Magnet cold mass high load supports thermal response and performance design correlation

General Dynamics Convair Division´s experience in the design, detail analysis, and manufacturing of structural supports for superconducting magnet cryostats suspended in a vacuum enclosure has created a data base that is well suited for the development of correlations of pertinent thermal performance criteria for stainless steel supports. The thermal requirements of these supports in fusion applications are well defined in the Mirror Fusion Test Facility (MFTF) and have been analyzed in detail for cooldown response and steady-state performance, using Convair´s Thermal Analyzer computer program. From the output of these thermal conditioning simulations, correlations Were developed for magnet LHe heating from supports in terms of strut geometric parameters. These correlations enable the user to estimate conservative transient and steady-state heat loads and the approximate time that steady-state operation conditions are reached during magnet cooldown. The dependent variables employed in these correlations are primarily the geometry of the support and location of the radiation shield intercept(s) along the support. Steady-state heat load is predicted by Equations (1) and (2). Equation (3) predicts the time history of the midpoint (warmest section) of the strut between cold-end pin and LN2intercept during cooldown. Equation (4) predicts the LHe heating history from the support during the terminal portion of the cooldown and Equation (5) predicts the total cooldown time for the strut to reach steady-state heat rate. These correlations replace the expensive, time-consuming computer simulations previously required. In addition to capabilities of determining thermal response, optimization of thermal performance through adjusting the location of the LN2- cooled heat intercepts, LN2-cooled liners, and radiation shields is also discussed.