Stable High-Tc rf SQUID NDE system operating in noisy environment

A high-Tc rf SQUID NDE system was developed for stable, long time operation in a noisy environment. To reduce the influence of high frequency electromagnetic interference (EMI), a carefully designed metal shielding made of 0.1 mm thick metal foil was used. With the metal shielding, the SQUID could still operate well when a cellular phone was used nearby although the cellular phone could produce very strong EMI noises. To reduce the influence of the line interference or low frequency noises, a compensation method was used in the SQUID-based NDE system. With the compensation, the low frequency and the line interference could be reduced well. Using this SQUID-based NDE system, we successfully performed the NDE measurements in a noisy environment.