Flexure systems for 4^th generation light source liquid-nitrogen-cooled x-ray mirrors

Abstract To fully utilize the improved photon beam characteristics afforded by fourth generation storage ring-based light sources, x-ray mirrors need two-axis angular positioners capable of sub-50 nrad minimum incremental motion (MIM) and better than 30 nrad stability with a first natural frequency >180 Hz. Instead of the folded leaf spring design adopted in [1] for lighter mirror systems where only a single motorized degree of freedom is needed, the M1 flexure system utilizes a high-strength titanium, monolithic, pitch/roll flexure body; state of the art piezo actuators; and a kinematic mounting scheme to achieve mrad angular ranges in a stiff, compact package. Suitably sized optics can be mounted to the flexure system in modular fashion. In this case the liquid-nitrogen-cooled, High Heat Load Optic (HHLO) [2][3], developed for the Advanced Light Source Upgrade (ALS-U) at Lawrence Berkeley Lab [4] is mounted to the flexure body. The use of liquid nitrogen introduces thermal management challenges throughout the assembly and in particular with the actuators which require heaters to prevent piezo damage during operation. The fundamental purpose of the flexure system is to meet the ALS-U environmental, motion, and stability requirements with a physical package that fits within the tight working envelope of the existing ALS infrastructure. Prototyping efforts have shown that the design meets most of the requirements with encouraging results where in situ measurements are not yet possible.