Abstract: SwissFEL, located at the Paul Scherrer Institute (PSI) in Switzerland, is a compact X-ray free-electron laser (FEL) driven by a high-brightness and low-energy electron beam. SwissFEL operates at 100 Hz with a standard bunch charge of 200 pC and a maximum electron beam energy of 6.2 GeV. It has two beamlines: Aramis, the hard X-ray beamline, in user operation since 2019, covering wavelengths from 0.1 to 0.7 nm; and Athos, the soft X-ray beamline, operating since 2021 for wavelengths between 0.7 and 5 nm. Aramis consists of 13 in-vacuum undulator modules, each with a 15 mm period and 4 m length. Athos features 16 APPLEX modules, each with a 38 mm period and 2 m length, capable of providing full polarization control. Inter-undulator magnetic chicanes in the Athos beamline enable unique operation modes, giving control over FEL properties such as peak power, pulse duration, and longitudinal coherence. This talk will present the status and progress at SwissFEL, focusing on accelerator and FEL physics aspects. We will show, for instance, high-resolution emittance measurements that reveal unprecedented values for an X-ray FEL, and attosecond time-resolved measurements of both electron and photon beams. We will also show the demonstration and implementation of several special operation modes, such as attosecond pulses, tunable two-color pulses, and mode-locked FEL.
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