23–28 Aug 2026
America/Los_Angeles timezone

Numerical evaluation of FEL instability in the Plasma Discharge Undulator

FRX02
28 Aug 2026, 08:55
25m
Invited Oral Presentation Session 9: Novel Accelerator and FEL Concepts Novel Accelerator and FEL Concepts (Invited)

Speaker

Andrea Frazzitta (Paul Scherrer Institute)

Description

The plasma discharge undulator (PDU) has recently been proposed as a compact, tunable, fully plasma-based undulation device. In the PDU, a high-current discharge within a capillary generates an azimuthal magnetic field providing strong linear focusing, while a controlled periodic modulation of the discharge axis acts as a geometric driving term, producing well-defined undulator oscillations at a wavelength distinct from the natural betatron motion. Proper beam injection conditions suppress collective betatron oscillations, significantly reducing the intrinsic undulator strength spread typical of conventional plasma undulators, while matched beam transport is ensured by the strong active plasma lens focusing. While the PDU is still in the experimental development phase, the feasibility of free-electron laser operation has been assessed through one-dimensional analytical estimates, including scaling relations for gain length, Pierce parameter, and the onset of longitudinal microbunching. These results are here supported by self-consistent numerical simulations of the beam–radiation interaction within the PDU, which show the emergence of FEL instability and the development of seeded longitudinal microbunching analogous to that observed in conventional magnetic undulators, establishing the PDU as a promising pathway toward miniaturized, tunable, plasma-based light sources.

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Author

Andrea Frazzitta (Paul Scherrer Institute)

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