The NRL Josephson junction monitoring experiment on HTSEE-II

An experiment designed to ride on the high temperature superconductor space experiment (HTSSE-II) satellite package is described, which monitors the current-voltage characteristics of two high temperature superconductor (HTS) Josephson junctions. The junctions are typical examples of the state-of-the-art at the time of incorporation, and were obtained from two industrial laboratories: TRW and Conductus. Stringent requirements on shielding the devices from RF interference and DC magnetic fields are necessary to ensure that the measurements are meaningful. An additional constraint is imposed by the necessity to minimize flow of heat into the device package. Engineering solutions to these problems, and the resulting performance of the measurement system, are described. The package and associated electronics have been integrated into the flight satellite.