Pulse tube cryocooler and method of manufacturing pulse tube cryocooler

A method of manufacturing a pulse tube cryocooler, the pulse tube cryocooler including a longitudinally extending pulse tube, and a regenerator extending in the longitudinal direction of the pulse tube and disposed in a sideways direction apart from and paralleling the pulse tube sideways direction, the method comprising:

• forming in the cooling stage a lateral-surface opening, and forming in the cooling stage a first heat-exchange surface extending in the sideways direction into the cooling stage from the lateral-surface opening;
• inserting an insert, furnished with a base-end portion and a second heat-exchange surface, through the lateral-surface opening such that the second heat-exchange surface extends in the sideways direction from the base-end portion and is disposed inside the cooling stage, opposing the first heat-exchange surface;
• fixedly fitting the insert into the cooling stage such that the base-end portion plugs the lateral-surface opening;
• and
• coupling one longitudinal end of the pulse tube and one longitudinal end of the regenerator to allow a working gas to flow between the two longitudinal ends;
• wherein
• between the first heat-exchange surface and the second heat-exchange surface the insert forms a clearance for flowing the working gas heat-exchange surface heat-exchange surface so that both the first heat-exchange surface and the second heat-exchange surface come into contact with the working gas.