Post on 30-Dec-2015
description
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.)
3/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
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
4/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
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
5/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
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
6/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
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
7/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
-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
8/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
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.
9/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
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
10/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
• 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.
11/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
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
12/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
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
13/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
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
14/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
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_ −+=
15/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
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)
ÉsÅ[ÉNÉJÉEÉìÉg
êî(cts)
0
5000
10000
15000
20000
25000
0 100 200 300 400 500 600
â∑ìx (Åé)
ÉsÅ[ÉNÉJÉEÉìÉg
êî(cts)
YAG:CeYAG:Ce
ZnS:AgZnS:Ag
Present dataFrom Z. Lin et al. PPPL TM392
16/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
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)
17/1410th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
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.