Carbon Nanotube Field Effect Emission Cathode for use with Free Electron Lasers - Video Portal
Carbon Nanotube Field Effect Emission Cathode for use with Free Electron Lasers
LT Christopher Pace, USN
Carbon nanotubes can be used to enhance electron emission electrodes for various applications through the effect of electric field enhancement due to their sharp tips. This has been demonstrated recently. However it is not known whether the surface topography of the substrate would provide magnification of the nanotubes field enhancement effect. We have tested if the effect is improved on copper electrodes, used in the field electron laser (FEL) by electrodes being polished, which would allow for more carbon nanotube growth than a rough surfaced substrate. This thesis explores this question by testing a rough surfaced and a polished surfaced cathode both with carbon nanotube growth using the same growth procedures. By using several tests of electric field induced current and calculating an enhancement factor, this thesis will analyze the differences between the two and whether or not polishing should even be an additional process step in fabricating this type of cathode. Finally, a cathode with no carbon nanotube growth will be subjected to an electric field to show that carbon nanotubes do provide an enhancement to current emittance. Discovering better ways to fabricate cathodes could enhance other fields such as free electron lasers and other applications.