Engineering topics
Publications and source records attributed to Garner, C. E..
The Dawn Project's mission is to rendezvous and map the two heaviest main belt asteroids Vesta and Ceres. The Ion Propulsion System (IPS) for Dawn will be used for the heliocentric transfer from the Earth to Vesta, orbit capture at Vesta, transfer to a low Vesta orbit, departure and escape from Vesta, the heliocentric transfer from Vesta to Ceres, orbit capture at Ceres, and transfer to a low Ceres orbit.
NASA's drive to reduce mission costs and accept the risk of incorporating innovative, high payoff technologies into its missions while simultaneously undertaking ever more difficult missions has sparked a greatly renewed interest in solar sails. This paper summarizes these on-going developments in solar sails.
Design characteristics and performance data of a 4.5-kW, thruster with anode layer (TAL) developed at the Central Research Institue for Machine Building (TsNIIMASH) are presented. The TAL is designated the D-100 with a discharge chamber of outer diameter approximately 100mm. Performance characteristics demonstrated by the D-100 and life estimates by TsNIIMASH make this thruster an excellent candidate for a wide range of station keeping, orbit raising, orbit maneuvering and JPL planetary missions.
In a NASA program to validate 30 cm Xenon ion thruster technology for use in planetary missions a combination of analysis and testing is being used to establish engine reliability. Five long duration tests are planned to identify new failure mechanisms and characterize the parameters which drive known damage accumulation failure modes.
Sputter yields have been measured for chemically-vapor deposited polycrystalline diamond, carbon-carbon composite, and molybdenum subject to bambardment with xenon ions at 150, 250, 500, and 750 electron volts. The diamond yield ranged from 0.12 to 0.33 over the range of energies investigated.
A T-100-3 Russian Hall plasma thruster, xenon flow control unit (XFCU) and US xenon propellant subsystem developed for the RHETT-1 propulsion system are described. The propellant system includes a pressure regulator, on/off valves, service valve and high/low pressure transducers, built to flight-like standards and assembled onto a mounting plate structure. ...
Performance and endurance testing of a 1.35 kW thruster with anode layer (TAL), developed at the Central Research Institute of Machine Building (TsNIMASH) is described.
This paper describes an optical technique developed for measuring small differential grid displacements due to thermal expansion of an ion thruster accelerator system. The technique is based on confocal scanning optical microscope type II. For the measurements of small displacements where there are distances on the order of a meter or more between the lens plane and the sample, some of the optical components are moved while the sample is kept fixed. The feasibility of applying this technique to measure the thermally induced ion thruster grid displacements was demonstrated in a bench-top simulation. It is noted that this technique can also provide information on grid movement resulting from thermal transients such as the start-up.
Design, development and preliminary testing of a two-engine xenon ion propulsion module for early flight evaluation is described. Extensive use is made of flight spare propellant system components and also engineering model 30-cm ion engines and assemblies originally developed for the Solar Electric Propulsion System program. Significant design features include a redundant propellant feed system that incorporates a novel gas pulse assembly for rapid and completely reliable engine startup, a central neutralizer subsystem with dual neutralizers for redundancy, and major ion engine performance improvements resulting in a nearly doubling of the 30-cm engine thrust in addition to operating on xenon rather than mercury propellant. At a module input power of 10.0 kw, maximum thrust and specific impulse are projected to be 0.4 N and 3,500 sec. respectively, for a total module efficiency of 67 percent. Total mass of the xenon ion module, including the propellant tank, is only 70.2 kg. The technical approaches taken towards developing and integrating the subsystems comprising this ion propulsion module are presented and discussed in detail.
High-velocity xenon ions used to drill holes of controlled size and distribution through tungsten layer that sheaths surface of controlled-porosity dispenser cathode of traveling wave-tube electron emitter. Controlled-porosity dispenser cathode employs barium/calcium/ aluminum oxide mixture that migrates through pores in cathode surface, thus coating it and reducing its work function. Rapid, precise drilling technique applied to films of other metals and used in other applications where micron-scale holes required. Method requires only few hours, as opposed to tens of hours by prior methods.