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 depositrz

Heat transfer rate @ surface

6.5kW/m2/K

Temperature @ surface (environment)

25oC

Temperature rise estimation (simulation input parameters)
Material

IG-43 (Toyo Tanso)
1850kg/m3

density

Temperature dependent material parameters(J/kg/K)

Specific Heat

Thermal conductivity(W/m/K)

2000
1500

100

1000

60500

200200400

600

800 1000 1200

Temperature (oC)

0200

400600800 1000 1200

Temperature (oC)Temperature rise estimation (simulation input parameters )Time structure : for the detailed study, two patterns were simulated.
Heat Load

102

34

10

1112

3.42

6.84

10.26

30.78

34.20

37.62

Time (sec)averaged

8spills/bunch
598ns

5µs58nsTemperature rise estimation
results : (I) distribution in the target
just before the 11th spillrz

Maximum Temperature : 45oC

just after the 11th spillrz

Maximum Temperature : 236oC

relative temp.
from 25oC

Temperature rise estimation( C)
results : (II) time dependence
o300

中心軸最高温度部
外表面最高温度部

250

250
C2C3C4C5C6C7C8C9C10C11C12

Maximum temperature at the center
236oC @maximum

C1200
温度（℃）

200

150

150

Maximum temperature on the surface

10010085oC @maximum

5050(Initial temp. : 25 oC)

00.0

5.0

05

10.0

15.0

20.0
25.0
経過時間（sec）

30.0

35.0

40.0

45.0

10 15 20 25 30 35 40 (sec.)
図ｸﾞﾗﾌｧｲﾄﾀｰｹﾞｯﾄの温度変化

Temperature is saturated(oC)300

中心軸最高温度部
外表面最高温度部

in a few spills.

250

250

200
温度（℃）

200

150

150

100100Temperature rise gradually decreased

5050

because of the temp. dependence of Cp.

037.619999

37.620000

37.620001

37.620002
37.620003
経過時間（sec）

37.620004

37.620005

37.62000 37.62002 37.62004
図ｸﾞﾗﾌｧｲﾄﾀｰｹﾞｯﾄの温度変化（Ｃ１2初期）

37.620006(sec.)

Thermal stress & displacements estimation( simulation input parameters )Temperature
Cycle 11 and 12
Material propertiesof the previous analysis
LinearYoung’s
250.0(oC)Cycle 11 Cycle 12

温度（℃）

200.0
200

Temperature（oC）

modulus（MPa）

Expansion
Coeff. (x10-6)

150.0
1500.010760

3.6814

100.0
100

20.0

10790

3.762063

50.0
50

100.0

10920

4.065344

200.0

11080

4.48612

400.0

11410

4.926584

0.000

2788 99 1010 11
11 1211 233 44 55 66 7
時間（sec）
Time(sec)

Two types of the stress analysis (LS-DYNA)
For the radial displacements (fast components)
time step : 1µs (from 0 to 205µs)
For the longitudinal displacements (slower components)
time step : 10µs (from 0 to 2050µs)

Thermal stress & displacements estimation
results : (I) equivalent stress
Just after the 11th spill

Maximum equivalent stress

6.8MPa(x10 MPa)Thermal stress & displacements
results : (II) displacements (radial direction)x10-3(mm)
6.0
5.0
4.0
3.0
2.0
1.0
5.0

5.000055.000105.000155.00020(sec.)

Displacement in the radial direction
Maximum displacement~ 6x10-3mm

Vibration cycle~ 6µs

Thermal stress & displacements
results : (III) displacement (longitudinal direction)x10-1(mm)

-1.00

-2.00

5.0

5.00055.00105.00155.0020(sec.)

Displacement in the longitudinal direction
Maximum displacement~ 2.5x10-1mm

Vibration cycle~ 250µsSummary & future prospects (I)FEM simulation results~ 236oC

Maximum temperature @ center(analytical : @ center ~ 250oC )Maximum temperature @ surface~ 85 oC

Maximum stress~ 6.8MPa(analytical ~ 7.5MPa)

Consistent with the analytical calculation.
Maximum displacement

radial~ 6x10-3mm

longitudinal ~ 2.5x10-1mm
Vibration cycle

radial~ 6µs

longitudinal ~ 250µs

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.
container(?)(To avoid the water to get in the middle of the beam.)water flow

Graphite target

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 schedule
FY 2003
FY 2004

FY 2005

simulation studies & basic cooling tests.
design the prototype (target holder, cooling system).
make the prototype and test.
design the target support & handling system.
measure the irradiation effects.
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