Multilayer films of TiC, Ti and Cu for the gravity probe B relativity mission gyroscopes

Abstract

Single-component and multilayer films of TiC, Ti and Cu have been produced by sputtering on fused quartz substrates and have been investigated for suitability as electrodes for the electrostatically suspended gyroscopes of Gravity Probe B. The main requirements for these films are low electron field emission in fields of 3 x 10 7 V m −1, low film stress, and good thermal and electrical conductivity in the temperature range 2 K–400 K. The films have been studied using X-ray diffraction, scanning electron microscopy (SEM), Auger electron spectroscopy, Rutherford backscattering spectrometry, and four-point resistivity techniques. SEM measurements indicate that the TiC films have very smooth surfaces and that multilayer films of TiC, Ti and Cu have reduced roughness as compared with the Ti-Cu multilayer films. Seven-layer 2.5 μm thick Ti-Cu films have been successfully used in the Gravity Probe B gyroscopes, meeting all requirements. Multilayer films of TiC Ti and Cu are at present being tested with the expectation that they will further improve gyroscope performance.