fast ion collective thomson scattering diagnostic for iter s.b. korsholm 1,2, h. bindslev 1, f....

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


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


ITER measuring requirements for fast ions

m-3

m-3


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.


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.


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?


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

http://efdasql.ipp.mpg.de/saibene/ITER_Eq_Restricted/equilibria_index.htm




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

| || || || || |

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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


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

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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


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

| || || |

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Standard H-modeReversed shear (neo * 1.4)

Main cause: Different plasma location


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


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


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


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


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


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


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


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


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


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


4-mirror HFS CTS receiver integrated into the ITER blanket

Location of the mirrors

Top view of blanket cut-out


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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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


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


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


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)


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


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:


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


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


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


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


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




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


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


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


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


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




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


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


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


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


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


fast ion collective thomson scattering diagnostic for iter s.b. korsholm 1,2, h. bindslev 1, f....

Documents

itpa diagnostics meeting

calculations iter requirements

iter measuring potential

cts system

cts future work slide

hfsfs system

mirror hfs receiver

lfsbs system