ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • Weitere Quellen  (13)
Sammlung
Datenquelle
Schlagwörter
Erscheinungszeitraum
  • 1
    facet.materialart.
    Unbekannt
    Wear Trends of the HERMeS Thruster as a Function of Throttle Point (2019)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-20
    Beschreibung: A series of short-duration (200 h) wear tests were conducted with two Hall Effect Rocket with Magnetic Shielding (HERMeS) technology demonstration units. Front pole covers, cathode keeper, and discharge channel wear were characterized as a function of discharge voltage, magnetic field strength, and chamber pressure. No discharge channel erosion was observed. Inner pole cover erosion was shown to be a weak function of discharge voltage with most erosion occurring at the lowest value, 300 V. The Technology Demonstration Unit (TDU) 3 keeper electrode eroded with each operating condition, with high magnetic field yielding the greatest erosion rate. The TDU-1 keeper electrode exhibited net deposition suggesting its configuration is more consistent with meeting overall HERMeS service life requirements. Ratios of molybdenum to graphite erosion rates suggests, with high uncertainty, that the sputtering ions are originating downstream of the thruster exit plane, striking the surface with small angles of incidence.
    Schlagwort(e): Spacecraft Propulsion and Power
    Materialart: NASA/TM-2019-219731 , IEPC?2017?207 , E-19456 , GRC-E-DAA-TN48801 , International Electric Propulsion Conference; Oct 08, 2017 - Oct 12, 2017; Atlanta, GA; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unbekannt
    Development Status of a Three-Dimensional Electron Fluid Model for Hall Thruster Plume Simulations (2018)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: A 3-D electron fluid model has been developed as a stepping stone to fully describe the electron current flow across magnetic fields inside a vacuum chamber and to provide electron flux to solar arrays for spacecraft surface charging model. A detailed description of the numerical treatment of the electric potential solver, including finite-volume formulation, implementation, and the treatment of boundary conditions, are presented in this paper. Verification tests of the model are presented.
    Schlagwort(e): Spacecraft Propulsion and Power
    Materialart: NASA/TM-2018-219962 , E-19572 , AIAA-2018-4808 , GRC-E-DAA-TN59053 , Joint Propulsion Conference, AIAA Propulsion and Energy Forum; Jul 09, 2018 - Jul 11, 2018; Cincinnati, OH; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unbekannt
    Update of the NEXT Ion Thruster Service Life Assessment with Post-Test Correlation to the Long Duration Test (2017)
    In:  CASI
    Details
    Publikationsdatum: 2019-08-13
    Beschreibung: The service life assessment for NASA's Evolutionary Xenon Thruster is updated to incorporate the results from the successful and voluntarily early completion of the 51,184 hour long duration test which demonstrated 918 kg of total xenon throughput. The results of the numerous post-test investigations including destructive interrogations have been assessed against all of the critical known and suspected failure mechanisms to update the life and throughput expectations for each major component. Analysis results of two of the most acute failure mechanisms, namely pit-and-groove erosion and aperture enlargement of the accelerator grid, are not updated in this work but will be published at a future time after analysis completion.
    Schlagwort(e): Numerical Analysis; Spacecraft Propulsion and Power
    Materialart: IEPC-2017-061 , GRC-E-DAA-TN44839 , International Electric Propulsion Conference (IEPC) 2017; Oct 08, 2017 - Oct 12, 2017; Atlanta, GA; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unbekannt
    Hybrid-Particle-In-Cell Simulation of Backsputtered Carbon Transport in the Near-Field Plume of a Hall Thruster (2018)
    In:  CASI
    Details
    Publikationsdatum: 2019-08-13
    Beschreibung: Magnetic shielding has eliminated boron nitride erosion as the life limiting mechanism in a Hall thruster but has resulted in erosion of the front magnetic field pole pieces. Recent experiments show that the erosion of graphite pole covers, which are added to protect the magnetic field pole pieces, causes carbon to redeposit on other surfaces, such as boron nitride discharge channel and cathode keeper surfaces. As a part of the risk-reduction activities for Advanced Electric Propulsion System thruster development, this study models transport of backsputtered carbon from the graphite front pole covers and vacuum facility walls. Fluxes, energy distributions, and redeposition rates of backsputtered carbon on the anode, discharge channel, and graphite cathode keeper surfaces are predicted.
    Schlagwort(e): Spacecraft Propulsion and Power
    Materialart: NASA/TM-2018-219719 , IEPC-2017-537 , E-19447 , GRC-E-DAA-TN48798 , International Electric Propulsion Conference; Oct 08, 2017 - Oct 12, 2017; Atlanta, GA; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unbekannt
    Wear Trends of the HERMeS Thruster as a Function of Throttle Point (2017)
    In:  CASI
    Details
    Publikationsdatum: 2019-08-13
    Beschreibung: A series of short-duration (200 hour) wear tests were conducted with two Hall Effect Rocket with Magnetic Shielding (HERMeS) technology demonstration units (TDU). Front pole covers, cathode keeper, and discharge channel wear were characterized as a function of discharge voltage, magnetic field strength, and chamber pressure. No discharge channel erosion was observed. Inner pole cover erosion was shown to be a weak function of discharge voltage with most erosion occurring at the lowest value, 300 volts. The TDU-3 keeper electrode eroded with each operating condition, with high magnetic field yielding the greatest erosion rate. The TDU-1 keeper electrode exhibited net deposition suggesting its configuration is more consistent with meeting overall HERMeS service life requirements. Ratios of molybdenum to graphite erosion rates suggests, with high uncertainty, that the sputtering ions are originating downstream of the thruster exit plane, striking the surface with small angles of incidence.
    Schlagwort(e): Spacecraft Propulsion and Power
    Materialart: GRC-E-DAA-TN45507 , International Electric Propulsion Conference; Oct 08, 2017 - Oct 12, 2017; Atlanta, GA; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unbekannt
    Hybrid-PIC Simulation of Backsputtered Carbon Transport in the Near-Field Plume of a Hall Thruster (2017)
    In:  CASI
    Details
    Publikationsdatum: 2019-08-13
    Beschreibung: Magnetic shielding has eliminated boron nitride erosion as the life limiting mechanism in a Hall thruster but has resulted in erosion of the front magnetic field pole pieces. Recent experiments show that the erosion of graphite pole covers, which are added to protect the magnetic field pole pieces, causes carbon to redeposit on other surfaces, such as boron nitride discharge channel and cathode keeper surfaces. As a part of the risk-reduction activities for AEPS thruster development, this study models transport of backsputtered carbon from the graphite front pole covers and vacuum facility walls. Fluxes, energy distributions, and redeposition rates of backsputtered carbon on the anode, discharge channel, and graphite cathode keeper surfaces are predicted.
    Schlagwort(e): Spacecraft Propulsion and Power
    Materialart: IEPC-2017-537 , GRC-E-DAA-TN45504 , International Electric Propulsion Conference (IEPC); Oct 08, 2017 - Oct 12, 2017; Atlanta, GA; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unbekannt
    Modeling an Iodine Hall Thruster Plume in the Iodine Satellite (ISAT) (2016)
    In:  CASI
    Details
    Publikationsdatum: 2019-08-13
    Beschreibung: An iodine-operated 200-W Hall thruster plume has been simulated using a hybrid-PIC model to predict the spacecraft surface-plume interaction for spacecraft integration purposes. For validation of the model, the plasma potential, electron temperature, ion current flux, and ion number density of xenon propellant were compared with available measurement data at the nominal operating condition. To simulate iodine plasma, various collision cross sections were found and used in the model. While time-varying atomic iodine species (i.e., I, I+, I2+) information is provided by HP Hall simulation at the discharge channel exit, the molecular iodine species (i.e., I2, I2+) are introduced as Maxwellian particles at the channel exit. Simulation results show that xenon and iodine plasma plumes appear to be very similar under the assumptions of the model. Assuming a sticking coefficient of unity, iodine deposition rate is estimated.
    Schlagwort(e): Spacecraft Propulsion and Power
    Materialart: GRC-E-DAA-TN37710 , Liquid Propulsion (LPS) Meeting; Dec 05, 2016 - Dec 08, 2016; Phoenix, AZ; United States|Programmatic and Industrial Base Meeting (PIB) Meeting; Dec 05, 2016 - Dec 08, 2016; Phoenix, AZ; United States|JANNAF Joint Subcommittee Meeting; Dec 05, 2016 - Dec 08, 2016; Phoenix, AZ; United States|Spacecraft Propulsion (SPS) Meeting; Dec 05, 2016 - Dec 08, 2016; Phoenix, AZ; United States|Modeling and Simulation (MSS) Meeting; Dec 05, 2016 - Dec 08, 2016; Phoenix, AZ; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unbekannt
    Modeling an Iodine Hall Thruster Plume in the Iodine Satellite (ISAT) (2016)
    In:  CASI
    Details
    Publikationsdatum: 2019-08-13
    Beschreibung: An iodine-operated 200-W Hall thruster plume has been simulated using a hybrid-PIC model to predict the spacecraft surface-plume interaction for spacecraft integration purposes. For validation of the model, the plasma potential, electron temperature, ion current flux, and ion number density of xenon propellant were compared with available measurement data at the nominal operating condition. To simulate iodine plasma, various collision cross sections were found and used in the model. While time-varying atomic iodine species (i.e., I, I+, I2+) information is provided by HPHall simulation at the discharge channel exit, the molecular iodine species (i.e., I2, I2+) are introduced as Maxwellian particles at the channel exit. Simulation results show that xenon and iodine plasma plumes appear to be very similar under the assumptions of the model. Assuming a sticking coefficient of unity, iodine deposition rate is estimated.
    Schlagwort(e): Spacecraft Propulsion and Power
    Materialart: GRC-E-DAA-TN37780 , Programmatic and Industrial Base (PIB) Meeting; Dec 05, 2016 - Dec 08, 2016; Phoenix, AZ; United States|Liquid Propulsion Subcommittee (LPS); Dec 05, 2016 - Dec 08, 2016; Phoenix, AZ; United States|Spacecraft Propulsion Subcommittee (SPS); Dec 05, 2016 - Dec 08, 2016; Phoenix, AZ; United States|Modeling and Simulation Subcommittee (MSS); Dec 05, 2016 - Dec 08, 2016; Phoenix, AZ; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unbekannt
    The Effect of Anode Position on Operation of a 25-A Class Hollow Cathode (2019)
    In:  CASI
    Details
    Publikationsdatum: 2019-11-07
    Beschreibung: The effect of the distance between a hollow cathode and a cylindrical anode on cathode operation is investigated for two anode geometries. Neutral flow simulations demonstrate that the anode diameter and distance from the cathode exit can elevate the downstream pressure as much as two orders of magnitude above what the cathode experiences while operating within a Hall thruster. Based on the results of this modeling, two axially-segmented cylindrical molybdenum anodes were constructed: a 64-mm diameter one that replicated the anode geometry used in recent NASA hollow cathode development testing and a larger 254-mm diameter one designed to reduce the neutral pressure in front of the cathode to thruster-like values. For each anode design, cathode performance was characterized for varying anode/cathode distance using metrics such as discharge voltage and oscillation magnitudes, and the ion voltage spectra were characterized using a radially-positioned retarding potential analyzer. It was found that as local neutral pressure decreased, discharge voltage and high-voltage ion content in the plume increased. For the 254-mm diameter anode, an ion voltage tail in excess of 200 V was found for nominal cathode flow rates. The implications of these results for standalone hollow cathode development tests are discussed.
    Schlagwort(e): Spacecraft Propulsion and Power
    Materialart: GRC-E-DAA-TN72893 , International Electric Propulsion Conference; Sep 15, 2019 - Sep 20, 2019; Vienna; Austria
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unbekannt
    Development Status of a 3-D Electron Fluid Model for Hall Thruster Plume Simulations (2018)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: A 3-D electron fluid model has been developed as a steping stone to fully describe the electron current flow across magnetic fields inside a vacuum chamber and to provide electron flux to solar arrays for spacecraft surface charging model. A detailed description of the numerical treatment of the electric potential solver, including finite-volume formulation, implementation, and the treatment of boundary conditions, are presented in this paper. Verification tests of the model are presented.
    Schlagwort(e): Spacecraft Propulsion and Power
    Materialart: GRC-E-DAA-TN58540 , AIAA/SAE/ASEE Joint Propulsion Conference; Jul 09, 2018 - Jul 11, 2018; Cincinnati, OH; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...