LH2 Absorber Review 1.R&D Motivation 2.Windows (absorber and vacuum) 3.Absorber manifold designs and flow tests 4.System integration 5.Near term plans.

LH2 Absorber Review 1. R&D Motivation2. Windows (absorber and vacuum)3. Absorber manifold designs and flow tests4. System integration5. Near term plans6. Summary

Minimize scattering Nonstandard window designs for absorber and vacuum vessel “SOLVED” Maximize heat extraction Optimal cryogenic designs IN PROGRESS Temperature and density stability: LH2 circulation

UNSOLVED

Mucool LH2 Absorber Issues

Safety No H2/O2 contact: containment, ventilation, controls IN

PROGRESS No ignition sources: instrumentation must be “safe”, RF cavities

“benign

Approx. eq. for emittance:

R

nn

LmEEds

dE

ds

d

2

)014.0(11 2

32

System Integration Confined operation, large B fields: system integrity and stability

IN PROGRESS Temperature range from room to Lhe: condensation issues

Measuring the “thinnest” thickness

1. Two different radii of curvature

2. Possibly not concentric

Modified torispherical design

If not at the center, where?

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

Windows tests

}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

Photogrammetric measurementsStrain gages ~ 20 “points”

Photogrammetry ~1000 points

CMM ~ 30 “points”

Photogrammetry

1. Contact vs. non-contact measurements (projected light dots)

2. “Several” vs. ~ thousand point measurements (using parallax)

3. Serial vs. parallel measurements (processor inside camera)

4. Larger vs. smaller equipment5. Better fit to spherical cap.

Updating camera and methods to prepare for “production mode”

Window shape measurement

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

Concave Convex

CMM data points

D. Kubik, J. Greenwood

Rupture tests

Leaking appeared at 31 psi ..outright rupture at 44 psi!

130 window

“350” window

“340” window1.

2.

3.

Burst at ~ 120 psi

Burst at ~ 120 psi

4.Burst at ~ 152 psi

Cryo test

Absorber window test results

Window #Test temp.

FEA results Test results

Minimum window thickness (mm)

Rupture pressure (psi)

Window thickness from CMM (mm)

Measured rupture pressure (psi)

1 293K 0.13 48 0.114 42

2 293K 0.33 117 0.33 119

3 293K 0.345

123 0.345 120

4 80K 0.33 156 0.33* 152

Discrepancies between photogrammetry and FEA predictions are < 5%

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)

Vacuum WindowsFNAL Requirements:

1. 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).

2. Non-destructive tests at room temperature:

a. External pressure to 25 psid to demonstrate no failures: no creeping, yielding, elastic collapse/buckling or rupture

b. Other absorber vacuum jacket testing to ensure its integrity

Internal pressure: burst at 83 psiNo buckling at 1st yield (34 psi)

Vacuum “bellows” window (34 cm diam):

LH2 Window R & D

Immediate future:• Manufacture and test of 21 cm “bellows”

absorber window • Manufacture and test of 34 cm vacuum

window – internal and external pressurization *new test*

• New aluminum alloy (stronger)• Optimize seals to manifold • Stability test in the Lab G magnet **

Internal heat exchange: Convection is driven by heater and particle beam.Heat exchange via helium tubes nearabsorber wall.

Flow is intrinsically transverse.

Convection absorber design

Output from 2-dim Computational Fluid Dynamics (CFD) calcs. (K. Cassel, IIT). Lines indicate greatest flow near beam center.

KEK prototype, S. Ishimoto

Force-flow Absorber

Mucool ~ 100 - 300W (E. Black, IIT) Large and variable beam width => large scale turbulence

Establish transverse turbulent flow with nozzles

External heat exchange:

Mucool design:E158 design:

LH2 Manifold R & D1. The driving physics issue in Mucool LH2

R & D is now fluid flow and heat removal

2. Two separate absorber designs1. “Pre-MTA” test (2003) : convection2. MTA operation (2004) : force flow

3. Flow simulations1. 3 dim FEA2. CFD

4. Flow tests5. Instrumentation

LH2 flow issues…Our Challenge: Large heat deposition and beam path is through entire

volume absorber!

1. Liquid must move everywhere, particularly in window volumes2. Need gauge of temperature and density uniformity

Questions:

• What is testable? • How quickly can simulations be verified by experiment?• What tests will be useful, and how quantitative can they be? • What level of instrumentation will convince us of sufficient

temperature uniformity?

Force flow simulations3 dimensional FE simulations are possible but CPU intensive (W. Lau, S. Wang)

3-dim and 2-dim flow simulations are consistent – use 2 dim fordesign and iteration. Preliminary results indicate that “bellows” window has better flow pattern in window volume.

Convection flow simulations

Heating Coil

Liquid Hydrogen

3-d grid:

Lau/Wang FE 3-d flow simulation of KEK LH2 absorber:

K. CasselCFD:

Flow TestsSchlieren testing of convection flow (water) test at

ANL (more quantitative program to run in 2003) J. Norem, L. Bandura

MTA Prestage with KEK absorber

1. LH2 setup and system integration2. Absorber manifold and containment will be

ready before the MTA!1. Exercise filling and purging of absorber2. Readout of temperature probes as a first

verification of temperature maintenance via convection

3. Instrumentation readout4. Can establish heat loading capacity sufficient

for MICE requirements UNSOLVED

MTA LH2 Experiment

Lab G magnet

RF cells

LH2 Cryostat

Beamline: C. Johnstone

Mucool Test Area LH2 Setup

Lab G magnet

MTA Force Flow Cryo System

Red - Hydrogen Blue – HeliumBased on E158 LH2 target system

Absorber/vacuum windows manufacture and test

Fluid flow/convection simulations

Instrumentation and data acq. development

Flow tests: Forced Flow, Convection

Safety Review

MTA test design finalization

MICE design

Japanese absorber pre-MTA LH2 run

Absorber/Solenoid Tests

2004

MTA LH2 absorber staging

Mucool 2003/2004

Summary Comments On LH2 R & D1. We have an established window design/manufacture/certification

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(s) 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. The above four points means that we have survived as a program the delay of the FNAL MTA construction – (KEK in “prestage” LH2 tests could help)

6. LH2 flow and heat conduction has now become the dominant physics concern for the absorber. The two flow designs will be pursued in parallel.

7. LH2 safety is the dominant engineering concern for the cooling cell, but there has not yet been any show-stopping problems.