Vacuum windows at JPARC

1
Vacuum windows at JPARC
Yoshikazu Yamada (KEK) T.Ishii, T.Iwashita,
M.Minakawa, Y.Oyama, H.Takahashi, et.al. 4th
International Workshop on the Neutrino Beams and
Instrumentation November 10, 2003

• Contents
• Introduction
• Vacuum windows at hadron beam line
• Helium gas cooling
• Vacuum windows at neutrino beam line
• primitive discussion

2
Hadron Neutrino beam lines
Neutrino beam line Single turn fast extraction 8
bunches in 5ms 3.3x1014proton/spill Cycle 3.53
sec.
Neutrino beam line
Hadron beam line
50 GeV PS
0.7sec.
Hadron beam line Slow extraction 0.7 sec.
Time(sec.)
3
Windows in hadron beam line
Beam dump (Low Pressure?)
50GeV PS10-8 Torr
Container of T1-target (air and water inside)
10-3 Torr Rotary pump
Fast reaction valve
NP-hall
Switch Yard
10-610-8 Torr Turbo Ion pump
Window for T1-upstream
Window for T1-downstream
SY Vacuum window
Vacuum chamber 20cm-f, SS or Al or Ti Connected
by Radial seal
Window for Dump
4
SY vacuum window

• Separate vacuum in SY(10-3Torr) from one in
  50GeV-PS (10-8Torr)
• Aluminum 20cm-f, 100mm-t
• Edge cooled at 30ºC by water or air
• Average deposit 3.5J/spill ? Temperature rise
  16(K) (SS 480(K) )
• (MARSANSYS)

Aluminum window
sr 1cm
Deposit (W/m3)
16(K)
Radius (cm)
5
Time dependence of temperature
Aluminum
Stainless Steel
300
Temperature(ºC)
Center
Center
Temperature(ºC)
46
30
30
60
0
60
0
Time(sec)
Time(sec)
Tgt1 min. T30 16 4 (ºC)
Tgt20 min. T 30 480 10 (ºC)
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Beam window for T1-target
T1 container

• Double wall (SS or Al)
• cooled by He flow in gap
• gap 1cm
• remote maintenance

Vacuum chamber 10-3 Torr
He
Air
T1 target
SS/Al
SS
SS
SS/Al
Beam axis
Primary beam line10-3 Torr
He 1g/cm2 1m/s
Downstream windows for T1 diameter30cm
Upstream windows for T1 diameter10cm
Water
7
Upstream window for T1 (T1-U)

• Separate vacuum of beam line (10-3Torr) from
  air(1atm) in T1 container
• SS/Al (beam-line side) and SS (T1 side) 10cm-f,
  variable thickness
• Cooled by He(1atm 1m/s) between two walls
• Average deposit10.2 J/spill on SS window
• (9.2 J/spill if t100mm)

SS window
2.5mm
sr 2mm
Deposit (W/m3)
Thickness (cm)
100mm
Radius (cm)
Radius (cm)
8
Temperature of window T1-U
Outer edge cooled to be 30ºC by water or
air One surface cooled by convection by Helium
Natural convection 10W/m2/K
Forced convection 100W/m2/K
SS window
SS window
320(K)
160(K)
Temperature rise 320 (K)
Temperature rise 160 (K)
9
Deformation/Stress of window T1-U
SS window
SS window
0.7mm
Max. stress due to pressure 200MPa_at_center ltTensil
e strength500MPa
Deformation0.7mm_at_center

• If t0.1mm(uniform)
• deformation2.1mm
• Stress310MPa_at_center,1000MPa_at_edge

10
Helium cooling at KEK-B factory
Double wall of Beryllium
100W heat
Vacuum chamber for interaction point
He
Beryllium
Aluminum
Aluminum

• Heat transfer coefficient
• 1g/s (6l/s, 1.7m/s)
• 120W/m2K(measured by U.Tsukuba)
• 164W/m2K(calculation)
• 220W/m2K(measured by IHI)

Helium cooled
Water cooled
Water cooled
He
11
Helium cooling system
water cooler
He tank
water pump
He compressor
He cooler
12
Downstream window for T1(T1-D)

• Separate vacuum chamber (10-3Torr) from air(1atm)
  in T1 container
• SS/Al (beam-line side) and SS (T1 side) 30cm-f,
  variable thickness
• Cooled by He(1atm 1m/s) between two walls
• Average deposit 1060 J/spill on SS window
• (115 J/spill if t0.1mm)

SS window
5mm
sr 5mm
Thickness (cm)
Energy deposit (W/m3)
100mm
Radius (cm)
Radius (cm)
13
Temperature/stress of window T1-D
SS window
SS window
3.3mm
170(K)
Outer edge cooled to be 80ºC Temperature
rise 170(K) _at_100W/m2K 810(K) _at_10W/m2K
Deformation3.3mm Stress due to pressure 450MPa
at center Tensile strength 500MPa
14
Window for beam dump

• Separate vacuum in beam line (10-3Torr) from air
  in beam dump
• Stainless Steel 50cm-f, variable thickness
• Simple wall or double wall with Helium cooling
• Average deposit 136 J/spill (98 J/spill if
  thickness is 1mm-t)

Energy deposit on window (W/m3)
Thickness (cm)
5mm
sr 5cm
1mm
Radius (cm)
Radius (cm)
15
Temperature/stress of window(dump)
SS window
SS window
8(K)
Outer edge cooled to be 30ºC Temperature
rise 8(K) _at_100W/m2K 64(K) _at_10W/m2K
Deformation5.7mm Stress due to pressure 200MPa
at R20cm ltTensile strength 500MPa
16
Windows in neutrino beam line
50GeV PS
Preparation Section
PS vacuum window (?)

• Separate vacuum in PSARCFF(10-6Torr)
• from one in 50GeV-PS (10-8Torr)

ARC Section (Super conducting)
Final Focusing Section
Target Station
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Window in Preparation Section

• Separate vacuum in PS(10-6Torr) from one in
  50GeV-PS (10-8Torr)
• 20cm-f, Al 26mm-t(?) or SS 10mm-t(?) (0.01 loss)
  (realistic?)
• Edge cooled at 30ºC by water or air
• Average deposit 0.68J/spill ? DT Al14(K),
  SS520(K)
• But, DT by single spill ? Al67(K), SS104(K)
• study on thermal stress and durability against
  heat cycle
• study with larger beam size

Al 26mm-t
Al 26mm-t
Deposit (W/m3)
sr 6mm (smallest case)
14(K)
Radius (cm)
18
Window for entrance of TS

• Separate vacuum in PS(10-6Torr) from He gas (1
  atm) in TS
• Aluminum 5cm-f?1mm-t (can be thinner)
• Edge cooled at 30ºC by water or air
• Average deposit 34J/spill ? DT 18(K)
• But, DT by single spill ? 82(K)
• study on thermal stress and durability against
  heat cycle
• double wall and Helium cooling?

Al 1mm-t
Al 1mm-t
Deposit (W/m3)
sr 6mm
18(K)
Radius (cm)
19
Summary

• We started to study on windows for 50GeV beam
  line.
• Average temperature rise and deformation/stress
  by
• pressure were estimated by MARSANSYS
• Conduction cooling for aluminum windows for
• Switch Yard of hadron beam line
• Preparation Section of neutrino beam line (?)
• Forced convection cooling by helium gas for
  windows for
• Upstream/downstream of T1 target in hadron beam
  line
• Beam dump in hadron beam line
• Entrance window of neutrino target station (?)
• Exit window of neutrino target station (??)

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Plan

• Study of thermal stress and shock wave
• Optimization of thickness
• Measurement of thermal transfer coefficient of He
  cooling
• Test production of windows and study durability
• Design and production of double wall window
• with Radial seal flange system developed
• by Y.Yamanoi et.al.

Proton beam
Double wall
He gas
Radial seal flange
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Backup
22
Hadron beam line in Switch-Yard
50GeV PS10-8 Torr
30m
SY Vacuum window
Fast reaction valve
10-610-8 Torr Turbo Ion pump (every 20m)
10-3 Torr Rotary pump (every 20m)
Vacuum chamber 20cm-f, SS or Al or Ti Connected
by Radial seal
23
Hadron beam line in NP-Hall
Container of T1-target (air and water inside)
Beam dump (Low Pressure?)
10-3 Torr
10-3 Torr
Window for T1-downstream
Window for T1-upstream
Window for Dump
10m
24
Neutrino target station
22m
33m
40t crane
11m
Ground level
Concrete blocks
Service pit
Final focus
Beam window
Iron shield
Machine room
Decay volume
Helium container
Beam window
Concrete
Stock room for activated parts
Baffle
Iron shield
Target 1st horn
2nd horn
3rd horn
25
T1 downstream window

• Diameter 30cm
• Vacuum side Aluminum
• Air(T1) side SS
• 0.1mm-t at center
• 5mm-t at edge (water cooled)
• Temperature rise of SS window at center
• 170ºC (forced convection by He flow(1m/s)
  100W/m2K)
• 810ºC (natural convection 10W/m2K)

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Remote maintenance for T1

• Maintenance work
• should be done at service space
• Disconnect cables and
• cooling tubes.
• Detach vacuum flanges.
• Replace shields with cask.
• Detach shaft, disks and
• upper plate, and
• move them to stock space.
• Install new parts with cask.
• Replace cask with shields.
• Connect cables and tubes.
• requires remote maintenance tools

motor
water
3m
shield
beam
target
beam
Front view
Side view
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Remote vacuum sealing

• Design specification
• Inner Diameter ?30cm
• Metal sealing
• Small leak1?10-10 Pam3/s
• Remote operation
• Operation time 15 min.
• Small force required
• Candidate
• Mechanical holding (V-block)
• Pillow seal
• Radial seal (under development)

Prototype of Radial seal developed by
Y.Yamanoi(KEK) , M.Tsuchiya(IHI Ltd) and Usui
Kokusai Sangyou Kaisya Ltd.
28
Remote lifting Tools

• Specification
• Up to 40t
• Short height
• Remote connection
• Video camera viewing
• Two or four points lifting
• Interlock for one-side lifting

Under design
Lifting tools from CERN and PSI
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Neutrino beam line
Fast-extracted proton beam line
Target station
Decay volume
Beam dump
50GeV PS
Super- Kamiokande

?µ beam of 1GeV

• nm? nx disappearance
• nm? ne appearance

31
Target and secondary beam lines
HR

• Production target T1
• Rotating Nickel disks
• thickness 54 mm
• radius 24 cm
• cooled by water
• developed by Y.Yamanoi
• et. al.

K1.8
K0
K1.1
Proton beam
NP-Hall