Adjustable distance liquid nitrogen metal dewar for high temperature super conductive quantum interferometer

Abstract

The distance adjustable liquid nitrogen metal dewar for high temperature superconductive quantum interferometer device (SQUID) includes inner tube, outer tube, neck pipe, cooling finger, distance regulating and protecting system, getter and multi-layer insulator. The dewar has main body made of non-magnetic stainless steel. The high temperature SQUID is adhered outside the bottom of oxygen-free copper cooling finger and the hollow cooling finger is filled with liquid nitrogen, so that the high temperature SQUID can operate in proper low temperature area and may be made to approach the measured matter via regulating the distance between the detecting window and the high temperature SQUID. The sandwiched layer between the inner tube and the outer tube is maintained at vacuum degree of 1E(-4) Pa and the inner tube and the neck pipe are wound with 40 layers of aluminum coated dacron film for heat insulation. Getter is set inside the heat insulator.

Description

Technical field: [0001] The invention relates to a liquid nitrogen metal Dewar. In particular, a high-temperature superconducting quantum interference device (SQUID) can be kept at a suitable working temperature, and the distance between the detection window and the high-temperature SQUID can be adjusted steplessly between 0.1-8 mm. Adjustable distance liquid nitrogen metal Dewar. It belongs to the field of cryogenic engineering and superconducting application technology. Background technique: [0002] A superconducting quantum interference device (SQUID) is a highly sensitive device that can measure weak magnetic flux changes. This kind of device must be placed in a low temperature and non-magnetic environment. The low temperature can ensure that the device is in a superconducting state, and the non-magnetism can ensure that the weak magnetic flux change signal can be measured. SQUID can be divided into liquid nitrogen temperature zone SQUID (low temperature SQUID) and l...

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Problems solved by technology

However, the production process of FRP Dewar is high, and its strength is not as good as that of metal Dewar. The distance between SQUID and the measured object cannot be adjusted.

In the article "High Temperature SQUID Magnetometer Nondestructive Testing Device and Its Application Research in Nondestructive Testing" published in Volume 24, Issue 4 of "Rare Metals", a non-magnetic stainless steel Dewar was designed. The Dewar is a wide-mouth container. The neck tube is not designed, the heat leakage is large, and the noise of liquid nitrogen evaporation may affect the detection of the magnetic field. Although the SQUID is also placed in the vacuum interlayer, the distance between the SQUID and the detection window cannot be adjusted

With the continuous development of high-temperature SQUID technology and the continuous improvement of detection level requirements, such a liquid nitrogen metal Dewar cannot meet the requirements of weak electromagnetic field and high sensitivity measurement

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