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Abstract: The electron beam dynamics in the presence of the linac structural wake field is studied. Trajectory manipulation is used to gain control of the transverse wake field-induced instability and this technique is also validated in the presence of shot-to-shot trajectory jitter. A specific script working with Courant–Snyder variables has been written to evaluate the residual banana shape after instability suppression in the presence of shot-to-shot trajectory jitter. [Copyright &y& Elsevier]

In this paper we discuss the design choices and construction strategy of the tapered undulator system designed for a high energy extraction efficiency experiment in the ultraviolet region of the electromagnetic spectrum planned for installation at the Argonne National Laboratory Linac Extension Area (LEA) beamline. The undulator is comprised of 4 sections pure permanent magnet Halbach array separated by short break sections, each one of them housing a focusing quadrupole doublet and a phase shifter. The quadrupoles use a novel hybrid design which allows one to vary the gradient and match the beam transversely. The undulator tapering profile is optimized to maximize the energy conversion efficiency from a 343 MeV 1 kA beam into coherent 257.5 nm radiation taking into account the longitudinal current profile generated by the linac. [ABSTRACT FROM AUTHOR]

We report observations of an intense, multi-band, sub-THz and THz radiation extracted from a ∼ 2-3 MeV electron beam with a flat transverse profile propagating in an oversized rectangular waveguide placed into a 3.25 mm gap of a planar undulator having 1.3 cm period and ∼ 20 cm length. Radiation outcoupling is accomplished using a horn antenna and a miniature permanent in-vacuum magnet separating the mm-sub-mm-waves and electron beam. A table-top experiment utilizes a radio frequency thermionic electron gun delivering a thousand momentum-chirped microbunches per macropulse and an alpha-magnet producing microbunches of a sub-mm length. Total radiated energy of a sub-millijoule per a microsecond radio frequency macropulse is demonstrated with flux more than ten micro-Joules per centimeter squared. With 1 THz filter the energy measured is about 1 microjoule and flux of a few micro-Joules per centimeter squared. [ABSTRACT FROM AUTHOR]