MRI cryostat cooled by open and closed cycle refrigeration systems
US5586437A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 6, 1995 |
| Grant date | Dec 24, 1996 |
| Priority date | — |
| Expiry date | Sep 6, 2015 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF25B2400/17
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A MRI cryostat, which contains a superconducting magnet operating in a bath of liquid helium, reduces the boil-off rate of helium by intercepting most of the heat in-leakage by means of a throttle cycle (TC) refrigerator operating at a low side temperature of about 90K. The main heat exchanger for the throttle cycle refrigerator is located within or immediately adjacent to the cryostat housing and delivers cold liquid to a cold heat exchanger that is in thermal contact with an outer radiation shield, support struts, neck tube and electrical leads inside the cryostat. Heat is intercepted by the outer shield from essentially all paths between a 300K ambient and a 4K load temperature, which temperature results from liquid helium boil-off to atmosphere. A second, inner radiation shield at 35K is cooled by gaseous helium that boils from the liquid helium bath. There are no moving parts of the refrigeration system in the cryostat. Thus, vibration, noise and disturbance of the magnetic field are reduced. The refrigerator installation is small and low in cost; power consumption is reduced relative to the prior art.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.