Precursory voltage signals in cosine theta Nb/sub 3/Sn high field model magnets

To understand the premature quenches of the Nb/sub 3/Sn high field model magnets, we also made mirror design model magnets, and studied their quenches. With one of the mirror magnet, HFDA-03A, which had extra lead cables installed, some precursory voltage signals were observed at soldered joints in the high field region, leading to quenches at high ramp rate. These voltage signals diminish with slower ramp rate. The ramp rate dependence of the quench behaviors is experimentally studied. In the course of these quench investigation we developed a method to cancel the inductive voltage in the voltage tap signals. This method proved very effective to understand clearly how the quenches are propagating in all parts of the magnets.