WO1991017601A1

WO1991017601A1 - Energy converter

Info

Publication number: WO1991017601A1
Application number: PCT/US1991/002920
Authority: WO
Inventors: David J. Fitzgerald
Original assignee: Fitzgerald David J
Priority date: 1990-05-02
Filing date: 1991-04-26
Publication date: 1991-11-14
Also published as: AU7793591A

Abstract

An energy converter having a source of electrons (2), an electron collector (27) and two electrodes (17, 18) of different electric potential placed so that electrons traveling from the electron source (2) to the electron collector (27) must pass between the two electrodes (17, 18). The electrons gain kinetic energy from the electric field between the two electrodes (17, 18). As the electrons reach the electron collector (27), the added kinetic energy causes a lowering of the electric potential of the electron collector (27) below that of the electron source (2). The difference in electric potential allows a current to flow through a wire (28) connecting the electron collector (27) with the electron source (2).

Description

ENERGY CONVERTER Background of the Invention The present invention relates generally to an apparatus for generating electric power, and more specifically to such an apparatus which operates by causing electrons, released from a cathode, to enter and be accel,rated by an electric field perpendicular to the electron's direction of travel. The electrons are then collected by an electron collector, creating a difference in electric potential between the cathode and the electron collector.

A thermionic energy converter is a well known device for converting heat energy into electric energy. In operation, an electron emissive cathode is heated. Heat energy drives electrons from the surface of the cathode into the space surrounding it. An electron collector placed near the cathode receives many of the emitted electrons. This over-abundance of electrons lowers the electric potential of the electron collector. Electrons possess a negative electric charge and are therefore attracted to an area of higher electric potential. In a thermionic energy converter, a wire is connected between the electron collector and the cathode from which the electrons were emitted. A current of electrons flows from the electron collector to the higher potential cathode. This current fulfills the purpose of the thermionic energy converter by providing power to an electric load connected somewhere between the electron collector and the cathode. It is a unique feature of the present invention that the work of adding kinetic energy to the electrons, which then shows up as a lower electric potential at the electron collector, is done by an electric field. Thermionic energy converters described in U.S. Patents Nos. 3,041,481, 3,202,844, 3,328,611 and 4,303,845 all use electric fields to guide and accelerate electrons but the electric fields described in these patents do not contribute directly to lowering the electric potential of the electron collector.

The Energy Conversion System described in U.S. Patent No. 4,772,816 injects electrons into mutually perpendicular electric and magnetic fields resulting in the electrons being driven onto an electrode. The energy to do this appears to come from the magnetic field. This is similar to the present invention in that it derives energy from a source other than heat alone but there is a disadvantage in the need for magnets. Magnets add unnecessarily to the cost of this electricity generating device and can also be heavy. The excess weight is especially detrimental in mobile applications, particularly in aircraft.

Summary of the Invention In current thermionic energy converters, the kinetic energy needed for electrons to travel from the cathode to the electron collector is derived from heat energy at the cathode. In the present invention, heat energy plays a minor role. Heat energy is only needed to eject electrons from the cathode and into the space around it. One version of the invention makes use of a cold cathode so that the electrons receive no contribution to their kinetic energy from heat. Electrons are pulled away from the cold cathode by a strong electric field.

It is a goal of this invention to improve the efficiency of thermionic energy converters by increasing the kinetic energy of electrons traveling between the cathode and the electron collector. In the simplest version of this invention, this is done by using an electron gun to send electrons into the space between two parallel, plate electrodes that carry different electric potentials. An electron gun, as can be seen in a cathode ray tube, consists of several cylindrical electrodes that together create an electric field which accelerates electrons away from the cathode and focuses the electrons into a narrow stream. The two parallel, plate electrodes are placed so that the difference in electric potential between them creates an electric field that is perpendicular to the path of approaching electrons. While passing through the electric field, the electron stream is deflected. The electric field must be non-parallel to the electron stream but the closer the electric field is to perpendicular the greater the deflection.

In order to generate electricity, the present invention takes advantage of the fact that the plate electrodes change the direction of the electron stream by accelerating the electrons in a direction that is perpendicular to their original direction of travel . After passing through the electric field between a pair of plate electrodes, the new velocity of the electrons is the vector sum of the original velocity and the velocity added by the electrodes.

Increased velocity means the electrons now have greater kinetic energy. The present invention allows the electrons to strike an electron collector and lower its electric potential to a level below that of the cathode. The difference in electric potential between the cathode and electron collector of this invention can be much greater than in thermionic energy converters of common design because the majority of the electrons' kinetic energy comes from passing through the perpendicular electric field rather than from heat energy.

Brief Description of the Drawings Fig. 1 shows a cross-section of an embodiment of the invention in which a stream of electrons is accelerated toward an electron collector by two pairs of flat plate electrodes;

Fig. 2 shows a cross-section of an embodiment of the invention in which the electron collector also serves as the low potential member of the electrode pair which accelerates the stream of electrons; and

Fig. 3 is a view of an embodiment of the invention in which electrons are emitted radially from a centrally located emitter. Detailed Description of the Preferred Embodiment

In Fig. 1, several electrodes and a heating element are seen inside evacuated chamber 1. The support structure for the heating element and electrodes is not shown. Cathode 2 is heated by heating element 3 to the point at which cathode 2 emits electrons. Heating element 3 can be heated by any means, but in this embodiment, it is electrically heated by a current from battery 4 through wires 5 and 6. Cathode 2, electrodes 7, 11 and 14 are cylindrical in shape and make up an electron gun, as is commonly found in cathode ray tubes. In cathode ray tube terminology, electrode 7 is the control grid, electrode 11 is the accelerating grid, and electrode 14 is the focus electrode. Together, the parts of the electron gun send out a stream of electrons that follows electron path 10. Electrode 7 possesses a lower electric potential than cathode 2. The electric field between cathode 2 and electrode 7 limits the number of electrons which can pass through electrode 7 to only those possessing a certain threshold kinetic energy. Electrode 7 receives its low electric potential from potential source 8 through wire 9. A potential source is any device, such as a battery which can produce and maintain an electric potential on an electrode. The flow rate of electrons passing through electrode 7 can be controlled by modulating the potential of electrode 7. Once through electrode 7 the electrons are accelerated and focused by electrode 11, which is at a higher electric potential than cathode 2, and electrode 14, which carries an even higher potential. Electrodes 11 and 14 are given their high potentials by potential sources 12 and 15 through wires 13 and 16 respectively.

After electrode 14, electrons move on toward electrodes 17 and 18. Electrode 17 is at a higher potential than electrode 18. When passing between electrodes 17 and 18, the electric field between electrodes 17 and 18 gives the electrons an acceleration perpendicular to their original direction of travel. When electrons leave electrodes 17 and 18 they are traveling at a greater velocity and in a different direction. Electrode 17 receives its electric potential from potential source 19 through wire 20 while electrode 18 receives its lower potential from potential source 21 through wire 22. It is important that the velocity of electrons reaching electrodes 17 and 18 be great enough so that the electrons pass between electrodes 17 and 18 without being drawn into contact with electrode 17.

The same acceleration occurs when the electrons pass between parallel, plate electrodes 23 and 24. Electrode 23 receives its potential from potential source 19 through wire 25. Electrode 24 receives its lower potential from potential source 21 through wire 26. As before, when electrons leave electrodes 23 and 24, they are moving faster and have changed direction.

The fast moving electrons have greatly increased their kinetic energy since leaving cathode 2. When the electrons reach electron collector 27, the high kinetic energy produces a low electric potential on electron collector 27. Due to the difference in electric potential energy between cathode 2 and electron collector 27, a current will travel from electron collector 27 through wire 28 to electric load 29 and then to cathode 2 by wire 30. The current provides power to electric load 29.

In Fig. 2, several electrodes and a heating element are seen inside evacuated chamber 31. The support structure for the heating element and the electrodes is not shown. Cathode 32 is heated by heating element 33 to the -1-

point at which cathode 32 emits electrons. Cathode 32 may be heated by any means, but in this embodiment, it is electrically heated by a current from battery 34 through wires 35 and 36. Cathode 32, electrodes 37, 41 and 44 make up an electron gun which sends out a stream of electrons along electron path 40. Electrode 37 receives a lower electric potential than cathode 32 from potential source 38 through wire 39. The electric field between cathode 32 and electrode 37 allows only high kinetic energy electrons to pass through electrode 37 and follow electron path 40.

Electrons then pass through electrodes 41 and 44 where the electrons are accelerated and focused by the electric field in that region. Electrode 41 receives its high electric potential from potential source 42 though wire 43. Electrode 44 is given a still higher potential from potential source 45 through wire 46.

Electrons move on toward electrodes 47 and 48 after leaving electrode 44. Electrode 47 receives its high potential from potential source 49 through wire 50. Electrode 48 develops a low potential by intercepting the stream of electrons. Electrode 48 is shaped so that a portion of it acts with electrode 47 to produce an electric field that accelerates and deflects incoming electrons. Electrode 48 is also the electron collector. As electrons are collected, a difference in electric potential develops between cathode 32 and electrode 48. The potential difference causes a current to flow from electrode 48 through wire 51 to electric load 52 and then on to cathode 32 through wire 53. The current provides power to electric load 52. In Fig. 3, the chamber which surrounds the energy converter and a support structure for the electrodes are not shown. Heating element 55, which extends through the center of cathode 54 and is electrically insulated from cathode 54, provides heat to cathode 54 and electron emissive band 59. Heating element 55 receives power from battery 56 through wires 57 and 58. Cathode 54 and the painted on band 59 are heated to a temperature at which band 59, having a lower work function than cathode 54, emits electrons. The electric potential of cathode 54 and band 59 is lower than the electric potential of electrodes 60 and 63 so electrons are drawn radially away from band 59. Electrodes 60 and 63 receive their high potential from potential sources 61 and 64 through wires 62 and 65 respectively. Electron paths 66 and 67 show two possible directions electrons could travel. It is intended that all electron paths curve to make contact with electron collector 71. Electrons take on this curved path because they are accelerated toward electrode 63 by the electric field between electrodes 68 and 63. Electrode 68 receives a lower electric potential than electrode 63 from potential source 69 through wire 70.

As in the energy converter devices shown in Figs. 1 and 2 , electrons gain kinetic energy as they pass through an electric field that is perpendicular to their direction of travel . This high kinetic energy causes a low electric potential to develop on electron collector 71 when the electrons eventually reach it. Due to the difference in electric potential between electron collector 71 and cathode 54, a current will flow from electron collector 71, through wire 72, electric load 73 and wire 74 to cathode 54. The current provides electric energy to electric load 73.

Claims

1. A method for generating electric energy, comprising: providing a cathode as an electron source, directing electrons emitted by the cathode into an electric field that is non-parallel to the direction the electrons are traveling, allowing the electrons to be accelerated while passing through the non-parallel electric field, catching the accelerated electrons in an electron collector so that the electric potential of the electron collector becomes less than the electric potential of the cathode; and connecting an electric load between the electron collector and the cathode so that a current will flow to provide power to the electric load.

2. A method according to claim 1 in which the cathode is a heated cathode.

3. A method according to claim 1 in which the cathode is coated with an electron emissive material.

4. A method according to claim 1 in which the cathode is a cold cathode.

5. A method according to claim 4 in which an electric field means is employed to draw electrons from the cold cathode.

6. A method according to claim 1 in which the electrons are emitted, accelerated and collected within an evacuated chamber.

7. A method according to claim 1 in which the non- parallel electric field is produced by two electrodes of different electric potential.

8. A method according to claim 1 in which the intensity of the non-parallel electric field can be modulated so that the kinetic energy added to the electrons passing through the non-parallel electric field can be controlled.

9. A method according to claim 1 in which the non- parallel electric field is perpendicular to the directed electrons.

10. An apparatus for generating electric energy, comprising: a cathode as an electron source, a means for directing electrons emitted by the cathode, a means for producing an electric field that is non-parallel to the directed electrons, an electron collector which develops an electric potential that is less than the electric potential of the cathode by receiving the electrons that have been accelerated by passing through the non-parallel electric field; and an electric load connected between the electron collector and the cathode so that a current flows which provides power to the electric load.

11. An apparatus according to claim 10 in which the cathode is a heated cathode.

12. An apparatus according to claim 10 in which the cathode is coated with an electron emissive material .

13. An apparatus according to claim 10 in which the cathode is a cold cathode.

14. An apparatus according to claim 13 in which an electric field means is employed to draw electrons from the cold cathode.

15. An apparatus according to claim 10 in which the electrons are emitted, accelerated and collected within an evacuated chamber.

16. An apparatus according to claim 10 in which the intensity of the non-parallel electric field may be modulated so that kinetic energy added to electrons passing through the non-parallel electric field may be controlled.

17. An apparatus according to claim 10 in which the non-parallel electric field is produced by two electrodes of different electric potential.

18. An apparatus according to claim 10 in which the non-parallel electric field is perpendicular to the directed electrons.