Outline For Thesis

Abstract, Intro (obviously)

Current experiments requiring the use of GaAs photo-guns - polarized electron beams
What is a photo-gun?
CEBAF Injector - What is it? How do we (currently) model it?

What is ionization & why is it bad for electron beam production & electron guns?
- Ion Back-Bombardment & QE degradation of the photocathode
  - How/where are ions formed in the photogun?
  - How many ions reach the photocathode and what are their energies?
  - How many of these ions contribute/correlate to QE damage?

Experimental ion mitigation techniques that are currently available:
- Clearing electrodes - ion precipitator
- Repelling electrodes - biased anode
Theoretical Techniques
- Other ion tracking codes (IBSimu, SIMION, etc.)

What do **I** bring to the table? Brief description/summary of
- GPT ionization custom element
- Biased anode as ion mitigation technique
- Analysis of how the charge lifetime scales with laser spot size (2017 experiments)
- Ion trapping experiments/simulations
How all of these help to solve the problem described above?
- Knowing how ions are formed and where they go through measurements and simulations, we can...
  - Predict the effectiveness of ion mitigation techniques (such as the biased anode)
  - Predict the QE degradation of the photocathode and its charge lifetime under various beam conditions
  - Identify the conditions under which ions can cause deleterious effects on the beam (in its creation and its stability) That is, we can identify the sources/causes of damaging ions.

Purpose - to create particle simulations, often of electron beams, and to track their movement within electromagnetic fields in real-time (as opposed to just getting the trajectory info)
How does it work? (perhaps with a flow chart?)
- Description of how particle distributions are created and what "macro-particles" are
- Built-in and custom elements with their respective locations (i.e. coordinate systems) are called by the GPT kernel. These elements include:
  - E-Field and B-Field maps, usually due to beam line components
  - Space charge routines
  - Custom elements (like the ionization custom element)
- Equations of motion are derived by solving the Poisson equation using the 5th-order Runge-Kutta Method with an adaptive stepsize control

Description of how the custom element works and is used to simulate ionization
- Ionization theory - Can be pulled from PSTP proceedings and tech notes
- Secondary Electron Differential Cross Section (SEDCS)
- Ion Energy Distribution (Maxwellian)
- Momentum/Energy Conservation?
Benchmarking with theory and IBSimu (Can be pulled from future GPT/IBSimu paper)...maybe put in the LIfeSize Runs Section?

Ion back-bombardment theory & how the biased anode will mitigate it (Can be pulled from PSTP)
Summer 2019 Biased Anode Experiments
- Experiments at CEBAF
- QE Measurements & Charge Lifetime Analysis
- QE Scan Analysis
- GPT Simulations (w/custom element)
- Results/Discussion
Similar for Winter 2019-2020 Experiments?