MHz sample delivery system for a seeded X-ray oscillator

C55-08a-270680-AbstractTo enable exploration of atomic and molecular systems at the angstrom/femtosecond scales for interferometry and X-ray quantum science, few to tens MHz repetition rate XFELs can be utilized to pump and seed a cavity based X-ray oscillator. In this approach, an XFEL pulse (5-10 keV) serves as a pump, creating population inversion in a solid medium and resulting in highly coherent amplified spontaneous emission (ASE) radiation. This radiation can be further filtered and returned with an X-ray cavity for subsequent seeding, similarly to a conventional active medium laser oscillator. However, the focused high intensity X-ray pulses are destructive to the lasing medium in a single shot; thus, in an oscillator configuration, it is required for an active medium material to be replenished with a new fresh sample before the next shot on the sub-microsecond time scale. In Phase I, our proposed solution will use copper as the gain medium, lasing at Ka1 transition. In order to maximize the number of copper atoms in the interaction region, this device will use copper foil targets, and to ensure replenishment of the copper gain medium, it will be rotated up to a target velocity of 300m/s. The disk will be driven with high-speed electric motors and supported by high-speed low friction bearings in order to achieve the required velocities. The spindle topology, foil support frame and critical dynamic balancing systematics will be studied. At these high speeds imbalances can be caused by deviations in the angular mass distributions on the order of <10 milligrams. Tradeoffs between a low friction low load air bearing solution and precision preloaded mechanical bearings will be studied. Alignment mechanisms and tolerance budgets will be established to ensure that the foil remains within the critical Rayleigh range of the pump laser. Considerations for operating conditions, such as atmosphere, gas or vacuum and a containment chamber with appropriately considered laser windows will be developed. A commercial version of the system may be utilized at multiple X-ray FEL facilities for ASE R&D. In addition, with some modifications, the system can be applied in other areas where non-degradable diagnostics, or beam targets are intercepted by beams of photons or charged particles, when the intensity is destructive to the sample without rapid replenishment. Such scenarios are quite ubiquitous, including well familiar to RadiaBeam high speed interceptive beam diagnostics, as well as rotating anodes and collimators for high intensity industrial accelerators (i.e., such as required for FLASH radiation therapy).