One of the main candidates for creating high-contrast for future Exo-Earth detection is an external occulter or sharshade. A starshade blocks the light from the parent star by flying in formation along the line-of-sight from a space telescope. Because of its large size and scale it is impossible to fully test a starshade system on the ground before launch. Instead, we rely on modeling supported by subscale laboratory tests to verify the models. At Princeton, we are designing and building a subscale testbed to verify the suppression and contrast of a starshade at the same Fresnel number as a flight system, and thus mathematically identical to a realistic space mission. Here we present the mechanical design of the testbed and simulations predicting the ultimate contrast performance. We will also present progress in implementation and preliminary results.
Surface Ni sulfides layers were formed on the surface of a Ti-50.0Ni alloy by reacting sulfur and Ni film deposited on
the alloy, and then microstructures, transformation behavior, shape memory characteristics, superelasticity and
electrochemical properties of a Ti-50.0Ni(at%) alloy with the sulfides were investigated. When Ni film deposited on a
Ti-50.0Ni alloy was annealed under the sulfur pressure of 100 kPa at 623 K, sulfides layers consisted of NiS and NiS<sub>1.97</sub>
were formed. When annealing was made at 648 K annealing with annealing time less than 0.9 ks, sulfides layers
consisted of NiS and NiS<sub>1.97</sub> were formed also, while only NiS<sub>1.97</sub> was formed when it was made for 1.8 ks. When
annealing was made at 673 K annealing with annealing time longer than 0.9 ks, only NiS<sub>1.97</sub> was formed. A Ti-
50.0Ni(at%) alloy with surface NiS<sub>1.97</sub> layer showed the two-stage B2-R-B19' transformation behavior, the perfect shape
memory effect and a partial superelasticity with a superelastic recovery ratio of 78 %. NiS<sub>1.97</sub> cathode showed a clear
discharge behavior with multi voltage plateaus. Discharge capacity of NiS<sub>1.97</sub> cathode decreased abruptly with
increasing number of cycles up to 3, above which it decreased gradually.