Dynamic displacements of the RHIC dipole cold mass with injection molded composite posts during quench conditions

摘要

The new design of the RHIC dipole magnets incorporate helium containment bellows having a convolution diameter of only 7.63 inches. The present bellows are 12.80 inches in diameter. The smaller bellows present a substantially reduced pressure area which can be expected to reduce proportionately the end force on the cold mass during a quench. But, the objection was raised that the smaller bellows would present greater obstruction to the helium flow during a quench thereby producing higher pressure differentials. This analysis was undertaken to address these assertions by predicting the dynamic displacements of the cold mass using the latest test data on the stiffness of the IMC posts, pressure-time histories acquired from the recent full cell tests of RHIC magnets, and the dimensions of the new expansion joints. The analysis treated the cold mass as an elastic body having a saggittal curvature. The technique of normal mode expansion of a lumped-parameter system was used to obtain the results and conclusions reported herein.