Abstract: A cold exchange system includes a Dewar flask having an inner vessel and an exterior vessel joined to and surrounding the inner vessel, defining an evacuable chamber therebetween. The flask includes an evacuation port through the inner and exterior vessels through which cryogenic gas contained in the inner vessel can evaporate during the cold exchange process. The exterior vessel includes a device port through which a device to be cooled extends. The device is housed in a housing that is engaged over the device port. A cold finger is in heat transfer contact with the inner vessel. A non-metallic flexible bellows is sealingly adhered to the cold finger at one open end of the bellows. The other open end of the non-metallic bellows is sealingly adhered at its other open end to a top plate which is vacuum fitted over the device port. The non-metallic bellows and device housing define a second evacuable chamber separate from the Dewar flask vacuum chamber.