ELECTRODYNAMIC TETHER PDF

ABOUT ELECTRODYNAMIC TETHER, ITS STABILIZATION, ITS ADVANTAGES. In an “electrodynamic tether drag” system, such as the Terminator Tether, the tether can be used to reduce the orbit of the spacecraft to which it is attached. The motion of the long conducting wire of a tethered satellite across the geomagnetic field creates an emf of about – V/m along the length of the tether.

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The charging battery load can be viewed as a resistor which absorbs power, but stores this for later use instead of immediately dissipating heat. Since it takes a much greater potential difference to collect an equivalent amount of ion current for a given areathe total current in the tether is reduced by a smaller amount. Electrodynamic Wlectrodynamic Unlike chemical and rocket systems, which must expell a propellant to create thrust, an electrodynamic tether generates thrust through Lorentz-force interactions with a planetary magnetic field.

If additional power is driven along the tether in the opposite direction to that in which it normally wants to flow the tether in theory could push negating propulsion against the Earth’s gravity to raise the shuttles orbit. As the current flows through the tether, heat is elcetrodynamic because of the tethed resistance tetther the conductive tether material so-called ohmic heating. Thermionic emission is the flow of electrons from a heated charged metal or metal oxide surface, caused by thermal vibrational energy overcoming the work function electrostatic forces holding electrons to the surface.

When the size of the sheath is much smaller than the radius of the collecting body then depending on the polarity of the difference between the potential of the tether and that of the ambient plasma, V — Vpit is assumed that all of the incoming electrons or ions that enter the plasma sheath are collected by the conductive body. System level configurations will be presented for each device, as well as the relative costs, benefits, and validation.

The parameters — magnetic field Btether length Land the orbital velocity v orb — are vectors that can be expressed in terms of this coordinate system, as in the following equations:. Solar radiation Lightning Equatorial electrojet. Once this is accomplished it will be possible electrodnamic apply this theory toward determining optimizations of system attributes. This super- strong and thin strand, also contains a tin coated, insulated copper wire bundle that makes it electrically conductive.

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As the satellite and tether move through the ionosphere the very high part of the Earth’s atmosphere the Shuttle flies elecrrodynamicthey “cut” through magnetic field lines, generating high voltage, electrical currents, and plasma disturbances you’ll find explanations of theses things scattered through these tetyer. Mission Commander Andrew M. Once released, the satellite will climb upward from the orbiter and away from Earth, aided by gravitational force and the use of its onboard thrusters, to attain a distance of To investigate these effects, the astronauts onboard will work with scientists and engineers on the ground, performing a wide variety of experiments.

Without loss of generality, it is assumed the tether system is in Earth orbit and it moves relative to Earth’s magnetic field.

The coordinates are the first thing that must be identified. Secondary factors, depending on the application, include cost, strength, and melting point.

Electrodynamic tether

In this regard, see also homopolar generator. Fortunately, there are plenty of free tteher available in the thin upper part of the atmosphere, called the ionosphere, where ultraviolet and x-ray radiation from the Sun knocks electrons from atmospheric gas molecules. The attached tether, with a diameter of 0.

Further discussion of this topic can be found. In reverse the EDT system could be used electdodynamic acceleration. The Shuttle Electrodynamic Tether System SETS will provide measurements eleftrodynamic the tether voltage and current and generate an electron beam in support of science investigations.

This creates a high density plasma plume which makes contact with the surrounding plasma. However, there is a way to turn this “bug” into a feature. Retrieved 15 March An electrodynamic tether is essentially a long conducting wire extended from a spacecraft.

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An electrodynamic tether is attached to an object, the tether being oriented at an angle to the local vertical between the object and a planet with a magnetic field. Science fiction author David Brin has made a good story from available; you might want to go read Tank Farm Dynamo. The boost mode is similar to the de-orbit mode, except for the fact that a High Voltage Power Supply HVPS is also inserted in series with the tether system between the tether and the higher positive potential end.

This “bare tether” concept was first proposed by Juan SanMartin, a professor of physics at the Polytechnic University of Madrid, Spain. The second layer is a negative layer at the edge of the low potential plasma the ambient plasma. The circuit’s resistance consist of three components:. Tether geometries outside this dimension have been addressed.

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An EDT takes advantage of two basic principles of electromagnetism: For Jupiter, however, there may be an alternative. There are a number of derivations that solve for the potentials and currents involved in an EDT system numerically. Many of these concepts overlap into other areas; however, they are simply placed under the most appropriate heading for the purposes of this table. The motion of the tether across the Earth’s magnetic field produces a voltage along the 12 mile tether. In the presence of a strong electric field, the potential outside the metal will be deformed along the line AB, so that a triangular barrier is formed, through which electrons can tunnel.

In any application where electrons are emitted across a vacuum gap, there is a maximum allowable current electrodyhamic a given bias due to the self repulsion of the electron beam. The story takes maybe fifteen minutes to read – it’s well worth it! The thermionic emission current density, J, rises rapidly with increasing temperature, releasing a significant number of electrons into the vacuum near the surface. An accelerating structure is typically placed in close proximity with electridynamic emitting material as in the below figure.

This voltage can be up to several hundred volts per kilometer. The only reason a tether picks up electrons is so the current in wire runs in one direction.

Electrons are accelerated from the insert region, through the orifice to the keeper, which is always at a more positive bias. The tether failed as a result of arcing and burning of the tether, electrodynmic to a tensile failure after a significant portion of the tether had burned away,” the report concludes.

As such the tether can be completely self-powered, besides the initial charge in the batteries to provide electrical power for the deployment and startup procedure. This video has been removed by the original poster at Youtube. The orbit of a satellite also could be changed as many times as needed if there is no dependency on a limited amount of propellant. You can think of a voltage as a height difference, such as between a mountaintop and a valley.

The direction of the electric field E is at right angles to both the tether’s velocity v and magnetic field B. Understanding electron and ion current collection to and from the surrounding ambient plasma is critical for most EDT systems.