Engineering topics

Friedly, V. J.

Publications and source records attributed to Friedly, V. J..

8 records

NASA NTRS1995

EPOP: The Electric Propulsion Orbital Platform

This paper describes the results of a one-year feasibility study for an Electric Propulsion Orbital Platform (EPOP), whose primary objective is to provide an instrumented platform for testing electric propulsion devices in space. The first flight, EPOP-1, is planned aboard the Shuttle-deployed Wake Shield Facility in March 1995, and will be designed around a commercial 1.8 kW, 0.5 hydrazine arcjet system. Specific subsystems are described, namely the arcjet and the power conditioning unit, the propellant and power systems, and Wake Shield Facility. Also, system engineering and integration issues are discussed. In an accompanying paper, the diagnostics and data acquisition and control systems are described in more detail.

Friedly, V. J.↗

NASA NTRS1995

EPOP Diagnostics and Data Acquisition

This paper describes the diagnostics that have been selected for the first flight of the Electric Propulsion Orbital Platform (EPOP-1), in which a 1.8 kW hydrazine arcjet will be flown and tested on the Wake Shield Facility. These diagnostics are: Langmuir probe measurements and video of the arcjet plume; three types of electromagnetic noise measurements; measurement of the voltage-current characteristic of the arc at different feed pressures; and measurement of other performance parameters such as pressures and temperatures of arcjet system components, thrust, and specific impulse. Also, the approach to data acquisition and control of the experiment is described.

Ruyten, W. M.↗

NASA NTRS1995

Electric Propulsion: Experimental Research

This paper describes experimental electric propulsion research which was carried out at the University of Tennessee Space Institute with support from the Center for Space Transportation and Applied Research. Specifically, a multiplexed LIF technique for obtaining vector velocities, Doppler temperatures, and relative number densities in the exhaust plumes form electric propulsion devices is described, and results are presented that were obtained on a low power argon arcjet. Also, preliminary Langmuir probe measurements on an ion source are described, and an update on the vacuum facility is presented.

Ruyten, W. M.↗

NASA NTRS1993

Spectroscopic investigations of beam-plasma interactions in an ion plume

We report the results of spectroscopic investigations of beam-plasma interactions in the plume from a 3 cm ion source operated on argon. Ion-electron, ion-neutral, and electron-neutral scattering are identified by studying the dependence of neutral and ion emission intensities on chamber pressure and mass flow rate, and by analyzing the emission lineshapes at a non-orthogonal angle to the plume axis. Through the Doppler shift, we are able to separate contributions from fast beam ions and fast charge-exchange neutrals on the one hand, and of slow neutrals and slow ions on the other. We discuss the application of this new technique to the characterization of beam plasma interactions in the downstream region of ion thruster engines, and its potential for identifying the processes which lead to grid erosion.

Ruyten, W. M.↗

NASA NTRS1993

Electric Propulsion Orbital Platform

This paper describes the Electric Propulsion Orbital Platform (EPOP), of which the primary objective is to provide an instrumented platform for testing electric propulsion devices in space. It is anticipated that the first flight, EPOP-1, will take place on the Shuttle-deployed Wake Shield Facility in 1996, and will be designed around a commercial 1.8 kW arcjet system which will be operated on gaseous hydrogen propellant. Specific subsystems are described, including the arcjet system, the propellant and power systems, and the diagnostics systems.

Friedly, V. J.↗

NASA NTRS1993

Diagnostics development for the Electric Propulsion Orbital Platform

We describe the development of the diagnostics systems for the first flight of the Electric Propulsion Orbital Platform (EPOP), which will center around the in-flight characterization of a 1.8 kW hydrogen arcjet system. In particular, we discuss a spacecraft communications experiment involving ground-to-spacecraft communications of the EPOP carrier; electrical probe measurements in the arcjet plume; and spectrally resolved plume imaging measurements of the same plume. The communications experiment is designed to measure small noise on the communications link which results from arcjet operation. The other two measurements primarily serve the purpose of characterization of the plume plasma. These measurements will be compared to similar measurements performed in a ground chamber to establish whether systematic differences exist between ground-based and in-flight performance of the arcjet system.

Ruyten, Wilhelmus M.↗

NASA NTRS1993

Experimental and analytical ion thruster research

The results of further spectroscopic studies on the plume from a 3 cm ion source operated on an argon propellant is reported on. In particular, it is shown that it should be possible to use the spectroscopic technique to measure the plasma density of the ion plume close to the grids, where it is difficult to use electrical probe measurements. How the technique, along with electrical probe measurements in the far downstream region of the plume, can be used to characterize the operation of a three-grid, 15 cm diameter thruster from NASA JPL is outlined. Pumping speed measurements on the Vacuum Research Facility have shown that this facility should be adequate for testing the JPL thruster at pressures in the low 10(exp -5) Torr range. Finally, we describe a simple analytical model which can be used to calculate the grid impingement current which results from charge-exchange collisions in the ion plume.

Ruyten, Wilhelmus M.↗

NASA NTRS1992

EPOP - Toward the realization of an Electric Propulsion Orbital Platform

This paper describes the results of a feasibility study for an Electric Propulsion Orbital Platform (EPOP), whose primary objective is to provide an instrumented platform for testing electric propulsion devices in space. It is anticipated that the first flight, EPO-1, will take place on the Shuttle-deployed Wake Shield Facility in 1996, and will be designed around a modified version of a commercial 1.8 kW hydrazine arcjet system, to be operated on gaseous hydrogen propellant. Specific subsystems are described, including the arcjet system, the propellant and power systems, and the diagnostics systems. Also, system engineering and integration issues are discussed.

Friedly, V. J.↗