Femtosecond response time measurements of a Cs2Te photocathode

TL;DR

This paper measures the femtosecond response time of a Cs2Te photocathode, demonstrating its suitability for generating and controlling THz electron bunches for advanced FEL applications.

Contribution

It provides the first femtosecond-scale response time measurement of Cs2Te photocathodes using two independent methods, confirming their fast response.

Findings

Response time of ~250 fs confirmed by two methods

Cs2Te photocathodes enable THz electron bunch generation

Potential for wide-range tunable THz FEL development

Abstract

We present the response time measurements of a Cs2Te photocathode illuminated with two 100 fs duration, variable time separation laser pulses at 266 nm wavelength. The response time was confirmed in dispersive region downstream of a 12-cell standing wave S-band acceleration structure using a well-known RF zero-crossing technique. At the same time it was also measured by changing mechanical path-length difference between two micro-bunches. Both methods agree that Cs2Te photocathode time response is of the order of 250 fs and thereby it is possible to generate and control a THz sequence of relativistic electron bunches by a conventional S-band RF gun. This result further opens a possibility to construct wide-range tunable THz FEL.