Low-Cost Thermal Management System for High Power X-Ray Optics

The next generation of X-ray beamlines are optimized to deliver photon energies between 400 to 1400 eV with full polarization control. The silicon mirrors and crystals used in such demanding beamlines must be capable of maintaining their ideal shapes to nanometer tolerance under powers greater than 250 W. The optics used in the beamline to manipulate the incoming beam are efficient only at cryogenic temperatures. Existing cooling solutions use pumped single-phase liquid nitrogen (LN) to reject heat via a cryo-cooler or a chiller to maintain the set point temperature. This presents significant challenges in terms of vibration, cost, size, and long-term maintenance requirements to implement along multiple beamlines. We proposed to develop an alternative low-cost cryogenic cooling system for thermal management of high power X-ray optics used in beamlines. The proposed thermal management system involves the use of a novel cryogenic thermosyphon to extract, transfer, and reject the heat load from the X-ray optics. In the Phase I program, the feasibility of the proposed cryogenic thermosyphon cooling system for X-ray optics was demonstrated through design, fabrication and experimental testing of a prototype. Results revealed a steady-state operations at 125 K with minimal temperature variation at all power levels of 250W and above. Vibrational impacts assessed were found to be negligible on the heat source and the cost analysis shows the thermosyphon prototype surpassed DOE's requirements, with a compact footprint (0.15 m³) and cost-efficiency ($30/W) compared to existing commercial technology. In Phase II, the thermosyphon will be scaled to reject higher powers with system level design and integration. The Phase II program will culminate with the fabrication and testing of a full- scale thermal management system for cooling of the optics in a national lab beamline facility. If successful, the technology developed in the Phase I and Phase II programs will provide a low-cost technology that is easily accessible to a wider range of research institutions and facilities that use beamlines, thereby helping to increase the pace of scientific discovery. The proposed system is also easily adaptable to thermal management of terrestrial and space applications such as cryopreservation, cryogenic propellant zero boil off tanks, observation satellites and permafrost applications.