Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Thrusters”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Kaufman thruster development at Lewis Research Center

The current status of research programs on mercury electron-bombardment thrusters is reviewed. Future thruster requirements predicted from mission analysis are briefly discussed to establish the relationship with present programs. Thrusters ranging in size from 5 to 150 cm diameter are described. These thrusters have possible near to far term applications extending from station keeping to primary propulsion. Beam currents range from 10 mA to 25 A at accelerating potentials of 500 to 5000 V.

Kerslake, W. R.↗
NASA NTRS1972

A 30-cm diameter bombardment thruster with a variable magnetic baffle.

Thruster performance and stability over a range of beam currents is a function of the hollow cathode propellant flow which depends in part on the baffle geometry. Variable magnetic baffles have been used to allow a change in baffle geometry to improve thruster performance and stability. Test results of a 30-cm thruster with magnetic baffle are presented. Thruster performance characteristics are analyzed to show how the magnetic baffle field strength can improve performance at a fixed beam current, as well as increase the range of ion beam current for throttling.

Bechtel, R. T.↗
NASA NTRS1972

Ion thruster thermal characteristics and performance.

Experimental and analytical studies of mercury-fed hollow cathode ion thrusters are presented. Pertinent thermal properties and plasma heating characteristics of the system have been determined through correlation and integration of temperature measurement data with a single stage Wiener-Kalman estimation technique. The resultant analytical network model is applied to predict the thermal performance of specified thruster systems under various operating conditions. The effects of solar intensity levels on the thruster thermal behavior, the dependency on the thruster dimension and multithruster design arrangements have been examined.

Wen, L.↗
NASA NTRS1972

The variable magnetic baffle as a control device for Kaufman thrusters.

The variable magnetic baffle described in this paper aids in control of electron flow from the hollow cathode plasma into the main discharge region by augmenting the fringe magnetic field which impedes this electron flow in conventionally baffled Kaufman thrusters. A passive, low loss, and automatic control device is obtained by using the discharge current to excite the control winding. Used in conjunction with typical thruster control loops, stable operation has been obtained over a 10:1 throttling range with a 30 cm thruster. Discharge ignition and overcurrent recycling is also facilitated through use of this device in a permanent magnet thruster.

Poeschel, R. L.↗
NASA NTRS1972

A 2000-Hour Durability Test of a 5-Centimeter Diameter Mercury Bombardment Ion Thruster

A 2000-hour durability test of a modified Hughes SIT-5 (Structurally Integrated Thruster, 5 cm) was conducted at the Lewis Research Center. The thruster operated with a translating screen thrust vector grid locked in position for 10 deg beam deflection. The test was essentially continuous except for seven stoppages of beam current. The neutralizer keeper voltage and thruster floating potential increased slightly with time. Performance profiles and maps of thruster characteristics were obtained at 453 and 2023 hours into the test. Overall efficiency was nearly constant at 31 - 32 percent, and operating characteristics were similar at both points in the test. A post-shutdown inspection showed negligible erosion damage to the accelerator and cathode baffle. Some erosion was found in the aperture of the neutralizer cathode.

Nakanishi, S.↗
NASA NTRS1973

Exhaust plume and contamination characteristics of a bipropellant (MMH/N2O4) RCS thruster

Results are presented for three recent tests in a series of thruster contamination experiments made in liquid helium-cooled environmental facility. The contaminating effects encountered on various materials, surfaces, and components, due to the exhaust products from a 5-pound thrust, bipropellant (MMH/N2O4) thruster are investigated. The angular distribution of plume effects around the periphery of the thruster established by transmittance changes of quartz samples over the wavelength range from 0.2 to 2.0 micrometer is studied, along with mass deposition rates at a specific location measured with a quartz crystal microbalance for three different experiments. Quadrupole mass spectrometer measurements of the exhaust products over the mass number range from 12 to 75; infrared transmittance measurements of contaminated samples for the wavelength range from 2.5 to 15 microns; and infrared transmittance measurements of residue from the thruster nozzle are also considered.

Spisz, E. W.↗
NASA NTRS1973

Testing and evaluation of the LES-6 pulsed plasma thruster by means of a torsion pendulum system

Performance characteristics of the LES-6 pulsed plasma thruster over a range of input conditions were investigated by means of a torsion pendulum system. Parameters of particular interest included the impulse bit and time average thrust (and their repeatability), specific impulse, mass ablated per discharge, specific thrust, energy per unit area, efficiency, and variation of performance with ignition command rate. Intermittency of the thruster as affected by input energy and igniter resistance were also investigated. Comparative experimental data correlation with the data presented. The results of these tests indicate that the LES-6 thruster, with some identifiable design improvements, represents an attractive reaction control thruster for attitude contol applications on long-life spacecraft requiring small metered impulse bits for precise pointing control of science instruments.

Hamidian, J. P.↗
NASA NTRS1973

Hollow cathode restartable 15 cm diameter ion thruster

The effects of substituting high perveance dished grids for low perveance flat ones on performance variables and plasma properties within a 15 cm modified SERT II thruster are discussed. Results suggest good performance may be achieved as an ion thruster is throttled if the screen grid transparency is decreased with propellant flow rate. Thruster startup tests, which employ a pulsed high voltage tickler electrode between the keeper and the cathode to initiate the discharge, are described. High startup reliability at cathode tip temperatures of about 500 C without excessive component wear over 2000 startup cycles is demonstrated. Testing of a single cusp magnetic field concept of discharge plasma containment is discussed. A theory which explains the observed behavior of the device is presented and proposed thruster modifications and future testing plans are discussed.

Wilbur, P. J.↗
NASA NTRS1974

Eight cm technology thruster development

A structural integrated ion thruster with 8-cm beam diameter (SIT-8) was developed for attitude control and stationkeeping of synchronous satellites. As optimized, the system demonstrates a thrust T=1.14 mlb (not corrected for beam V sub B = 1200 V (I sub sp = 2200 sec) total propellant utilization efficiency nu sub u = 59.8% (is approximately 72% without auxiliary pulse-igniter electrode), and electrical efficiency n sub E 61.9%. The thruster incorporates a wire-mesh anode and tantalum cover surfaces to control discharge chamber flake formation and employs an auxiliary pulse-igniter electrode for hollow-cathode ignition. When the SIT-8 is integrated with the compatible SIT-5 propellant tankage, the system envelope is 35 cm long by 13 cm flange bolt circle with a mass of 9.8 kg including 6.8 kg of mercury propellant. Two thrust vectoring systems which generate beam deflections in two orthogonal directions were also developed under the program and tested with the 8-cm thruster. One system vectors the beam over + or - 10 degrees by gimbaling of the entire thruster (not including tankage), while the other system vectors the beam over + or - 7 degrees by translating the accel electrode relative to the screen electrode.

Hyman, J., Jr.↗
NASA NTRS1974

Cyclic fatigue analysis of rocket thrust chambers. Volume 2: Attitude control thruster high cycle fatigue

A finite element stress analysis was performed for the film cooled throat section of an attitude control thruster. The anlaysis employed the RETSCP finite element computer program. The analysis included thermal and pressure loads, and the effects of temperature dependent material properties, to determine the strain range corresponding to the thruster operating cycle. The configuration and operating conditions considered, correspond to a flightweight integrated thruster assembly which was thrust pulse tested. The computed strain range was used in conjuction with Haynes 188 Universal Slopes minimum life data to predict throat section fatigue life. The computed number of cycles to failure was greater than the number of pulses to which the thruster was experimentally subjected without failure.

Miller, R. W.↗
NASA NTRS1973

An engineering model 30 cm ion thruster

Thruster development at Hughes Research Laboratories and NASA Lewis Research Center has brought the 30-cm mercury bombardment ion thruster to the state of an engineering model. This thruster has been designed to have sufficient internal strength for direct mounting on gimbals, to weigh 7.3 kg, to operate with a corrected overall efficiency of 71%, and to have 10,000 hours lifetime. Subassemblies, such as the ion optical system, isolators, etc., have been upgraded to meet launch qualification standards. This paper presents a summary of the design specifications and performance characteristics which define the interface between the thruster module and the remainder of the propulsion system.

Poeschel, R. L.↗
NASA NTRS1973

Endurance testing of a 30-cm Kaufman thruster

Results of a program to demonstrate lifetime capability of a 30-cm Kaufman ion thruster with a 6000 hour endurance test are described. Included in the program are (1) thruster fabrication, (2) design and construction of a test console containing a transistorized high frequency power processor, and control circuits which provide unattended automatic operation of the thruster, and (3) modification of a vacuum facility to incorporate a frozen mercury collector and permit unattended operation. Four tests ranging in duration from 100 to 1100 hours have been completed. These tests and the resulting thruster modifications are described. The status of the endurance test is also presented.

Collett, C. R.↗
NASA NTRS1973

A north-south stationkeeping ion thruster system for ATS-F

A one millipound cesium ion thruster system experiment designed for the ATS-F satellite will be used to demonstrate north-south stationkeeping for synchronous satellites. Development effort leading to the present design will be described and test data for qualification and flight acceptance tests will be presented. These include a review of EMI evaluations tests made with the power conditioning subsystem and the thruster simulator, and an extended system operational test. During the extended test, 90 on-off cycles simulated thruster operation in orbit. A planned 18,000 hour ground test of a flight qualified thruster will be discussed.

James, E.↗
NASA NTRS1973

Integrated thruster assembly program

The program is reported which has provided technology for a long life, high performing, integrated ACPS thruster assembly suitable for use in 100 typical flights of a space shuttle vehicle over a ten year period. The four integrated thruster assemblies (ITA) fabricated consisted of: propellant injector; a capacitive discharge, air gap torch type igniter assembly; fast response igniter and main propellant valves; and a combined regen-dump film cooled chamber. These flightweight 6672 N (1500 lb) thruster assemblies employed GH2/GO2 as propellants at a chamber pressure of 207 N/sq cm (300 psia). Test data were obtained on thrusted performance, thermal and hydraulic characteristics, dynamic response in pulsing, and cycle life. One thruster was fired in excess of 42,000 times.

Source record↗
NASA NTRS1974

Low voltage 30-cm ion thruster development

The basic goal was to advance the development status of the 30-cm electron bombardment ion thruster from a laboratory model to a flight-type engineering model (EM) thruster. This advancement included the more conventional aspects of mechanical design and testing for launch loads, weight reduction, fabrication process development, reliability and quality assurance, and interface definition, as well as a relatively significant improvement in thruster total efficiency. The achievement of this goal was demonstrated by the successful completion of a series of performance and structural integrity (vibration) tests. In the course of the program, essentially every part and feature of the original 30-cm Thruster was critically evaluated. These evaluations, led to new or improved designs for the ion optical system, discharge chamber, cathode isolator vaporizer assembly, main isolator vaporizer assembly, neutralizer assembly, packaging for thermal control, electrical terminations and structure.

King, H. J.↗
NASA NTRS1974

Optical properties of mercury ion thruster exhausts and implications for science instruments

Emission from the exhaust plume of a 30 cm mercury ion thruster was measured from 160 to 600 nm as a function of axial and radial distance from the thruster discharge chamber. The spectrally dispersed absolute intensities were used to construct an empirical volume rate function. The function was integrated along a typical instrument field of view, and the resulting apparent brightness was compared with instrument sensitivities to evaluate the extent of optical interference. Most of the emitted radiation came from UV lines of excited mercury atoms and ions, with no observable continuum emission. The intensity levels degraded rapidly with distance from the thruster so that optical interference was negligible for fields of view not intercepting the beam axis. The operation of only one instrument, a zodiacal photopolarimeter, was considered incompatible with simultaneous thruster operation.

Monahan, K. M.↗
NASA NTRS1975

Studies of internal sputtering in a 30-cm ion thruster

Initial studies have been made of the sputtering and deposition phenomena in a 30-cm thruster. Sputtering rates, of the cathode baffle, one of the main sources of sputtered material in a thruster, have been measured by weight loss as a function of several thruster parameters. Sputtering rates were found to increase with both cathode flow rate and beam current when constant discharge voltage of 37 volts and power loses of 185 ev/ion were maintained. Sputtering rates were reduced 24% as discharge voltage was decreased from 37 to 33 volts while keeping discharge power constant. Qualitative agreement was found between sputtering rates obtained by the weight loss and those implied by spectroscopically observed line intensities of the excited iron sputtered atoms. After the completion of the sputtering tests, deposition and sputtering sites inside the thruster were identified.

Mantenieks, M. A.↗
NASA NTRS1975

A 20000-hour endurance test of a structurally and thermally integrated 5-cm diameter ion thruster main cathode

A 5-cm diameter mercury ion thruster main cathode has completed over 20,000 hours of operation in an ongoing lifetime endurance test. The cathode operating parameters remained at acceptable performance levels throughout the test, the first 9175 hours of which were part of a thruster endurance test. After 20,000 hours, the cathode discharge was easily restarted, the tip orifice indicated negligible erosion and the tip heater showed no degradation. The cathode-isolator- vaporizer assembly, a major thruster subsystem, has thus successfully demonstrated an operational lifetime capability of 20,000 hours, which is the lifetime goal of the 8-cm diameter auxiliary propulsion ion thruster.

Wintucky, E. G.↗