Method and device for precooling a cryostat

A method for operating a cryostat comprising a vacuum container that houses an object to be cooled, the vacuum container having a neck tube that connects the vacuum container to an area outside of the cryostat, the method comprising:

• maintaining a temperature of the object to be cooled during an operating phase by locating a cold head of a two-stage cooler in the neck tube such that the cold head cools a cryogenic working medium that condenses and flows through a heat pipe to a thermal contact surface that is thermally conductively connected to the object to be cooled, the working medium absorbing heat from the thermal contact surface, evaporating and returning to the cold head via the heat pipe;
• prior to locating the two-stage cooler in the neck tube, cooling the vacuum chamber during a pre-cooling phase by inserting a short circuit block into the neck tube, the short circuit block fitting within the neck tube and heat pipe and having a first end external to the heat pipe that is thermally connected to a cooling device and a second end in contact with the thermal contact surface, the short circuit block comprising a thermally conductive material core that facilitates cooling of the thermal contact surface by the cooling device and an outer contour that lies directly adjacent to an inner contour of the heat pipe when located therein;
• and
• blowing the cryogenic working medium into the neck tube during removal of the short circuit block and insertion of the two-stage cooler into the neck tube so as to minimize an entry of ambient gas into the vacuum chamber while providing the working medium to the heat pipe.

A method for cooling down a cryostat comprising a vacuum container that houses an object to be cooled, the vacuum container having a neck tube that connects the vacuum container to an area outside of the cryostat, the method comprising:

• cooling the vacuum chamber during a pre-cooling phase to a first target temperature by inserting a short circuit block into the neck tube, the short circuit block fitting within the neck tube and having a first end external to the heat pipe that is thermally connected to a cooling device and a second end in contact with a thermal contact surface that is thermally conductively connected to the object to be cooled, the short circuit block comprising a thermally conductive material core that facilitates cooling of the thermal contact surface by the high-power cooling device;
• removing the short circuit block from the neck tube in an intermediate phase when the first target temperature is reached and introducing a two-stage cooler with a cold head into the neck tube and cooling the vacuum chamber to a second target temperature which is below the first target temperature;
• and
• maintaining the second target temperature of the object to be cooled during an operating phase with the two-stage cooler located in the neck tube.