Novel THz radiation source based on compact linear accelerator.

Marie Curie Research Fellow: Konstantin Lekomtsev

Research objectives:

• to investigate Cherenkov and Smith - Purcell mechanisms for THz radiation generation using EM simulation tools and propose an efficient target configuration and observation geometry;

• to build a radiation source that provides high peak power levels and based on a compact linear accelerator technology with a fs-duration beam;

• to evaluate possible applications of the investigated radiation mechanisms for beam position and bunch length diagnostics;

• to provide knowledge exchange between partner organisations and other interested parties via seminars, satellite and progress meetings, conferences and workshops;

• to improve public awareness about the ongoing research via outreach activities;

• to develop project management skills.

Generation of THz radiation from dielectric mm-scale capillaries with reflectors.

Demonstrated that coherent Smith Purcell Radiation, with intensity comparable to that of coherent Transition Radiation, can be generated as a result of introducing a corrugation in a mm-scale dielectric capillary and can be emitted through an outer dielectric boundary not covered by a reflector.

Detailed information on https://doi.org/10.1016/j.nimb.2017.02.058

Laser Undulator Compact X-ray source (KEK LUCX) facility in Japan:

Installation of capillaries in a vacuum chamber at LUCX:

Crosscheck with Transition Radiation for central (zero transverse off-set) and non-central beam propagation; and crosscheck with a PIC simulation:

Drive-Witness acceleration scheme based on corrugated dielectric mm-scale capillary.

An experimental scheme based on a mm-scale corrugated capillary proposed as an accelerator/decelerator with an adjustable wakefield pattern, and was used to study beam dynamics at different transverse beam off-sets.

Detailed information on http://vrws.de/ipac2017/papers/wepva018.pdf

Two bunches were accelerated up to 8 MeV in a 3.6 cell S-band RF gun. The RF gun introduced time – energy correlation in a beam, producing a drive and a witness of slightly different energies. When a beam was dispersed by the bending magnet different time slices were projected to different transverse coordinates on the Yttrium Aluminium Garnet screen.

Capillary structures:

Beam images on the YAG screen for a reference measurement (beam without capillary) and a measurement with a corrugated capillary (off-central beam propagation).

Measurement of acceleration (red filling) and deceleration (green filling) of a witness bunch as a function of the distance between drive and witness bunches.