The present invention relates to a method of thermally disconnecting a cryogenic vessel (2) of a cryostat (1) from a refrigerator (7), e.g. during transportation of the cryostat (1). In order to provide a simple and reliable technique for thermally disconnecting the refrigerator (7) from the cryogenic vessel (2), the cryogenic vessel (2) is connected with the refrigerator (7) by means of an input channel (17) and an output channel (18), wherein the input channel (17) and the output channel (18) are adapted to provide a loop system for a convection circulation of cryogen through the refrigerator (7).

A method is provided for precooling a cryostat having a hollow cold head turret into which a neck tube protrudes and connects an object to be cooled to the exterior of the cryostat, wherein a cold head having a cold head stage for cooling a cryogenic working medium may be introduced into the neck tube. During a condensation operation the cryogenic working medium flows through a heat pipe into an evaporator chamber which is thermally conductively connected to the object to be cooled. During a precooling phase a precisely fitting, thermally conductive short circuit block is inserted through the neck tube into the heat pipe to provide thermal conduction between the object to be cooled and a cooling device. The short circuit block is removed from the heat pipe after the target temperature is reached, and heat is subsequently transmitted through the heat pipe during a condensation operation.

The present invention relates to a cryocooler suitable for gas liquefaction applications, that comprises a coldhead with one or more refrigeration stages; further comprising: a refrigerator compressor for distributing compressed gas-phase cryogen inside the coldhead; a heat exchanging coil arranged at least partially around the external region of the coldhead; at least one extraction orifice communicating a gas circulation circuit inside the coldhead with the heat exchanging coil; acting said extraction orifice/s as pass-through port/s which allow the gas inside the coldhead to flow through the inside of the heat exchanger coil for exchanging heat with the exterior thereof, and wherein the heat exchanging coil is adapted to connect and redirect the gas to one return port connected to the gas circulation circuit. Another object of the invention relates to a cryogen-gas liquefaction system and a method for liquefaction of gases that comprises said system.