Thermal interface having improved high-temperature operating range

Abstract

A cryostat includes a thermal interface located at a first end and a cryocooler located at a second end. A thermal link has a thermal connector thermally linking the thermal interface and the cryocooler below a critical temperature. The thermal link is separated from one of the thermal interface and the cryocooler above the critical temperature. A method of operating the cryostat is also disclosed.

1 . An apparatus comprising:
 a thermal interface;   a cryocooler; and   a thermal link having a thermal connector that provides a first physical link between the cryocooler and the thermal interface when the temperature of the thermal interface is below a critical temperature;   wherein the thermal link is adapted to cause the first physical link to be terminated when the temperature of the thermal interface reaches the critical temperature and to prevent reconnection of the first physical link when the temperature of the thermal interface is at a temperature that is above the critical temperature.   
     
     
         2 . The apparatus according to  claim 1 , wherein the thermal link further comprises:
 a base that is connected to the cryocooler and the thermal connector; and   a first member that provides a second physical link between the cryocooler and the thermal interface when the temperature of the thermal interface is below the critical temperature and when the temperature of the thermal interface is above the critical temperature.   
     
     
         3 . The apparatus according to  claim 2 , wherein the coefficient of thermal expansion of the first member is larger than the coefficient of thermal expansion of the thermal connector. 
     
     
         4 . The apparatus according to  claim 2 , wherein the first member comprises a sleeve that surrounds the thermal connector. 
     
     
         5 . The apparatus according to  claim 2 , wherein thermal expansion of the first member causes the thermal connector to disconnect from the thermal interface when the temperature of the thermal interface is equal to or greater than the critical temperature. 
     
     
         6 . The apparatus according to  claim 2 , further comprising a spacer positioned between the first member and the base, the spacer having lower thermal conductivity than the first member. 
     
     
         7 . The apparatus according to  claim 2 , wherein the thermal interface further comprises a disk that is positioned between one end of the thermal connector and the thermal interface and is removably secured to the thermal interface. 
     
     
         8 . The apparatus according to  claim 2 , wherein the base comprises a first recess and the thermal interface comprises a second recess, one of the first and second recesses being sized to retain the thermal connector therein when the temperature of the thermal link is equal to or greater than the critical temperature and to prevent deflection of the thermal connector. 
     
     
         9 . The apparatus according to  claim 1 , wherein the thermal conductivity of the thermal connector varies inversely with temperature. 
     
     
         10 . The apparatus according to  claim 1 , wherein the critical temperature is in the range of 350 degrees Kelvin to 800 degrees Kelvin. 
     
     
         11 . The apparatus according to  claim 1 , wherein the thermal interface is in contact with one from the group of: a cryostat, a digital scanning calorimeter, a gas chromatograph, a microscope, an X-ray diffractor, a porosity measurement device, and a vibrating scanning magnetometer. 
     
     
         12 . The apparatus according to  claim 1 , further comprising a sleeve that covers at least a portion of the thermal link and at least a portion of the thermal interface. 
     
     
         13 . A method comprising:
 (a) cooling a thermal interface to a first temperature using a cryocooler, the thermal interface having a heating element and being connected to a cryocooler through a thermal link having first and second portions;   (b) heating the thermal interface with the heating element from the first temperature to a second temperature, the second temperature being greater than the first temperature; and   (c) during the heating step, causing a first portion of the thermal link to physically disconnect from the cryocooler or the thermal interface when the thermal link reaches a critical temperature, the critical temperature being between the first and second temperatures.   
     
     
         14 . The method according to  claim 13 , wherein the heating step further comprises heating the thermal interface with the heating element from the first temperature to a second temperature, the second temperature being greater than 800 degrees Kelvin. 
     
     
         15 . The method according to  claim 14 , further comprising:
 (d) maintaining a cold tip of the cryocooler at a temperature no greater than 350 degrees Kelvin during the heating step.   
     
     
         16 . The method according to  claim 13 , wherein the heating step further comprises heating the thermal interface with the heating element from the first temperature to a second temperature, the second temperature being greater than 1000 degrees Kelvin. 
     
     
         17 . The method according to  claim 16 , further comprising:
 (e) maintaining a cold tip of the cryocooler at a temperature no greater than 350 degrees Kelvin during the heating step.   
     
     
         18 . The method according to  claim 13 , wherein step (c) further comprises maintaining a physical link between the thermal interface and the cryocooler via a second portion of the thermal link when the thermal link is equal to or greater than the critical temperature. 
     
     
         19 . The method according to  claim 13 , wherein step (c) further comprises causing a first portion of the thermal link to physically disconnect from the cryocooler or the thermal interface due to the second portion of the thermal link having a greater coefficient of thermal expansion than the first portion. 
     
     
         20 . The method according to  claim 13 , wherein step (c) further comprises cooling the sample to a first temperature using a cryocooler, the first temperature being less than 150 degrees Kelvin.