Elliptic-beam helix TWTAs have applications in rf amplification requiring high efficiency, high power, broad bandwidth and lower cost. Key markets will be commercial satellite communications, both space and ground stations, military radar and communications and non-lethal weapons systems, and commercial wireless base station amplifiers. This technology can be used to increase performance of all vacuum electron devices (VEDs) that use linear beams such that it will revitalize the market for highly reliable high power VEDs. The elliptic-beam helix TWTA will provide NASA deep space missions with both increased efficiency and increased power over current state of the art rf transmitters while reducing weight, volume, voltage and complexity. In general, high-efficiency, high-power elliptic-beam TWTAs align with NASA's vision for space exploration by increasing the science data rate-of-return for exploration missions, and by enabling deeper, more sophisticated exploration of the solar system. In particular, high-efficiency, high-power elliptic-beam TWTAs would benefit the R&D programs in the NASA Glenn Research Center's Exploration Systems Division.