1. Nick Shipman - Thursday, 04 August 2011
Progress Report
Status
System I
System II
Nick Shipman - Thursday, 04 August 2011

2. This week Lab work – Gap not constant in variable T sample holder
– Temperature controller broken (have replaced)
– More “global pollution 0” measurements in System 1
Fixed Gap Design – Good progress
Capacitance distance measurement – no more luck with UTI yet
Helped give a joint MeVArc highlight presentation at the RF group meeting
Installed and started learning how to use CST Microwave Studio – fine so far…
Wrote simple Matlab function to calcualte the Murphy-Good improvement to the Fowler-Nordheim field emission current, I will use this later to see how easy it would be to devolve Beta and the work function by varying the temperature.

3. CST Microwave Studio Tutorials
Fixed Gap Design
It looks like it will be possible to construct the fixed gap system from 80mm diameter discs despite the large ~550kg force
However the dielectric used to separate the discs will need to run most of the way around the circumference.
Still to do
Make some vacuum conductance calculations to ensure we can pump down the volume between the discs in a reasonable time.
Decide on the details of the antennae which we will use.
Decide on an appropriate fall off geometry at the edge of the disc through simulatio0ns to minimise field enhancement.

4. MeVArc Summary: Dislocations
Marc Fivel – 3D Discrete Dislocation Dynamics Simulations
TEM video showing a Frank Read Source in action
Persistent Slip Band formation – Model/Simulation/Experimental Evidence
Aarne Pohjonen – Dislocation mechanisms on a near surface void
Steve Fitzgerald – Dislocations
Model for protrusion formation under E field supported by simulations
Details of the experimental evidence for the required voids
May explain conditioning and BD resistance ranking by crystal structure {
MeVArc Programme
MeVArc Highlights
Nick Shipman - Wednesday, 03 August 2011

5. 1. TEM video showing a Frank-Read source in action
Taken using Transverse-Electron-Microscopy
TRDIS simulation of Frank Read source
“A Frank-Read Source is a mechanism explaining the generation of multiple dislocations in specific well spaced slip planes in crystals when they are deformed.” Wikipedia

6. 2. Persistent Slip Band Formation
One frame from the new nodal 3D discrete dislocation simulation code Numodis which was used to simulate low strain fatigue in AISI 316L Steel.
~10um
An SEM image courtesy of Markus Aicheler showing the damage due to pulse surface heating on copper.

8. Upcoming/Ongoing Capacitance measurements with UTI More CST
Fixed Gap Design