Target R&D for the J-PARC neutrino
experiment (II)
Yoshinari Hayato (KEK/IPNS)for the J-PARC target R&D group
Temperature rise estimation (simulation input parameters)Target size 30mm φ x 900mm L
Energy deposit 58kJ/spill
Maximum energy deposit 185.9J/g
Distribution of the energy deposit
z
r
6.5kW/m2/KHeat transfer rate @ surface25oCTemperature @ surface (environment)
Temperature rise estimation (simulation input parameters)
Material IG-43 (Toyo Tanso)density 1850kg/m3
Temperature dependent material parametersThermal conductivitySpecific Heat
0 200 400 600 800 1000 1200 0 200 400 600 800 1000 1200
500
1000
1500
2000
(J/kg/K) (W/m/K)
20
60
100
Temperature (oC) Temperature (oC)
Temperature rise estimation (simulation input parameters )Time structure : for the detailed study, two patterns were simulated.
30.78 34.20.42
Hea
t Loa
d 1 2 3 4 10 11 12
0 3 6.84 10.26Time (sec)
37.62
averaged 8spills/bunch
5µs
598ns
58ns
Temperature rise estimationresults : (I) distribution in the target
relative temp. from 25oCjust before the 11th spill
r
just after the 11th spill
z Maximum Temperature : 45oC
Maximum Temperature : 236oC
r
z
図 グラファイトターゲットの温度変化
0
50
100
150
200
250
300
0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0
経過時間(sec)
温度
(℃
)
中心軸最高温度部
外表面最高温度部
C1C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12
50
100
150
200
250
(oC)
Maximum temperature at the center
Maximum temperature on the surface
図 グラファイトターゲットの温度変化(C12初期)
0
50
100
150
200
250
300
37.619999 37.620000 37.620001 37.620002 37.620003 37.620004 37.620005 37.620006
経過時間(sec)
温度
(℃
)
中心軸最高温度部
外表面最高温度部
50
100
150
200
250
(oC)
37.62000 37.62002 37.62004 (sec.)
0 5 10 15 25 3020 35 40 (sec.)
Temperature rise gradually decreasedbecause of the temp. dependence of Cp.
Temperature is saturatedin a few spills.
236oC @maximum
85oC @maximum(Initial temp. : 25 oC)
Temperature rise estimationresults : (II) time dependence
Thermal stress & displacements estimation ( simulation input parameters )
20.0
Linear ExpansionCoeff. (x10-6)
Young’smodulusTemperature
Temperature
0.0
50.0
100.0
150.0
200.0
250.0
0 1 2 3 4 5 6 7 8 9 10 11 12
時間(sec)
温度
(℃)
Cycle 11 Cycle 12
Cycle 11 and 12 of the previous analysis
50
100150200(oC)
0 1 32 54 6 7 98 1110Time (sec)
Material properties
(oC) (MPa)0.0 10760 3.6814
10790 3.762063100.0 10920 4.065344200.0 11080 4.48612400.0 11410 4.926584
Two types of the stress analysis (LS-DYNA)
time step : 1µs (from 0 to 205µs)For the radial displacements (fast components)
For the longitudinal displacements (slower components)time step : 10µs (from 0 to 2050µs)
Thermal stress & displacements estimationresults : (I) equivalent stress
Just after the 11th spill
Maximum equivalent stress
(x10 MPa)
6.8MPa
Thermal stress & displacementsresults : (II) displacements (radial direction)
5.000055.0 5.00010 5.00015 5.00020
1.0
2.03.04.0
5.06.0
x10-3(mm)
(sec.)
Displacement in the radial direction~ 6x10-3mmMaximum displacement
Vibration cycle ~ 6µs
Thermal stress & displacementsresults : (III) displacement (longitudinal direction)
5.00055.0 5.0010 5.0015 5.0020
-2.00
-1.00
x10-1(mm)
(sec.)
Displacement in the longitudinal direction~ 2.5x10-1mmMaximum displacement
Vibration cycle ~ 250µs
Maximum temperature @ center
Maximum temperature @ surface
FEM simulation results~ 236oC
~ 85 oC(analytical : @ center ~ 250oC )
Summary & future prospects (I)
Maximum stress ~ 6.8MPa(analytical ~ 7.5MPa)
Consistent with the analytical calculation.
~ 6x10-3mmradialMaximum displacement~ 2.5x10-1mmlongitudinal
~ 6µsradialVibration cycle~ 250µslongitudinal
Summary & future prospects (II)Remaining questions / problems
1 piece or split the target into smaller pieces?Off centered tolerance has to be estimated.
(Non-uniform heating may cause the problem.)
Can we put the graphite target in the water?Is it necessary to put the target in the container
(to avoid graphite to touch the cooling water)?If we split the target into smaller pieces,
we have to put the target in the container.
water flow
Graphite target
(To avoid the water to get in the middle of the beam.)container(?)
Schematic view of the possible target (cooling) system
Summary & future prospects (II)Irradiation effects
Target may shrink by ~1(a few?)%Large target (L=900mm) may not be possible.
If we put the target in the container, they will be separated.
How to hold the target (in the container)?
Plan to measure the irradiation effects on the material properties
Very rough scheduleFY 2003 simulation studies & basic cooling tests.
design the prototype (target holder, cooling system).FY 2004 make the prototype and test.
design the target support & handling system.measure the irradiation effects.
FY 2005 mockup tests (including supports & handling system).material determination.
変形倍率200倍にて表示赤ライン=変形前変形値単位=mm
A部拡大図 B部拡大図
グラファイトターゲット熱応力衝撃解析:変形図 (⑦ 軸変形最大=5.000125sec)拡大図
Target R&D for the J-PARC neutrino experiment (II)