Margaret A. Ryan

Further Expanding the Capabilities of the JPL Electronic Nose to Include Post-fire Constituents

The JPL Electronic Nose (ENose) team is currently expanding the capabilities of the Third Generation ENose to include oxygen detection and post-fire constituents (CO and HCl). The JPL ENose was developed as an event monitor for spacecraft cabin air with nearreal-time data analysis and was designed to detect, identify and quantify eleven chemical species (analytes). Each generation of JPL ENose was re-optimized the sensing array to suit the selected analytes, which were detected over a clean, well-defined background; the most recent generation included microhotplate sensor substrates to allow for an expansion of sensing materials in the array. The Third Generation JPL ENose recently completed more than 3200 hours (> 6 months) of continuous operation aboard the US Lab on the International Space Station (ISS). Adding the detection of post-fire constituents poses a more complex challenge that includes sensor selection, air sampling and data analysis. Post-fire constituents include air particulates, carbon monoxide and acid gases. In this paper we will discuss sensor selection for carbon monoxide and we will present results for several polymerbased sensors that have been tested for carbon monoxide response.

Electrode, current collector, and electrolyte studies for AMTEC cells

Studies of components for AMTEC devices at JPL have focussed on electrode materials, materials and construction of the current collection network, and the [beta][double prime]-alumina solid electrolyte. Electrode materials include thin films of molybdenum metal and metal alloys such as PtW and RhW. Surface self-diffusion coefficients have been determined for Mo electrodes in the temperature range 1050--1200 K, and for RhW at 1125 K. The diffusion coefficients have been used in a grain growth model to predict electrode operating lifetimes at temperatures in this range. Current collection networks sputtered with a thin film of platinum have decreased total electrical resistance in an operating device by 35%. Electrolyte studies have found no mechanical stress or chemical degradation induced by long term operation. Further electrolyte studies have focussed on synthesis of both sodium and potassium [beta][double prime]-alumina ceramic. Potassium [beta][double prime]-alumina solid electrolyte has potential application in a potassium-based AMTEC device which operates at a hot side temperature of [similar to]1000 K.