CRYOGENIC TESTS ON HERA DIPOLES

A facility for cryogenic tests of the HERA superconducting dipoles manufactured in ANSALDO has been built. The dipoles are tested without iron yoke up to a current of 7400 Amps in a liquid helium bath at 4.6 K. During the quench the magnet circuit is closed on a dump resistor; voltage at the ends of the two half-coils, current and current rate (this is directly measured using a Rogowsky coil) are recorded. Then, starting from these values, the resistance evolution of the two half-coils is calculated. Besides the helium bath temperature and pressure are measured and their evolution is plotted. We report also a description of the plant and of the measurement apparatus.