Engineering topics

Pellegrini, Claudio

Publications and source records attributed to Pellegrini, Claudio.

4 records

DOE OSTI2023

Development of spinning-disk solid sample delivery system for high-repetition rate x-ray free electron laser experiments

X-ray free-electron lasers (XFELs) deliver intense x-ray pulses that destroy the sample in a single shot by a Coulomb explosion. Experiments using XFEL pulse trains or the new generation of high-repetition rate XFELs require rapid sample replacement beyond those provided by the systems now used at low repletion-rate XFELs. We describe the development and characterization of a system based on a spinning disk to continuously deliver a solid sample into an XFEL interaction point at very high speeds. We tested our system at the Linac Coherent Light Source and European XFEL hard x-ray nano-focus instruments, employing it to deliver a 25 μm copper foil sample, which can be used as a gain medium for stimulated x-ray emission for the proposed x-ray laser oscillator.

47 OTHER INSTRUMENTATION↗

DOE OSTI2023

Seeded stimulated X-ray emission at 5.9 keV

X-ray free-electron lasers (XFELs) provide intense pulses that can generate stimulated X-ray emission, a phenomenon that has been observed and studied in materials ranging from neon to copper. Two schemes have been employed: amplified spontaneous emission (ASE) and seeded stimulated emission (SSE), where a second color XFEL pulse provides the seed. Both phenomena are currently explored for coherent X-ray laser sources and spectroscopy. Here, we report measurements of ASE and SSE of the 5.9 keV Mn K α 1 fluorescence line from a 3.9 molar NaMnO 4 solution, pumped with 7 femtosecond FWHM XFEL pulses at 6.6 keV. We observed ASE at a pump pulse intensity of 1.7×10 19 W/cm 2 , consistent with earlier findings. We observed SSE at dramatically reduced pump pulse intensities down to 1.1×10 17 W/cm 2 . These intensities are well within the range of many existing XFEL instruments, which supports the experimental feasibility of SSE as a tool to generate coherent X-ray pulses, spectroscopic studies of transition metal complexes, and other applications.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2022

Generation of intense phase-stable femtosecond hard X-ray pulse pairs

Significance The generation of phase-stable femtosecond X-ray pulse pairs will advance nonlinear spectroscopies and imaging, providing direct insight into the coupled motions of electrons and nuclei with resolution on the electronic length scale and timescale. This paper presents the generation of such pulse pairs in the X-ray domain. The approach uses X-ray free-electron laser pulses to induce highly directional, intense, phase-stable pairs of superfluorescence and seeded stimulated emission at the 5.9 keV manganese Kα 1 line. The finding is evidenced by strong interference fringes in the superfluorescence and stimulated emission signals.

43 PARTICLE ACCELERATORS↗

DOE OSTI2022

Tunable x-ray free electron laser multi-pulses with nanosecond separation

X-ray Free Electron Lasers provide femtosecond x-ray pulses with narrow bandwidth and unprecedented peak brightness. Special modes of operation have been developed to deliver double pulses for x-ray pump, x-ray probe experiments. However, the longest delay between the two pulses achieved with existing single bucket methods is less than 1 picosecond, thus preventing the exploration of longer time-scale dynamics. We present a novel two-bucket scheme covering delays from 350 picoseconds to hundreds of nanoseconds in discrete steps of 350 picoseconds. Performance for each pulse can be similar to the one in a single pulse operation. The method has been experimentally tested with the Linac Coherent Light Source (LCLS-I) and the copper linac with LCLS-II hard x-ray undulators.

47 OTHER INSTRUMENTATION↗