outline concept and system candidates

R & D Status of Lost Alpha Measurement- Development of Scintillators

M. Nishiura, M. Isobe, N. Kubo, T. Hirouchi,M. Sasao, K. Shinto, M. Okamoto, S. Kitajima, and S.V. Konovalov

NIFS, Tohoku Univ. and Kurchatov Institute

OUTLINE

Concept and System Candidates Location of Detection : the geometrical restriction

and orbits of escaping alpha particles Development of Ceramic Scintillation materials Summary and Future work

2/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao

Concept and System Candidates

Candidates of Measurement Tools

Points- measurement : Energy and pitch-angle resolved

Faraday-cup detectors,

Scintillator probes,

Bolometric Imaging (Peterson et al.)

Loss imaging:

IR camera imaging,

Camera imaging of scintillators on the FW

Gamma Ray (Kipty et al.)


Sensors

(1) selective sensitivity to alpha particles,

(2) low sensitivity to other ions, neurons, electrons

(3) stable at high temperature (~ 700 K),

(4) wide dynamic range and linearity,

(5) mechanical endurance under conditions of high temperature

and radiation exposure.

Signal types and transfer-methods should be considered.

Faraday-cup detectors - current (micro A-mA)

Scintillator probes - 400 - 600 nm

Bolometric Imaging (IR)

Loss imaging:

IR camera imaging (IR)

Camera imaging of scintillators on the FW - 400 - 600 nm

Requirements to the System


Location of Detection : the geometrical restriction

FW CeramicSchintillator

The CAMERAupper port 11

viewing

Camera imaging:The upper port 11 is used for the viewing camera, and the ceramic scintillators are fixed using blanket gaps and slit, or extra shallow pits.

Probes : better to be installed on the bottom of the port plug.

Probes (FC, Schintillator,Bolometric)

180200220240260280Θ0510152025

Heat Load (kW/m2)

H

eat L

oad

(kW

/m2 )

#16 #17port


Be

FW

alpha

viewing

Ceramic

Schintillator

EXAMPLE A:

Ceramic Schintillators are fixed in holes on the top end of FW (Cu backing) of the BM #17 and view from the upper port camera.

A

Location of Detection : the geometrical restriction

A

X


Orbit calculation for Detector position A

-3

-2

-1

0

1

2

3

4

5 6 7 8 9 10

r10AFW.dat_11.56 8:13:49 PM 05.11.6

R (m)

Drift Orbits of pitch angle (-π/2 0)to

Detector Position

First wall

The detector position A, is not good, by two reasons.1) Drift orbits might not touch the wall surface ? (should be confirmed ).2) The poloidal angle of the lost position is not the best

-2.2

-2

-1.8

-1.6

-1.4

-1.2

7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 8

r10AFW.dat_11.56 8:13:49 PM 05.11.6

R (m)

Drift Orbits of pitch angle (-π/2 0)to

Detector Position

First wall

(-Drift Orbits of pitch angle π/2 0)to

AA

A


-3

-2

-1

0

1

2

3

4

5 6 7 8 9 10

Z (m)

R (m)

Detector

Position

B

First wall

Drift Orbits of pitch angle (- π /2 0)to

Orbit calculation for Detector position B

Detector position B :Moving upward poloidally along the slits on the BM #16, drift orbits cover wider area of returning position. Those might be suitable to observe the MHD loss.There might be possibility to observe alpha losses with probes on the bottom of port plug.However, the coverage of wider area of poloidal angle is needed as the basic understanding.

Extra Holes


Development of Ceramic Scintillation materials

Two applications

Scintillator probes Camera imaging of scintillators on the FW

The required properties of a scintillation plate to be used on ITER are as follows:

• high sensitivity to alpha particles,

• low sensitivity to other ions, neurons, electrons, gamma rays,

• stable emission at high temperature (~ 700 K),

• Wide dynamic range and liniearity,

• mechanical endurance under conditions of high temperature and radiation exposure.

• No-irradiation damage

It had been known that the sensitivity of ceramic scintillator diminishes under high temperature, above 100o C.

The characteristics of ceramic sheets in which scintillation materials are blended have been tested.


Scintillation materials Center

wavelength (nm)

Sensitivity NaI:Tl =100

Decay time

Remarks

YAG:CeÅiP46Åj 550 5 70ns

Diminish above 200Åé

ZnS:AgÅiP11/P22Åj 455 25 10-80 ms

Diminish above 200Åé

Almost no emission at 300ÅéÅD

YAG:DyÅiYAG:EuÅj 585 (595,611)

10 -20 ms

Al2O3:Cr 649

Diminish linearly as the temperature increase. Almost no emission at 300Åé

Y2O3:Eu(P56) 611

1 ms -1ms Almost constant up to 300Åé

Gd2SiO5:Ce(GSO) 430 2.5-20 30-60ns

Gd2O2S:Pr,Ce,F Ceramics

510 13 3 ms

Comparison of Scintillation materials


• Mix scintillation materials, ceramic bond, and H2O

• Dry in room temperature• Baking in vacuum at T>150 ℃

Y3Al5O12:Ce ※ceramic bond

Y3Al5O12:Ce

Scintillation plates

Fabrication of ceramic-like Scintillation plates

The reference : ZnS(Ag) which is deposited on the glass plate is tested. LHD lost ion probe uses this type.


Irradiation experiment at 4.5 MV-Dynamitron(FNL) at Tohoku Univ.

• Bombardment by p, 4He, at 1- 100 nA

• Irradiation stage is equipped with – Optical Fiber head to a spec

trometer (PM-1)– FC, CCD camera– Heaters, thermo-couples

4.5MV-Dynamitron

ScintillatorHeater and thermo couple

Spectrometor

Beam transport line

Scinntillator test chamber

Scintillator test chamber


Results from 3MeV H+, He+ Beam bombardment

Experimental results for the ceramic-like scintillators - preheated at 150 ℃

• The linearity of the emission intensity to the beam influx is good up to > 4x1012 ions/(cm2 s). Typical influx expected at ITER is ranging in 1012 ~ 1014 ions/(cm2 s)

• But the degradation was observed soon after one minute beam irradiation.

Typical video image for Y3Al5O12:Ce with Aron ceramic

60x103

50

40

30

20

10

0

Counts

5004003002001000

Substrate temperature (ºC)

Y3Al5O12:Ce with Aron ceramic

H+ 30nA

Beam intensity changed.

12x103

10

8

6

4

2

0

Counts

200150100500

Beam current (nA)

5x1012

43210He

+flux (ions/(cm

2s))

Y3Al5O12:Ce with Aron ceramic

Synergetic Effect of

Temperature and Irradiation


Irradiation damage of YAG:Ce and ZnS:Ag at the room temperature

Before beam irradiation, the heat treatment up to 450 ºC had been carried out for two hours.

YAG:Ce•He+ beam current (nA) 36.50,◇ □37.10,

37.05, 36.65,△ ◇ □34.25, 35.6, 35.25,△ ◇ □35.75•Flux ~1.8x 1012 ions/(cm2 s)

•The substrate temperature keeps constant at 17 ºC during the beam irradiation.

ZnS:Ag•He+ beam current (nA) 34.25,◇ □36.00,

36.50, 34.00△ ◇• room temperature

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

0 20 40 60 80 100 120 140 160

è∆éÀéûä‘(min)

ÉsÅ[ÉNÉJÉEÉìÉgêî(cts)

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

0 5 10 15 20 25 30

è∆éÀéûä‘ (min)

ÉsÅ[ÉNÉJÉEÉìÉg

êî(cts)

YAG:CeYAG:Ce

ZnS:AgZnS:Ag

Irradiation time (min.)

Irradiation time (min.)0

0 160

30


Effect of pre-heating treatment on the irradiation degradation.

Before beam irradiation, the heat treatment up to 450 ºC had been carried out for two hours.

•From above equations, the time constant of the degradation can be obtained as wo=77, and w=100.

•After a year operation, t=107/60 min, the intensity degradation with baking becomes smaller than that without baking. It is found that the emission intensity becomes 0.33 of the original.

6x104

5

4

3

2

1

0

Counts

16012080400

Time (min.)

3MeV He+ 30nA

w/o baking with baking

1.0

0.8

0.6

0.4

0.2

0.0

Normalized intensity

16012080400

Time (min.)

3MeV He+ 30nA

w/o baking with baking

YAG:Ce withAaron ceramic

( )twoInt 013.0exp8.019.0_ −+=

( )twInt 01.0exp72.033.0_ −+=


Dependence of emission for YAG:Ce and ZnS:Ag on temperature

YAG:Ce•450 ºC, two hours baking before experiments

ZnS:Ag•400 ºC, two hours baking before experiments•He+ beam current (nA) ◇38.00,□36.50,△36.00 •After the irradiation, the degradation of the fluorescent intensity is observed.

0

5000

10000

15000

20000

25000

30000

35000

0 100 200 300 400 500 600

â∑ìx (Åé)


êî(cts)

0

5000

10000

15000

20000

25000

0 100 200 300 400 500 600

â∑ìx (Åé)


êî(cts)

YAG:CeYAG:Ce

ZnS:AgZnS:Ag

Present dataFrom Z. Lin et al. PPPL TM392


Summary and Future work

Studies of ITER integration for several systems are started.

Ceramic-like schintillation-material can be fixed in shallow pits on the FW, and viewed from the upper port camera of #11.

Probes for energy and angle-resolved measurement, Faraday-cup detectors, scintillator probes, Bolometric Imaging detectors can be installed in the bottom of diagnostic ports.

Full-gyro orbit calculations including realistic detector designs and detailed 3D FW shapes, are needed, and now under preparation.

The ceramic schintillators newly developed were tested with 1-3 MeV alpha beam and the linearity of the emission intensity to the beam influx is good up to > 4x1012 ions/(cm2 s).

Typical influx expected at FW of ITER is ranging in 1012 ~ 1014 ions/(cm2 s)


Summary and Future work

The ceramic schintillators newly developed were tested with 1-3 MeV alpha beam. The test under high temperature shows that the efficiency of some ceramic schintillators does not change on temperature upto 300 ºC, but changes by dose accumulation.

Irradiation effect is large for ZnS:Ag, but less for a ceramic-like schintillators of YAG:Ce, and it becomes stronger by preheating treatment.

->One year operation of ITER corresponds to continuous bombardment of flux of 1

40 min.:1.8x 1012 ions/cm2 /s, total fluence:9x1017 ions/(cm2) ． Our present experimental test showed that degradation of emission efficiency of a ceramic-like schintillators of YAG:Ce is less than 33%. A experiment to test improvement by heating recovering treatment is planned.

outline concept and system candidates

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