  At the Walther-Mei{\ss}ner-Institut (WMI), a new cryogen-free 3He/4He
dilution refrigerator (DR) has been completed; the cryostat will be employed to
cool experiments on superconducting quantum circuits for quantum information
technology and quantum simulations. All major components have been made at the
WMI. The DR offers lots of space at the various stages of the apparatus for
microwave components and cables. E. g., the usable space at the mixing chamber
has a height of more than 60 cm and a diameter of 30 cm (mixing chamber
mounting plate). To cool cables and cold amplifiers, the DR is equipped with a
separate 4He-1K-loop which offers a cooling power of up to 100 mW near 1K. The
refrigeration power of the still is 18 mW at 0.9 K; the diameter of its
mounting plate is 35 cm. The cryostat rests in an aluminum trestle on air
springs to attenuate building vibrations. It is precooled by a Cryomech
PT410-RM pulse tube cryocooler (PTC) which is mechanically decoupled from the
vacuum can of the cryostat by a bellows assembly. The two stages of the PTC are
thermally connected to the DR via copper ropes. There are no nitrogen cooled
traps with this DR to purify the gas streams of the 3He and 4He loops; instead,
charcoal traps are mounted inside the DR at the first stage of the PTC. The
dilution unit has three heat exchangers; its base temperature is 11 mK and its
cooling power is 300 {\mu}W at 100 mK.
