US 12,456,566 B2
Cryocooler and magnetic shield
Yosuke Matsumura, Nishitokyo (JP); Takaaki Morie, Yokosuka (JP); and Jun Yoshida, Yokosuka (JP)
Assigned to SUM ITOMO HEAVY INDUSTRIES, LTD., Tokyo (JP)
Filed by SUMITOMO HEAVY INDUSTRIES, LTD., Tokyo (JP)
Filed on Mar. 1, 2022, as Appl. No. 17/683,358.
Application 17/683,358 is a continuation of application No. 16/584,938, filed on Sep. 26, 2019, granted, now 11,342,100.
Application 16/584,938 is a continuation of application No. PCT/JP2018/012578, filed on Mar. 27, 2018.
Claims priority of application No. 2017-068412 (JP), filed on Mar. 30, 2017.
Prior Publication US 2022/0270796 A1, Aug. 25, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. F25B 9/14 (2006.01); F25B 9/00 (2006.01); F25B 9/10 (2006.01); F25D 19/00 (2006.01); G01R 33/38 (2006.01); G01R 33/3815 (2006.01); G01R 33/421 (2006.01); H01F 6/04 (2006.01); H05K 9/00 (2006.01)
CPC H01F 6/04 (2013.01) [F25B 9/002 (2013.01); F25B 9/10 (2013.01); F25B 9/145 (2013.01); F25D 19/006 (2013.01); G01R 33/3804 (2013.01); G01R 33/3806 (2013.01); G01R 33/3815 (2013.01); G01R 33/421 (2013.01); H05K 9/0075 (2013.01); F25B 2309/001 (2013.01); F25B 2309/1406 (2013.01); F25B 2309/1428 (2013.01); F25B 2500/11 (2013.01); F25B 2500/12 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A cryocooler comprising:
a cooling stage cooled to a cryogenic temperature around or below 4.2 K;
a cylinder which includes the cooling stage on a terminal of the cylinder;
a displacer which includes a magnetic regenerator material and is accommodated in the cylinder so as to be able to reciprocate in the cylinder; and
a tubular magnetic shield which is installed on the cooling stage and extends along the cylinder outside of the cylinder,
wherein the tubular magnetic shield is formed of a normal conductor and a product of an electrical conductivity in a temperature range of 10 K (Kelvin) or less and a thickness of the tubular magnetic shield is formed to have a conductance of 60 MS (Mega-Siemens) to 1980 MS,
wherein the tubular magnetic shield is formed of pure copper and cooled to the cryogenic temperature around or below 4.2 K.