Speaker
Description
Laser-based high power THz generation advances rapidly, enabling THz-driven electron acceleration beyond the breakdown limits of conventional RF-driven structures. For this purpose the polarization of the externally coupled THz pulse has to match the required TM₀₁ mode. Vice versa, beam-driven high power THz generation also relies on the TM₀₁ mode and requires efficient out-coupling and transport. A crucial step in both applications is the conversion between the fundamental mode and the TMTM₀₁ in a compact manner, which can be achieved efficiently in a double bend geometry¹.
However, the double bend mode converter is fully integrated with the chained neighbouring devices. The embedding imposes challenges on the independent characterization of the converter, especially due to the strict tolerances. Utilising the wake field excited by an externally injected electron beam reduces the de-embedding complexity due to the requirements for THz in-coupling.
Following tolerance studies, a beam-based experiment at ARES at DESY is proposed to study the conversion quality of the mode converter at 165 GHz, the design frequency envisioned for the TWAC project². The wake-driven excitation enables a wideband characterization around the design frequency.
A gently compressed (≈1 ps rms) high charge (≈50 pC) electron bunch is passed through a dielectric loaded waveguide, thereby exciting the TM01 mode. The out-coupled, sub-µJ THz pulse will be polarization filtered to determine the relative mode content between the residual unconverted TM₀₁ and the expected TE₁₁.
Funding Agency
The TWAC project is funded by the European Union‘s Horizon Europe research and innovation programme (EIC Pathfinder scheme) under grant agreement n. 101046504.
Footnotes
() M. J. Kellermeier et al. in Proc. IPAC'23, Venice, Italy, May 2023, pp. 2916-2919. doi:10.18429/JACoW-IPAC2023-WEPA113
(*) C. Bruni et al., in Proc. IPAC'23, Venice, Italy, May 2023, pp. 1468-1471. doi:10.18429/JACoW-IPAC2023-TUPA061
| Paper status | Resubmitted proceeding files received and assigned to an editor. Accepted. |
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