MuCool Convection Absorber R

1
MuCool Convection Absorber RD

• Mary Anne Cummings
• Muon Collaboration Meeting
• Berkeley, CA
• Feb. 14, 2005

2
Absorber RD

• Two LH2 absorber designs are being studied
• Handle the power load differently

Forced-Flow. External cooling loop with
cryostat designed for absorber operation inside
the Lab G solenoid
Convection-cooled. Has internal heat exchanger
(LHe) and heater KEK System
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Forced-flow Absorber
Mucool 100 - 300W (E. Black, IIT)
Large and variable beam width requires
large scale
turbulence Establish transverse turbulent flow
with nozzles
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Convection Absorber

• Takes advantage of natural convection transverse
  to beam path
• Flow in the absorber is self-regulating, i.e.
  larger heat input gt more turbulence gt
  enhanced thermal mixing
• Is likely to work best for large aspect ratio
  (L/R) absorbers
• Conceptually simpler and less expensive to build
  and maintain than forced-flow design
• BUT..
• Difficult to ensure against boiling at very high
  Rayleigh numbers
• Can only apply to moderate heat loads
• modifications/enhancements
• What is the largest heat load/ LH2 volume?

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MTA
The MTA is focus and locus of Mucool activity

• LH2 Absorber tests LH2 Facility!
• RF testing (805 and 201 MHz)
• Continue/finish cryo-Infrastructure
• High pressure H2 gas absorbers
• Linac Beam construction

In 2005
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LH2 program at MTA

• Successful first test of liquid hydrogen
• Safety review succeeded
• Monitoring and controls system inplemented
• Solid FNAL LH2 cryo group

Summer 2004
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The interim cooling system
LH2 gas house
He pump, flow meter etc.
L-He Dewar, Transfer line, Valve box
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KEK Absorber
PtCo He-IN
PtCo W-He-OUT (center)
PtCo W-He-OUT (bottom)

• Electronics upgrades
• LH2 level sensor
• New temp probes
• Temp probes inside He lines

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KEK absorber II
G-He Heater
PtCo 1 - 8
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½ fill on Jul-9 no leak at 20K
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First data from MTA KEK absorber test
Data on July 27
04 Goal more heat absorption with stable
operation
Temp probe readings
July 15, 20W heat deposition, stable temps
Warm He flow
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Temperature uniformity
Distribution of temp. probes (central tubes
introduce new artifice!)
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First KEK test summary

• 1. Cold-He Cooling test was an excellent
  learning experience both from the operational
  and monitoring ends but all problems
  encountered were successfully resolved.
• Large heat input 23 W to 20 m transfer tube
  made thermal vibration. ? Solved by cold G-He
  system
• High temperature G-He was sent to absorber when
  Dewar was changed. ? 2 Dewars (500 L) were used
  simultaneously.
• The absorber was filled of L-H2 full without
  leaking, and was well controlled continuously
  with and without heat input.
• The FNAL cryo-group is now operating the absorber
  with G-He heater.
• Preliminary heat deposition test looked promising

14
LH2 R D FY 2005

• Second KEK test (upgraded instrumentation) Next
  test
• New absorber instrumentation
• New internal temperature probe Internal temp.
  probes for He lines
• Level sensors
• Shorter transfer line install lift into the
  access pit for dewars
• Physics issues
• Stable and expeditious cooldown
• Temperature stability and uniformity - MICE
  instrumentation
• Heat absorption
• Better handles on heat exchange efficiency
• New central heater OR run without central
  tubes..
• Next R D Focus (beyond MICE)
• Possible low intensity beam run
• What is the highest heat load possible for
  convection absorbers?
• Improvements to the LHe/LH2 interface?
• Implement ducts (increase the turbulent flow near
  the surface)

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KEK Absorber Instrumentation Upgrade

•   
• Modifications
• (1) Heater (gas heater to electrical one)
• - Shigeru is asking to the FNAL safety
  committee and cryo-group to select acceptable
  electrical heater.
• - Needs modification of window for the
  feed thorough for central heater
•  
• (2)   Thermometer
• Change PtCo sensor to Cernox 1050SD.
• We have 10 calibrated sensor 8 will be in
  absorber, 2 for Cold-He in/out
• Needs 5 more for level sensor, but uncalibrated
  one is OK.
• 4 wires for each sensors to make test of
  LakeShare read-out.
• (3)   Thermometer housing for the
  thermometers at Cold-He in/out.
• (4)   Needs some reading of Cold-He flow
  rate and signal to KEK DAQ..
• (5)   Needs H2 gas pressure signal to KEK
  DAQ
• (6)   Needs additional connectors at top.

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KEK Absorber Schedule

•   Schedule and test process
• (1)   Needs design
• Window new central heater
• New heater
• Thermometer housing Tee
• (2)   Fabrication of parts and a window
• (3)   Send parts to FNAL
• (4)  Assemble the parts at MW9 (Absorber
  Body and one-side window are not changed)
• R.T. and LN2 pressure/leak test at MW9 ----
  KEK-group, 2-3 weeks at MW9
• (5)   Send the KEK cryostat to MTA and
  assemble ---- FNAL cryo-group
• (6)   Safety agreement and preparation of
  cooling test
• (7)   Cooling test ---- FNAL group and KEK
  group
•  
• IBM-PC desk top for DAQ --- Makoto Yoshida is
  taking care to pouches and send it to MW9,
  Windows Xp pro English OS  

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Wiring and Connecters ( I )
Thermometers and Level Sensor in LH2
LH2
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?
L-H2/LHe Level sensor in absorber
Resistance Thermometer
DC mA
T TB dT, R RB dR
?
Liquid Level
T TB , R RB
DC Current for L-H2/LHe should be optimized (KEK
RD).
V4
V3
LHe
LH2
CX-1050-SD
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Safety

• For LH2, two principles driving system design
• O2 and LH2 separation
• No ignition sources
• At FNAL guidelines for the LH2 absorber system
• America Society of Mechanical Engineers (pressure
  and vacuum vessels, etc.)
• National Electrical Code lt (Class I Division
  II, or instrinsically safe)
• Compressed Gas Associates
• Fermilab Environment Safety and Health Code
• Ignition sources electrical, friction, impact,
  auto-ignition
• Minimum energy for ignition of H2 is 0.017 mJ at
  1 atm.
• Combustion H2 /air ratio from 4 to 75
• PRIMARY SAFETY MECHANISM IS VENTING LH2 OUT OF
  THE AREA

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Safety Issues to be resolved

• Window certification
• Design certification different for
  vacuum/absorber windows
• Tentative real window certification (could be
  the same as MICE)
• Materials inspection
• Measurement
• Sub-elastic limit pressure tests
• Hydrogen zone (re) defined
• Problem for FNAL is that if all of the LH2 were
  to vaporize into the MTA at STP, the highest
  possible concentration of H2 is 7.
• RAL sets the standard from ATEX (French
  ATmospheres Explosives) adopted by the EU in July
  2003
• Zone 0 possible explosive concentration for
  extended periods
• Zone 1 possible explosive concentration for lt
  1000 hrs/year
• Zone 2 possible explosive contratcion for lt 10
  hrs/year
• Will be resolved in the context of a next project
  (forced-flow, e.g.)

21
Data acquisition

• Lakeshore 218S (UIUC)
• 8 channel cryo temperature monitor
• 20mV (diodes) or 50 mW (RTD) resolution
• 10s of mK at 20K
• 16 readings/s (/channel)
• GPIB interface (to PC)
• 4 units in-hand (and a spare)
• Will need to consider (re)calibration protocols
• Annually?
• DAQ for later beam runs?
• Who has this responsibility?

22
Vapor deposition onto windows

• System
• Vacuum vessel
• Target filament (Ti)
• Quartz crystal
• Oxygen system
• Safety review
• Removal of inflammatory material
• Isolation of electrical elements

23
Test setup

• First run with broken window
• cleaning
• leak checking
• deposition calibration

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Coating R D in progress

• Ti O - not Ti O2
• Need to temperature regulate the system - fixable
• Possibly not needed for certain optical
  measurements?

Ready to be shipped
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Last Slide

• A fluid program, whose funding is not clear
• Hasnt gone like my talks have advertised over
  the last 2.5 years, but there is always progress.
• The program as diverged with the MICE absorber
  but the MuCool program is still complementary and
  of use to MICE..
• Beam tests will be the next milestone