fast ion collective thomson scattering diagnostic for iter s.b. korsholm 1,2, h. bindslev 1, f....
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Fast ion collective Thomson scattering diagnostic for ITER
S.B. Korsholm1,2, H. Bindslev1, F. Leipold1, F. Meo1, P.K. Michelsen1, S. Michelsen1, A.H. Nielsen1, E. Tsakadze1, and P.P. Woskov2
1 Association EURATOM-Risø National Laboratory, Technical University of Denmark2 MIT Plasma Science & Fusion Center
This work was supported by the European Communities under the contract of Association between EURATOM/Risø and carried out within the framework of the European Fusion Development Agreement [under EFDA Contract 04-1213 and EFDA Task TW6-TPDS-DIADEV.D2]. The views and opinions expressed herein do not necessarily reflect those of the European Commission.
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Outline of the talk
• ITER measurement requirements for confined fast ions
• Overview of the 60 GHz CTS diagnostic for ITER
• Measuring potential in alternative scenarios
• Modeling and measurements of the required HFS blanket cut-out
• Current state of design – a four mirror HFS receiver
• Robustness to misalignment
• Measurements of fuel ion ratio and bulk ion drift velocity by CTS
• Future work
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Tools developed and used in the studies
Scattering calculationsITER requirements for ’s
CEMFinite difference
code
Vertical beam properties
Gauss3D
Horizontal beam properties
Design of mirrors
Mock-up
Measured beam properties
Design of gap
Current memory
limitations
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
ITER measuring requirements for fast ions
m-3
m-3
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Schematic of the scattering geometry – LFS-BS
ki ks
k
B
(a) (b)
ki ks
k
B
ki ks
k
B
(a) (b)
The LFS-BS system resolves the perpendicular ion velocity component.
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Schematic of the scattering geometry – HFS-FS
Receiver
Probe B
ks
ki
k
Receiver beam
Probe beam
The HFS-FS system resolves the parallel ion velocity component.
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Capabilities of the 60 GHz CTS system
• Using current or near term technology, it meets ITER measurement requirements for fusion alphas
• Robust mechanically – no moveable components
• Simultaneous measurements of 10 positions for each system
• For the ELMy H-mode scenario within the engineering constraints, a previous study demonstrated:
• Requirements met at different plasma parameters
• Sufficient beam overlap in the spectral range (dispersion effects).
• Robustness of the overlap against variations of density such as sawteeth
• Robustness of the localization of the measurement against variations of density such as sawteeth
• Operation in alternative scenarios?
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Measuring potential in reversed shear scenario
Parameter Standard H-Mode Reversed shear
Bo (T) -5.3 -5.425
Ne(0) (m-3) 10.24 1019 7.27 1019
Te(0) (keV) 24.7 23.9
Rmag (m) 6.41 6.66
Zmag (m) 0.68 0.52
Ip (MA) 15 9
N 1.842 2.567
p 0.661 1.529
ITER operating scenario database
0 0.5 1 1.50
2
4
6
8
10
12
Normalized flux coordinate
Ele
ctro
n d
en
sity
(1
019 m
-3)25
Elmy H-modeReversed shear
0 0.5 1 1.50
5
10
15
20
Normalized flux coordinate
Ele
ctro
n t
emp
erat
ure
(k
eV)
http://efdasql.ipp.mpg.de/saibene/ITER_Eq_Restricted/equilibria_index.htm (password protected), Yuri Gribov, website maintained by Gabriella Saibene
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Measuring potential of HFS receiver – ELMy H-mode
4 4.5 5 5.5 6 6.5 7 7.5 8 8.50
1
2
3
4
5
6
7
8
R (m)
L/4
| || || || || |
| || || |
| || |
| || || |
| |
| |
| |
| || || |
| |
DS: 0.4DS: 0.7DS: 1.0DS: 1.2
DS: 0.4 (neo = 4.10 1019 m-3)DS: 0.7 (neo = 7.17 1019 m-3)DS: 1.0 (neo = 10.24 1019 m-3)DS: 1.2 (neo = 12.29 1019 m-3)
ITER CTS: Scenario 2 (ELMy H-mode)L is the resolving power, i.e. the system figure of merit.
L/4 ≥ 1 ⇒ 16 velocity bins
Pin = 1 MW
Integration time: 20 ms
ECE noise 200 eV
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Measuring potential of HFS receiver – reversed shear
4 4.5 5 5.5 6 6.5 7 7.5 8 8.50
1
2
3
4
5
6
7
8
R (m)
L/4
| || || || || |
| || |
| || || |
| || |
| |
| || |
| || |
| |
| |
| |
DS: 0.4DS: 0.7DS: 1.0DS: 1.2
DS: 0.4 (neo = 2.91 1019 m-3)DS: 0.7 (neo = 5.09 1019 m-3)DS: 1.0 (neo = 7.27 1019 m-3)DS: 1.2 (neo = 8.72 1019 m-3)
ITER CTS: Scenario 4 (Weakly reversed shear)
Pin = 1 MW
Integration time: 20 ms
ECE noise 200 eV
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Comparing effects of scenarios on HFS receiver - scaled ne
4 4.5 5 5.5 6 6.5 7 7.5 8 8.50
1
2
3
4
5
6
7
8
R (m)
L/4
| || || |
| |
| |
| || || |
| |
| |
Standard H-modeReversed shear (neo * 1.4)
Main cause: Different plasma location
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Modification of the LFS port plug
• Taking into account more detailed engineering constraints
• Minor changes in mirror locations ⇒ no significant changes in scattering calculations
• Small cut of the welding edge of the port plug front plate frame
HFS-FS probe 1st mirror
Plug front plate (edge region)
Plug front plate anchor point
LFS-BS Probe1st mirror
LFS-BS Probe2nd mirror
HFS-FS Probe2nd mirror
LFS-BS Horn array
LFS-BS receivermirror
Fuel Ion RatioHorn array
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Challenges of the HFS-FS receiver
• Receiver quasi-optics located behind HFS blanket modules
• Integration issues
• Spatial constraints
• Very astigmatic beams
• Detected signal transmitted in in-vessel waveguides (via upper port)
• Similar challenges to the HFS reflectometer
• Opening angle of the beam determined by height of
slit/blanket cut-out.
• Direct implication to the CTS signal
• Feasibility study: To satisfy measuring criteria
≤ 7° h = 30 mm⇒
3 4 5 6 7 8 9 10
-5
-4
-3
-2
-1
0
1
2
3
4
5
R / m
z / m
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Mock-up Mark I of the ITER HFS CTS receiver at Risø
Quasi-optical
emitterhorn
Measuring rig
Detector
emitterhorn
mirror
Emitterhorn
Blanket modules
• Non-astigmatic mirrors
• problem is split up in horizontal and vertical ⇒ two sets of mirrors
• Goals:
• verify vertical opening angle calculations
• study effect of horizontal cut-out
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Opening angle of HFS receiver beam – measurements
h = 30 mm ⇒
= 7.5° (7 °)
h = 20 mm ⇒
= 9.4° (10.5 °)
-15 -10 -5 0 5 10 15-15
-10
-5
0
5
10
15051005-25L3h30d350
Horizontal (cm)
Ver
tical
(cm
)
Wy= 38 mm
-15 -10 -5 0 5 10 15-15
-10
-5
0
5
10
15051005-27L3h20d350
Horizontal (cm)
Ver
tical
(cm
)
Wy =45 mm-15 -10 -5 0 5 10 15
-15
-10
-5
0
5
10
15051004-14L2h20d350
Horizontal (cm)
Ver
tical
(cm
)
-15 -10 -5 0 5 10 15-15
-10
-5
0
5
10
15051004-18L2h30d350
Horizontal (cm)
Ver
tical
(cm
)
Wy =90 mm
Wy= 111 mm
Distance from blanket1,1 m 1,8 m
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Blanket cut-out for the HFS receiver – top view
First Mirror
Blanket module key
Beams (extreme cases)
Blanket #3 Blanket cut-out
First Mirror
Blanket module key
Beams (extreme cases)
Blanket #3 Blanket cut-out
Width front = 580 mmWidth back = 410 mm
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Blanket cut-out for the HFS receiver – front view
Blanket Cut-out Height = 28 mmWidth front = 580 mmWidth back = 410 mm
Spacer (in yellow )= 8 mm
Vertical Gap = 10 mm
Blanket #4
Blanket #3
Blanket Cut-out Height = 28 mmWidth front = 580 mmWidth back = 410 mm
Spacer (in yellow )= 8 mm
Vertical Gap = 10 mm
Blanket #4
Blanket #3
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
ITER CTS HFS receiver mock-up Mark II - Astigmatic mirrors
• Upgrade of codes to calculate 3D astigmatic mirrors
• 2-mirror mock-up with astigmatic mirrors
• to study astigmatic beams and compare to code
• to study propagation of off-axis beams
Side view
Zoom on cut-out
Front view
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Results of ITER CTS mock-up Mark II – beam propagation
Distance from blanket: 180 cmDistance from blanket: 64 cm
-10 -5 0 5 10-30
-25
-20
-15
-10
-5
0
5
10
Distance (cm)
Dis
tanc
e(cm
)
ITER061108-02f200c41D000.txt
( xc, yc ) = ( 0.04, -9.04 )P = ( 1.00, 0.02 ), W = 2.13P = ( 0.02, -1.00 ), W = 13.43
-10 -5 0 5 10-30
-25
-20
-15
-10
-5
0
5
10
Distance (cm)
Dis
tanc
e(cm
)
ITER061108-12f200c41D000.txt
( xc, yc ) = ( -2.23, -6.98 )P = ( 0.99, 0.13 ), W = 3.64P = ( 0.13, -0.99 ), W = 4.61
Note that numbers in graphs are dimensions in 110 GHz frame (which is the frequency of source)
60 GHz frame
0 0.5 1 1.520
25
30
35
40
45
50
55
Distance (m)
Bea
m r
adiu
s(m
m)
No plate, x
W0= 20.73(mm)
Z0=1107.89(mm)
Angle= 2.40
0 0.5 1 1.520
25
30
35
40
45
50
Distance (m)B
eam
rad
ius(
mm
)
Horizontal
W0= 20.91(mm)
Z0=1078.11(mm)Angle= 2.38
0 0.5 1 1.50
50
100
150
200
250
Distance (m)
Bea
m r
adiu
s(m
m)
No plate, y
W0= 6.51(mm)
Z0=-25.86(mm)
Angle= 7.63
0 0.5 1 1.50
50
100
150
200
250
Distance (m)
Bea
m r
adiu
s(m
m)
Vertical
W0= 6.22(mm)Z0= 35.48(mm)Angle= 8.00
Fit
Theory
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Shortcomings of 2-mirror receiver
Studies showed that 2-mirror systems have
• very astigmatic beams ⇒ distortion of off-axis beams
• large degree of focusing ⇒ very sensitive to misalignment
Mirror #2
Horns
Cooling manifold
Mirror #1
Fund. Wave-guides
Blanket Module key
Beam
Mirror #2
Horns
Cooling manifold
Mirror #1
Fund. Wave-guides
Blanket Module key
Beam
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
ITER CTS HFS mock-up Mark III – 4-mirror receiver
• 4-mirrors ⇒ less focusing
• less sensitive to misalignment
• Realistic geometry / Actual antenna mock-up
• Currently being produced in 1:1 scale, i.e. for 60 GHz source
• Goals are to:
• demonstrate an engineering solution to the HFS CTS antenna
• study misalignment
• investigate different horn configurations etc.
• measure the throughput
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
4-mirror HFS CTS receiver integrated into the ITER blanket
Location of the mirrors
Top view of blanket cut-out
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Effects of misalignment – CEM modeling and scattering calc
4 4.5 5 5.5 6 6.5 7 7.5 80
1
2
3
4
5
6ITER CTS
R (m)
L/4
| || |
| || || |
| || || || |
| |
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| |
| |
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| |
| |
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| || | | || || || || |
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rec : 6rec : 4rec : 2rec : 0rec : -2rec : -4rec : -6
Plasma center +
Vertical receiver misalignment: DS = 1.0
Slit height = 6λ = 30 mm
Aligned beam 4° tilt of beam
Scattering calculations predict:
Vertical misalignment of receiver is less sensitive than for the probe
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Additional measurements – fuel ion ratio
• Similar but separate LFS receiver (same aperture)
• Same probe or separate low power probe – 10 kW
• Temporal resolution of 100 ms
• Limited influence of impurity content
• Could be tested on TEXTOR or ASDEX Upgrade
Zeff 1.82 2.37 4.60
σRi 0.146 0.151 0.138
LFS probe transmission line
LFS receiver transmission line
Horn array
WaveguidesMitre bends
Quasi-opticalmirrors
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Additional measurements – bulk ion drift velocities
• Toroidal bulk ion drift velocity
• readily obtained from the HFS-FS fast ion CTS system
• uncertainty approximately 20 km/s
• Poloidal bulk ion drift velocity
• needs a separate probe and receiver - vertically off-set
• low power probe – 10 kW
• uncertainty approximately 4.5 km/s
• little dependence of impurities
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Future work
• EFDA task TW6-TPDS-DIADEV: Effects of RF- and NBI-generated fast ions on the measurement capability of diagnostics
• Modeling of increased neutron flux
• EFDA task TW6-TPDS-DIASUP: ITER CTS 2007
• Propose a comprehensive outline plan for the full development of the CTS diagnostic for ITER
• engineering designs for both the HFS receiver system and the port-mounted components
• critical issues: • limited space
• nuclear heating
• neutron streaming
• thermal mechanical studies (misalignment)
• waveguides and feed-throughs (collaborate with reflectometry team)
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Summary
• A number of design and test tools have been developed
• a series of mock-ups
• finite difference codes
• 3D astigmatic Gaussian beam codes for mirror shapes
• Key design criteria confirmed
• Blanket cut-out for HFS receiver
• Potential further development of the diagnostic to measure
• fuel ion ratio
• toroidal and poloidal bulk ion drift velocity
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
The resolving power L
• The resolvong power L, is a measure of the information of the fast ion velocity distribution, independent on number of nodes
• Unitless by normalizing with the target accuracy • L2 is approximately the number of nodes resolved with the target
accuracy (provided uncertainties at all nodes are independent)
• 16 nodes ⇒ L > 4 ⇒
60 GHz HFS-FS:
60 GHz LFS-FS:
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Opening angle of HFS receiver beam – calculation
Near field
Gaussian half width – far field
Feasibility study:
2D full wave calculations of the beam pattern through a slit.
Asymptotic opening angle:
To satisfy measuring criteria:
≤ 7° ⇒ h = 30 mm
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Vertical distance between blankets = 14 mm
Probe f (GHz): 60
Rec f (GHz): 60
L/4 Tnoise (eV): 200
Probe Y: 0.798
Probe : 195
Probe : 94.79
Probe diam: 0.200, 0.200
rec diam: 0.350, 0.014
Probe f (GHz): 60
Rec f (GHz): 60
L/4 Tnoise (eV): 200
Probe Y: 0.798
Probe : 195
Probe : 94.79
Probe diam: 0.200, 0.200
rec diam: 0.350, 0.014
Probe f (GHz): 60
Rec f (GHz): 60
L/4 Tnoise (eV): 200
Probe Y: 0.798
Probe : 195
Probe : 94.79
Probe diam: 0.200, 0.200
rec diam: 0.350, 0.014
4 4.5 5 5.5 6 6.5 7 7.5 80
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5ITER CTS
R (m)
L/4
Probe f (GHz): 60
Rec f (GHz): 60
L/4 Tnoise (eV): 200
Probe Y: 0.798
Probe : 195
Probe : 94.79
Probe diam: 0.200, 0.200
rec diam: 0.350, 0.014
DS: 0.4DS: 0.7DS: 1.0DS: 1.2
3 4 5 6 7 8 9 10
-5
-4
-3
-2
-1
0
1
2
3
4
5
R / m
z / m
Vertical distance between blankets = 14 mm
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Vertical distance between blankets = 20 mm
3 4 5 6 7 8 9 10
-5
-4
-3
-2
-1
0
1
2
3
4
5
R / m
z / m
Probe f (GHz): 60
Rec f (GHz): 60
L/4 Tnoise (eV): 200
Probe Y: 0.798
Probe : 195
Probe : 94.79
Probe diam: 0.200, 0.200
rec diam: 0.350, 0.020
Probe f (GHz): 60
Rec f (GHz): 60
L/4 Tnoise (eV): 200
Probe Y: 0.798
Probe : 195
Probe : 94.79
Probe diam: 0.200, 0.200
rec diam: 0.350, 0.020
Probe f (GHz): 60
Rec f (GHz): 60
L/4 Tnoise (eV): 200
Probe Y: 0.798
Probe : 195
Probe : 94.79
Probe diam: 0.200, 0.200
rec diam: 0.350, 0.020
4 4.5 5 5.5 6 6.5 7 7.5 80
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5ITER CTS
R (m)
L/4
Probe f (GHz): 60
Rec f (GHz): 60
L/4 Tnoise (eV): 200
Probe Y: 0.798
Probe : 195
Probe : 94.79
Probe diam: 0.200, 0.200
rec diam: 0.350, 0.020
DS: 0.4DS: 0.7DS: 1.0DS: 1.2
Vertical distance between blankets = 20 mm
ITPA Diagnostics Meeting, Princeton, March 26 - 30, 2007
Vertical distance between blankets = 30 mm
3 4 5 6 7 8 9 10
-5
-4
-3
-2
-1
0
1
2
3
4
5
R / m
z / m
Probe f (GHz): 60
Rec f (GHz): 60
L/4 Tnoise (eV): 200
Probe Y: 0.798
Probe : 195
Probe : 94.79
Probe diam: 0.200, 0.200
rec diam: 0.350, 0.030
Probe f (GHz): 60
Rec f (GHz): 60
L/4 Tnoise (eV): 200
Probe Y: 0.798
Probe : 195
Probe : 94.79
Probe diam: 0.200, 0.200
rec diam: 0.350, 0.030
Probe f (GHz): 60
Rec f (GHz): 60
L/4 Tnoise (eV): 200
Probe Y: 0.798
Probe : 195
Probe : 94.79
Probe diam: 0.200, 0.200
rec diam: 0.350, 0.030
4 4.5 5 5.5 6 6.5 7 7.5 80
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5ITER CTS
R (m)
L/4
Probe f (GHz): 60
Rec f (GHz): 60
L/4 Tnoise (eV): 200
Probe Y: 0.798
Probe : 195
Probe : 94.79
Probe diam: 0.200, 0.200
rec diam: 0.350, 0.030
DS: 0.4DS: 0.7DS: 1.0DS: 1.2
Vertical distance between blankets = 30 mm
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