Thermal Analyses of the SMES ETM Power Bus Cryostat

Abstract

In order to ensure reliable operation of the Superconducting Magnet Energy Storage Engineering Test Model (SMES-ETM), the conductor in the power bus must meet similar performance requirements as the entire coil during both steady state and transient operating modes. Lumped parameter thermal analyses are performed to evaluate steady state performance and assess risk involved with failure modes associated with the superconducting bus cryostat. Transient heat fluxes to the superfluid helium vessel are calculated for the loss of bus vacuum and the loss of nitrogen shroud cooling. The elapsed time to reach the critical heat flux in superfluid helium is calculated using the heat conductivity function for these cases. It is concluded that in the event of bus cooling failure, barring catastrophic loss of vacuum, the bus and cryostat can function for limited periods of time without interrupting ETM operations.