Engineering topics

Byers, D. C.

Publications and source records attributed to Byers, D. C..

At least 19 records

NASA NTRS1984

The NASA Electric Propulsion program

It is pointed out that the NASA Electric Propulsion program is aimed at providing technology for auxiliary and primary propulsion functions for earth-orbital and planetary space missions. Efforts in electrostatic propulsion include analyses of ion propulsion for Geosynchronous (GEO) and planetary spacecraft, continued preflight efforts associated with the Ion Auxiliary Propulsion System (IAPS), and research and technology for advanced and simplified ion thruster systems. In the area of electromagnetic propulsion, studies were conducted regarding the feasibility and impacts of the use of electromagnetic launchers. Research on magnetoplasmadynamic (MPD) thrusters, electromagnetic launchers, and Hall current thrusters was also performed. Studies in the electrothermal sector included an evaluation of electric propulsion options for the Space Station, taking into account also resistojets, a pulsed electrothermal thruster, and arc jets.

Byers, D. C.↗

NASA NTRS1984

NASA's space energy technology program

NASA's Space Energy Systems program is concerned with the development of technology for space missions requiring high performance, such as geostationary orbit communication satellites and planetary spacecraft, and high capacity, such as the planned Space Station and lunar bases; these two requirements often lead to great differences in system design. The program accordingly addresses a wide range of candidate technologies, which encompasses photovoltaics, chemical energy conversion and storage, thermoelectric conversion, power management and distribution, and thermal management.

Mullin, J. P.↗

NASA NTRS1980

Electric propulsion and power

The development of electric propulsion systems is discussed and the benefits of these systems to various space mission requirements are outlined. The characteristics and development status of 8 and 30 cm mercury ion thrusters and solar electric propulsion systems are reported. In addition the advantages of an inert gas thruster for Earth orbital missions are examined and include its capability for operation at higher values of specific impulse, the ease at which it can be integrated with space systems, and it's low pollution potential.

Byers, D. C.↗

NASA NTRS1980

Nuclear electric propulsion system utilization for earth orbit transfer of large spacecraft structures

The paper discusses a potential application of electric propulsion to perform orbit transfer of a large spacecraft structure to geosynchronous orbit (GEO) from LEO, utilizing a nuclear reactor space power source in the spacecraft on a shared basis. The discussions include spacecraft, thrust system, and nuclear reactor space power system concepts. Emphasis is placed on orbiter payload arrangements, spacecraft launch constraints, and spacecraft LEO assembly and deployment sequences.

Silva, T. H.↗

NASA NTRS1980

Upper stages utilizing electric propulsion

The payload capabilities of upper stages using electric propulsion for a LEO to GEO orbit transfer mission are discussed. Payloads are calculated using an established methodology which employs assumptions concerning state-of-the-art electric propulsion technology. The effects on payloads are examined for variations of total mass in LEO (MLEO), thrusting (trip) times, propellant type, specific impulse, and power source specific mass. It is found that the ratios of payload masses to total mass in LEO are insensitive to MLEO, which allows a highly condensed presentation of the overall payload capability. Electric stages are shown capable of delivering payloads in thrusting times less than 50 days with the payloads increasing rapidly with increase in thrusting times. Payload capabilities exceeding those attainable with chemical propulsion are possible using state-of-the-art electric propulsion technology.

Byers, D. C.↗

NASA NTRS1980

Orbital transfer of large space structures with nuclear electric rockets

This paper discusses the potential application of electric propulsion for orbit transfer of a large spacecraft structure from low earth orbit to geosynchronous altitude in a deployed configuration. The electric power was provided by the spacecraft nuclear reactor space power system on a shared basis during transfer operations. Factors considered with respect to system effectiveness included nuclear power source sizing, electric propulsion thruster concept, spacecraft deployment constraints, and orbital operations and safety. It is shown that the favorable total impulse capability inherent in electric propulsion provides a potential economic advantage over chemical propulsion orbit transfer vehicles by reducing the number of Space Shuttle flights in ground-to-orbit transportation requirements.

Silva, T. H.↗

NASA NTRS1980

Upper stages utilizing electric propulsion

The payload characteristics of geocentric missions which utilize electron bombardment ion thruster systems are discussed. A baseline LEO to GEO orbit transfer mission was selected to describe the payload capabilities. The impacts on payloads of both mission parameters and electric propulsion technology options were evaluated. The characteristics of the electric propulsion thrust system and the power requirements were specified in order to predict payload mass. This was completed by utilizing a previously developed methodology which provides a detailed thrust system description after the final mass on orbit, the thrusting time, and the specific impulse are specified. The impact on payloads of total mass in LEO, thrusting time, propellant type, specific impulse, and power source characteristics was evaluated.

Byers, D. C.↗

NASA NTRS1979

Characteristics of primary electric propulsion systems

The use of advanced electric propulsion systems will provide cost and performance benefits for future energetic space missions. A methodology to predict the characteristics of advanced electric propulsion systems was developed and programmed for computer calculations to allow evaluation of a broad set of technology and mission assumptions. The impact on overall thrust system characteristics was assessed for variations of propellant type, total accelerating voltage, thruster area, specific impulse, and power system approach. The data may be used both to provide direction to technology emphasis and allow for preliminary estimates of electric propulsion system properties for a wide variety of application.

Byers, D. C.↗

NASA NTRS1979

Primary electric propulsion for future space missions

A general methodology is presented which allows prediction of the overall characteristics of thrust systems employing electron-bombardment ion thrusters. Elements of the thrust system are defined and their characteristics presented in a parametric fashion. Two system approaches are evaluated where power management and control elements and thruster characteristics were substantially different. For an assumed system approach, the methodology presented predicts overall system properties, such as input power and mass, when major mission and thrust system parameters, such as trip time and specific impulse, are assumed.

Byers, D. C.↗

NASA NTRS1979

Characteristics of primary electric propulsion systems

The use of advanced electric propulsion systems is expected to provide cost and performance benefits for future energetic space missions. A methodology to predict the characteristics of advanced electric propulsion systems was developed and programmed for computer calculations to allow evaluation of a broad set of technology and mission assumptions. The impact on overall thrust system characteristics was assessed for variations of propellant type, total accelerating voltage, thruster area, specific impulse, and power system approach. The data may be used both to provide direction to technology emphasis and allow for preliminary estimates of electric propulsion system properties for a wide variety of applications.

Byers, D. C.↗

NASA NTRS1979

Primary electric propulsion for future space missions

The paper presents data and a methodology to allow preliminary definition of electric propulsion systems. The elements comprising the thrust system are described parametrically. As an example, thruster performance is presented as a function of specific impulse and propellant type. Two power management and control (PMAC) approaches are considered to illustrate the use of the methodology. Power source characteristics are disregarded in the system description. One PMAC concept assumes a dc power input to the thrust system and all thruster power conditioned in a conventional manner; the other PMAC approach assumes an ac power source.

Byers, D. C.↗

NASA NTRS1978

A review of electron bombardment thruster systems/spacecraft field and particle interfaces

This paper collates and summarizes information on the field and particle interfaces of electron bombardment ion thruster systems. Major areas discussed are the nonpropellant particles, neutral propellant, ion beam, low energy plasma, and fields. Spacecraft functions and subsystems reviewed are solar arrays, thermal control systems, optical sensors, communications, science, structures and materials, and potential control. An appendix is included to facilitate identification of specific interaction areas.

Byers, D. C.↗

NASA NTRS1978

A review of electron bombardment thruster systems/spacecraft field and particle interfaces

Information on the field and particle interfaces of electron bombardment ion thruster systems was summarized. Major areas discussed were the nonpropellant particles, neutral propellant, ion beam, low energy plasma, and fields. Spacecraft functions and subsystems reviewed were solar arrays, thermal control systems, optical sensors, communications, science, structures and materials, and potential control.

Byers, D. C.↗

NASA NTRS1976

Electron bombardment propulsion system characteristics for large space systems

Presented are the results of an analysis of electron bombardment ion propulsion systems for use in the transportation and on-orbit operations of large space systems. Using baseline technology from the ongoing primary propulsion program and other sources, preliminary estimates of the expected characteristics of key system elements such as thrusters and propellant storage systems have been performed. Projections of expected thruster performance on argon are presented based on identified constraints which limit the achievable thrust and/or power density of bombardment thrusters. System characteristics are then evaluated as a function of thruster diameter and specific impulse.

Byers, D. C.↗

NASA NTRS1976

Electron bombardment propulsion system characteristics for large space systems

The results of an anlaysis of electron bombardment ion propulsion systems for use in the transportation and on-orbit operations of large space systems are presented. Using baseline technology from the ongoing primary propulsion program and other sources, preliminary estimates of the expected characteristics of key system elements such as thrusters and propellant storage systems were performed. Projections of expected thruster performance on argon are presented based on identified constraints which limit the achievable thrust and/or power density of bombardment thrusters. System characteristics are then evaluated as a function of thruster diameter and specific impulse.

Byers, D. C.↗

NASA NTRS1974

Sputtering Holes with Ion Beamlets

Ion beamlets of predetermined configurations are formed by shaped apertures in the screen grid of an ion thruster having a double grid accelerator system. A plate is placed downstream from the screen grid holes and attached to the accelerator grid. When the ion thruster is operated holes having the configuration of the beamlets formed by the screen grid are sputtered through the plate at the accelerator grid.

Byers, D. C.↗

NASA NTRS1972

Improved high voltage insulator for use in vacuum

High voltage insulator for electron bombardment ion thruster has electric field directed through dielectric material and electrons emitted by field emission are constrained in negative junction region. Surface flashover and unstable operation are eliminated, and maximum voltage is limited only by dielectric strength of material, aluminum oxide in this case.

Byers, D. C.↗

NASA NTRS1972

Design, fabrication, and operation of dished accelerator grids on a 30-cm ion thruster.

Several closely-spaced dished accelerator grid systems have been fabricated and tested on a 30-cm diameter mercury bombardment thruster and they appear to be a solution to the stringent requirements imposed by the near-term, high-thrust, low specific impulse electric propulsion missions. The grids were simultaneously hydroformed and then simultaneously stress relieved. The ion extraction capability and discharge chamber performance were studied as the total accelerating voltage, the ratio of net-to-total voltage, grid spacing, and dish direction were varied.

Rawlin, V. K.↗