High resolution thermometry using the magnetic penetration depth of superconducting films

被引：0

作者：

Yeager, CJ ^{[1
]}

Shirron, PJ ^{[1
]}

DiPirro, MJ ^{[1
]}

机构：

[1] NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA

来源：

ADVANCES IN CRYOGENIC ENGINEERING, VOL 43 PTS A AND B | 1998年 / 43卷

关键词：

D O I：

暂无

中图分类号：

O414.1 [热力学];

学科分类号：

摘要：

A Penetration Depth Thermometer (PDT) has been under development for potential use in microgravity critical point experiments. The active element is a superconducting film whose thickness is comparable to the magnetic penetration depth (5-20 nm). Field penetration is strongly temperature dependent just below the transition (similar to 0.9 -1.0 T-c). Fields are generated and sensed by using excitation and pickup coils located near the film. Using a de SQUID sensor for readout, temperature resolution on the order of 0.1 nK/root Hz can be obtained. Earlier work using aluminum films (T-c=1.69 K) demonstrated a maximum sensitivity of 1 nK/root Hz. Improvements in coil design have since yielded a factor of 3 improvement. PDT's have been made with aluminum films deposited on a planar sapphire substrate with transition temperatures greater than the lambda point in superfluid helium. For performance tests, a cryostat has been constructed where the PDT will be in an experimental cell filled with superfluid. This will provide thermal stability better than 0.1 nK/root Hz. Results of the current design are presented.

引用

页码：757 / 763

页数：3