2. Summary of Work
Major Projects:
Cell Design
Getter Design & Support Structure
Insert Support Structure & Heat Analysis
Window Gasket Seal Test and Simulations
Side Projects:
Learning Thermal Stress Analysis
KATRIN Project
Cryocooler Repair
3. Cell Design:
Design Features:
Gold gasket sealed OR soldered gas
line
Screws directly into bus bar for
stability (6 screws)
Symmetric window seals for
consistency.
10 cm of space for adaptability in
coil winding
4. Getter System Design:
Design Features:
Cube at center minimizes space
requirement and removes need for custom
attachment piece.
Includes filler valve & Ion gauge in assembly
Getter contained within standard CF nipple
Feedthrough to power getter
Each component is easily accessible.
Fits within large iso cross, close to insert.
5. Getter Support Structure
& Gas Line:
Design Features:
Supported by ‘blank flange’ piece
Combines blank, gas line input &
support structure
Very Stable – Stainless Steel
Leaves majority of iso cross open.
Does not block bore.
Gas line remains close to insert
6. Insert Support Structure
Design Features:
Adequate Thermal barrier between
bus bar and iso cross (confirmed in
MATLAB)
Lower Ring, attachment piece & pipes
made of G-10
High structural stability: Pipes allow
essentially no flex or vibration
Screws directly into bus bar
Applies both upwards & downwards
force to insert from iso cross.
8. Test Seal Preparation:
Prepared the test apparatus to begin
mechanical testing of the gold gasket seal.
Modified previous pieces in the shop to allow
us to attach the cold plate and test cell
together inside the iso cross.
For this purpose, created the bracket plate
with Martin.
Apparatus:
• Helium supply
(bottom left),
• Temperature
sensor (bottom right),
• Cold plate (upper
right),
• Test cell (right
middle)
9. First Test- Corner Seal
We initially tested the corner seal
design, as shown (sapphire window).
First tested this at room temperature,
then decided to go straight to a face
seal.
Unsuccessful initially- the gold gasket
was too large.
Once the correct gasket was used, the
seal was successful.
10. Mechanical Simulation:
Sapphire Window
Digging more into AutoCAD Inventor, I
used in-CAD NASTRAN to perform
mechanical simulations of the window
under the stress required to compress the
gold gasket.
Performed Face Seal (Upper) & Corner
seal (Lower) stress analysis
Most realistic constraints:
Gasket contact surface is axial constrained
Opposing surface is where force is applied
Cylindrical side is constrained in the radial
directions.
Conclusion: Force Required for Gasket
compression will not break sapphire
window.
11. Face Seal Test:
Setup
Cell is sealed with alternating aluminum &
titanium screws to alternatively provide
compression during cold & hot cycling.
Cell is fastened to cold plate inside of iso cross,
with temperature sensors attached with Kapton
tape.
For initial heat cycle, heating rope is wrapped
around the outer iso cross.
Full setup with leak checker attached & helium
input (bottom left).
12. Face Seal Test:
Conclusion
Peter and I ran the hot and then cold cycle
multiple times.
Conclusion: The face seal for the sapphire
window reasonably seals for the required
temperature range.
Curve in Leak rate at the end: Peter removed
and replaced helium source Leak rate
approx. 1.0E-08. Leak checker is quite old…
Heat damage to
bracket plate:
Cooling with
liquid nitrogen:
13. Mechanical Simulation & Test:
Calcium Fluoride Window
Using the same constraints, I did an analysis for the CaF2
windows.
Maximum force (0.5” OD, 0.396” Bore, 0.45 O-Ring) is 265
Ibs.
Is this sufficient for gold ring compression?
Previously estimated about 500 Ibs of force is required, currently
trying to confirm that with simulations, but proving difficult.
Put CaF2 in previous setup – very quickly broke windows.
Take away: Surface was rough from failed soldering attempt-
surface roughness is a stress amplifier.
Result: Back the window with a Kapton ring
14. Future Work For CaF2 Test Seal:
Once modified test cell & window holder (accurately simulates final
design) are received from the shop, Peter and I will perform that test.
Room temperature- If successful continue to heat loading
If Unsuccessful we’ll need to visit other options, such as sealing between
the window holder and cell faces, which relieves the compressive force
from the window.
Work on simulations using a different software- Simulation Mechanical
from AutoCAD to model gold gasket compression force requirement.
16. Thank You!
Thank everyone in this project, you’ve all made my time
here a wonderful experience, full of learning and growth.
A special thank you to Martin, who’s taught me an
incredible amount, Hamish who has been constantly
supportive, and Jared for getting me in here in the first
place.
