Pulse duration:
up to 10 ns;
Total energy: 5 J.
Laser-induced Breakdown Spectroscopy (LIBS):
Laser with Q-switch at 532 nmPulse duration: up to 10 ns;
Total energy: 5 J.Operation without plasma
TEC
Movable target holder
Quadrupol MS
Fast IR linear array
camera
Fiber coupling
TEXTOR Tokamak
Laboratory Device
YAG Laser
Limiter lock system 1
Optical diagnostic D (H/D ratio) D, Dγ, CD CII, CIII
Pulse duration: 0.1-20ms
Spot size : 4-20 mm2
Power density: 20-120 kW/cm2
Status of work : laser induced desorption TEC
Laser-Spot
( a-C:D on Graphite)
0.0 0.4 0.80
1000
2000
Te
mp
era
ture
T /
°C
Radius r / mm
calculatedradial Temperatureafter
1 ms x 80 kW/cm2
SpotRadius
Mean power Density: 95 kW/cm2
SIMS: 96% Reduction of D-Inventory,
Hig
her
P,
t
0.0 0.5 1.0 1.5
0.0
0.5
1.0
1.5
0
500
1000
1500
Temperature
2nd Shot
1st Shot
Num
ber
of R
elea
sed
Mol
ecul
es /
10
15
t / ms
Tem
pera
ture
T /
°C
Mass 4
Closed valves
180 nm a-CH layer on graphiteTECThermal desorption: qualification in Lab experiments
Graphite EK98 target exposed to TEXTOR plasma, LDS measured
45 nm (2.2x1017 H/cm2), ±30%
Laser-desorption of pre-coated samples for calibration
TEC
LID has been qualified in TEXTOR to measure in situ and shot by shot
fuel retention in C materials ( PSI contribution)
Application in TEXTOR with H Spectroscopy
Sample surface at 48 cm 49 cm 50 cm
Application in TEXTOR with H Spectroscopy
46
47
48
49
50Rad
ial P
ositi
on r
/ cm
Rad
ial P
ositi
on r
/ cm
Rad
ial P
ositi
on r
/ cm
5130 50405060
FWHM: 3.3 cm FWHM: 5.3 cmFWHM: 2.0 cm
46
47
48
49
50
46
47
48
49
50
Quantification of H light needs large optical view
Good agreement with S/XB literature values for r < 49 at TEXTOR
LCFS
Plasma
Experimental setup: limiter lock III
Ablation: qualification in TEXTOR
ALT- II Limiter,r=46.0cm
Plasma
Spectrometer
2D spectroscopyFilters:D (656.3 nm)CII (426.7 nm)WI (400.8 nm)
C-W Twin Limiter can be rotated
Plasma
He-Ne Laser
Amplifiers
Telescope
Pwith Q-switcht=20ns Q=20J
mirror
TEC
r = 48 cmSspot= 0.3 cm2
TEC
Trilateral Euregio Cluster
Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich
Tungsten test limiter with
140 nm a-C:D coating
Tungsten substrate
Second laser shotr = 50 cmSspot= 0.16 cm2First laser shot
580 600 620 640 660 6800
100
200
300
400
500
600
CII(678.4nm)
CII(658nm)H(656nm)CII(589nm)
inte
nsity
/ a
.u.
wavelength / nm
r = 48 cmSspot= 0.4 cm2
Ruby Laser (20 J max) in 20
ns time scale
Ablation: qualification in TEXTOR
larger laser spot
reduced spot, same power
Ti melting
TEXTOR test limiter (Ti), coated
by Textor plasma
For C-layers deposited on W and Ti, an operational window exits for complete C layer ablation (one laser shot) without ablation of substrate
TEC
TECSummary
Laser fuel desorption and material ablation with spectroscopic detection in TEXTOR standard plasmas has been sufficiently qualified in TEXTOR
Next steps: Conceptual design of a system for possible ITER application (2008)
Procurement of a laser with ≈ 120 J for ≈ 10 ms. Manufacture of beam line and detection (2009)
Testing of the system in the laboratory (2010)
Installation and testing of the system in a fusion plasma 2011 (e.g. TEXTOR)