Observation of Coherently-Enhanced Tunable Narrow-Band Terahertz Transition Radiation from a Relativistic Sub-Picosecond Electron Bunch Train

TL;DR

This paper reports the experimental generation of tunable, narrow-band terahertz transition radiation using a train of relativistic electron bunches, with potential applications in beam diagnostics.

Contribution

It demonstrates a method to produce tunable narrow-band THz radiation from relativistic electron bunch trains and explores its application in enhancing bunch length diagnostics.

Findings

Narrow-band THz radiation with 20% bandwidth at 0.5 THz was achieved.

Tunable frequency range from 0.37 to 0.86 THz was demonstrated.

Application to extend the dynamic range of bunch length diagnostics was shown.

Abstract

We experimentally demonstrate the production of narrow-band ($\delta f/f \simeq20$% at $f\simeq 0.5$ THz) THz transition radiation with tunable frequency over [0.37, 0.86] THz. The radiation is produced as a train of sub-picosecond relativistic electron bunches transits at the vacuum-aluminum interface of an aluminum converter screen. We also show a possible application of modulated beams to extend the dynamical range of a popular bunch length diagnostic technique based on the spectral analysis of coherent radiation.