Speaker
Description
Terahertz (THz)-driven electron manipulation is a novel technique being explored with the goal of compact, efficient acceleration, compression, and deflection of electrons with tight-scale time control. In the Terahertz Acceleration Group, we have demonstrated significant advances in the field of novel electron manipulation methods, mainly using dielectric-lined waveguides (DLWs). We have designed, optimised, and experimentally tested structures for both acceleration and deflection applications. A crucial challenge to address in this frequency regime is the coupling between laser-generated Terahertz sources and the required modes of the DLWs as it is vital to maximise the energy delivered to the interaction region. Laser-driven THz sources produce a Gaussian beam in free space, which does not trivially map to required modes of the DLWs. Additionally, the THz beam spot size is large relative to the cross-section of a typical interaction waveguide. It is therefore required to have a large aperture to capture the spot, then taper down while simultaneously converting to the required modes to couple into the dielectric-lined region.
To correctly match the aperture mode for accelerating structures, two oppositely phased lobes of the beam are required. This may be achieved with a phase-shifter plate to offset part of the pulse. Here, we also demonstrate a novel approach where two THz spots are generated, thus allowing for increased tailoring of the pulse profile at the aperture, which allows for further optimisation.
Coupling structures for both acceleration and deflection are presented, including detail on the design, optimisation, and fabrication. Our new two-spot coupler design shows up to 74% coupling between the free space beam and the accelerating mode of the DLW, while the design for the deflecting-mode coupler achieves up to 86% efficiency.
| Presenting Author | Laurence J. R. Nix |
|---|---|
| Is the Presenting Author a PhD Student or Early Career Scientist ? | No |
| Area of research | Advanced accelerator concepts |