Determining the quality of space tether in a nondestructive manner

We propose a nondestructive method to determine the quality of each bond in an electric solar wind sail (E-sail) tether. The method is verified by a method similar to the standard destructive pull test [1]. The setup that we built for the proposed in-line tether quality measurement comprises a custom-built ultrasonic bonder, a laser doppler vibrometer, an ultrasonic generator, contact resistance measurement electronics, and a laser-ultrasonic device. During the bonding process the setup continuously measures voltage and current driving the ultrasonic transducer, the bonding lower wedge displacement, the contact resistance of the bond interface and a laser-induced high frequency pulse transmission through the bond interface. The post-production analysis results are correlated with the destructive bond pull test results to identify a target signal path. Staying on this path should ensure strong bonds. This work is part of our efforts towards the produce to specification concept in the ESAIL programme.