Adiabatic demagnetization apparatus

Abstract

The present disclosure is to a method of controlling an adiabatic demagnetization apparatus. The method includes varying at least operation parameter of the adiabatic demagnetization apparatus.

1 . A method of controlling an adiabatic demagnetization apparatus operating in continuous demagnetization refrigeration, CADR, mode, comprising:
 cycling at least two adiabatic demagnetization units of the adiabatic demagnetization apparatus between respective first temperatures and second temperatures with varying cycling frequency, wherein the cycling frequency is varied during the operating of the adiabatic demagnetization apparatus in the CADR mode based on a change of a heat load, and wherein the cycling frequency is increased when the heat load increases and the cycling frequency is decreased when the heat load decreases.   
     
     
         2 . The method of  claim 1 , wherein the adiabatic demagnetization apparatus includes a total number n of adiabatic demagnetization units, wherein n≥2 or 3, wherein:
 the n adiabatic demagnetization units are connectable in series by thermal switches. 
 
     
     
         3 . The method of  claim 1 , wherein the cycling frequency is varied based on a heat load applied to a last stage n of the n adiabatic demagnetization units. 
     
     
         4 . A method of controlling an adiabatic demagnetization apparatus operating in continuous demagnetization refrigeration, CADR, mode, comprising:
 operating a plurality of thermal switches of the adiabatic demagnetization apparatus in a first switching mode if at least one of a first target temperature is set and a first heat load is applied; and   in response to at least one of (i) a change of a target temperature from the first target temperature to a second target temperature and (ii) a change of a heat load from the first heat load to a second heat load during the operating of the adiabatic demagnetization apparatus in the CADR mode,   operating the plurality of thermal switches in a second switching mode different from the first switching mode.   
     
     
         5 . The method of  claim 4 , wherein
 the first target temperature is different from the second target temperature.   
     
     
         6 . The method of  claim 4 , wherein the plurality of thermal switches includes a total number a of thermal switches, wherein a≥2. 
     
     
         7 . The method of  claim 4 , wherein:
 thermal switches, which are not operated in at least one of the first switching mode and the second switching mode, are closed.   
     
     
         8 . A machine readable medium comprising instructions executable by one or more processors to implement the method of  claim 4 . 
     
     
         9 . A controller for an adiabatic demagnetization apparatus, comprising:
 one or more processors; and   a memory coupled to the one or more processors and comprising instructions executable by the one or more processors to implement the method of  claim 4 .   
     
     
         10 . An adiabatic demagnetization apparatus, comprising the controller according to  claim 9 . 
     
     
         11 . A cryostat, comprising the adiabatic demagnetization apparatus according to  claim 10 . 
     
     
         12 . The method of  claim 1 , wherein the first temperature is higher than the second temperature. 
     
     
         13 . The method of  claim 1 , wherein the adiabatic demagnetization apparatus includes a total number n of adiabatic demagnetization units, wherein n≥2 or 3, wherein:
 a number m of adiabatic demagnetization units of the n adiabatic demagnetization units is cycled between respective first temperatures and second temperatures, wherein m≤n, and wherein m=n−1. 
 
     
     
         14 . A machine readable medium comprising instructions executable by one or more processors to implement the method of  claim 1 . 
     
     
         15 . A controller for an adiabatic demagnetization apparatus, comprising:
 one or more processors; and   a memory coupled to the one or more processors and comprising instructions executable by the one or more processors to implement the method of  claim 1 .   
     
     
         16 . An adiabatic demagnetization apparatus, comprising the controller according to  claim 15 . 
     
     
         17 . A cryostat, comprising the adiabatic demagnetization apparatus according to  claim 16 . 
     
     
         18 . The method of  claim 4 , wherein
 the first heat load is different from the second heat load.   
     
     
         19 . The method of  claim 6 , wherein a number b of the a thermal switches is operated in the first switching mode, and a number c of the a thermal switches is operated in the second switching mode. 
     
     
         20 . The method of  claim 4 , wherein:
 more thermal switches are operated when at least one of (i) the target temperature is changed to a lower target temperature and (ii) the heat load increases.