Abstract
Satellite Test of the Equivalence Principle (STEP) proposes to use niobium thin film strip-line circuits on precision quartz assemblies to achieve on-orbit differential acceleration sensitivities of 10-18 g. The acceleration is determined from a displacement measurement under known spring stiffness. Currents trapped in niobium circuits (400 nm thick, 100 mum wide) provide magnetic spring forces, and in conjunction with a SQUID magnetometer, the displacement measurement. We have studied the effect of substrate surface roughness on the critical current and temperature of niobium thin film strip-line circuits. We have observed a critical current that decreases with increasing surface roughness, with no change in critical temperature. We attribute the decrease in critical current to a flux penetration barrier at the strip-line edge that decreases with increasing surface roughness. This is a significant finding for the development of the STEP instrument, since anomalous flux penetration at the edge of circuits can degrade performance, add SQUID sensor noise, and lead to trapped flux instabilities.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
