Current LH2 Absorber R

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Current LH2 Absorber RD in Mucool

• Mary Anne Cummings
• Nufact 02
• Imperial College, London
• July 3, 2002

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Mucool LH2 Absorber Collaboration

• E. L. Black, M. Boghosian, K. Cassel D. M.
  Kaplan, W. Luebke, Y. Torun
• Illinois Institute of Technology
• S. Ishimoto, K. Yoshimura
• KEK
• M. A. Cummings, A. Dyshkant, D. Hedin, D. Kubik
• Northern Illinois University
• D. Errede, M. Haney
• University of Illinois, Urbana-Champaign
• M. Reep, D. Summers
• University of Mississippi
• Y. Kuno
• Osaka University
• G. Barr, W. Lau

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Topics

1. Window tests
2. Instrumentation and flow tests
3. FNAL Linac test facility preparation

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Mucool LH2 Absorber Issues
Approx. eq. for emittance
Design/test drivers

• Cooling channel requires minimum heating
• Low Z material ? maximize radiation length
• Minimize window thickness/Z while retaining
  structural integrity
• Nonstandard window design

• Absorber Heat Management
• Refrigeration 100-250 W heat deposition from
  beam (8W/cm)
• Temperature and density stability LH2
  circulation
• Novel flow and convection schemes

• Safety
• No LH2/O2 contact containment, ventilation,
  controls
• No ignition sources instrumentation must be
  safe, RF cavities benign
• New instrumentation technology

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Window tests

• The issue A non-standard thin window design
• No closed form expression for maximum stress
  vs. volume pressure
• FEA (finite element analysis)
• geometry
  stress
• material
  strain
• volume pressure
  displacement

• Procedure (for manufacture quality control and
  safety performance) Three innovations
• Precision measurement of window (now, with
  photogrammetry!)
• FEA predictions (inelastic deformation)
• Performance measurement (photogrammetry)
• 1. Room temp test pressure to burst
  4 X MAWP (25 psi)
• 2. Cryo test
• a) pressure to below elastic limit to confirm
  consistency
• b) pressure to burst (cryo temp nitro)
  5 X MAWP
• from ASME UG 101 II.C.3.b.(i)
  

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Non-standard thin windows
Exploit the structural stability of the spherical
cap with a tapered/inflected connection to a
solid flange
Modified torispherical window (Black/Cummings)
Bellows inflected window (Black/Lau)
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Window manufacture (U of Miss)
Flange/window unit machined from aluminum piece
Backplane for window pressure tests
Backplane with connections, and with window
attached
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How to determine the thinnest thickness

1. Two different radii of curvature
2. Possibly not concentric

Modified torispherical design
If not at the center, where?
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CMM vs. Photogrammetry

• Contact vs. non-contact measurements
• Several vs. thousand measurements
• Serial vs. parallel measurements
• Larger vs. smaller equipment
• Better fit to spherical cap.
• Photogrammetry is choice for shape measurement

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Stellar parallax
1AU
d
r
d
fixed targets
scale bar
Photogrammetry
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Difference between measured shape and design
Convex
Concave
CMM data points
Whisker z(measured)-z(design)
Given the design radius of curvature of the
concave and convex surfaces, z(design) was
calculated for the (x,y) position of each target
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Rupture tests
130 m window
340 m window
Burst at 120 psi
1.
3.
Leaking appeared at 31 psi ..outright rupture at
44 psi!
Burst at 151 psi
2.
4.
Burst at 120 psi
350 m window
Cryo test
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Photogrammetry resolution
Alignment of sides
Small triangle fit
D
Use spherical fit of small triangles D 341.0mm
( 5.5mm) (- 10mm)
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FEA Calculations
Finite Element Analysis

• Non-elastic region included
• Three dimensios necessary for vibrational
  analysis

Window/flange simulation
Stress distribution at the yield point
Window/flange cross section
FEA, non-elastic region included

• Displacement vs. radius under pressure
• NIU photogrammetry results and FEA calculations

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Window performance summary

1. Descrepancies between CMM and photogrammetry are
   larger than their intrinsic errors
2. Descrepancies between photogrammetry and FEA
   predictions are lt 5

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Convection absorber design
Convection is driven by heater and particle
beam.Heat exchange via helium tubes near absorber
wall. Flow is intrinsically transverse.
Internal heat exchange
Output from 2-dim Computational Fluid Dynamics
(CFD) calcs. (K. Cassel, IIT). Lines indicate
greatest flow near beam center.
Qualitatively demonstrated but parameters need to
be measured. Prototyping of this design is being
done by Shigeru Ishimoto et al at KEK.
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Forced-Flow Absorber Design
External Heat Exchange
Mucool 100W (E. Black, IIT) Large and
variable beam width gt large scale
turbulence Establish transverse turbulent flow
with nozzles

• For 8W/cm heat deposition, need to cycle 0.05
  volumes/sec LH2 (e.g. 240W/30cm).
• Nozzle design complicated - needs prototyping
  and testing.

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Flow Tests
Three dimensional LH2 flow simulations (W. Lau)
Schlieren testing of convection flow (water)
test at ANL

1. Nozzle arrangement
2. Heat application
3. Cryo tests

Testing 3-dimensional simulations with water
flow test at NIU
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Infrared flow test setup
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Instrumentation

• Temperature/density uniformity inside LH2
• Safety instrumention inside vacuum area
• Detectors for cooling measurements

Safety Issues 1. Limits the amount of
energy/(area or vol) 2. Physical size of the
signal feedthroughs 3. Seals from signals to
electronics wires fibers tubes
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Experiment Signals- Absorber
signals

• temperature 12
• pressure transducers see under cryo
  2
• Photogrammetry/optical (??) 2
• laser occlusion sensor (??) 4
• piezo vibration sensors 2
• Optical fiber strain gauges 2
• bolometry 44
• O2 sensors 3per each of 5 flanges 15
• H2 sensors on exhaust line 10
• CCD camera 2 images
• MICE channels N

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Design of LINAC LH2 Absorber Beam Test