1. Field of the Invention
The field of the invention, charged particle jet engines, have been around in the form of ion jet engines for over fifty years and have been used as propulsion devices for very low thrust space applications. Attempts have been made to create an ion jet engine for use in the atmosphere using ions created out of the atmosphere itself. These attempts in the atmosphere have to date been unsuccessful in that the very low thrust produced required such high power input that other forms of propulsion have been shown to be far more efficient.
The reason for the very poor efficiency and low thrust is that until the present invention described here, the majority of the energy used to generate thrust was wasted in the creation of charged particles and by the inefficient method used to transfer energy from the accelerated charged particles to the neutral reaction mass molecules due to the interaction of the mean free path and the space charge generated reverse electric field.
2. Descriptions of Related Prior Art
In an ion engine, thrust is produced by ionizing neutral atoms or molecules and accelerating these ions, the reaction mass, by an electric field. The amount of thrust is equal to the reaction mass times the acceleration of that mass or the reaction mass times the change in velocity of the mass. To change the velocity of the reaction mass, energy must be supplied to that mass. The energy that must be supplied is equal to one half the mass times the change in velocity of the mass squared. Maximum energy efficiency is obtained by creating the greatest thrust for the least amount of supplied energy. Energy efficiency can be maximized by accelerating the largest reaction mass possible to the minimum velocity necessary to achieve the desired thrust.
In space applications, especially where energy can be obtained from solar energy or nuclear sources, the reaction mass must be minimized since it must be carried by the spacecraft itself. In this situation you want to accelerate the smallest mass to the highest velocity possible. You are minimizing the expenditure of mass by using relatively large amounts of energy. The overall energy efficiency of ion engines is very low when mass is being minimized but the thrust per unit mass is very high. Because the amount being accelerated is so small, most ion engines are only able to generate a few ounces of thrust at most. Still, in space applications where reaction mass is limited, they can be far more efficient than conventional rockets.
When an ion engine travels through a liquid or gaseous medium where the reaction mass does not have to be carried, it then becomes possible to maximize energy efficiency by accelerating the maximum amount of the medium possible. There have been attempts to build ion jets that operate in the atmosphere but to date these devices have produced only exceedingly small amounts of thrust very inefficiently because of a lack of understanding about how these devices really work.
With minor variations, these attempts consisted of two electrodes, the first either a thin wire supported over the second electrode that is either a flat plate aligned with the wire so that the thin edge of the plate is pointed toward the wire as in FIG. 1A or as a grid as shown in FIG. 1B, or the first electrode is a sharp point coaxial to a second ring electrode spaced at some distance from the first electrode as shown in FIG. 1C. A high voltage is then applied between the two electrodes and if the device is light enough and the voltage is sufficient, it will rise off the ground.
While the use of accelerated charged particles to create thrust goes all the way back to Robert Goddard in 1906, Konstantin Tsiolkovsky in 1911, and Herman Oberth in 1929, the first person to conduct experiments in electrostatic propulsion in air was Thomas Towsend Brown in the 1950's and early 1960's. His patents describe the use of two electrodes to both ionize and then accelerate the ions between the two electrodes to produce thrust. Because he was not clear and did not seem to recognize and express in these patents the mechanism whereby thrust was produced, later researchers developed two theories to explain the lifting force on these devices. The first is based on the work of Thomas Towsend Brown and Dr. Paul Alfred Biefeld usually referred to as the Biefield-Brown effect which has become associated with a theory that this lifting force is due to an as yet unknown interaction between an asymmetrical electrical field produced by an “asymmetrical capacitor” and either a gravitational field or some hypothetical unknown field or medium in space. The second explanation is that these devices create ions that are accelerated thereby producing thrust. Recent experiments performed in a vacuum have shown the second explanation to be the correct one and that contrary to the many patents issued using asymmetrical capacitors, the force based on this interpretation of the Biefield-Brown effect simply does not exist.
Part of the confusion occurs because the number of ions created and the accelerations they undergo based on the voltage and current between the two electrodes is too small to account for the thrust produced. When the additional mass of neutral air molecules accelerated by collisions with the accelerated ions is considered, the observed thrust is fully accounted for.
Also in the late 1950's and early 1960's, Glen E. Hagen developed an improvement on what has become known as a “Lifter” that is similar to the device of T. T. Brown in that it also used two electrodes to both create the ions and then accelerate them. Glen E. Hagen seems to be the first to realize that energy efficiency increases when more mass is accelerated at a lower velocity. His improvements consisted of maximizing the amount of mass accelerated by increasing the area of the electrodes. Alexander P. De Seversky used this same basic structure in his “Ionocraft” as did W. J. Coleman et al.
In the early 1970's, Robert S. Fritzius combined two pairs of electrodes of opposite polarity so that once the ions were accelerated, they would neutralize each other. In the late 1990's, Kenneth E. Burton took the basic Coleman device and reversed the polarity of the electrodes so that negative ions were created instead of positive ions.
In all known applications of ion thrusters in the atmosphere, they are all based on an ionizing electrode (5) in all drawings, either a sharp point FIG. 1C (5) or a thin wire FIG. 1A (5) and FIG. 1B (5), separated from an accelerating electrode (4) of either a plate, grid, or ring. The high voltage (8) applied between the two electrodes (3,4) both ionizes and accelerates the ions. While these devices will lift an ounce or two in air, attempts to increase the thrust to useable amounts have so far failed due to the lack of understanding of how to maximize the thrust while minimizing the energy required to generate that thrust.