Simulation of short pulse photoemission in a micro-diode with implications for optimal beam brightness

TL;DR

This paper uses molecular dynamics simulations to analyze short-pulse photoemission in microdiodes, revealing optimal beam brightness during transition regimes and emphasizing the importance of emitter spot size for electron emission efficiency.

Contribution

It introduces a detailed simulation approach to identify emission regimes and optimal conditions for beam brightness in microdiodes under short-pulse photoemission.

Findings

Maximum beam brightness occurs during transition from source-limited to space-charge limited regimes.

Emitter spot size critically influences the critical charge density for emission.

Three distinct emission regimes are identified and characterized.

Abstract

Molecular dynamics simulations, with full Coulomb interaction are used to model short-pulse photoemission from a finite area in a microdiode. We demonstrate three emission regimes, source-limited emission, space-charge limited emission for short-pulses, and space-charge limited emission for the steady state. We show that beam brightness is at a maximum during transition from the source-limited emission regime to the space-charge limited emission regime for short pulses. From our simulations it is apparent that the important factor is the emitter spot size when estimating the critical charge density for short-pulse electron emission.