The SPARC_LAB (Sources for Plasma Accelerators and Radiation Compton with Lasers and Beams) facility at the INFN (National Institute of Nuclear Physics) laboratory in Frascati is being upgraded to accommodate a new user facility as part of the SABINA (Source of Advanced Beam Imaging for Novel Applications) project. A new beamline dedicated to SABINA will be equipped with three APPLE-X undulators to deliver IR/THz radiation with photon pulses in the ps range, with energy of tens of µJ, and with the possibility of choosing between linear, circular, or elliptical polarization. The APPLE-X, designed and built by KYMA S.p.a., guarantees the possibility to vary the gap amplitude between the magnet's arrays and their relative phase. The entire system, from mechanics to the kinematic subsystems, has been designed from scratch, and a structural analysis has been carried out to evaluate the production. The undulators were delivered to Frascati in 2023 and, in collaboration with ENEA, a further investigation campaign was launched on the mechanical parts in the vicinity of the permanent magnets, using strain measurements based on optical methods. Fiber Bragg Grating (FBG) sensors consist of a phase grating inscribed in the core of a single-mode fiber, whose Bragg-diffracted light propagates back along the fiber. If bonded to the mechanical structure, they can be used as strain sensors. By following the variations in the scattered spectrum, it is possible to perform strain measurements. Using multiple FBGs applied at selected locations on the undulator, several measurements were made by following the different possible kinematics, but also by studying the quiescent response as a function of the ambient temperature. The results show a clear deformation of the structure related to the temperature changes and magnetic forces, but its magnitude is compatible or lower with respect to the one calculated with the finite elements methods and, moreover, they are well within the tolerances required for the functionality of the undulator. The tests, therefore, confirm the reliability of the mechanical structure.
Mechanical strength investigations of the APPLE-X undulator using Fiber Bragg Grating strain measurements
Polimadei A.;Nguyen F.;Petralia A.;Caponero M. A.;
2025-01-01
Abstract
The SPARC_LAB (Sources for Plasma Accelerators and Radiation Compton with Lasers and Beams) facility at the INFN (National Institute of Nuclear Physics) laboratory in Frascati is being upgraded to accommodate a new user facility as part of the SABINA (Source of Advanced Beam Imaging for Novel Applications) project. A new beamline dedicated to SABINA will be equipped with three APPLE-X undulators to deliver IR/THz radiation with photon pulses in the ps range, with energy of tens of µJ, and with the possibility of choosing between linear, circular, or elliptical polarization. The APPLE-X, designed and built by KYMA S.p.a., guarantees the possibility to vary the gap amplitude between the magnet's arrays and their relative phase. The entire system, from mechanics to the kinematic subsystems, has been designed from scratch, and a structural analysis has been carried out to evaluate the production. The undulators were delivered to Frascati in 2023 and, in collaboration with ENEA, a further investigation campaign was launched on the mechanical parts in the vicinity of the permanent magnets, using strain measurements based on optical methods. Fiber Bragg Grating (FBG) sensors consist of a phase grating inscribed in the core of a single-mode fiber, whose Bragg-diffracted light propagates back along the fiber. If bonded to the mechanical structure, they can be used as strain sensors. By following the variations in the scattered spectrum, it is possible to perform strain measurements. Using multiple FBGs applied at selected locations on the undulator, several measurements were made by following the different possible kinematics, but also by studying the quiescent response as a function of the ambient temperature. The results show a clear deformation of the structure related to the temperature changes and magnetic forces, but its magnitude is compatible or lower with respect to the one calculated with the finite elements methods and, moreover, they are well within the tolerances required for the functionality of the undulator. The tests, therefore, confirm the reliability of the mechanical structure.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
