The figure presents a concept of a bipolar miniature electrostatic ion thruster for maneuvering a small spacecraft. The ionization device in the proposed thruster would be a 0.1-micronthick dielectric membrane with metal electrodes on both sides. Small conical holes would be micromachined through the membrane and electrodes. An electric potential of the order of a volt applied between the membrane electrodes would give rise to an electric field of the order of several megavolts per meter in the submicron gap between the electrodes. An electric field of this magnitude would be sufficient to ionize all the molecules that enter the holes.

A Proposed Miniature Bipolar Electrostatic Ion Thruster would include anionization membrane. An electric potential between the membrane electrodeswould produce an electric field that would generate ions.
In a thruster based on this concept, one or more propellant gases would be introduced into such a membrane ionizer. Unlike in larger prior ion thrusters, all of the propellant molecules would be ionized. This thruster would be capable of bipolar operation. There would be two accelerator grids — one located forward and one located aft of the membrane ionizer. In one mode of operation, which one could denote the forward mode, positive ions leaving the ionizer on the backside would be accelerated to high momentum by an electric field between the ionizer and an accelerator grid. Electrons leaving the ionizer on the front side would be ejected into free space by a smaller accelerating field. The equality of the ion and electron currents would eliminate the need for an additional electron- or ion-emitting device to keep the spacecraft charge-neutral. In another mode of operation, which could denote the reverse mode, the polarities of the voltages applied to the accelerator grids and to the electrodes of the membrane ionizer would be the reverse of those of the forward mode. The reversal of electric fields would cause the ions and electrons to be ejected in the reverse of their forward-mode directions, thereby giving rise to thrust in the direction opposite that of the forward mode.

This work was done by Frank T. Hartley of Caltech for NASA's Jet Propulsion Laboratory.

Topics:
Gases Metals On-board energy sources Physical Sciences Propellants Spacecraft Vehicles
This Brief includes a Technical Support Package (TSP).
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Miniature Bipolar Electrostatic Ion Thruster

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NASA Tech Briefs Magazine

This article first appeared in the November, 2006 issue of NASA Tech Briefs Magazine (Vol. 30 No. 11).

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Overview

The document is a Technical Support Package for the Miniature Bipolar Electrostatic Ion Thruster, identified as NPO-21057, published by NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. It is part of NASA Tech Briefs, which disseminate information on aerospace-related developments with broader technological, scientific, or commercial applications.

The Miniature Bipolar Electrostatic Ion Thruster represents an innovative advancement in propulsion technology, particularly for space exploration. Ion thrusters are known for their efficiency and ability to provide continuous thrust over extended periods, making them suitable for deep-space missions where traditional chemical propulsion systems may be less effective.

The document emphasizes the importance of compliance with U.S. export regulations, indicating that the information may contain proprietary data from Caltech/JPL. It serves as a reminder that users must adhere to applicable laws when utilizing the information provided.

Additionally, the Technical Support Package outlines the availability of further assistance through the NASA Innovative Partnerships Program, which aims to foster collaboration between NASA and various sectors, including industry and academia. This program is designed to promote the commercialization of NASA technologies and facilitate the transfer of knowledge and innovations developed through government-funded research.

For those seeking more detailed information on research and technology related to the Miniature Bipolar Electrostatic Ion Thruster, the document directs readers to the NASA Scientific and Technical Information (STI) Program Office. The STI Program Office provides access to a wide range of publications and resources that can enhance understanding of aerospace technologies and their applications.

The document also includes contact information for the NASA STI Help Desk, offering support for inquiries related to the technical information provided. This includes a telephone number, fax number, and email address for direct communication.

In summary, the Technical Support Package for the Miniature Bipolar Electrostatic Ion Thruster serves as a comprehensive resource for understanding this advanced propulsion technology, its potential applications, and the avenues available for further exploration and collaboration within the aerospace community.