Project 8: Summary of WorkBy: Callum Lamb

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

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

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.

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

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.

Drawings…

Lots and lots…

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)

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.

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.

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).

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:

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

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.

Side Projects:

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.