Index of content:
Volume 35, Issue 2, March 2017
- Papers from the 29th International Vacuum Nanoelectronics Conference
35(2017); http://dx.doi.org/10.1116/1.4968007View Description Hide Description
Analytic image charge approximations exist for planar and spherical metal surfaces but approximations for more complex geometries, such as the conical and wirelike structures characteristic of field emitters, are lacking. Such models are the basis for the evaluation of Schottky lowering factors in equations for current density. The development of a multidimensional image charge approximation, useful for a general thermal-field emission equation used in space charge studies, is given and based on an analytical model using a prolate spheroidal geometry. A description of how the model may be adapted to be used with a line charge model appropriate for carbon nanotube and carbon fiber field emitters is discussed.
35(2017); http://dx.doi.org/10.1116/1.4968511View Description Hide Description
Future advanced light sources and x-ray free electron lasers require fast response from the photocathode to enable short electron pulse durations as well as pulse shaping, and so the ability to model delays in emission is needed for beam optics codes. The development of a time-dependent emission model accounting for delayed photoemission due to transport and scattering is given, and its inclusion in the particle-in-cell code MICHELLE results in changes to the pulse shape that are described. The model is applied to pulse elongation of a bunch traversing an rf injector, and to the smoothing of laser jitter on a short pulse.