Duller, G.M.A. Magrath, D.L. Nagy, M. Olafsson, B. JACoW Publishing Geneva, Switzerland 2673-5520 978-3-95450-250-9 10.18429/JACoW-MEDSI2023-WEOAM02 English 121-124 controls cryogenics vacuum synchrotron optics Contribution to a conference proceedings 2024 2024-07 https://doi.org/10.18429/JACoW-MEDSI2023-WEOAM02 https://jacow.org/medsi2023/papers/weoam02.pdf The use of liquid nitrogen for cooling of synchrotron equipment is widespread. The cryogenic sub-coolers commonly employed come with some significant drawbacks such as cost, complexity, stiffness of distribution lines, and vibration induced by pressure variations. The typical sub-cooler is capable of handling 2-3kW of absorbed power whilst many optics require no more than 50-150W of cooling. We present a Vacuum Aspirated Cryo-cooling System (VACCS) which overcomes many of these disadvantages and which allows cryo-cooling to be implemented more widely. The VACCS system uses a vacuum, generated with no moving parts, to draw LN2 through a heat exchanger. Thus the system does not have to be pressure rated. We describe our designs for highly flexible distribution lines. A simple control system offers variable temperature at the heat exchanger by varying the flowrate of LN2. A system is installed at Diamond which allows the independent control of three zones. A test rig has demonstrated cooling capacity in excess of 100W for a monochromator crystal assembly and controlled temperatures -194¿-120C.