Tests on waveform synthesis in a new cryocooler setup

A new experimental setup based on a two-stage cryocooler has been developed at INRIM for operation with Josephson arrays. Recently some parts of the setup have been upgraded in order to allow the synthesis of waveforms; in particular, a well suited rigid rf coaxial cable with bandwidth exceeding 30 GHz has been mounted. We describe preliminary results obtained in tests of waveform synthesis with pulse-driven Josephson arrays fabricated at PTB. Unipolar sinewaves at 1.25 kHz and amplitudes ranging up to tens of millivolts were generated. Results are then discussed in relation with the specific thermal issues posed by He-free cooling.