Sue O'Brien

Effects of microgravity on ZBLAN optical fibers utilizing a sounding rocket

Samples of ZBLAN optical fiber were heated to the pulling and crystallization temperature in microgravity aboard a sounding rocket and on the ground at 1g. This was done in order to better understand the effects of gravity on the crystallization behavior of ZBLAN fibers. Samples heated in 1g at both temperatures crystallized. Samples heated to the crystallization temperature in microgravity were contaminated with water upon re-entry. Samples heated to the pulling temperature showed no evidence of crystallization in microgravity.

A methodology for mapping system engineering challenges to recommended approaches

Our current research is focused on identifying system engineering approaches that address four key development challenges in a tightly constrained, rapid reaction environment: 1) changing and emerging requirements; 2) conflicting stakeholder priorities; 3) concurrent sustainment and development activities; and 4) integration of independently evolving components. We are building a concept map of the key elements that form a strategic bridge between development challenges and the specific methods, processes, and tools that successfully address those challenges. In this paper, we present our methodology for constructing a robust mapping that incorporates interviews, surveys, and rigorous analysis methods. We summarize the results from interviews with sponsor personnel, the results of a best practices survey of 116 professionals, and qualitative analysis of the survey responses.

Vapor Transport Growth of Organic Solids in Microgravity and Unit Gravity

Abstract: Thin films of an organic nonlinear optical (NLO) material, N, N‐dimethyl‐p‐(2,2‐dicyanovinyl) aniline (DCVA), have been grown in space and on the ground by physical vapor transport in an effusive ampoule arrangement. The thin film growth technique developed on the ground is a direct result of information gleaned from experiments in microgravity. This paper covers the results of our experimental investigations for establishing “ideal” terrestrial conditions for deposition of a DCVA film. The active control during the deposition process was exercised by three deposition variables: the material source temperature, the background pressure external to the growth ampoule and the substrate temperature. Successful growth occurred when the difference in temperature between the source material and the copper substrate was 14°C and the background nitrogen pressure was such that the transport was either diffusive or convective. A qualitative diffusion limited boundary was estimated to occur at a pressure of approximately 20 torr. We have probed the DCVA thin films with visible‐near infrared reflection absorption spectroscopy, polarized Fourier transform infrared spectrometry, differential interference contrast optical microscopy, and stylus profilometry.