A SMES Shuntable Vapor-Cooled Current Lead Array Reduces Liquid Helium Usage and Improves Reliability
In a conventionally designed vapor-cooled current lead, the geometry is governed by the criterion that the cryogen heat input is minimized at the maximum design current. At lower currents, the heat input due to conduction gives rise to a performance penalty in a SMES device because of its variable current duty cycle. A new design has been tested that uses an array of parallel current leads with independent liquid helium level control which significantly reduces the time-averaged cryogen heat load in a superconducting magnet that operates at variable currents. At reduced magnet currents, one or more leads can be “shunted out” by lowering the liquid helium level in those leads. Test data indicates that an order of magnitude reduction in cryogen heat load is possible at zero current compared to conventionally optimized leads, and about a factor of two reduction is achievable for a typical SMES operating cycle.
KeywordsResidual Current Current Lead Lead Array Lead Assembly Superconducting Magnetic Energy Storage
Unable to display preview. Download preview PDF.
- 1.Defence Nuclear Agency (DNA) contract with Bechtel Inc: DNA 001: 92: C: 0065.Google Scholar
- 2.Lock, J. M., “Optimization of Current Leads into a Cryostat”, Cryogenics, December 1969.Google Scholar
- 3.SMES/ETM, Phase 1 Final Report, by Bechtel National, under contract DNA 001–88-C-0028, July 1990.Google Scholar
- 4.Thompson, C. A., et. al., “Cryogenic Properties of Copper”, data sheet provided by the National Institute of Standards and Technology (NIST), Boulder, Colorado, July 1990.Google Scholar
- 5.Wilson, M. N., “Superconducting Magnets”, Carendon Press Oxford, 1983.Google Scholar