Ultrashort electron bunch generation by an energy chirping cell attached rf gun

K Sakaue,R Kuroda,M Washio,M Mizugaki,T Takatomi,Y Koshiba,J Urakawa

doi:10.1103/physrevstab.17.023401

Abstract

We present a new design for a rf electron gun to be used in ultrashort ($\ensuremath{\sim}1\text{ }\text{ }\mathrm{ps}$) electron bunch generation. Using both simulation and measurement we evaluated the principle of this new type rf gun and were able to confirm an ultrashort bunch generation. During simulation, a bunch length of less than 100 fs(rms) with a $100\text{ }\mathrm{pC}/\text{bunch}$ charge was confirmed at the optimum operating condition. The principle is to produce a linearly distributed longitudinal phase space by using an attached output cell specially designed for energy chirping. Such phase space distribution can be rotated by the velocity difference in the bunch. We already fabricated an energy chirping cell attached rf gun and successfully observed 0.2 THz coherent synchrotron radiation, which corresponds to less than 500 fs bunch. Such an electron gun can be used as a compact THz light source and a new electron injector with an ultrashort bunch.

Highlights

We have been developing a photocathode rf electron gun in collaboration with KEK and Waseda University
We present a new design for a rf electron gun to be used in ultrashort (∼1 ps) electron bunch generation
Using both simulation and measurement we evaluated the principle of this new type rf gun and were able to confirm an ultrashort bunch generation

Summary

Introduction

We have been developing a photocathode rf electron gun in collaboration with KEK and Waseda University. At KEK-LUCX (Laser Undulator Compact X ray source), we have successfully produced more than 300 bunches/trains with a 1 nC charge [2], and this is being used to study compact x-ray sources based on laser-Compton scattering [3,4]. At Waseda University, we have been performing pulse radiolysis experiments with psec bunches [5] and laser-Compton scattering experiments [6]. If an ultrashort electron bunch can be produced, the temporal resolution of the pulse radiolysis system will be further improved down to the fs range and the luminosity of laser-Compton scattering will increase. The ultrashort electron bunch will produce other applications due to its coherent radiation. Bunches with less than 1 ps can coherently produce THz radiation, which can be used in application for compact radiation sources

Methods

Results

Conclusion