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  • 1
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    Measuring the spacecraft and environmental interactions of the 8-cm mercury ion thrusters on the P80-1 mission (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The subject interface measurements are described for the Ion Auxiliary Propulsion System (IAPS) flight test of two 8-cm thrusters. The diagnostic devices and the effects to be measured include: 1) quartz crystal microbalances to detect nonvolatile deposition due to thruster operation; 2) warm and cold solar cell monitors for nonvolatile and volatile (mercury) deposition; 3) retarding potential ion collectors to characterize the low energy thruster ionic efflux; and 4) a probe to measure the spacecraft potential and thruster generated electron currents to biased spacecraft surfaces. The diagnostics will also assess space environmental interactions of the spacecraft and thrusters. The diagnostic data will characterize mercury thruster interfaces and provide data useful for future applications.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Electroplating and stripping copper on molybdenum and niobium (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Molybdenum and niobium are often electroplated and subsequently stripped of copper. Since general standard plating techniques produce poor quality coatings, general procedures have been optimized and specified to give good results.
    Keywords: MATERIALS
    Type: LEW-12151 , NASA Tech Briefs (ISSN 0145-319X); 3; 1; P. 60
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    NASA TECHNICAL REPORTS
  • 3
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    Optimization of electrostatic dual-grid beam-deflection system (1972)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Tests were performed to minimize accelerator grid erosion of a 5-cm diameter Kaufman ion thruster due to direct beam impingement. Several different screen hole diameters, pillow-shape-square screen holes, and dished screen grids were tried. The optimization was accomplished by copper plating the accelerator grid before testing each grid configuration on a thruster for a 2-hour run. The thruster beam sputtered copper and molybdenum from the accelerator grid where the beam impinged. The observed erosion patterns and measured accelerator currents were used to determine how to modify the accelerator system. The lowest erosion was obtained for a 50-percent open area pillow-shape-square-aperture screen grid, dished 0.043 centimeter convex toward the accelerator grid, which was positioned with the center of the screen grid 0.084 centimeter from the accelerator grid. During this investigation the accelerator current was reduced from 120 to 55 microamperes and was also more uniformly distributed over the area of the accelerator grid.
    Keywords: PROPULSION SYSTEMS
    Type: NASA-TM-X-68096 , E-7012
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Accelerated life test of sputtering and anode deposit spalling in a small mercury ion thruster (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Tantalum and molybdenum sputtered from discharge chamber components during operation of a 5 centimeter diameter mercury ion thruster adhered much more strongly to coarsely grit blasted anode surfaces than to standard surfaces. Spalling of the sputtered coating did occur from a coarse screen anode surface but only in flakes less than a mesh unit long. The results were obtained in a 200 hour accelerated life test conducted at an elevated discharge potential of 64.6 volts. The test approximately reproduced the major sputter erosion and deposition effects that occur under normal operation but at approximately 75 times the normal rate. No discharge chamber component suffered sufficient erosion in the test to threaten its structural integrity or further serviceability. The test indicated that the use of tantalum-surfaced discharge chamber components in conjunction with a fine wire screen anode surface should cure the problems of sputter erosion and sputtered deposits spalling in long term operation of small mercury ion thrusters.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-TM-X-3269 , E-8152
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    NASA TECHNICAL REPORTS
  • 5
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    Ion beam thruster shield (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An ion thruster beam shield is provided that comprises a cylindrical housing that extends downstream from the ion thruster and a plurality of annular vanes which are spaced along the length of the housing, and extend inwardly from the interior wall of the housing. The shield intercepts and stops all charge exchange and beam ions, neutral propellant, and sputter products formed due to the interaction of beam and shield emanating from the ion thruster outside of a fixed conical angle from the thruster axis. Further, the shield prevents the sputter products formed during the operation of the engine from escaping the interior volume of the shield.
    Keywords: SPACECRAFT PROPULSION AND POWER
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  • 6
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    Gadolinium-hydrogen ion exchange of zirconium phosphate (1972)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The Gd(+3)/H(+) ion exchange on a commercial zirconium phosphate ion exchanger was investigated in chloride, sulfate, and phosphate solutions of Gd(+3) at gadolinium concentrations of 0.001 to 1 millimole per cc and in the pH range of 0 to 3.5. Relatively low Gd(+3) capacities, in the range of 0.01 to 0.1 millimole per g of ion exchanger were found at room temperature. A significant difference in Gd(+3) sorption was observed, depending on whether the ion exchanger was converted from initial conditions of greater or lesser Gd(+3) sorption than the specific final conditions. Correlations were found between decrease in Gd(+3) capacity and loss of exchanger phosphate groups due to hydrolysis during washing and between increase in capacity and treatment with H3PO4. Fitting of the experimental data to ideal ion exchange equilibrium expressions indicated that each Gd(+3) ion is sorbed on only one site of the ion exchanger. The selectivity quotient was determined to be 2.5 + or - 0.4 at room temperature on gadolinium desorption in chloride solutions.
    Keywords: CHEMISTRY
    Type: NASA-TN-D-7053 , E-7061
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    Fast on-line gas chromatograph analysis of H2, O2, and CO2 in the off-gas from a reactor experiment (1970)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Hydrogen, oxygen and carbon dioxide in off-gas stream from nuclear reactor experiment using on- line gas chromatography
    Keywords: CHEMISTRY
    Type: PITTSBURGH CONFERENCE ON ANALYTICAL CHEMISTRY AND APPLIED SPECTROSCOPY; Mar 01, 1970 - Mar 06, 1970; CLEVELAND, OH
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    NASA TECHNICAL REPORTS
  • 8
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    In-pile gamma dosimetry measurements with oxalic acid (1969)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: In-pile gamma dosimetry measurements with oxalic acid
    Keywords: NUCLEAR ENGINEERING
    Type: NASA-TM-X-62893 , NATL. SYMP. ON DEVELOP. IN IRRADIATION TESTING TECHNOL.; Sep 09, 1969 - Sep 11, 1969; SANDUSKY, OH; UNITED STATES
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    NASA TECHNICAL REPORTS
  • 9
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    Planned flight test of a mercury ion auxiliary propulsion system. I - Objectives, systems descriptions, and mission operations (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A planned flight test of an 8-cm diameter, electron-bombardment mercury ion thruster system is described. The primary objective of the test is to flight qualify the 5 mN thruster system for auxiliary propulsion applications. A seven year north-south stationkeeping mission was selected as the basis for the flight test operating profile. The flight test, which will employ two thruster systems, will also generate thruster system space performance data, measure thruster-spacecraft interactions, and demonstrate thruster operation in a number of operating modes. The flight test is designated as SAMSO-601 and will be flown aboard the Shuttle-launched Air Force Space Test Program P80-1 satellite in 1981. The spacecraft will be 3-axis stabilized in its final 740 km circular orbit, which will have an inclination of at least 73 degrees. The spacecraft design lifetime is three years.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: AIAA PAPER 78-647-I , International Electric Propulsion Conference; Apr 25, 1978 - Apr 27, 1978; San Diego, CA; US
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    NASA TECHNICAL REPORTS
  • 10
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    Solutions for discharge chamber sputtering and anode deposit spalling in small mercury ion thrusters (1975)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Proposed solutions to the problems of sputter erosion and sputtered material spalling in the discharge chamber of small mercury ion thrusters are presented. The accelerated life test evaluated three such proposed solutions: (1) the use of tantalum as a single low sputter yield material for the exposed surfaces of the discharge chamber components subject to sputtering, (2) the use of a severely roughened anode surface to improve the adhesion of the sputter-deposited coating, and (3) the use of a wire cloth anode surface in order to limit the size of any coating flakes which might spall from it. Because of the promising results obtained in the accelerated life test with anode surfaces roughened by grit-blasting, experiments were carried out to optimize the grit-blasting procedure. The experimental results and an optimal grit-blasting procedure are presented.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-TM-X-71675 , AIAA PAPER 75-399 , 11th Elec. Propulsion Conf; Mar 19, 1975 - Mar 21, 1975; New Orleans, LA; United States
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