Thesis outline
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Introduction
- Magnetized electron beam
- Applications of the magnetized electron beam
- Magnetized electron cooling
- Jefferson Lab magnetized electron source for the JLEIC cooler
Generation of the magnetized electron beam
- Experimental setup (DC HV gun, photocathode, cathode solenoid, RF laser, focusing solenoids, etc.)
- Beam diagnostics
Beam dynamics
- Beam matrix
- Phase space
- Emittance (thermal, phase space, geometric)
- Effective(drift) emittance (emittance of a magnetized beam)
- Measuring/calculating the beam emittance
Space charge effect
- Space charge effect in a magnetized electron beam
Simulations on the magnetized electron beam
ASTRA
- Initial particle distribution
- Field maps (3D E field map, 2D B field map)
- Space charge calculation mechanism
- Emittance
GPT
- Initial particle distribution (Laser*QE image processing)
- Field maps (3D E field map, 2D B field map)
- Space charge calculation mechanism
- Emittance
Post-processing (MATLAB)
Characterization of the magnetized electron beam
Experimental method
- Beam size vs solenoid I
- Rotation angle vs solenoid I
- Emittance vs solenoid I - three different laser sizes
- Emittance vs laser spot sizes - max solenoid current
ASTRA/GPT simulations (Simulations of all the above variations)
- Conclusions (comparisons -measurements vs simulations, mismatch oscillations, negative rotation angles, etc.)
Experimental and numerical simulation results of the space charge dominated magnetized electron beam
Experimental method
- Pulse energy vs extracted charge-for different magnetizations
- Space charge current limitation dependence on gun high voltage-for different magnetizations
- Space charge current limitation dependence on pulse width-for different magnetizations
- Space charge current limitation dependence on laser spot size-for different magnetizations
GPT simulations
- Conclusions (Comparison-measurements and simulations)
Redesigning and performance of the photogun
- Existing electrostatic design
- Modified electrostatic design
- Polishing and gun assembly
- High voltage conditioning