Patent Number: 043476210
Section: summary

BACKGROUND OF THE INVENTION In the system of the invention a strong applied electric field is crossed with (i.e., established essentially at right angles to) a very strong annular-confinement magnetic field directed axially within an annular confinement chamber, and a stream or several streams of high-kinetic-energy tightly-looping fusible ions mixed with space-charge-neutralizing electrons is by ion and electron optical methods introduced into the chamber at a location within but non-adjacent to the walls of the annular chamber, the stream having appropriate values of electric potential and potential gradient and cross-sectional dimensions, these being controlled by circumstances of the introduction of the stream into the chamber, whereby the ions and space-charge-neutralizing electrons will move generally arcuately at right angles to both field directions at a crossed-field advance velocity determined by the electric field and the magnetic flux density thus being approximately at right angles to the annular axis of the chamber. The ions of the stream, because of the strength of the magnetic field, assume a confined tightly-looping quasi-trochoidal type of motion, or motion segments, with the kinetic energy in the small diameter looping components of the ion motions greatly exceeding the kinetic energy in the relatively slow crossed-field advance motion. The duration of the confinement into controlled flow paths is made sufficient to produce fusion events at a substantial rate resulting in the release of high kinetic energy neutrons and positively-charged particles whereby this kinetic energy may be converted into usable heat, chemical energy or directly converted into electric energy. The method and apparatus of the invention utilize crossed strong electric and magnetic fields to control the location, dimensions, and flow of the stream, and by the use of interrelated potentials impressed upon the stream as related to potentials within the location in the fusion chamber at which the stream is introduced maintains the stream out of contact with the chamber walls. Because the ion energies and densities are controlled by the circumstances of their introduction into the fusion chamber, they can in combination be large enough so that throughout the duration of the ions' flight paths within the fusion chamber, a duration that is controllable, the fusion power generation per unit volume of stream can be great enough so that substantial power generation can be obtained in a relatively small volume of the reacting stream. The invention pertains to a system for producing nuclear fusion, and particularly relates to the confinement, that is, to the control of the location, dimensions, potential structure, and flow rate, of a stream of fusible positive ions, with associated separately produced electrons that are present solely to neutralize the ion space charge, such control being by the use of crossed electric and magnetic fields having directions wholly or primarily at right angles to one another. The high kinetic energy ions introduced into the annular reaction chamber assume a looping quasi-trochoidal type of motion. This motion is characterized in the invention by the kinetic energies in the small diameter looping components of the ion motions exceeding, by a factor of the order of 10 or more, and extending in cases to factors of thousands or tens of thousands or more, the kinetic energies in the relatively slow crossed-field-advance motions with which the ions circulate circumferentially around the axis of the annular reaction chamber. While the advantages of producing energy, in the form of heat or electricity, through the nuclear fusion process has long been appreciated, because of the very high kinetic energies (often expressed in terms of extremely high temperatures) at which fusion occurs, and because of other physical limitations, it has not been possible to bring about adequate confinement or control and so utilize nuclear fusion principles in a commercial manner. It has been recognized that nuclear fusion reactions can be confined within magnetic fields, and fusible fuel which has been completely ionized to form an assembly of positive ions and free electrons, often called a plasma, has been proposed to be confined within crossed electric and magnetic fields as disclosed in U.S. Pat. No. 3,029,199. In that patent the magnetic flux lines loop around the interior axis of the annular chamber, the ion and electron stream therefore circulating generally parallel to that interior axis, occupying only a very limited portion of the available magnetic field region. Furthermore, in U.S. Pat. No. 3,029,199 the ionization and imparting of kinetic energy to the ions is the result of passage of electric current between the electrodes of the chamber, thus establishing a plasma, a method that has not been used successfully to produce the ion kinetic energy needed for fusion. In U.S. Pat. No. 3,120,475 there is disclosed an electric mirror machine that employs electrodes at differing potentials in combination with a magnetic field. Its primary high density, high energy confined flow occurs parallel to the axis of the magnetic field and for the most part parallel to a congruent electric field, the magnetic and electric fields being almost entirely congruent in the important region where the charged particles are reflected from their approach to the two ends of the enclosure. In this patent the primary purpose of the electric field is to cause reflections of the ions back and forth from and between the two on-axis ends of the enclosure in their movements essentially parallel to the magnetic flux lines and two positive repelling electrodes are required on the convergent end sections; to cause the repelling field to exist there must be a strongly negative electrode elsewhere, this being the electrode centered on the meridian plane extending parallel to the axis along the inner surface of the central portion of the enclosure, which must be remote from the active playing region where the plasma exists in order not to interfere with it either physically or by electric field influences. Thus two electrodes, both positive, are at the extreme ends and near the axis of the structure, whereas the negative electrode centers in the central plane of the structure and is remote from the axis. U.S. Pat. No. 3,120,475 employs ion injection from a simple ion gun, a method that is not feasible with magnetic flux densities strong enough to provide confinement at ion densities and energies needed for fusion. In my U.S. Pat. No. 3,501,376 I disclose a method and apparatus for confining a monopolar (i.e., using ions alone) stream of fusible ions by using crossed electric and magnetic fields. However, the prior art disclosures have not been sufficient to overcome the many problems in creating and maintaining a commercially usable fusion reaction, and one of the problems results from the inability of known apparatus to maintain the confinement of fusible positive ions at a sufficient combination of high kinetic energy and high density to permit a sufficient rate of neutron and positively-charged particle production. In the majority of existing proposed engineering applications for fully ionized gases, whether for fusion or other purposes, the presence of a magnetic field, usually an extremely strong magnetic field, is an essential item. In many of the related analytical treatments and engineering studies great emphasis is placed on the powerful magnetic influences that prevent the "guiding centers" of the charged particles' motions from moving across magnetic flux lines from one "tube of flux" to another. The guiding center concept arises from the fact that in a strong magnetic field a charged particle's motion consists of a small diameter circular looping in the plane at right angles to the magnetic field direction, superimposed on certain kinds of straight line or slowly curving motions. It is helpful to consider the straight line or slowly curving motions as being translations of the guiding centers of the loop, no physical object being at a "guiding center," with the looping motion as a whole translating as movements of the guiding center require, the looping component remaining parallel to its original plane. In the absence of any electric field, the guiding center can move only in one direction, i.e., that of the magnetic field, to or fro. This is a very strong limitation, particularly for the nuclear fusion reaction art wherein the magnetic field may often be strong enough so that even for very large kinetic energies of the ions the diameter of their looping motions is only a very few centimeters, or even a very few millimeters, and therefore in many cases small relative to the dimensions of the fusion-reaction chamber. This powerful tendency for confinement of the guiding center to its original position in the magnetic-flux structure is described in terms of "magnetic pressure", which is proportional to the square of the magnetic flux density. Closely related to this behavior is the fact that the magnetic force on a charged particle does not add to nor subtract from its kinetic energy, because the magnetic force is always at right angles to the direction of the particle's motion, so does not affect its scalar velocity, nor its kinetic energy. In a converging magnetic field translation of the guiding center in the direction of the magnetic field will alter the division of the kinetic energy as between the looping motion energy content and the translational motion energy content. This happens in the familiar magnetic mirror machine intended to produce fusion, being a behavior wholly different in principle from that occurring in the electric mirror apparatus of U.S. Pat. No. 3,120,475 referred to earlier. However, in the presence of an electric field that has its major component at right angles to the direction of the magnetic field, there is a very powerful influence that compels the guiding centers to move across magnetic flux lines, in a direction at right angles to both the electric and the magnetic fields, thus producing the straight line or slowly curving component of motion referred to earlier. Under these conditions the resulting movement has as one component what is called the "crossed-field advance velocity" in the prescribed direction. Electromagnetic theory, and also simple rule-of-thumb considerations, require that for the straight line crossed-field advance velocity existing when both fields are uniform, this velocity expressed in meters per second must equal the cross direction electric field component in volts per meter divided by the magnetic flux density in webers per square meter. This crossed-field advance velocity is the same in direction and magnitude for particles of the two kinds of electric charge, and is independent of the mass of the particle and the amount of its electric charge, and is therefore the same for the electrons as for the positive ions. The direction of the looping component superimposed on the crossed-field advance velocity is clockwise for one kind of particle, and is counterclockwise for the other. The radius of the looping component is inversely proportional to the magnetic flux density, proportional to the square root of the kinetic energy content of the looping component of the motion, and proportional to the square root of the mass of the particle. Because of the dependence on particle mass, the radius of the electron looping is for given kinetic energy very much smaller than for the ions, for example by a factor of about 60 for deuterons; in addition, for the embodiments envisioned for this invention the electron energies are expected to be substantially less than the ion energies. For any charged particle so moving, the total average kinetic energy is the simple sum of three energies; that in the crossed-field advance motion, that in the circular looping motion superimposed on the advance motion, and that in the linear motion parallel to the direction of the magnetic field. For each particle the angular velocity in radians per second is invariant, being numerically the same as the cyclotron radian frequency governed by the magnetic flux density and the ratio of electric charge to mass for the particle. Even in the presence of extensive occurrence of collisions between particles, every individual segment of a particle's motion will have the crossed-field advance velocity as a component of its motion in the prescribed direction; thus a swarm of particles having many collisions will move as a body with the crossed-field-advance direction and magnitude. When tightly-looping high-kinetic-energy particle motions appear in the presence of curvature and convergence of the crossed fields, but with the loops being small enough so that there occur only very minor changes in field directions or intensities within individual loops, the crossed-field advance concept applies for the motions of the guiding centers, with however, a centrifugal force effect contributing to the governing of the magnitude of the crossed-field advance velocity; however, this velocity's direction remains always at right angles to both fields. In the embodiments of my invention these centrifugal force effects will contribute only to a very small degree to the governing of the magnitude of the crossed-field advance velocity of the guiding centers. This requirement for the existence of the crossed-field advance velocity of the guiding centers is potentially a very powerful resource for compelling streams of charged particles, of ions or electrons or both intermixed, to move across magnetic flux lines in prescribed paths, and this can include movement from outside to inside of a region of very strong magnetic field, as for example into a region in which the very strong magnetic field confines a fully ionized gas at energies adequate to cause fusion. It is also a resource that can be used to compel streams of such particles to circulate in crossed-field advance paths, and at controlled rates of advance, within a crossed-field fusion reaction chamber, but this resource has not been utilized to its potential in the prior art devices. SUMMARY OF THE INVENTION It is an object of the invention to provide method and apparatus for producing and confining, i.e., keeping together and controlling the location and dimensions of, a stream of fusionable ions and space-charge-neutralizing electrons at ion density and ion kinetic energy adequate to produce a fusion reaction, wherein the stream of ions and electrons is confined within one or more annular chambers having strong magnetic fields imposed thereon, the electric field being essentially at right angles to the direction of the magnetic field, and the magnetic and electric fields and the suitably established electric potentials thereof producing a tightly looping slow forward motion of the stream particles, the tightly looping motions being in planes at right angles to the magnetic field and the slow forward motion being in the direction at right angles to both the magnetic field and the electric field, and the chamber being surrounded by a neutron-absorbing material for utilizing the heat and other energy resulting from the stopping therein of the high kinetic energy neutrons and charged particles resulting from the fusion, and for protecting the current carrying main coil that produces the strong magnetic field from being damaged by passage of such neutrons and charged particles into and through that coil. A further object of the invention is to provide a method for producing and confining a stream of fusible ions of a density and kinetic energy that will produce a nuclear fusion reaction wherein the stream is confined within crossed magnetic and electric fields and the reaction chamber is of an annular configuration and the ions of the stream assume a tightly looping quasi-trochoidal slow forward motion, the forward motion being at right angles to both the electric and the magnetic fields, the stream of ions being introduced into the annular chamber at potentials and with potential gradient corresponding to the potentials and potential gradient of the electric field in the reaction chamber at the location of the stream entry into the chamber, so providing proper initiation of the slow forward motion of the charged particles at right angles to the applied magnetic and electric fields. A further object of the invention is to provide a method for producing and confining a stream of fusible ions and space-charge-neutralizing electrons of a density and ion energy that will produce a nuclear fusion reaction wherein the stream is confined within crossed electric and magnetic fields and the reaction chamber is of an annular configuration and the ions of the stream assume a tightly-looping quasi-trochoidal slow forward motion, the forward motion being at right angles to both the electric and the magnetic fields, the stream of ions and space-charge-neutralizing electrons being introduced into the annular chamber at potentials and with potential gradient corresponding to the potentials and potential gradient of the electric field in the reaction chamber at the location of the stream entry into the chamber, so providing proper initiation of the slow forward motion of the charged particles at right angles to the applied magnetic and electric fields. An additional feature of the invention is to provide apparatus for confining and maintaining a nuclear fusion reaction wherein the confinement of the fusible ions occurs within an annular chamber subjected to crossed electric and magnetic fields, and means are provided for introducing a stream of fusionable ions and space-charge-neutralizing electrons into the chamber at potentials and potential gradient suitably related to the potentials and potential gradient of the chamber location at which the ions and electrons are introduced. A further object of this invention is to provide means for introducing streams of electrons alone, of controlled total charge content, that will circulate in paths at right angles to the applied electric and magnetic fields in the annular reaction chamber, this circulation being parallel to the circulation of the mixed stream of fusible ions and space-charge neutralizing electrons, these streams of electrons alone being located by circumstances of their introduction either essentially adjacent to but outside of the boundaries of the mixed ion and electron stream or at some distance from those boundaries, being between those boundaries and the annular walls of the fusion reaction chamber; such streams will originate at the point of introduction of the mixed ion and electron stream into the reaction chamber, and may be placed to provide such streams on either or both sides of the mixed stream, between the mixed stream and the enclosing electrode walls, details of location to be such as may be found most advantageous; these streams will serve to aid in controlling the potential gradient in the applied electric field direction within the mixed ion and electron stream, thus aiding in governing the rate of crossed-field advance circulation of the mixed stream at right angles to the applied electric and magnetic fields. A further object of the invention is to provide apparatus confining a nuclear fusion reaction wherein an annular chamber is utilized, the chamber being defined by inner and outer tubular electrodes across which the electric field is produced, and the chamber is surrounded by a magnetic field producing electric coil, and material for absorbing neutrons and high kinetic energy charged particles resulting from the fusion reaction circumscribe the chamber inwardly of the magnetic coil structure. Yet another object of the invention is to provide apparatus for confining and controlling a stream of fusible ions and space-charge neutralizing electrons while being transferred to a fusion reaction chamber, or between reaction chambers. Another object of the invention is to provide apparatus for confining and controlling a stream of fusible ions and space-charge neutralizing electrons while being transferred to a fusion reaction chamber, or between reaction chambers, by having the mixed ion and electron streams move at the crossed-field advance velocity along channels in which crossed electric and magnetic fields exist, the cross electric field being produced by a potential difference being maintained between two electrically conducting faces of the channel, with a magnetic field being established at right angles to this electric field and to the direction of advance of the charged particles along the channel. An additional object of the invention is to provide apparatus for confining and controlling a stream of fusible ions and space-charge neutralizing electrons while being transferred to a reaction chamber, or between chambers, by having the mixed ion and electron stream move at the crossed-field advance velocity along channels in which crossed electric and magnetic fields have been established, the cross electric field being maintained between two electrically conducting faces of the channel, with a magnetic field being established at right angles to the electric field and to the direction of advance of the charged particles along the channel, and with "end hat" systems of electrodes at suitable polarities and voltages across the faces of the channel through which the magnetic flux lines pass, one set of electrodes, i.e., rods or wires parallel to one another and at right angles to the applied electric field direction, having suitably determined potentials positive to the nearest stream portion, to repel back into the stream ions whose random motions parallel to magnetic flux lines may tend to make them move out of the channel along the flux lines; the other set of similar electrodes, slightly displaced in the magnetic field direction from the first set being at a suitably determined negative potential to repel electrons whose random motions may make them tend to move out along magnetic flux lines; the set of such electrodes that is nearer to the mixed ion and electron stream is a grid or otherwise penetrable structure to allow the particles not repelled by it to pass on through it to be in turn repelled by the other set of electrodes. Within each of the two sets the potentials of the individual rods or wires are varied from high potential to low potential to make there exist across the end of the channel through which the magnetic flux lines pass a potential gradient corresponding to the potential gradient in the mixed ion and electron stream that is advancing along the channel. A further object of the invention is to provide apparatus for confining and controlling a stream of ions and space-charge neutralizing electrons while being transferred to an annular chamber such as a fusion reaction chamber, or between chambers, by having the mixed ion and electron streams move at the crossed-field advance velocity along channels in which crossed electric and magnetic fields exist, the cross electric field being produced by a potential difference being maintained between two electrically conducting faces of the channel, with a magnetic field being established at right angles to this electric field and to the direction of advance of charged particles along the channel, and including means for maintaining present streams of electrons alone, of controlled total charge content, that advance at the crossed-field advance velocity at right angles to the applied electric and magnetic fields in these channels, this movement being parallel to the movement along the channel of the mixed streams of ions and space-charge neutralizing electrons, these streams of electrons alone being located by circumstances of their introduction either essentially adjacent to but outside of the boundaries of the mixed ion and electron streams, or at some little distance from those boundaries but between them and the electrically conducting faces of the channels; such streams will originate at the point of introduction of the mixed stream into the channel, details of the location between the mixed stream and the wall being such as will be found most advantageous; such streams of electrons alone may be maintained in either or both of the regions between the mixed stream and the two electrically conducting walls of the channel; these streams will serve to aid in controlling the potential gradient in the applied electric field direction within the channel, thus aiding in governing the rate of crossed-field advance of the mixed ion and electron stream along the transfer channel. Yet another object of the invention is to provide apparatus for confining and maintaining a stream of fusible ions and space-charge neutralizing electrons within a pair of annular reaction chambers subjected to strong crossed electric and magnetic fields. The ions and electrons move in a confined tightly looping quasi-trochoidal slow motion at right angles to both fields, with slow travel through the chamber, and upon reaching the end of one of the reaction chambers being transferred to a concentric annular reaction chamber for travel in the opposite axial direction, and upon reaching the end of the second chamber being reintroduced into the first chamber whereby a continuous recirculation of the stream is possible producing a duration of reaction and energy and density of ions to efficiently produce fusion events. A further object of the invention is the inclusion of methods both of continuous operation of the apparatus, that is, steady-state operation over long periods of time, and alternatively of intermittent operation for successive short-duration periods, with waiting or low-level operation periods in between. Reasons for this can include the need for cooling of equipment and for disposition of bursts of rapid releases of fusion energy. Included is the possibility in operation of using short period introduction of specially designed magnetic field configurations, also possible use of a changing magnetic field that will by transformer action generate electron currents in the streams in directions parallel to the main magnetic field, as for example to modify the magnetic field within the reaction regions. In the practice of the invention a fusion reaction chamber is of an annular configuration, with however the two tubular electrodes bounding the annular region not necessarily circular in section, although the shapes of the cross-section of the tubular electrodes must be arcuate without sharp corners, thus possibly being oval or two semi-ovals open into one another beyond the mid-sections of their long dimensions; the length dimension of the tubular electrodes may be linear in form, or may be arcuate. The inner diameter of the chamber is defined by a tubular electrode if the section is circular, and an outer electrode is radially aligned with the inner electrode and in spaced relationship thereto whereby a reaction chamber is defined between the electrodes, and except for the introduction of the stream of charged particles an extremely high vacuum is maintained within the reaction chamber or chambers and within stream transfer channels into and between chambers. A material having a high neutron absorption characteristic, such as gadolinium or lithium or a compound of lithium surrounds the outer electrode, and there are included there circulating means whereby the heat absorbed by the neutron absorbing substance as it absorbs the neutrons and other high kinetic energy particles may be removed for utilization. A coil surrounds the neutron absorbing material in radial alignment with the fusion chamber, and the purpose of the coil is to produce a strong magnetic field throughout the chamber. The inner and outer electrodes are energized with opposite potentials wherein a strong electric field, in addition to the magnetic field, exists within the reaction chamber, and as the fields are at right angles to each other a movement of the stream of fusible ions and electrons occurs in a circumferential direction around the axis common to the two electrodes bounding the reaction chamber; a small circumferential component of the magnetic field, around that axis, is provided as by currents along the electrodes or auxiliary coils; and this causes the motion of advance at right angles to both the electric and magnetic fields to become that of a short pitch helix, so that very slow travel occurs in a direction parallel to the helical axis, that is, the electrode system axis, along the long dimension of the chamber. A stream of fusible ions and negative space charge carrying electron streams, are separately formed exteriorly of the reaction chamber, intermixed, and introduced into the chamber at values of electric potential and potential gradient related to the potential and potential gradient within the chamber at the location of stream introduction; the passage of the mixed stream from the exterior to within the reaction chamber, involving movement of charged particles across magnetic flux lines, is accomplished by channels in which the crossed-field advance is caused by the proper maintaining of crossed electric and magnetic fields within the channels; in this manner confinement and control of the stream is initiated and facilitated. In an embodiment of the invention a pair of concentrically related tubular inner and outer electrodes is utilized defining concentric annular reaction chambers, and at the ends of the chambers crossed-field transfer channels are provided whereby the circulating streams of ions and electrons may be transferred from one chamber to the other as the ends of the channels are engaged by the particles in their travel that occurs slowly in the axial directions of the helical or curved axis helical nature of their circulation in the reaction chambers. The combination of electric potentials and circumferential component of the magnetic field is such that the particle travel movement within the reaction chambers in the axial direction is in the opposite direction within the other chamber such that a continuous recirculation of the ions and electrons may take place. In this embodiment crossed-field transfer channels are provided, with controls as to flow passage in them, for introducing and removing the streams of ions and electrons, thus controlling the duration of confinement for an average number of particles; in this manner the densities and kinetic energies of the ions in the stream may be controlled. Upon removal of a stream or stream portion from the reaction chamber via an exit channel, the kinetic energy remaining in the removed ions is extracted by a combination of means involving putting the energy primarily into the crossed-field advance velocity rather than looping motion, by control of magnitudes of crossed fields, then employing one or another kinds of magnetohydrodynamic means to convert a substantial part of the energy directly into electrical form. Such treatment adds to the efficiency of the total energy conversion, but is not an essential item in my invention. Within ion streams in accord with the invention the directions and magnitudes of the local crossed-field advance velocities of the guiding centers are governed by the total electric field and potential structure. This total field structure exists as the superposition of the local contributions to the field due to the space charge of space-charge waves that will exist in the streams, on the applied electric field as it would be in the absence of space charge, with account taken also of space-charge sheaths that may exist at stream edges either by design of the stream-introduction system or from imbalances in the boundary terminations of the space-charge waves. In assemblies of charged particles nature prefers ordered vibratory systems as compared to non-ordered or random motions; the space-charge waves that comprise the ordered vibratory systems may be expected to consist of ordered and advancing arrays of potential hills and valleys in the streams, due to ordered non-uniform positioning of the ions with their positive charges and electrons with negative charges. These may be very high-potential variations; the crossed-field-advance paths of the guiding centers within the streams will lie along contours of such potential hills and valleys, which may impel the guiding centers back and forth across the stream in directions parallel to the applied electric field, such motion being superimposed on the gross aspect crossed-field advance of the stream as a whole. The kinds of electric-circuit environments envisioned here for crossed-field transport, confinement, and control of fully-ionized gases, and in particular the electrodes that are adjacent to the stream parts of the electric circuit, will not be spatially periodic, and will therefore not support an electromagnetic field coupling between the space-charge waves and the circuit. In the absence of such coupling, space-charge waves terminate at the stream boundaries, as is true for space-charge waves in plasmas and in electron beams similarly not coupled to circuits. Therefore in the regions outside the streams, that is, between the controlled by design stream locations and the electrode surfaces, the effects of the applied electric field can be made to dominate, thus not permitting charge transport to the electrode boundaries. The average potential gradient in a stream can be strongly affected by the presence of net positive or negative layers of charge along the inner and outer stream faces, and by streams of electrons alone, if present, between the stream and the electrodes bounding the annular region in which the stream exists. Such charge layers along the stream surfaces, and streams of electrons, can in principle be established by design arrangements at the points of stream injection into transport or into circulation. In regard to the formation by natural forces of charge layers along the surfaces of the mixed ion and electron streams, my invention envisions the use of streams in which the magnetic flux density is strong enough so that at the ion kinetic energies adequate to produce fusion the diameters of the looping components of the ions' motions are substantially smaller than the electric field direction spacings between the electrodes bounding the annular regions, and in most cases substantially smaller than the extent of the mixed ion and electron stream in the electric-field direction. Now note that with such patterns as to magnitudes, each ion will because of its looping motion spread its electric charge out over a distance at right angles to the magnetic field that is equal to the looping diameter. The similar spread of the charge of the electrons will be very much less, because of the greatly smaller mass and lower average energies of the electrons; at equal energies the diameter-ratio is 60 for a stream having deuterons as the ions. With this difference in extent of the charge content existing, it is evident that if in a stream the ions and electrons are in fact uniformly distributed as to densities, there will appear a positive charge layer at both of the two faces of the stream; it is to be expected that to some degree such charge layers will in fact appear, and will have effects on the potential distribution within the stream, effects which can be accounted for in the design of the stream introduction arrangements. More generally, this inequality between the spatial spread of the charge carried by the ions and that carried by the electrons will affect all details of the relations between charge distribution and particle distribution in the space-charge waves within the stream, and so influence the shapes of the hills and valleys of potential in the space-charge waves, whose presence will influence the average rates of occurrence of elastic collisions between the ions and of collisions resulting in fusion events. Such space-charge waves are essential aspects of "instabilities" that have been the objects of very extensive research and development activities toward employing fully-ionized gases to cause useful controlled nuclear fusion. Various of the resources existing in the state of the art of such research and development can be employed to aid in confining and controlling the streams of my invention, more particularly the sources of arranging the coils to establish useful gradients in the magnetic flux density in the regions where the streams exist. In spite of the underlying basic similarity to Tokomak machines in the suggested use of toroidal geometry the principles of operation are totally different. In particular in my invention the ions are produced and given energy by ion optical means, before mixing with the electrons, so that there is no need for there occurring, as in the Tokomak machine, a strong magnetically generated transient electric field to cause ionization and initiate the enhancement of ion energy. Thus in my apparatus there need not exist at any time electric currents in the streams whose magnetic effects are comparable with those due to the main coils that provide the very strong magnetic field. Thus the spatial gradations that may be needed in the magnetic fields within the annular regions where the streams exist may be caused either by passing currents in the electrodes bounding the annular regions, or by tailoring details of coils subordinate in effects to the main coil. As mentioned earlier, some circumferential component of the magnetic field is necessary to cause the helical or quasi-helical travel of the stream from turn to turn. The poloidal type of magnetic field that results is also advantageous in aiding confinement of the stream to its desired location away from the electrode surfaces. Random motions of the ions in directions parallel to the magnetic field are not generally harmful within the reaction region because such motions merely transfer the shifting ions from one turn of the helical motion to an adjacent one. Within the crossed-field channels used to introduce the stream into the region of strong magnetic field, and at turn-around ends of the helical tavels, it will be necessary to use "end hat" types of electrodes familiar in microwave magnetron design, except that here double end hats are used, to suppress random motions in the direction of the magnetic field that will result from elastic collisions between the ions of the stream. It should be emphasized that because in my invention the kinetic energies needed for fusion are given to the ions before their introduction into the fusion reaction region, and the densities in the streams are governed in combination by the densities in the stream entrance channels and the crossed-field advance velocity in the fusion stream circulation, the designer and operator of the device has at his disposal the determination of both ion kinetic energy and ion density, two of the three major factors in bringing about stream attributes adequate to cause fusion at a useful rate. The third major factor, duraction of the stream under conditions of adequate energy and density, is provided by making it possible, if needed, to have the stream travel over and back many times in adjacent annular chambers. This may not be necessary, but is an available resource. Under the conditions as so stated, it will be possible to have fusion occur at high rates of power production per unit volume in the stream or streams, permitting high rates of power generation in not excessive volumes of the apparatus. One aspect of my invention consists of provisions for using state-of-the-art means for producing ions in substantial amount outside of the region of strong magnetic field, accelerating these ions to high kinetic energies, as for example through 20,000 or more volts of accelerating potential, causing convergence of the several streams and mixing with separately produced electrons for space-charge neutralization, this convergence being produced by using a specially designed configuration of magnetic field of conventional engineering magnitudes, properly coordinated with the accelerating electric field and the electric-field component of the crossed-field channel into which the combined streams of high-kinetic energy ions and low or moderate kinetic energy electrons are introduced, this being the channel via which the mixed ion-and electron stream is passed into the region of strong magnetic field by the crossed-field resource. While in the portion of the crossed-field channel that is outside the region of very strong magnetic field it may be found convenient to have essentially all of the ion kinetic energy in the crossed-field advance motion, with the stream ion-and-electron density being relatively low because of the high crossed-field advance velocity that is possible because of the moderate value of the magnetic flux density. As the stream enters between turns of the main coil into the region of very strong magnetic field the crossed-field-advance velocity becomes immediately relatively slow, with most of the kinetic energy being in tightly looping components of the ion motions, which are, because of the strong magnetic field, small relative to the physical extent of the crossed-field entrance channel in the direction of the electric field. At the same time, because the total rate of particle transfer remains the same as in the outside the coil region, the ion and electron density becomes very much larger in view of the slower advance velocity. The path of the stream-entrance channel within the region of strong magnetic field, through its passage through the neutron-absorbing blanket, is maintained such that the electric field across the channel is always at right angles to the direction of the strong magnetic field; this can be consistent with having its path carry the stream to the required point of release of the stream into the annular fusion reaction region, in the necessary crossed-field direction. The occurrence of fusion events in the part of the channel that lies within the neutron absorbing blanket should probably be avoided, as fusion products released therein could reach the main coil without passage through the entire thickness of the blanket. By controlling the electric cross field within this part of the channel the along-the-channel crossed-field advance velocity can be controlled. Thus an increase of the crossed-field advance, with the total rate of particle passage remaining the same, reduces the particle density, which can in this way be kept below the density needed for significant production of fusion products. An essential aspect of my invention is that the ion and electron stream is carried away from the point of release from the entrance channel at the same rate of particle flow as that of its release from the channel. This is accomplished by having the crossed-field arrangements in the annular reaction chamber carry the entering particles away in the circumferential direction around the interior of the annular reaction chamber. Thus the chamber readily accepts the stream as fast as it enters; of course the density in the stream will be made greater in the reaction chamber than in the entrance channel, by making the crossed-field advance occur more slowly, thus not only increasing the density, but putting more of the energy into the looping components, thus favoring a high collision rate as needed to encourage fusion. In the outside-the-strong-field assembly of the ion source means and the ion accelerating means it is necessary to have the stream of ions at its convergence into the crossed-field channel have its proper potential gradient across the stream, this being necessary to give the appropriate crossed-field advance velocity within the channel. But at the same time all portions of the ion stream must have a common forward kinetic energy, which must be acquired by acceleration through a potential difference that is the same for all parts of the stream, this acceleration occuring in the ion optical system. To have this come about it is necesary that the various portions of the ion sources, or the several sources, from which the stream originates, be at progressively different potentials for the different portions of the stream, in order that after being accelerated through a common amount of potential difference the ions will all have the same forward energy yet enter the crossed-field channel at graded values of electric potential so producing the required potential gradient within the channel. All this is possible within state-of-the-art engineering practices. A basic concept of my invention is that the ion-electron stream is to circulate along helical or quasi-helical paths within the annular fusion reaction chamber, with relatively slow travel in the along the helix axis direction, in order that the ions may remain long enough in the fusion reacting condition to produce substantial fusion energy. However, eventually the ion stream must either be terminated within the region of very strong magnetic field or brought out through an exit channel for termination outside the region of very strong magnetic field. The ions, and to a uncertain degree the electrons, will still have very considerable kinetic energies at the time and place where termination is desired, whether inside or outside the strong-field region. By bringing the stream across flux lines to the region outside the region of very strong magnetic field, via crossed-field exit channels similar to the entrance channels, considerable freedom becomes available as to means for usefully recovering the energy. In this outside region, where the magnetic flux densities will be of conventional magnitudes, a few thousand gauss, in order to maintain the stream within the channel it is necessary for essentially all of the kinetic energy to be in the crossed-field advance velocity along the channel, for in these moderate magnetic flux densities the looping components would have undesirably large diameters if they contained a significant part of the energy. By appropriate use of MHD methods, ("magnetohydrodynamics," using crossed-field technology), it would certainly be possible to extract a large part of this kinetic energy by direct conversion into electrical form. In my invention, in which the looping motion diameter will be small relative to fusion chamber dimensions, only the crossed-field-advance motion as due to all existing field causes, will produce major unwanted flow of particles across magnetic flux lines in the radial direction toward electrodes. To cause such flow across the flux lines of the very strong magnetic field caused by the main coil, flux lines lying parallel to the axis of the cylindrical or toroidal annular regions, an electric field would have to be in the direction of the gross-aspect crossed-field advance, that is, circumferential in the cylindrical embodiment, and circumferential around the short-dimension section in the toroidal embodiment. But such a field cannot be produced by voltages on the electrodes of the structure of my invention; it can only exist because of the presence of space charge within the stream. But space charge does not exist in the region between the stream and the electrode walls in my invention, hence one of the advantages of my invention in controlling the location of the stream. In evaluating any approach to avoiding harmful effects of space-charge waves in tendencies they may have toward causing escape of the charged particles to the enclosing walls of a fusion chamber, it is extremely important to have clearly in mind the fact that with charged-particle densities of the magnitudes needed for controlled fusion in a fully ionized gas under magnetic field containment, being of the order of 10.sup.14 or 10.sup.15 or more ions and electrons per cubic centimeter, an extremely small inequality percentagewise, between densities of ions and electrons will give rise to extremely large electric field strengths. For example, a planar, sinuisoidally-varying space-charge wave having an amplitude of 1000 volts and a wave length of one centimeter has as its space-charge-density amplitude, i.e., greatest value, that caused by an ion-density excess over the electron density, or vice versa, of only about 2.times.10.sup.10 per cubic centimeter. That is, at the maximum space-charge density in such a wave on the positive potential portion, the ion density exceeds the electron density by only 0.01% (one part in 10,000) of a typical fusion device plasma or stream density of 2.times.10.sup.14 per cubic centimeter. For a 10,000-volt space-charge wave of one-centimeter wave length this would change to 0.1% (one part in 1000) of the stream of particle density 2.times.10.sup.14. And this excess would be less for a longer wave length, varying fact inversely as the square of the wave length. Of course such a space-charge wave has a steep potential gradient at its zero potential location, and this potential gradient causes the charged particles to have a crossed-field advance along this zero potential contour of the wave, both kinds of particles moving in the same direction. With a magnetic flux densityof 100,000 gauss, for a 10,000 volt space-charge wave at a wave length of one-half centimeter, this crossed-field advance gives a deuteron an energy due to this advance of 16,500 electron volts, which is in the range of expected ion introduction energies. If as is to be expected, the phase velocity of advance of the space-charge wave is less or greater than the crossed-field advance of the stream as a whole, the particles overtake the wave (or vice versa), thus experiencing alternately down-slopes and up-slopes of the potential hills and valleys, so giving the guiding center short-range to-and-fro crossed-field advance motions alternately toward one and then the other edge of the stream. At stream edges, where hills and valleys end, crossed-field advance motions carry the guiding centers around the ends of th hills and valleys; thus they do not move out into the charge-free spaces toward the chamber walls. The quasi-trochoidal motions of the ions comprise a superposition of small-diameter loopings on the just described oscillations of the guiding centers. The to-and-fro oscillations occur parallel to the advancing contours of the potential hills and valleys, thus being in the cross-stream direction of the applied electric field. This is all in addition to the gross aspect crossed-field advance motion in the prime circumferential direction, carrying the stream along its short-pitch helical travel. The wave lengths of these space-charge waves will not be less than the without-the-wave diameter of the looping motion, because the loops are not likely to reach over the tops of the hills, and this agrees with the observation that the spatial periodicity of the flute instability has a similar limitation. Whatever their average energies, the electrons will move very precisely along contours of these hills and valleys, as their looping motions will be extremely small in diameter. As the ions, at the ends of their cross-direction crossed-field advancing, turn around at the ends of the potential hills at the edges of the stream there will come into play a centrifugal force on them tending to move them out into the region between the stream and the walls of the annular chamber within which the stream circulates. As has been stated earlier, the total paths of the guiding centers can be influenced by centrifugal force effects, and this influence will appear here. In order to prevent this centrifugally caused outward movement from causing a serious tendency for ion escape from the stream, the radial electric field due to the potential applied to the bounding electrodes may be made considerably greater than the electric fields within the space-charge waves. Othewise there might be a "potential trough" extending out into the space-charge free region outside the stream, along whose sides a substantial number of guiding centers might slide toward the enclosure walls. But with adequate domination of these edge-of-the-stream electric fields by the applied fields, the charged particles will not escape to the walls. At the very high ion densities and kinetic energies that will be required to produce in the annular reaction chambers nuclear fusion at a useful rate there will be a great many elastic collisions. Actually, the rate of such collisions should be greater in the presence of the high-energy looping components of the motion than would occur due to ordinarily conceived random motions. The most important collisions will be those between the ions, rather than between ions and electrons or between electrons and electrons. The electron mass is small enough so that at collision with an ion there is very little exchange of energy, and very little transfer of momentum to the ion. However, at ion-with-ion collisions there do occur substantial exchanges of energy and momentum, and alterations in the directions of motion of the colliding particles. In the presence of the strong magnetic fields here envisioned ion-with-ion collisions cannot cause either colliding particle of a collision to take on a continued movement across magnetic flux lines, as would be necessary to result in escape of the ion from the stream. For if as a result of a collision an ion's motion is initially aimed across flux lines, and if it then continues around the tight loop called for by its kinetic energy and the magnetic field, it will move only a very short distance (half the loop diameter) across magnetic flux lines and will then via the looping motion return to a point actually a half-diameter from its collision point in the opposite direction from its initial motion, and eventually return to the collision location position in the magnetic field structure. No net positional change of the guiding center has resulted from the collision. If collisions interfere with progress around the loop, successive segments of loop motions will add up to give statistically the same result as an individual loop, as far as effects on guiding-center motions are concerned .