ECVT Researches at NASA

  • Electrical Capacitance Volume Tomography With High-Contrast Dielectrics

    This work was done by Mark Nurge of Kennedy Space Center

    ABSTRACT: The Electrical Capacitance Volume Tomography (ECVT) system has been designed to complement the tools created to sense the presence of water in nonconductive spacecraft materials, by helping to not only find the approximate location of moisture but also its quantity and depth. An exploded view of the ECVT Sensor shows the face of one of the two 4 × 4 arrays of conductors. Each sensing element is 1.9 cm on a side, placed on 2-cm centers, and separated from the opposing array by 3.3 cm. The ECVT system has been created for use with a new image reconstruction algorithm capable of imaging high-contrast dielectric distributions. Rather than relying solely on mutual capacitance readings as is done in traditional electrical capacitance tomography applications, this method reconstructs high-resolution images using only the self-capacitance measurements. The image reconstruction method assumes that the material under inspection consists of a binary dielectric distribution, with either a high relative dielectric value representing the water or a low dielectric value for the background material. By constraining the unknown dielectric material to one of two values, the inverse math problem that must be solved to generate the image is no longer ill-determined. The image resolution becomes limited only by the accuracy and resolution of the measurement circuitry. Images were reconstructed using this method with both synthetic and real data acquired using an aluminum structure inserted at different positions within the sensing region.

  • Fuel Mass Gauging Under Zero-G Based on Electrical Capacitance Volumetric Tomography Techniques

    PI: Manohar Deshpande, NASA/Goddard Space Flight Center

    ABSTRACT: The current state-of-the-art methods of mass gauging of cryogenic liquids in microgravity conditions are based on the global behavior of the storage tank and do not take into account random fuel distribution. Under NASA’s IPP program, NASA Goddard Space Flight Center (GSFC) engineers have developed and tested a proximity/near field non-invasive sensor which allows performing reliable and robust mass gauging of fuel stored in a tank subjected to zero/micro-gravity environment. This project intends to use the zero-G environment provided by parabolic flights to test and advance this electrical capacitance volumetric tomography (ECVT) technology to measure mass of propellant fuel stored in a tank operating in a zero-G environment.