FNAL Absorber Program

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FNAL Absorber Program

• Mary Anne Cummings
• NuFact 03
• Columbia University, NYC
• June 9, 2003

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Topics

1. RD Motivation
2. Windows (absorber and vacuum)
3. Absorber manifold designs and simulations
4. Schlieren flow tests
5. System integration
6. Near term plans
7. Summary

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Mucool LH2 Absorber Issues
Approx. eq. for emittance

• Cooling channel requires minimum heating
• Low Z material ? maximize radiation length LH2
• 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 H2/O2 contact containment, ventilation,
  controls
• No ignition sources instrumentation must be
  safe, RF cavities benign
• Confined operation, large B fields system
  integrity and stability

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Thin Windows Design
Tapered thickness from window edges can further
reduce the minimum window thickness near beam
Progression of window profiles tapered (1)
and bellows (2 3)
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Window manufacture (U of Miss)
Flange/window unit machined from aluminum piece
(torispherical 30 cm diam)
Backplane for window pressure tests
Backplane with connections, and with window
attached
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Measuring 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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Windows tests

• 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 photogrammetric
  volume measurements
• FEA predictions inelastic deformation, 3 dim
  included in calcs.
• Performance measurement photogrammetric space
  point measurement

• Progress towards meeting FNAL Safety Guidelines
• Absorber and vacuum window guidelines understood
• Absorber window test completed
• FEA/data agreement established

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Photogrammetric measurements
Strain gages 20 points
CMM 30 points
Photogrammetry 1000 points
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Photogrammetry

• Contact vs. non-contact measurements (projected
  light dots)
• Several vs. thousand point measurements
  (using parallax)
• Serial vs. parallel measurements (processor
  inside camera)
• Larger vs. smaller equipment
• Better fit to spherical cap.
• Photogrammetry is the choice for shape
• and pressure measurements

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Window shape measurement
D. Kubik, J. Greenwood
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
photogrammetry measurements
1.
4.
2.
1.
Burst at 120 psi
350 m windows
Cryo test
Burst at 152 psi
3.
130 m window
Leaking appeared at 31 psi ..outright rupture at
44 psi!
Burst at 120 psi
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Absorber window test results

• Performance measurement (photogrammetry)
• 1. Room temp test pressurize to burst
  4 X MAWP (25 psi)
• 2. Cryo test
• a) pressure to below elastic limit to confirm
  consistency
• with FEA results
• b) pressure to burst (cryo temp LN2)
  5 X MAWP
• from ASME UG 101 II.C.3.b.(i)
  

Discrepancies between photogrammetry and FEA
predictions are lt 5
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Vacuum Windows

• FNAL Requirements
• Burst test 5 vacuum windows at room temp. to
  demonstrate a burst pressure of at least 75 psid
  for all samples. (pressure exerted on interior
  side of vacuum volume).
• Non-destructive tests at room temperature
• External pressure to 25 psid to demonstrate no
  failures no creeping, yielding, elastic
  collapse/buckling or rupture
• Other absorber vacuum jacket testing to ensure
  its integrity

Vacuum bellows window (34 cm diam)
No buckling at 1st yield (34 psi)
Internal pressure burst at 83 psi
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Convection absorber design
Internal heat exchange
Convection is driven by heater and particle
beam.Heat exchange via helium tubes near absorber
wall. Flow is intrinsically transverse.
Output from 2-dim Computational Fluid Dynamics
(CFD) calcs. (K. Cassel, IIT). Lines indicate
greatest flow near beam center.
KEK prototype, S. Ishimoto
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Force-flow Absorber
External heat exchange
Mucool 100 - 300W (E. Black, IIT)
Large and variable beam width gt
large scale
turbulence
Establish transverse turbulent flow with
nozzles
E158 design
Mucool design
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Force flow simulations
3 dimensional FE simulations are possible but CPU
intensive (W. Lau, S. Wang)
3-dim and 2-dim flow simulations are consistent
use 2 dim for design and iteration. Optimize
needed flow by minimizing the pressure drop in
the absorber
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Convection flow simulations
Lau/Wang FE 3-d flow simulation of KEK LH2
absorber
3-d grid
K. Cassel CFD
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LH2 flow issues

• Our Challenge
• Large heat deposition and beam path is through
  entire volume absorber!
• 1. Liquid must move everywhere
• 2. Need gauge of temperature and density
  uniformity
• Questions
• What measurements are useful?
• Are realistic flow simulations realizable?
• What tests will be useful, and how quantitative
  can they be?
• What is the behavior at the window surface?
• What is the maximum heat load of convection
  absorbers?
• What is the maximum efficiency achievable by
  forced flow?
• Can we hybridize these for a real cooling channed?

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Flow Tests Schlieren
Schlieren testing of convection flow (water) test
at ANL an optical method to study heat flow from
beam. J. Norem, L. Bandura, M.A.Cummings, E.
Black.
First test at ANL beam perpendicular to optical
path
Transverse beam data
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Schlieren tests (cont)
Second test at ANL beam colinear to optical path
First attempts at quantifying the flow
data Working with K. Cassel and W. Lau and S.
Wang to optimize absorber for flow Will be
adding temperature probes to give absolute
measurement
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MICE Absorber-coil integration
One design that meets RALs safety containment
requirements Edgar Black

1. LH2 safety (containment)
2. Magnetic field measurements
3. Assembly certification
4. Absorber exchangeabilty
5. Instrumentation

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MTA LH2 Experiment
Beamline C. Johnstone
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Mucool Test Area LH2 Setup
Lab G magnet
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More Cryo system pictures

• LH2 Pump assembly (B. Norris et al)
• Pump torque transition,
• Motor outer shield,
• Cooling system,
• Pumping system of the outer shield,
• Relief valves piping.

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KEK convection prototype test in MTA
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Mucool 2003/2004

• Absorber/vacuum windows manufacture and test
• Fluid flow/convection simulations
• Instrumentation and data acq. development
• Schlieren results
• Safety Review
• MTA test design finalization
• MICE absorber/coil design finalization
• Japanese absorber pre-MTA LH2 run
• Absorber/Solenoid Tests
• 2004
• KEK absorber/instrumentation tests
• MTA Force flow LH2 absorber staging
  

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Summary Comments On LH2 R D

1. We have an established window design/manufacture/c
   ertification program, for absorber and vacuum
   windows, completed tests on the first window
   prototype, and have made many technical
   improvements on design.
2. We have developed new applications for
   photogrammetry (NIM article and masters degree
   in progress!).
3. Several projects have developed from LH2 absorber
   concerns, ideal for university and student
   participation.
4. MICE participation has advanced the Mucool
   program the two absorber designs are
   complementary integration problems are being
   solved possible hybrid absorber for a real
   cooling channel likely.
5. Schlieren technique giving us a quantitative
   measurement of heat flow.
6. KEK absorber to be tested this fall in the MTA.
7. LH2 flow and heat conduction has now become the
   dominant physics concern for the absorber. The
   two flow designs will be pursued in parallel.
8. LH2 safety is the dominant engineering concern
   for the cooling cell, but there has not yet been
   any show-stopping problems.