A pulse tube refrigerator/cryocooler apparatus including: an inlet for receiving a cyclically moving volume of gas; a regenerator device fluidly connected to the inlet for storing and recovering thermal energy from the gas; a pulse tube fluidly connected to the regenerator; and a conduit fluidly connected at one end to the pulse tube and fluidly connected at its opposite end to a container, said container providing a storage volume for gas, wherein apparatus is configured such that the cyclically moving gas enters the regenerator in a direction parallel to its elongate axis.