Ⅱ类超导体制冷效应的热力学分析

Thermodynamic Study on Refrigration Effect of Type-Ⅱ Superconductors

以超导热力学唯象理论为基础 ,讨论了Ⅱ类超导体样品当外场从 0增加到临界场Hc2 (T)过程中的制泠效应 .结果表明 :样品从Meissner态到低场混合态和从高场混合态到正常态相变为二级相变 ,无制冷效应 ,但是样品处在混合态区域时因外场增加有可能产生制冷效应 ,因而该区域是超导制冷实验研究的重点 .

According to the phenomenological theory of thermodynamics,we discuss the refrigeration effect of type-Ⅱ superconductors which are exposed to a slowly increasing magnetic field from 0 to the critical field H c 2 ( T ).It is found that the phase transition from Meissner state to mixed state near lower critical field and from mixed state near upper critical field to normal state is second order and it is impossible to offer refrigeration effect,while it probably exists refrigeration effect in mixed state with increasing external field,which may be the key problem of experiment in refrigeration of superconductivity.