Michael R. LaPointe

DESIGN AND OPERATION OF MW-CLASS MPD THRUSTERS AT THE NASA GLENN RESEARCH CENTER

A diverse range of in-space propulsion requirements has rekindled interest in the development and deployment of high power electromagnetic thrusters. Magnetoplasmadynamic (MPD) thrusters can effectively process megawatts of electrical power, providing several newtons of thrust over a broad range of specific impulse values. As the lead NASA center for electric propulsion, the Glenn Research Center has established a MW-class pulsed thruster test facility to improve the performance of high power MPD thrusters. Thruster simulations using the state-of-the-art MACH2 code provide a well-balanced program of numerical analysis and experimental validation that is expected to lead to improved high power thruster performance. This paper provides an overview of the pulsed power facility at NASA GRC, describes the MACH2 code and recent numerical results, and outlines current GRC plans for high power MPD thruster testing and simulation.

MW-Class Electric Propulsion System Designs for Mars Cargo Transport

Multi-kilowatt electric propulsion systems are well developed and have been used on commercial and military satellites in Earth orbit for several years. Ion and Hall thrusters have also propelled robotic spacecraft to encounters with asteroids, the Moon, and minor planetary bodies within the solar system. High power electric propulsion systems are currently being considered to support missions to near earth asteroids, piloted as cargo transport for sustained lunar or Mars exploration, and for very high-power piloted missions to Mars and the outer planets. NASA Mars Design Architecture 5.0 as a reference, a Using preliminary parametric analysis was performed to determine the suitability of a nuclear powered, MW-class electric propulsion system for Mars cargo transport. For this initial analysis, high power 100kW Hall thrusters and 250- -kW VASIMR engines were separately evaluated to determine optimum vehicle architecture and estimated performance. The DRA 5.0 cargo mission closed for both propulsion options, delivering a 100 t payload to Mars orbit and reducing the number of heavy lift launch vehicles from five in the baseline DRA 5.0 architecture to two using electric propulsion. Under an imposed single engine-out mission success criteria, the VASIMR system took longer to reach Mars than did the Hall system, arising from the need to operate the VASIMR thrusters in pairs during the spiral out from low Earth orbit.

The Effects of a Magnetic Field on the Crystallization of a Fluorozirconate Glass

An axial magnetic field of 0.1T was applied to ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fibers during heating to the glass crystallization temperature. Scanning electron microscopy and x-ray diffraction were used to identify crystal phases. It was shown that fibers exposed to the magnetic field did not crystallize while fibers not exposed to the field did crystallize. A hypothesis based on magnetic work was proposed to explain the results and tested by measuring the magnetic susceptibilities of the glass and crystal.

Eliminating crystals in non-oxide optical fiber preforms and optical fibers

A method is provided for eliminating crystals in non-oxide optical fiber preforms as well as optical fibers drawn therefrom. The optical-fiber-drawing axis of the preform is aligned with the force of gravity. A magnetic field is applied to the preform as it is heated to at least a melting temperature thereof. The magnetic field is applied in a direction that is parallel to the preforms optical-fiber-drawing axis. The preform is then cooled to a temperature that is less than a glass transition temperature of the preform while the preform is maintained in the magnetic field. When the processed preform is to have an optical fiber drawn therefrom, the preforms optical-fiber-drawing axis is again aligned with the force of gravity and a magnetic field is again applied along the axis as the optical fiber is drawn from the preform.

High power electromagnetic thrusters for spacecraft propulsion

High power electromagnetic plasma thrusters are being developed as primary in-space propulsion systems for future robotic and piloted space missions. Electromagnetic thrusters effectively process megawatts of electrical power, providing a wide range of specific impulse values to meet a variety of in-space propulsion requirements. Potential applications for high power thrusters include the orbit raising and maneuvering of large space platforms, lunar and planetary cargo transport, piloted planetary missions, asteroid rendezvous and sample return, and robotic deep space exploration. The NASA Glenn Research Center is developing MW-class magnetoplasmady-namic (MPD) thrusters and pulsed inductive thrusters (PIT) to support these diverse mission requirements. This paper provides an overview of the current GRC research program, describes the operating principles, challenges, and status of each technology, and outlines plans for further development.Copyright

An overview of the NASA Advanced Propulsion Concepts program

NASA Advanced Propulsion Concepts (APC) program for the development of long-term space propulsion system schemes is managed by both NASA-Lewis and the JPL and is tasked with the identification and conceptual development of high-risk/high-payoff configurations. Both theoretical and experimental investigations have been undertaken in technology areas deemed essential to the implementation of candidate concepts. These APC candidates encompass very high energy density chemical propulsion systems, advanced electric propulsion systems, and an antiproton-catalyzed nuclear propulsion concept. A development status evaluation is presented for these systems. 45 refs.