Experiments were performed to measure the thermal conductivities of two-particle sizes of alumina (Al2O3) powder (1.0 and 0.01 mum) and molded Min-K insulation materials in vacuum. The thermal conductivity data are correlated as a function of temperature, from 340 to 900 K, to within +/-10% and +/-5% for the Al2O3 and Min-K, respectively. The Min-K thermal conductivity is the lowest and least dependent on temperature. For the same hot and cold side temperatures, the conductance of the Min-K is similar to2-3 orders of magnitude higher than the lateral conductance of 60 and 240 molybdenum multifoil insulation, respectively. The conductance of the Min-K, however, is about an order of magnitude lower than the axial conductance of both the 60 and 240 molybdenum multifoil insulation. (C) 2000 Elsevier Science Ltd. All rights reserved.