A Novel Emission Electron Microscope for the Study of Field Emission Cathodes and Their Emittance

• Main Author: Enderich, Daniel A
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2018
• Subjects: Condensed matter physics; Electrical engineering; Physics
• ISBN: 9780438360556; 0438360559

Vacuum electronic devices (VEDs) serve an important role as high-power and/or high-frequency sources of RF radiation. To access higher power and higher frequency regimes, VEDs will require greater current densities and lower emittance electron beams. Field emission cathodes show tremendous promise in satisfying these needs, but much remains to be learned about how the cathode structure affects the emittance of the resulting beam. Some theoretical work has been published, but no experimental data has been produced to guide and validate these theoretical developments. In this dissertation, I motivate the need for a better understanding of these cathodes for application in VEDs. I show why emittance is such an important figure of merit for electron beams and how it relates to the beam current density. I demonstrate that the only way to acquire the data necessary to test the recent theoretical developments regarding emittance is to construct a focusing field emission electron microscope (f-FEEM) capable of resolving individual emission sites with large magnification. I provide design guidelines for constructing such an f-FEEM, and I present initial test data validating its performance. Finally, I propose future research directions that will improve the performance of the f-FEEM and open up new areas of research.