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  • 1
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    Development of an electrostatic positioner for space material processing (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: This paper describes an electrostatic positioning instrument which was developed at the Jet Propulsion Laboratory to enable experimenters to conduct containerless material science experiments in space. Samples that are to be studied are electrically charged and controlled by the electrostatic force produced by a set of properly arranged electrodes. Three different types of positioners are described, i.e., the dish type, the ring type, and the tetrahedral type. In all these systems, the positioning and the damping of the sample is accomplished by a feedback control system. The advantage of this electrostatic positioning method, in comparison to the other methods, such as acoustic and electromagnetic, lies in the fact that it can operate in a high vacuum and does not require the material to be electrically conductive as long as the material can carry a certain amount of charge.
    Keywords: ASTRONAUTICS (GENERAL)
    Type: Review of Scientific Instruments (ISSN 0034-6748); 56; 307-317
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Electric Field Containerless Processing Technology (1985)
    In:  CASI
    Details
    Publication Date: 2014-10-04
    Description: The objective of this task is to develop the science and technology base required to design and construct a high temperature electric field positioning module that could be used by materials scientists to conduct containerless science experiments in a low gravity environment. Containerless science modules that employ electric fields to position and manipulate samples offer several advantages over acoustic or electromagnetic systems. The electric field system will operate not only at atmospheric pressures but also in a vacuum, in contrast to the acoustic modules which can only operate in atmosphere where the acoustic forces are sufficient. The electric field technique puts minimum energy into the sample, whereas the electromagnetic system can deposit energy into the sample through eddy current heat as well as physical mixing in the sample. Two types of electric field modules have been constructed and tested to date. One employs a charged sample and uses electrostatic forces to position and control the sample. The second type of module induces electrical polarization of the sample and electric field gradients to position and control the sample.
    Keywords: ASTRONAUTICS (GENERAL)
    Type: NASA, Washington Microgravity Sci. and Appl. Program Tasks; p 195
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Development of electrostatic levitator at JPL (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Preliminary results on the design and operation of electrostatic levitators developed at JPL are reported. Particular attention is given to the single-axis levitators for ground-based operation and for operation in the reduced gravity environment. Descriptions are given of the design principles and the performance of final products. A levitator designed for zero-g environment is shown. It is a single-axis system, so there is no active lateral damping. Two ring and two disk electrodes are included. The ring electrodes always maintain a constant voltage difference with respect to the central disk electrodes. This is to ensure that there is always a centering force that does not depend on the voltage difference between the top and bottom electrodes. As the ring-to-disk voltage increases, there is a proportionate increase in the centering force.
    Keywords: ASTRONAUTICS (GENERAL)
    Type: Materials processing in the reduced gravity environment of space; Annual Meeting; Nov 16, 1981 - Nov 18, 1981; Boston, MA
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Containerless processing technologies at the Jet Propulsion Laboratory (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: Acoustic and electrostatic levitation (EL) techniques for maintaining sample-wall distance in order to ensure contamination-free conditions during microgravity materials science experiments on board the Shuttle are examined. A laboratory model for acoustic containerless (AC) processing is described, noting the use of three commercially available drivers for sample levitation. The arrangement of the speakers results in a point node to which a liquid drop sample migrates. Varying the field through manipulation of the dB levels and phase of the drivers' outputs permits control of sample position and movement. Rotation of a styrofoam ball at 2000 rpm has been achieved. Oscillations can also be induced. An advanced version of the AC system is analytically defined, with further studies mentioned for stable levitation modes using a cylindrical chamber and optimizing acoustic power transfer between hot and cold regions. A tetrahedral EL system has proven to work in a reduced gravity environment. El involves imparting an electrical charge to an object and then positioning and maintaining it through use of EM fields. The presence of human operators to perform the processing on the Shuttle is mentioned as offering real-time capability of altering the experimental conditions.
    Keywords: ASTRONAUTICS (GENERAL)
    Type: IAF PAPER 82-165
    Format: text
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