US3477012A

US3477012A - Thermionic converter

Info

Publication number: US3477012A
Application number: US659484A
Authority: US
Inventors: Robert L Laing
Original assignee: ROBERT L LAING
Current assignee: ROBERT L LAING
Priority date: 1967-08-09
Filing date: 1967-08-09
Publication date: 1969-11-04
Anticipated expiration: 1986-11-04

Description

Nov. 4, 1969 R. L. LAING THERMIONIC CONVERTER 4 Sheets-Sheet 2 Filed Aug. 9, 1967 FIE 5' INVENTOR. eoazer .L. 4 4/1116 Maw A r men/5V Nov. 4, 1969 R. L. LAING 4 THERMIONIC CONVERTER Filed Aug. 9, 1967 '4 Sheets-Sheet 5 INVENTOR. 165 805552 4. 44/06 F IE 11 ATTOPA/EI N v- 4. 1969 R. L. LAING 3,477,012

THERMIONIC CONVERTER Filed Aug. 9, 1967 4 Sheets-Sheet 4 J40 i 14Z FIE 8 J55 J52 II 155 INVENTOR.

EOEEEZ AAA/Iva BY X United States Patent O US. Cl. 322-2 21 Claims ABSTRACT OF THE DISCLOSURE A thermionic converter in which a source of heat is used to apply heat to a cylindrical cathode which is surrounded by a cylindrical anode for accelerating the passage of the electrons from the cathode to at least one collector disposed adjacent an end of the anode and in which there is magnetic means surrounding the anode and producing a magnetic shield generally parallel to the axis'of the anode for confining the electrons emitted by the cathode and minimizing the tendency of said electrons to engage said anode in passing from the cathode to the collector, there being a utilization circuit connected between the collector and the cathode to draw the energy from the collector, this utilization circuit being free of any external electrical source of power of the same order of magnitude of energy as that of the source of heat for heating the cathode.

BACKGROUND OF THE INVENTION The present invention is concerned with a three-element type of thermionic converter in which there is a cathode for emitting electrons, an anode for accelerating the electrons, and a collector to which the electrons go after passing the anode. In such a device, there is a utilization circuit connected between the collector and the cathode and the load device is connected in this utilization circuit. The thermal energy to be converted into electrical energy is applied to the cathode to cause electrons to be emitted therefrom and the primary function of the source of power connected to the anode is to apply a potential such as to cause the electrons to be accelerated. Desirably, no appreciable current flow is in the anode circuit so that the source of power connected to the anode does not substantially contribute to the power input to the converter.

In the Laing and Feemster Patent 3,275,923, in which the present applicant is a co-inventor, use is made of a relatively fieldless hollow collector. As is pointed out in this patent, the hollow collector has the advantage that once the electrons leave the anode and enter the hollow collector, they are repelled away from each other to engage the walls of the collector. Thus, any tendency for a virtual cathode to be formed by reason of the space charge from slow-moving electrons in front of the collector surface is very substantially reduced or eliminated. In this prior patent, however, the electron beam is confined to a direct line extending from the cathode so that the cathode emission is reduced by the space charge depressed field of the beam.

In the Hatsopoulos Patent 2,915,652, there is disclosed a three-element thermionic converter in which a cross field is used to deflect the electrons leaving the cathode and to cause them to be directed towards a collector plate which is either flat or in some cases, convex. An arrangement of this type has the drawback that a virtual cathode is formed adjacent the collector surface by reason of the space charge from slow-moving electrons, as previously mentioned. This tends to retard the passage of electrons from the cathode to the collector.

SUMMARY OF THE INVENTION The present invention is concerned with a thermionic converter having a portion similar to a magnetron in- 3,477,012 Patented Nov. 4, 1969 lCC jection gun for providing an electron stream. This means for providing an electron stream includes an accelerating means for accelerating the charged particles, which accelerating means has an elongated curved surface spaced from and at least partially surrounding a cylindrical surface for emitting charged particles, and a magnetic means surrounding the accelerating means and producing a magnetic field generally parallel to the longitudinal axis of the curved surface of the accelerating means for confining the charged particles emitted by the emitting surface and minimizing the tendency of the charged particles to engage the accelerating means. While I have shown a cathode as the means for emitting the charged particles, the

shown the accelerating means as an anode having a positive voltage applied thereto, the invention contemplates the possibility of a similar arrangement using ions or other charged particles instead of electrons. Where the particles are charged positively, the polarities of the various voltages applied to the various electrodes will be opposite to those employed with electrons.

In one broad form of my invention, the anode is a cylindrical member completely surrounding the cathode and the collector is adjacent one end of the cathode. In fact, there may be a pair of collectors employed, one adjacent each end of the anode. In another broad form of my invention, the anode extends only partially around the cathode and the collector surrounds the cathode and anode so that the charged particles or electrons move past the anode and engage the surrounding cylindrical surface constituting the collector surface.

In some instances, 1 may employ a hollow collector having an opening facing the region between the cathode and anode. There may also be employed an additional collector in the form of a flat plate. In addition, the collector may be disposed intermediate the opposite ends of the anode, and may take the form of a helical coil. Instead of a flat plate, it is possible to employ two hollow collectors each having an opening facing the region between the cathode and anode. It is also possible to have the magnetic field diverge in the direction of the opening in the collector to facilitate entry of the electrons into the collector. The means for heating the cathode may take various forms. In some instances, this may take the form of a flame designed to heat the interior of the electron emissive surface. Or the cathode may enclose or be composed of radioactive material. In other instances, the cathode may be tubular and the source of heat may be a source of heated fluid which is circulated through the cylindrical cathode. It is also possible to employ a reflector adapted to be exposed to solar energy and in which the cathode is adjacent the focal point of the reflector.

The anode may take various forms. For example, it .is possible to employ axial barlike electrodes which extend axially inside of the anode and are maintained at a different potential than the anode. It is also possible to employ an additional electrode, disposed between the anode and collector and which is maintained. at a potential such as to maximize the amount of energy withdrawn from the converter.

In the direct beam device of the Laing and Feemster Patent 3,275,923, the forces necessary to drive the electrons onto the negative collector are derived from the combination of mutual repulsion due to space charge in an essentially fieldless negative collector plus the velocity caused by cathode heat. In the Hatsopoulos Patent 2,915,- 652, the forces necessary to drive the electrons onto the flat or convex collector are derived primarily from the heat energy of electrons leaving the cathode. In the present invention, the forces that cause electrons to be driven onto the negative collector are derived not only from the mutual repulsion of space charge and a concave relatively fieldless collector, plus the velocity imparted to the electrons due to cathode heat, but in addition to this, considerable extra velocity is imparted to the electrons towards the axial ends of the magnetron injection gun or compression chamber due to the magnetic fields which are established both in axially spinning electrons called Bohr magnetrons, and also in electrons spinning in a magnetron orbit. Additional forces are built up due to accumulation of space charge in the magnetron compression chamber, all of which enhances the velocity of the electrons towards the negative collector. These effects are further increased by the fact that the charged particles are forced out of the chamber at areas of irregularities or openings in either the electrostatic field or electromagnetic field, or a combination of both, due to the generation of space charge waves at such areas so that the charged particles leave the compression chamber with greater individual kinetic energy than the average kinetic energy of the charged particles within the compression chamber. Because of this additional energy, the charged particles can be collected on a highly charged collector electrode.

Therefore, while a converter of the type shown in the Hatsopoulos patent is able to produce output voltages of less than minus one volt, the present invention enables voltages of 200 volts at the maximum output efliciency, and open circuit voltages up to 900 volts, in actual experiments.

In addition to the possible modifications of my invention described above, various other modifications and various other objects of the invention will be apparent from the accompanying specification and drawing.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a vertical sectional view of one form of my thermionic converter with a flame being shown as the means for heating the electron emissive surface;

FIGURE 2 is a fragmentary view showing a modification;

FIGURE 3 is a vertical sectional view of a further form of my invention employing a. magnetic member adjacent the collector aperture and showing radioactive material as the source of heat, and also showing an additional collector in the form of a disc disposed intermediate the opposite ends of the anode;

FIGURE 4 is a vertical sectional view of a further form of my invention employing a substantially spherical collector at one end of the anode and showing a perma nent magnet for producing a magnetic field which diverges outwardly adjacent the opening to this collector;

FIGURE 5 is a' vertical sectional view of a still further form of my invention in which the cathode is in the form of a tube through which hot fluid is circulated and in which there is an intermediate helically wound coil concentric with the cathode and anode and disposed between the two;

FIGURE 6 is a vertical sectional view of a further species of my invention in which the anode is provided with axial bars which are electrically insulated from the anode and which are maintained at a lower potential than the anode proper;

FIGURE 7 is a cross-sectional view of the thermionic converter of FIGURE 6, the section being taken along a plane defined by the line 7-7 of FIGURE 6;

FIGURE 8 shows a species in which certain of the electrodes are contoured to maximize the collection of electrons on the collector surface. In addition, in FIG- URE 8, I have shown a parabolic reflector designed to reflect the solar energy into the interior of the electron emitting cathode;

FIGURE 9 is a further form in which the anode is only partially cylindrical and in which the electrons are deflected past the anode onto the interior of a cylindrical collector;

FIGURE 10 is a cross-sectional view taken along the line ltll0 of FIGURE 9; and

FIGURE 11 shows a modification of the species of FIGURES 9 and 10 in which an additional electrode has been inserted, which electrode is curved to conform with a potential plane existing within the collector and which is maintained at an intermediate potential such as to maximize the passage of electrons to the collector surface.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGURE 1, my thermionic converter is shown as comprising a cylindrical hollow cathode 11 which is closed at its upper end and is open at its lower end. The cathode may either be formed of an electron emissive material, such as thoriated tungsten, or may be coated on its exterior surface with a suitable electron emissive material. The lower end of the cathode is hermetically sealed at 12 to a circular base member 13 of heat resistant insulating material, such as ceramic. A cylindrical collector 14 has a closed upper end 15 and a lower open end which closely fits over the base member 13 and is suitably hermetically sealed thereto. The collector 14 may either be of highly conductive material or may be formed of less conductive material with an interior conductive coating.

Also secured to the base member 13 in any suitable manner is a cylindrical anode member 17 which is mounted within the assembly with the axis thereof parallel to the axis of the cathode 11 and the collector 14. An auxiliary collector 18 in the form of an apertured disc surrounds the cathode 11 and is secured to the upper surface of the insulating base member 13 coaxially of cathode '11.

In some instances, it is desirable to employ a probe 19 which is shown as being electrically connected at 20 to the collector 15. As will be explained in more detail, the probe 19 acts as the pickup probe to aid in the collection of the electrons by the collector 14 or acts as to shift the electric field lines in such a way as to maximize the collection of electrons by the collector.

The entire equipment described so far is hermetically sealed together and evacuated. The techniques of such evacuation and sealing are well known and are not described in detail herein.

Surrounding the unit adjacent the anode 17 is a cylindrical permanent magnet 22 which cylindrical magnet is coaxial with the anode 17 and produces a magnetic field generally parallel to the surface of the anode 17.

Various means may be employed for heating the cathode 11. Since the device is intended to function as a thermionic converter, the source of heat may be any suitable source of heat which it is desired to convert into electricity. In the particular embodiment in FIGURE 1, I have shown a conventional burner 23 in which the lilime therefrom extends into the interior of the cathode The anode 17 is maintained at a positive potential with respect to cathode 11 by any suitable source of voltage shown for illustrative purposes as a battery 25, the positive terminal of which is connected by conductor 26 to the anode 17 and the lower terminal of which is connected to ground at 27, this connected to the cathode 11 through conductor 28.

In the operation of my device, as will be presently described, the heat to be converted to electricity is used to heat the cathode and the electrons emitted therefrom are caused to move to the interior surface of the collector 14 and onto the auxiliary collector 18. Because of the electrons being negative, the

collectors

14 and 18 become highly negative.

A suitable load device 30 has one terminal thereof connected by

conductors

31 and,32 to the collector 14 and has the opposite terminal thereof connected to ground by conductor 33. The load 30 is thus connected between the collector 14 and ground so that the electrons accumulating on collector 14 can flow thro gh the load device 30 ground connection 27 being,

back to the cathode 11. The load device 30 is similarly connected through

conductors

28, 33, 31, and 34 between the cathode and the auxiliary. collector 18 so that the electrons accumulating on auxiliary collector 18 can flow through

conductors

34 and 31, the load device 30 and

conductors

33 and 28 back to the cathode 11. In some cases, it may be desirable to employ a separate load device between the auxiliary collector 18 and the cathode since the, negative potential which the auxiliary collector 18 assumes may be different than that assumed by the collector 14.

Referring to the operation of FIGURE 1, the electrons emitted from the cylindrical surface 11 are attracted to the annular anode 17. They are prevented, however, from actually engaging the anode 17, to any appreciable extent, by the magnetic field produced by magnet 22, the lines of force of which run parallel to the anode 17 between the anode 17 and cathode 11. The beam of electrons is thus deflected and tends to travel in the space between the cathode 11 and anode 17. The effect of the magnetic field tends to cause the electrons to rotate so that they tend to travel in a helical path between the cathode 11 and the anode 17. As the electrons spin in magnetron orbits in the chamber between the anode 17 and the cathode 11, they are repelled out of that region by their own mutual repulsion, and also are magnetically attracted to the poles of the magnet, which are adjacent to the collector, due to both electron axial and magnetron spin velocities. As they approach the upper end of anode 17, they are also repelled by the lower electrons into the hollow space formed by collector 14. Once they enter this hollow collector, they are in a relatively field-free region and are repelled by each other to engage the interior wall of the collector much as electrons go to the outside of a hollow Van de Graaif generator collector. The electrons which pass downwardly engage the auxiliary collector 18. Both the electrons engaging the wall of the hollow collector 14 and those engaging the flat auxiliary collector 18 flow through the load 30 back to the cathode.

The pickup probe 19, where used, tends to aid the electrons in passing to the wall of the hollow collector since this probe is located centrally of the hollow collector and is engaged by those electrons furthest from the wall of the collector. Furthermore, as pointed out above, the probe acts to shift the electric field lines to maximize the collection of electrons by the collector. The latter effect can be obtained even if the probe is insulated from the collector and the potential thereof adjusted for maximum collection.

With the arrangement just described, it is possible to obtain very high voltages as compared with a conventional thermionic converter. As pointed out above, instead of a voltage output of less than a volt, I have obtained voltages of approximately 200 volts between the collector and the cathode while drawing maximum power through the load. By employing the magnetic field 22 to prevent the electrons engaging the anode 17 and by giving the electrons a spiraling effect, it is possible for a much larger propor tion of the electrons leaving the cathode 11 to be forced onto the collector surface with only 'a relatively small portion of the electrons engaging the anode surface, As has been pointed out, the ideal situation is to have the anode 17 act merely as a means for attracting the electrons without any of the electrons ever touching the anode. Under ideal conditions, the current flowing in the anode circuit should be substantially negligible.

The arrangement of FIGURE 1 in which the flat collector 18 is directly connected by

conductors

34 and 32 to the hollow collector 14 tends to create. an oscillatory condition due to transient eflects causing imaging currents at

collectors

14 and 18, which are fed from each collector back to the other. In one particular instance, a frequency component of 50 mHz. was found to exist. This further aids in the collection of the electrons.

6 In FIGURE 2, I have shown a modified form of pickup probe. In this case, the probe instead of being in the form of a longitudinal wire-like electrode, as in FIGURE 1, is in the form of a circular ring 36 which is connected at 20 to the collector 14, This ring has the advantage of having a somewhat extended surface which is engaged by more of the electrons entering the collector chamber.

FIGURE 3 shows a further modification of my invention. In this case, the hollow collector 44 is of substantially the same configuration as collector 14 of the species of FIGURE 1. Instead, however, of employing a flat insulating disc, I employ a cup-shaped insulator member 43 which is provided at its upper end with an inturned flange 45. The cathode 41, as with cathode 11, is hollow and has an open lower end. Since I have shown radioactive material 46 as the source of heat in this modification, I have shown the lower end of the cathode as being closed by the insulating member 43 so that the interior of the cathode is sealed from the atmosphere. It is to be understood that even though the cathode 41 is entirely within the enclosure formed by insulating member 43 and collector 44, it is desirable to have the lower end of the cathode 41 sealed to the upper surface of insulating member 43 to prevent the escape of radioactive material into the area surrounding the cathode. The anode 47 in this modification is in the form of an annular sleeve which engages the interior of the upstanding cylindrical wall of the cupshaped insulating member 43, this cylindrical wall serving to electrically insulate the anode 47 from the collector 44.

In the modification of FIGURE 3, there is a cylindrical magnetic pole piece 48 which is secured on top of the flange 45 of the insulating member 43 and which is formed of magnetic material. This magnetic member tends to aid the entry of the electrons into the hollow collector 14 in several ways. In the first place, the line of force of the magnetic field do not extend beyond the magnetic member 48 because of the fact that this magnetic member forms an easier means of passage of the magnetic lines of force into the area between the anode and cathode. Furthermore, the magnetic field extends more closely adjacent to the anode by reason of being directed by the downwardly turned fiange of magnetic member 48. The magnetic field thus has less effect on the emission from the cathode. To aid this effect, I also provide a lower magnetic cylindrical sleeve 49 which is of the same diameter as the downwardly turned flange of magnetic member 48. This tends to shorten the air gap in the magnetic field causing it to pass more closely adjacent to the interior of the anode 49. Located adjacent to the cylindrical magnetic sleeve 49 is an auxiliary collector 51 which has an upturned cylindrical portion 52. This auxiliary collector member 51, like collector member 44, is of conductive material. A further advantage of the

magnetic members

48 and 49 is that these tend to attract the electrons to the collector since each electron tends to act like a tiny magnet due to both axial spin and magnetron orbital spin. Thus, the

magnetic members

48 and 49 not only serve to limit the extent of the magnetic field and decrease its tendency to enter the hollow collector 44 but they also serve to confine the magnetic lines of force more closely to an area adjacent to the anode 47 and further to aid the electrons in being magnetically attracted into the collector areas.

' A further feature of the modification of FIGURE 3 is that I provide an auxiliary intermediate collector 53. This auxiliary collector 53 is in the form of a fiat annular disc having a central aperture therethrough, the disc being suitably mounted by a suitable means, not shown, concentrically with the cathode 31 with the cathode extending through and spaced from the walls of the apertured disc in the collector 53.

' As with the species of FIGURE 1, a positive voltage is maintained between the anode 47 and the cathode 41 by a suitable source of voltage such as battery 55, the positive terminal of which is connected by conductor 56 to the anode 47 and the negative terminal of which is connected by conductor 57 to ground connection 58 to which the cathode is connected. In the present embodiment, I employ three loads 59, 60 and 61. The load 60 corresponds to load 30 of FIGURE 1, being connected between the main collector 44 and the cathode. The load 59 is connected between the magnetic member 49 associated with collector 51, and the cathode. The load 61 is connected between the intermediate collector 53 and the cathode. By using three separate loads, it is possible for each of the collectors to be maintained at a different potential and to obtain the maximum efiiciency in collection of the electrons on the respective collector surfaces.

The intermediate collector 53 has the advantage that there is some tendency for a portion of the electrons to be attracted to the center of the magnetic compression chamber and by placing the collector 53 in an intermediate portion of this chamber, such electrons are collected by collector 53 and caused to flow through load 61.

The modification of FIGURE 4, like the modification previously described, employs a hollow cylindrical cathode 64 which extends through an aperture in an insulating disc 65 which may be of ceramic material. The cathode 64 is hermetically sealed to the disc 65 and the interior of the cathode is heated by a suitable source of heat such as a burner 66, the flame of which extends into the interior of cathode 64. A cylindrical anode 67 is sealed at its lower end to the insulating disc 65, this anode being mounted concentrically with respect to the cathode 64. Secured to the upper end of the anode 67 is a spherical conductive collector member 68 which has an opening 69 therein adjacent the interior of the anode member 67. A ceramic spacer sleeve 70 is interposed between the collector 68 and the upper end of the anode member 67, being hermetically sealed to both the anode and the col lector.

In the modification of FIGURE 4, I have provided for a divergent magnetic field. To accomplish this, I provide an annular magnetic member 71 shown as a permanent magnet. This magnetic member is provided with upper and lower

annular openings

72 and 73 to provide opposite pole portions. The lower magnetic opening 73 is disposed adjacent the lower end of anode member 67 and the upper opening 72 surrounds the lower portion of the spherical collector 68. It will be noted that the upper opening 72 is substantially larger than the lower opening 73. In order to guide the magnetic lines of force, I have .provided a cylindrical magnetic member 75 which converges upwardly and which is of substantially the same diameter as the opening 73 at the lower end of the magnet. The upper portion of magnetic member 75 converges so that the interior of the upper end of this member more closely approaches the exterior of the cathode member 64. It will be readily apparent from the lines of force indicated by

reference numerals

76 and 77 that the magnetic field is initially confined by the magnetic member 75 to a point closely adjacent to the cathode 64. As it passes upwardly to the upper portiton of magnet 71, it diverges. The effect of this is to permit the electrons to diverge as they pass upwardly. By confining the electrons at the lower end of the chamber and permitting them to diverge as they pass upwardly, the tendency for the electrons to engage the anode 67 is minimized and the tendency of the electrons to enter the interior of the hollow chamber 68 is increased. Once they enter the hollow collector chamber 68, they are in a relatively field-free region and the mutual repulsion of the electrons causes them to spread out and engage the interior of the collector.

As with the other modifications, a load device 80 is connected between the collector 68 and the cathode 64 through connections which are readily apparent from the drawing. Similarly, as with the other modifications, the anode 67 is maintained at a suitable positive potential with respect to the cathode by a suitable source of tial, such as battery 81.

In the species of FIGURE 5, the cathode 82 is in the form of a cylindrical tube through which hot fluid is circulated. The hot fluid is the source of heat energy which is to be converted into electrical energy. It is to be understood that the' portion of the tube 82 extending through the converter is coated with a suitable electron emissive material.- The anode 83 is in the form of a cylindrical sleeve which is sealed at its end to annular insulating

members

84 and 85 of heat resistant insulating material, such as ceramic. Sealed to the interior of these annular insulating

members

84 and 85, respectively, are cylindrical members 86 and 87 which are formed of magnetic material. and constitute part of the collector structure. Further annular insulating

members

88 and 89 are sealed to the collector members 86 and 87 and to the cathode tube 82. Extending between the two magnetic collector members 86 and 87 and electrically connected thereto is a helically wound wire 91 of electrically conductive material. The helical turns of the coil 91 are preferably wound in the same direction as the direction of rotation of the magnetic beam, this direction of rotation being determined by the polarity of the magnetic field. Where the coil is wound in the same direction as the direction of magnetic field, the current flowing through the coil between the two magnetic collector members 86 and 87 tends to attract the moving electrons just as two wiresconducting current in the same direction are attracted to one another. For relatively small currents, it may be desirable to have the helical coil 91 wound in the opposite "direction to the direction of rotation of the magnetic field so that there is more tendency for the electrons to engage the turns of the wire 91. Or the helical wire 91 may be wound in opposite directions in each axial direction beginning at the center of the coil.

'Itis, of course, to be understood, as with the other species, that the interior of the chamber enclosed by anode 83 is highly evacuated in a manner commonly employed in electronic discharge devices.

Surrounding the sealed unit enclosed by the anode 83 is a cylindrical permanent magnet 93 having inturned opposite ends which are apertured to provide opposite poles. The cathode 82 extends through the apertures in the magnet 93. The magnet 93 produces a magnetic field which extends generally to the anode 83 within the same.

Still referring to the species of FIGURE 5, a suitable source of potential such as the battery 94 is connected between the anode 83 and the cathode'82 so as to apply a positive potential to the anode 83. A suitable load device 96 is connected between the magnetic collector member 87 and the cathode 82 so as to be connected between the collector assembly and the cathode.

In the arrangement of FIGURE 5, the electrons leaving the cathode are attracted to the anode 83 but are prevented from engaging the anode 83 to any substantial extent by the magnetic field created by magnet 93. The electrons are thus forced to travel spirally in opposite directions. Some of these electrons are collected by the helical wire 91 and some enter the magnetic collectors 86 and 87, being attracted thereto by the magnetic action between the collector members and the spinning electrons. The electrons fiow through the load device 96 back to the cathode.

Referring to the species of FIGURE 6, the cathode is indicated by the reference numeral 99. This cathode is either formed of electron emissive material or coated with an electron emissive coating. The cathode takes the form of an inverted hollow tube as in the other species. Extending into this tube is a burner 100 which is of a type which burns a mixture of gas and air or oxygen and acetylene, etc. A gas supply line 101 supplies gas to the burner and an air supply line 102 supplies air thereto. The gas and air are passed through

passages

103 and 104, respectively,

potenand pass out through the burner 100 where they are mixed and burned. As with some of the other modifications, the anode 105 takes the form of a cylindrical sleeve of conductive material. This sleeve is secured at its opposite ends to annular members 106 and 107 of suitable heat resistant insulating material, being hermetically sealed thereto. Hermetically sealed to the inner wall of the annular insulating disc 106 is a cup-shaped collector member 110, likewise formed of conductive material. Secured to the interior surface of the annular insulating member 107 is a flat collector plate 111 of conductive material. This flat collector plate, along with the rest of the assemblage, is supported from the cathode 99 by an interposed annular insulating member 112 which is hermetically sealed to the collector plate 111 and to the cathode 99.

In this modification, I provide a plurality of auxiliary anodes 114 in the form of longitudinal bars or cogs of conductive material. As best shown in FIGURE 7, which is a cross-sectional view taken along the line 77 of FIGURE 6, these bars 114. are uniformly spaced about the periphery of the cathode 99 being suitably spaced therefrom. Each of the bars 114 is insulated from the main anode 105 by a series of insulating posts 115.

The entire assemblage including the collector members and the anode member with the enclosed cathode and auxiliary anode members 114 is hermetically sealed and evacuated. Surrounding this evacuated structure is an electromagnetic winding 117 which produces a magnetic field similar to that of the other species, this magnetic field passing between the anode and cathode and generally parallel thereto. Any suitable energizing means, not shown, is employed for energizing the winding 117.

In this species, as shown, I maintain the main anode 105 at a higher potential than the auxiliary bar electrodes 114. A first source of power, such as a battery 118 is connected between the cathode and the auxiliary anodes 114. While I have shown the connection to only one of these anodes, it is to be understood that a similar electrical connection is made between battery 118 and the other auxiliary anodes. A second source of power such as a battery 119 is interposed between the auxiliary anodes and the main anode 105 so that the main anode 105 is maintained at a higher potential than the auxiliary anodes. While I have shown the auxiliary anodes as being maintained at a lower potential than the main anode 105, in some instances, it may be desirable to have the auxiliary anodes at the higher potential, relying upon the spacing between the auxiliary anodes to prevent the electrons from engaging the auxiliary anode. The effect of the auxiliary anodes connected as shown in the drawing, however, is to minimize any tendency of the electrons to pass to the high potential anode 105. This, of course, is aided by the effect of the electromagnetic field.

While I have shown longitudinally extending bars 114 as constituting the auxiliary anode, it is to be understood that these auxiliary anodes or anode may take any other form. For example, it is possible to employ, instead of bars, a coiled wire such as wire 91 of FIGURE 5. In such a case, the coiled wire, instead of acting as auxiliary collector as in FIGURE 5, would act as an auxiliary anode, being maintained at a different potential than the main anode.

It is also possible to have the longitudinally extending bars connected to the opposite collector members and act as part of the collector structure, instead of being connected to a source of voltage to act as auxiliary anodes. These bars in such an arrangement would function in a manner similar to the coiled wire 91 of FIGURE 5. In such a case, the bars may be concave to increase the collecting effect.

It is also possible for the bars 114 or a coiled wire such as wire 91 to be connected to a variable negative source of voltage to function as a grid. In such a case, this auxiliary electrode or electrodes would be insulated from the anode and collector as is the case with the bars 114.

In the modification of FIGURE 8, I have shown an arrangement in which solar energy is employed to heat the cathode. Furthermore, I have shown an arrangement in which certain of the electrodes are curved to more effectively direct the electrons onto the collector surface. Referring specifically to FIGURE 8, the thermal converter is supported from a parabolic mirror by a plurality of struts 126 which engage an inverted cupshaped collector 127 of suitable conductive material. The cathode 128 is cylindrical and hollow with the hollow portion facing downwardly, as in other modifications. Secured to the cathode 128 is a conical flange 129 of conductive material which is hermetically sealed at its outer upper edge to an annular ring 130 of suitable heat resistant insulating material such as a ceramic. The anode 131 is basically cylindrical but curves inwardly so that its diameter at its upper end is substantially less than its diameter at its lower end. This lower outer edge of the anode 131 is hermetically sealed to the insulating member 130 and to a second similar annular insulating member 133 which, in turn, is hermetically sealed to the lower end of the collector 127. Thus, the cathode, the anode and the collector are held together to form a hermetically sealed enclosure which is suitably evacuated.

The cathode 128, in this embodiment, is provided with an elongated inverted conical electrode 135 which electrode is of conductive material and functions as a focusing electrode. Because the electrode is connected to the cathode, it is at the same ground potential as the cathode. In this embodiment, I have also shown a curved shield 137 which is either integral with or conductively secured to the lower end of the collector 127 and extends upwardly and inwardly from this lower end. The general curvature of this shield corresponds approximately to the curvature of the anode 131. The shield 137 functions as a Faraday shield to tend to reduce the effect of the electrons to go to the anode 131.

To further aid the direction of the electrons, I provide a beam controlling sole 139. A conductor 140 connected thereto through an insulator 141 located in the upper wall of collector 127 extends to a suitable source of positive voltage such as a battery 142. The battery 142 tends to maintain the sole at a slightly positive potential with respect to the cathode, this positive potential being relatively small, however, as compared with the voltage applied to the anode 131.

Permanent magnet 141 extends around the outside of the collector 127 and serves to provide an axial field which passes between the anode 131 and the cathode 128 including the focusing electrode 135.

As with the other forms of the invention, the anode 131 is maintained at a positive potential with respect to the cathode 128 by a suitable source of power such as a battery 143. Similarly, a suitable load 144 is connected between the collector 127 and the cathode 128 so that the electrons reaching the collector flow through this load resistor back to the cathode.

The parabolic mirror 125 is designed so that the rays of sun indicated by the reference numerals 146 are reflected into the interior of cathode 128. It other words, the cathode 128 is located at the focal point of the parabolic mirror 125. Because of this arrangement, the cathode 128 can be intensely heated by the solar energy directed onto the reflecting surface of mirror 125. It is to be understood, of course, that the arrangement involving the parabolic mirror 125 may be used with other forms of the invention and that as far as the modification of FIGURE 8 is concerned, other forms of heating the cathode may be employed.

Referring generally to the operation of the thermionic converter of FIGURE 8, electrons leaving the surface of cathode 128 are directed as indicated by dotted lines 148 upwardly between the anode 131 and the focusing elec- 1 1 trode 135. They are prevented from engaging the anode 131 by the combined effects of the electromagnetic field and the Faraday shield 137. After passing upwardly beyond the end of the anode 131, they are immediately repelled from each other so as to engage the interior wall of the collector 127. This action is aided by the beam directing sole which exerts an attractive force upon the electrodes to further accelerate the same. At the same time, because of its relatively low positive potential and because of the fact that the electrons by the time they reach the region of the sole have obtained sutficient velocity in paths away from the sole, relatively few of the electrons engage the sole, substantially all of them passing beyond the sole and engaging the interior walls of the collector from whence they are drawn away through the load 144. With this type of arrangement, in which the various beam guiding surfaces are curved, the electrons are very effectively directed towards the interior collector surface with relatively little loss to the anode or other auxiliary electrodes.

The arrangement of FIGURES 9 and 10 operates in a somewhat different manner in that the electrons instead of passing out beyond the end of the cathode are directed outwardly from the cathode in a curved path to engage a collector surface which is generally coextensive longitudinally with the cathode. In this modification, as will be presently explained, the anode does not encircle the cathode but merely extends part way around it permitting the electrons to pass beyond the edge of the anode and engage the collector.

Referring specifically to the structure shown in FIG-

URES

9 and 10, the cathode is indicated by the reference numeral 150. This cathode, like that of the other modifications is preferably of tubular form having the lower end thereof open. This lower end extends through and is sealed to a ceramic base plate 151. A suitable means, not shown, may be employed for introducing heat into the interior of the cathode 150 to cause the same to emit electrons. Also secured to the insulating base plate 151 is an inverted cup-shaped collector 152, the lower open end of which is hermetically sealed to the insulating base plate 151. The enclosure formed by the collector 152 and the base plate 151 is evacuated as in the other species. Also secured to the base plate is an anode member 151 which, unlike the other species, is only semi-cylindrical, as best shown in FIGURE 10. A sole electrode 154 is also secured to the insulating base plate 151. This sole, as shown in FIGURE 9, is of substantially the same vertical extent as the anode 153 and the cathode 150. As best shown in FIGURE 10, the sole 154 has a curved portion 155 which is curved so as to be concentric with the cathode 150, the radius of curvature being somewhat larger than that of cathode 150 so as to be spaced therefrom. The intermediate portion of the sole 154 is in the form of a flat plate 156. The outer portion of the ,sole' is bent at an angle to portion 156 and closely approaches but is spaced from the collector 152. The collector is surrounded by a permanent magnet 158 having a magnetic field parallel to the cathode 150.

The anode 153, as in the other species, is maintained at a relatively high positive potential with respect to the cathode by a suitable source of potential such as a battery 160. A load device 161 is connected between the collector 152 and ground and hence between the collector and the cathode. Another load device 162 is connected between the sole 154 and the cathode.

In operation, the electrons leaving the cathode 150 tend to approach the anode 153 being attracted thereby. The magnetic field, however, produced by the magnet 158 is effective as indicated by the dotted lines 164 to deflect the electrons away from the anode 153 causing them to pass outwardly from beyond the right-hand edge of the anode 153 to engage the inner surface of collector 152. Due to the rotative effect of the magnetic field and the slowing down of the electrons as they approach the negative and an acceleration of the electrons as they move back towards the accelerating anode, the electrons will follow a trochoidal path as indicated by the dotted lines. The electrons so engaging the collector cause the collector to assume a relatively high negative voltage and these electrons are conducted through the load 161 back to the cathode. Any electrons which continue to curve around in a clockwise direction, if they travel far enough, due to the mutual repulsion between the electrons, will engage the sole 154. These electrons will be picked up by the sole and will travel back through load resistor 162 to the cathode. The sole 154, by reason of the stray electrons engaging the same, tends to assume a somewhat negative voltage, the magnitude of which is determined by the magnitude of load resistor 162. The sole 154, being maintained at this negative voltage, prevents any electrons from returning to the cathode 150. It also protects against any electrons continuing to move in a clockwise direction until they engage the positively charged anode 153. The electrons traveling in this clockwise direction are thus either forced onto the sole 154 or onto the collector 152. In either case, the energy resulting from the movement of these electrons is utilized in either of the

loads

161 or 162.

The arrangements of FIGURES 9 and 10, by reason of the concave collector 152, the provision of the sole and the general organization of the unit, result in relatively high output voltages as compared with conventional crossed-field thermionic converters. I have obtained in one embodiment, a voltage output of l00 volts, such voltage being very much higher than those obtained with conventional thermionic converters. As with my other embodiments, the magnetic field acts to compress the space charge causing it to assume the nature of a compression chamber and due, in part to areas of irregularities or openings in either the electrostatic field or electromagnetic field or a combination of both, the charges leaving the compression chamber have much greater individual kinetic energy than the average kinetic energy of the charges within the compression chamber. Because of this additional energy, the electrons can be collecteo on the highly charged collector electrode 152.

While I have shown the base member 151 as being of insulating material, it is also possible for this to be of conductive material and either integral with or electrically connected to the collector member 152. In such a case, it is, of course, to be understood that the cathode 150, the anode 153 and the sole 154 will be suitably insulated fro-m this lower member. The advantage of picking the lower member of conductive material is that any electrons which spiral out above or below the anode 153 will engage a conductive surface of the collector and will increase the current flowing through the load 161.

The species of FIGURE 11 shows an additional feature shown in connection with a thermionic converter of the type shown in FIGURES 9 and .10 but which can be employed with the other species. In order to enable a ready comparison of FIGURES 9 and 10 with FIGURE 11, the same reference characters have been used in connection with FIGURES 9 and 10, as far as identical elements are concerned. Thus, there is a cathode 150, semicylindrical anode 153, a cylindrical collector 152 and a sole electrode 154. In addition to the elements included in the species of FIGURES 9 and 10, I have a further electrode 170 which is curved to conform to an equipotential surface within the chamber formed by collector 152. This further curved electrode 170 will be of substantially the same height as the anode 153 and is connected through an adjustable load to the cathode 150. Because the auxiliary electrode lies in the path of electrons, it will tend to assume a negative charge by reason of the electrons engaging this element. By adjusting the load 165, the amount of this negative voltage can be adjusted. It is preferable to adjust the negative voltage so that the voltage is slightly less negative than would otherwise exist along the equi-potential surface 13' existing at the location of this electrode 170. It has been found in actual experiments that by doing so, the electrons tend to travel deeper into the collector region and then to be deflected through the area between the righthand end of the electrode and the right hand end of anode 153, as shown by the dotted lines 175. As with the arrangement of FIGURES 9 and 10, the electrons tend to follow a trochoidal path. It has been found in actual experiments that the efficiency of the unit is greatly increased when such an additional electrode is employed.

While I have shown the additional electrode 170 in coniiction with a thermionic converter of the type shown in FIGURES 9 and 10, it is to be understood that a similar type of electrode could be employed in connection with the other species. In each case, the contour of the additional electrode would be selected to conform with an equi-potential surface existing at the area in which it is located.

It is also to be understood that in connection with any of the embodiments of my invention that a suitable grid can be employed between the cathode and the anode to vary the emission from the cathode and hence to vary the output current.

While I have referred in numerous cases to electrodes being cylindrical in the specification and claims, it is to be understood that the term cylinder is to be construed in its broad geometric sense as the surface formed by any line being continuously moved parallel to a fixed line. In other words, the term cylindrical as used in the specification and claims is not intended to be limited to a right circular cylinder.

CONCLUSION It will be seen that I have provided a thermionic converter in which a magnetic field is employed to hold the electrons under compression until they are forced out of the compression chamber at areas of irregularities or openings in the electrostatic or electromagnetic field. At such irregularities, space charge waves are generated and the charged particles leave the compression. chamber with greater individual kinetic energy than the average kinetic energy of the charges within the compression chamber. Because of this additional energy, the charged particles can be collected on a high-1y charged collector electrode with great efficiency. The magnetic fields generated by the rotating electrons are an additional aid in generating velocity towards the collectors. Since the energy exchanges between the heat input, the charged particles in the=cross-field space, and the collector are extremely complex, no effort has been made to explain these exchanges, except to point out the various actions known or suspected to occur. For purposes of brevity, it should be sufficient to note that the combination of a cathode to which heat is added, with a magnetron-like compression chamber, and a concave or hollow collector enables an output voltage much higher than the one or two-volt limits of conventional thermionic converters. By reason of the employment of a concave collector surface, the presence of a virtual cathode in front of the collector surface is materially reduced. It will also be seen that my arrangement is broad enough to contemplate either forcing' the electrons or other charged particles out of the end of the chamber 'into or onto collectors disposed at the ends thereof or to cause the charged particles to pass out sidewise beyond the anode to engage an adjacent concave collector surface.

While I have shown a number of embodiments of my invention, it is to be understood that this is for purposes of "illustration only and that the scope of the invention is to be limited solely by the appended claims.

I claim as my invention:

1. A thermionic converter for converting heat energy to electrical energy comprising:

an enclosure including a cylindrical thermionic electron emissive cathode designed to emit electrons from the exterior cylindrical surface thereof when said cathode is heated, means for accelerating said electrons comprising a. an anode having an elongated curved surface spaced from and at least partially surrounding said cathode, and collector having a concave conductive surface within said enclosure and disposed so that said conductive surface extends beyond one extremity of said anode so as to be in the path of electrons emitted by said cathode and moving past said curved surface of said anode, a source of heat for applying heat to said cathode, said source of heat being of a magnitude such that it constitutes the primary source of external energy applied to said converter,

means for applying a positive voltage between said anode and cathode to accelerate the passage of electrons from said cathode to said collector,

magnetic means surrounding said anode and producing a magnetic field generally parallel to the longitudinal axis of the curved surface of said anode for confin- .ing the electrons emitted by said cathode and minimizing the tendency of said electrons to enage said anode,

and means operative to withdraw the electrical energy from said converter resulting from the heat applied to said cathode,

said means including a utilization circuit connected between said collector and said cathode to withdraw the energy from said collector due to the electrons engaging the conductive surface thereof, said utilization circuit being free of any external electrical source of power of the same order of magnitude of energy as that of said source of heat.

2. The converter of claim 1 in which the anode is a cylindrical member completely surrounding said cathode and in which the collector is adjacent one end of said anode.

3. The converter of claim 1 in which the anode extends only partially around the cathode and in which the collector surrounds the cathode over a sector through which the anode does not extend.

4. The converter of claim 2 in which the collector is hollow and has an opening facing the region between said cathode and anode.

5. The converter of claim 2 in which the magnetic field diverges in the direction of the collector.

6. The converter of claim 2 in which there is an additional collector disposed intermediate the opposite ends of said anode.

7. The converter of claim 6 in which the additional collector is in the form of a he-lically wound coil.

8. The converter of claim 6 in which the additional collector is in the form of a flat plate.

9. The converter of claim 2 in which the collector consists of two portions each disposed adjacent an opposite end of said anode.

10. The converter of claim 9 in which the two portions of said collector are each hollow and each has an opening facing the region between said cathode and anode.

11. The converter of claim 1 in which the cathode is tubular and in which the source of heat is a source of heated fluid which is circulated through said cylindrical cathode.

12. The converter of claim 1 in which the cathode includes radioactive material which constitutes the source of heat.

13. The converter of claim 1 in which the collector is of magnetic material.

14. The converter of claim 1 in which the collector is hollow and one or more pick-up probes or field forming electrodes are placed within, or form the end of the collector.

15. The converter of claim 1 in which the source of heat is a reflector adapted to be exposed to solar energy and in which the cathode is adjacent to the focal point of the reflector.

16. The converter of claim 1 in which axial barlike electrodes extend axially inside of said anode and are maintained at a different potential than said anode.

17. The converter of claim 1 in which there is an additional electrode disposed beyond one extremity of the anode and which is maintained at a potential such as to maximize the amount of energy withdrawn from said converter.

18. The converter of claim 1 in which there is a coupling between electrodes of the converter to cause oscillations which aid electron flow to the collector.

19. The converter of claim 1 in which there is a grid for controlling electron flow from the cathode.

20. A thermionic converter for converting heat energy to electrical energy comprising:

an enclosure including a cylindrical thermionic electron emissive cathode designed to emit electrons from the exterior cylindrical surface thereof when said cathode is heated,

means for accelerating said electrons comprising an anode having an elongated curved surface spaced from and at least partially surrounding said cathode, and

a collector having a conductive surface within said enclosure and extending across the corresponding axial ends of said cathode and said accelerating means so that said conductive surface lies across the path of electrons emitted by said cathode and moving past the end of said curved surface of said anode,

a source of heat for applying heat to said cathode, said source of heat being of a magnitude such that it constitutes the primary source of external energy applied to said converter,

magnetic means surrounding said anode and producing a magnetic field generally parallel to the longitudinal axis of the curved surface of said anode for confining the electrons emitted by said cathode and minimizing the tendency of said electrons to engage said anode,

said means including a utilization circuit connected between said collector and said cathode to withdraw the energy from said collector due to the electrons engaging the conductive surface thereof, said utiliza- 1 6 tion circuit being free of any external electrical source of power of the same order of magnitude of energy as that of said source of heat. z 21. A thermionic converter for converting heat energy to electrical energy comprising:

an enclosure including v a cylindrical source of charged particles designed to cause charged particles to move from the exterior cylindrical surface thereof when said electrode is heated,

means for accelerating said charged particles comprising a second cylindrical electrode surrounding said first named electrode, and

a collector having a conductive surface within said enclosure and extending adjacent one end of said second electrode,

a source of heat for introducing heat within the interior of said first named hollow electrode, said source of heat being of a magnitude such that it constitutes the primary source of external energy applied to said converter,

means for applying a voltage between said second electrode and said first named electrode to accelerate the passage of charged particles from said first named electrode to said collector,

magnetic means surrounding said second electrode and producing a magnetic field generally parallel to the axis of said second electrode for confining the charged particles moving from said first electrode and minimizing the tendency of said charged particles to engage said second named electrode, and means operative to withdraw the electrical energy from said converter resulting from the heat applied to said cathode,

said means including a utilization circuit connected between said collector and said first named electrode to Withdraw the energy from said collector due to the charged particles engaging the conductive surface thereof, said utilization circuit being free of any external electrical source of power of the same order of magnitude of energy a as that of said source of heat.

References Cited UNITED STATES PATENTS 8/1966 Fox 310-4 9/1966 Laing et a1. 322-2 U.S. Cl. X.R.