Patent ID: 8418479

Claim:
A pulse tube expander for a cryostat, the expander comprising: an elongated pulse tube comprising a warm end and a cold end, the warm end of the elongated pulse tube connected to a buffer assembly and the cold end of the elongated pulse tube connected to a helium condenser; a first stage pulse tube comprising a warm end and a cold end, the warm end of the first stage pulse tube connected to the buffer assembly and the cold end of the first stage pulse tube connected to a first stage heat station, the warm end of the elongated pulse tube being proximate to the warm end of the first stage pulse tube; a spacer for spacing apart a first stage regenerator and a second stage regenerator, a first distance between the warm end of the elongated pulse tube and the spacer defines a first portion and a second distance between the cold end of the elongated pulse tube and the spacer defines a second portion; the first stage regenerator disposed in the first portion; the second stage regenerator disposed in the second portion; and the first stage pulse tube disposed co-axially with the elongated pulse tube and the first stage regenerator, the first stage pulse tube being disposed between the elongated pulse tube and the first stage regenerator, the first stage pulse tube being in direct contact with the elongated pulse tube and the first stage regenerator.