Reconstruction of sub-femtosecond longitudinal bunch profile measurement data

M K Weikum,R W Assmann,Z M Sheng,G Andonian,U Dorda

doi:10.1088/1742-6596/874/1/012079

Abstract

With a current trend towards shorter electron beams with lengths on the order of few femtoseconds (fs) to sub-femtoseconds both in conventional and novel accelerator communities, the need for diagnostics with equivalent attosecond resolution is increasing. The proposed design for a sub-femtosecond diagnostic by Andonian et al. (2011, Phys. Rev. ST Accel. Beams 14 072802) is one such example that combines a laser deflector with an RF deflecting cavity to streak the electron beam in the horizontal and vertical direction. In this paper, we present a tool for the reconstruction of the longitudinal beam profile from this diagnostic data, which can be used both for the analysis of planned experiments and testing of different beam scenarios with respect to their specific setup requirements. Applying this method, the usefulness of the device for measurements in a number of example scenarios, including plasma-accelerated and ultrashort RF-accelerated electron beams, is discussed.

Highlights

Both the need for short, high current electron beams for application in advanced radiation generation schemes, like Free-Electron Lasers (FELs), and the natural bunch length reduction to femtoseconds in novel accelerators, such as plasma-based devices, have led to an increased interest in ultrashort electron beams and their measurement in the accelerator community
The current standard for bunch length diagnostics comprises a wide range of setups including electrooptical detectors, devices based on coherent and incoherent transition radiation and transverse deflecting cavities, most of which can resolve electron beams on the order of few to tens of femtoseconds [2,3,4] and are not suitable as diagnostics in the attosecond regime
The setup of this diagnostic is a combination of a laser modulator, i.e. a high power laser pulse in the TEM10-mode co-propagating with the electron beam in a few-period undulator, and a transverse deflecting RF cavity (RF-TDS), followed by a drift space and a screen for measuring the transverse beam profile

Summary

Introduction

Both the need for short, high current electron beams for application in advanced radiation generation schemes, like Free-Electron Lasers (FELs), and the natural bunch length reduction to femtoseconds in novel accelerators, such as plasma-based devices, have led to an increased interest in ultrashort electron beams and their measurement in the accelerator community. The setup of this diagnostic is a combination of a laser modulator, i.e. a high power laser pulse in the TEM10-mode co-propagating with the electron beam in a few-period undulator, and a transverse deflecting RF cavity (RF-TDS), followed by a drift space and a screen for measuring the transverse beam profile.

Results

Conclusion