X-Message-Number: 6626
Date: Sat, 27 Jul 1996 06:31:34 -0700 (PDT)
From: Doug Skrecky <>
Subject: cryostat variants

 In Message #6604  (Thomas Donaldson) wrote: 
 >preserve a head for centuries so long as we keep it at -150 deg C ... 
 What we will need is some engineering work to find out a better form of
 STORAGE, too. I would say that this issue is really crucial to the cost
 of vitrified storage; not only that, but some kind of passive system,
 which maintains the right temperature WITHOUT continual power input,
 very likely WOULD be patentable.<

 Water/ice will stay near 0 C till all the ice is melted. Perhaps a
 liquid which freezes at around -150 would fit the bill. Freon 12 for
 example freezes at -158, yet boils only at -29. For a cryostat
 containing a mixture of solid/liquid freon 12 the temperature of -158
 would effectively preclude expensive boiloff. Liquid freon could be
 drained periodically from the cryostat, refrozen and then added back
 inside. 

 Another possibility would be to use sorbitol or some other "solid" 
 cryoprotectant with a glass transition greater than -78 so that then
 cold storage could use dry ice. 


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