CRYOGENIC THERMOELECTRIC COOLER WITH A PASSIVE BRANCH

Cryogenic thermoelectric coolers have been fabricated from an active e lement (polycrystalline Bi0.88Sb0.12) and three different passive elem ents, a high-T-c superconductor (polycrystalline YBa2Cu3O7-delta) and lengths of high purity copper and aluminum wires. The results for a si ngle couple show that for low, hot junction (sink) temperatures the su perconducting element gives rise to maximum temperature drops of 6.6 d egrees K at 70K and 7.3 degrees K at 75K in applied magnetic fields of 0.0 and 0.07 T, respectively. Temperature drops of similar to 9 and 1 1K, respectively, are expected for such a couple when form factors are taken into account. The copper couple with an applied magnetic field resulted in large cooling Delta T values at T-hot = 150 and 293K, indi cating the importance of metallic passive elements for intermediate si nk temperatures. Performance curves for the superconductor based cryog enic thermoelectric cooler show promise with further improvement possi ble by the use of single crystalline Bi0.85Sb0.15.