Thermal studies of a high gradient quadrupole magnet cooled with pressurized, stagnant superfluid

A 2-m long superconducting model of an LHC Interaction Region quadrupole ma gnet was wound with stabrite coated cable. The resulting low interstrand re sistance and high AC losses presented the opportunity to measure magnet que nch performance in superfluid as a function of helium temperature and heat deposition in the coil, Our motivation was to duplicate the high radiation heat loads predicted for the inner triplet quadrupoles at LHC and study the coil cooling conditions in the magnet. At the Magnet Test Facility in Ferm ilab's Technical Division, the magnet quench performance was tested as a fu nction of bulk helium temperature and current ramp rate near the planned hi gh luminosity interaction region field gradient of 205 T/m. AC loss measure ments provided a correlation between current ramp rate and heat deposition in the coil. Analysis indicates that the results are consistent with there being little participation of superfluid helium in the small channels insid e the inner layer in the heat removal from the coil. However magnet perform ance will be limited by the outer coil pole turn in LHC at a current level well above the operating current.