Mucool LH2 Absorber Progress and Pauses

Mary Anne Cummings

FNALAugust 12, 2002

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

Mucool LH2 Absorber Issues

Safety No LH2/O2 contact: containment, ventilation, controls No ignition sources: instrumentation must be “safe”, RF

cavities “benign” New instrumentation technology

R

nn

LmEEds

dE

ds

d

2

)014.0(11 2

32emittance

eqn.:

Design/test drivers:

“FNAL” Progress1. Non-standard absorber windows designed2. Non-standard vacuum containment window

designed3. 5 & 9.5 mil thin windows manufactured4. Correct FEA analyses completed with predictions

for window performance under pressure5. Photogrammetric techniques developed for

volume measurements6. Photogrammetric techniques developed for

window pressure test performance 7. Window predictions and data consistent!8. Test Area proposed and ALMOST on “mass shell”!9. Test Area Absorber system designed.

“Offshore” Progress1. Convection prototype built2. Convection prototype cryogenically operated3. Convection calculations 4. Three dimensional flow test demonstration5. Schlieren test program started6. NIM Articles in progress7. Window predictions and data consistent!

“Non-standard” thin windowsExploit the structural stability of the spherical capwith a tapered/inflected connection to a solid flange

Modified torisphericalwindow (Black/Cummings)

“Bellows” inflectedwindow (Black/Lau)

Xi

t

diameter

R

r r

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?

Manufacture to rupture

130 window“350” window

“340” window

2.

3.

Burst at ~ 120 psi

Burst at ~ 120 psi

4.

Burst at ~ 151 psi

Cryo test

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

1.

CMM vs. Photogrammetry

1. Contact vs. non-contact measurements 2. “Several” vs. ~ thousand measurements3. Serial vs. parallel measurements4. Larger vs. smaller equipment5. Better fit to spherical cap.

Photogrammetry is choice for shape measurement

Strain gage vs. Photogrammetry

1. Contact vs. non-contact measurements 2. Smaller spot vs. extended length3. No messy wiring on the window test setup!4. Better systematics – no added material!5. Better coverage!

Photogrammetry is choice for strain measurement

d

1AU

r

d

p

p

scale bar

fixed targets

Photogrammetry resolution

convex concave convex concave

dR

r

2cos

1sin

2

RRd

R

r

Alignment of sides

D’

Small triangle fit

Use spherical fit of small trianglesD = 341.0m ( 5.5m) + (- ~10m)

Stress distribution at the yield point

FEA CalculationsFinite Element Analysis

Non-elastic region included

Three dimensios necessary for vibrational analysis

Window/flangesimulation

Window/flange cross section

FEA, non-elastic region included Displacement vs. radius under pressure:

NIU photogrammetry results and FEA calculations

Window performance summary

Summary of burst pressures and thicknesses

Window number Temperature Measured burst pressure (psi) FEA burst (psi) FEA burst pressure (psi) CMM thickness (um) Photogrammetry thickness(um)thickness=127um design thickness=127um

1 room 43.5 48 na 114 na

Window number Temperature Measured burst pressure (psi) FEA burst (psi) FEA burst pressure (psi) CMM thickness (um) Photogrammetry thickness(um)thickness=345um design thickness=330um

2 room 119 123 117 357 na3 room 120 123 117 346 na4 LN 151 162 156 365 331.6

1. Descrepancies between CMM and photogrammetry are larger than their intrinsic errors

2. Descrepancies between photogrammetry and FEA predictions are < 5%

Design of LINAC LH2 Absorber Beam Test

x

z

accelerator

absorber

Multiple scattering

RF cavity

Physicist’svision

Engineer’svision

Heat Absorption and Temperature Maintenance

1. What are the usable predictions from simulations?

2. What are the meaningful measurements?3. Radical changes: flat windows?

Design:

1. What do we need for temp/density measurements?

2. Window heating3. Strain gauging

Monitoring:

Safety Review

1. Windows (absorber) holdup: MACC, FEA & data pts

2. Windows (Vacuum) holdup will be the same3. Manifolds Mucool Responsibilities4. Instrumentation Mucool 5. Cryogenics FNAL

The Near Program

1. MICE and FNAL LINAC program merge2. Convection Absorber schedule for LINAC3. Instrumentation and DAQ integration4. The LINAC/MICE cooling cell designs

Experiment Signals- Absorber

• 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”

#signals

Instrumentation

1. Temperature/density uniformity inside LH22. Safety instrumention inside vacuum area3. Detectors for cooling measurements

Safety Issues: 1. Limits the amount of energy/(area or vol)

2. Physical size of the signal feedthroughs3. Seals from signals to electronics:

wiresfiberstubes