前言过去已经报道了好几种液氮液面控制器的设计。这些设计利用了铜线圈、锗二极管、铁磁舌簧继电器或碳电阻器等的电阻随温度而变的特性。在其中的一些设计中,是通过使用外部气压源来完成液氮供给的。在我们的试验过程中,运用了低温恒温器以把研究领域扩大到液氩的范围。由于要在85～103K 范围中操作,故我们使用液氮作为 Preface In the past several designs of liquid nitrogen level controller have been reported. These designs take advantage of the temperature-dependent resistance of copper coils, germanium diodes, ferrite reed relays or carbon resistors. In some of these designs, liquid nitrogen is supplied through the use of an external pressure source. In our experiments, a cryostat was used to extend the field of study to the scope of liquid argon. Because we want to operate in the 85 ~ 103K range, so we use liquid nitrogen as