Abstract: The present invention relates to a particular needle-orifice fluid flow regulator to be used in a cryocooler. The flow regulator comprises a fluid outlet port adapted to receive therethrough a pressurized cooling fluid via a conduit. The needle is arranged for variable positioning relative to said outlet and temperature responsive needle positioning means for positioning said needle relative to said port as a function of temperature, whereby the needle is floatingly mounted relative to said needle positioning means. The positioning means is adapted to apply displacement forces to the needle along an axis which extends through said fluid outlet port, being constructed in a manner which enables to maintain the needle substantially coaxial with the outlet port. The fluid outlet port has a funnel shaped portion with a relatively narrow end arranged for fluid communication with said conduit configured to engage and guide the needle into mating engagement with the fluid outlet port.