Difference between revisions of "Outline For Thesis"
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== Abstract, Intro (obviously) == | == Abstract, Intro (obviously) == | ||
| + | |||
| + | ===Current Experiments - Motivation for Research=== | ||
*Current experiments requiring the use of GaAs photo-guns - polarized electron beams | *Current experiments requiring the use of GaAs photo-guns - polarized electron beams | ||
*What is a photo-gun? | *What is a photo-gun? | ||
| − | *Description of | + | *CEBAF Injector - What is it? How do we (currently) model it? |
| + | |||
| + | ===Description of problem - Ionization === | ||
| + | |||
| + | *What is ionization & why is it bad for electron beam production & electron guns? | ||
**Ion Back-Bombardment & QE degradation of the photocathode | **Ion Back-Bombardment & QE degradation of the photocathode | ||
***How/where are ions formed in the photogun? | ***How/where are ions formed in the photogun? | ||
***How many ions reach the photocathode and what are their energies? | ***How many ions reach the photocathode and what are their energies? | ||
***How many of these ions contribute/correlate to QE damage? | ***How many of these ions contribute/correlate to QE damage? | ||
| − | |||
| − | |||
| − | |||
| − | ** | + | ===Current Solutions === |
| + | |||
| + | *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.) | ||
| + | |||
| + | ===The "Thesis" statement === | ||
| + | *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. | ||
| − | |||
== Ionization Simulations with GPT Custom Element == | == Ionization Simulations with GPT Custom Element == | ||
===GPT Description === | ===GPT Description === | ||
| + | *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 | ||
| − | + | === GPT Custom Element Algorithm === | |
| − | === | + | *Description of how the custom element works and is used to simulate ionization |
| − | + | **Ionization theory - Can be pulled from PSTP proceedings and tech notes | |
| − | * Can be pulled from PSTP proceedings and tech notes | ||
| − | |||
**Secondary Electron Differential Cross Section (SEDCS) | **Secondary Electron Differential Cross Section (SEDCS) | ||
**Ion Energy Distribution (Maxwellian) | **Ion Energy Distribution (Maxwellian) | ||
**Momentum/Energy Conservation? | **Momentum/Energy Conservation? | ||
| − | |||
| − | |||
| − | |||
*Benchmarking with theory and IBSimu (Can be pulled from future GPT/IBSimu paper)...maybe put in the LIfeSize Runs Section? | *Benchmarking with theory and IBSimu (Can be pulled from future GPT/IBSimu paper)...maybe put in the LIfeSize Runs Section? | ||
Revision as of 09:32, 29 May 2020
Abstract, Intro (obviously)
Current Experiments - Motivation for Research
- 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?
Description of problem - Ionization
- 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?
- Ion Back-Bombardment & QE degradation of the photocathode
Current Solutions
- 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.)
The "Thesis" statement
- 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.
- Knowing how ions are formed and where they go through measurements and simulations, we can...
Ionization Simulations with GPT Custom Element
GPT Description
- 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
GPT Custom Element Algorithm
- 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?
Biased Anode To Mitigate Ion Back-Bombardment
- 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?
Analyzing 2017 LifeSize Runs with GPT/IBSimu
- Description of Experiment
- Analysis of results with GPT custom element
- Comparison & benchmarking with IBSimu
Ion Trapping at the Gun Test Stand (GTS)
- Theory
- Ion Trapping Experiments - Ghost Beam and Steel Shield
- GPT Simulations (w/custom element)
- Results/Discussion