Collider bypass diode thermal simulations and measurements for the SSCL

Warm bypass diodes will be used as a component of a quench protection system to bypass an exponentially decaying current of 36 sec time constant and peak current of 7000 A. Temperature excursions due to approximately 252 kAsec are studied using ANSYS, a finite element analysis program. A parabolic current waveform of similar energy but higher MIITs (1058 MIIT) was applied to the bypass circuit and a temperature excursion was measured at various locations. The procedure of current waveform generation and thermal measurements is illustrated. A comparison of the simulation technique with actual measurements confirms the accuracy of the bypass diode assembly model. This assembly is installed at the SSC half-cell string test facility and results are extremely encouraging.<
>