Synchronous plasma packet accelerator

Charged particles are entrained on a straight or curved path by a traveling magnetic field moving along that path with its magnetic flux vector transverse thereto. The general direction of entrainment is the same for particles of either polarity. The initial relative velocity between the traveling field and the particle drives the latter into motions along a quasi-cycloidal trajectory in the direction of field travel at an average particle speed nearly equal to the field velocity. Streams of charged particles may be accelerated into streams separated from any material objects such as vessel walls, magnetic structures, electrodes, etc. This confinement is achieved predominantly by the balanced interaction of the forces exerted on the particles by the traveling magnetic field and their inertial forces. Auxiliary confining fields may be applied for redirecting to the main stream any particles scattered by secondary effects. The traveling field may be generated by a group of electromagnets, with or without cores, spaced along the path and excited in staggered phase relationship; by an angular offsetting of the polar axes of adjoining electromagnets, the quasi-cycloidal trajectories may be twisted into spacial curves designed to keep the particle stream within preselected boundaries without the need for separate magnetic focussing fields. Periodic reversals of the travel direction of the magnetic field result in reciprocation of the particle streams for inducing collisions between oppositely moving particle streams in adjoining sections.

FIELD OF THE INVENTION 
Our present invention relates to a particle accelerator in which ions and 
electrons forming a plasma are driven along a predetermined path to attain 
a certain speed, e.g. for the purpose of inducing chemical or nuclear 
reactions. 
BACKGROUND OF THE INVENTION 
In conventional systems of the Cyclotron type the particles are accelerated 
in a high-frequency electric field set up between hollow segmental 
electrodes, termed dees, the particles being constrained by a constant 
transverse magnetic field to spiral outwardly in a path centered on the 
field axis. The frequency of the electric driving field, acting 
intermittently upon the particles, must be correlated with their 
mass/charge ratio which therefore must be the same for all particles to be 
accelerated in synchronism. Moreover, the sense of acceleration and 
therefore the direction of motion depends on the polarity of the particle. 
If an attempt were made to accelerate a gaseous plasma in such systems, 
the polarity dependent direction of motion of the particles and the 
diversity of their mass-charge ratios would cause turbulence and untimely 
collisions between particles travelling at different velocities and 
directions; the resulting non-uniformity of particle velocities prevents 
the attainment of controlled conditions for the desired nuclear or 
chemical reactions. 
Similar considerations apply to Betatrons and Tokomak accelerators, in 
which particles of different polarities are driven in opposite directions 
by a stationary magnetic field perpendicular to their orbital plane whose 
intensity increases monotonically during each propulsion cycle. When 
driving a plasma, most of the field energy is transferred to the 
electrons, which causes power losses and excessive turbulence of the 
plasma flow. 
Another conventional way of imparting high kinetic energies to molecular 
particles is by heating a gas to a very high temperature, such as that 
produced by a plasma arc. This method of particle acceleration, however, 
is uneconomical since it produces a wide range of particle energies, not 
confined to the characteristic energy level of a desired reaction, in 
accordance with the Maxwell-Boltzmann law of energy distribution in a 
heated gas. Moreover, the unwanted energy bands may also give rise to 
parasitic side reactions. 
In an application filed on even date herewith by one of us, Thomas I. Ress, 
Ser. No. 418,858 filed 11-26-73 and now U.S. Pat. No. 3,935,503 there has 
been disclosed a system for the synchronous entrainment of charged 
particles (electrons and ions) by a magnetic field revolving with constant 
angular velocity about the axis of a closed vessel of generally 
cylindrical or toroidal configuration, the angular velocity of this field 
so chosen that the particles acquire the desired energy. If the power of 
the magnetic drive field per unit volume exceeds a critical magnitude, 
such rotary accelerator configurations cause, during start-up, many 
particle collisions and rapid ionization of the entire gas volume admitted 
into the vessel, followed by the acceleration of a circular plasma stream 
to an average velocity equal to the velocity of the rotary drive field. An 
auxiliary magnetostatic field aligned with the axis of field rotation 
limits the radially outward excursions of the plasma particles. 
OBJECTS OF THE INVENTION 
The primary object of our present invention is the effective utilization, 
in a particle accelerator, of specific dynamic effects caused by the 
unidirectional entrainment of both positively and negatively charged 
particles of a plasma by a traveling magnetic field. 
A more particular object of our invention is to utilize said entrainment 
method for containing the moving plasma particles within pre-determined 
flow boundaries mainly by the balanced interaction of electro-magnetic 
forces exerted by the traveling magnetic field and inertial reaction 
forces of the driven particles. 
Another object of our invention is to drive the entrained plasma within a 
vessel into rapid reciprocating oscillations based on the energy flow from 
the traveling field during particle acceleration, and the return of their 
kinetic energy during their deceleration to the driving field. This 
resonance phenomenon involving mostly the plasma ions in proportion to 
their mass may be used for prolonging the residency and interaction time 
of plasma particles in the accelerator vessel to increase the rate of 
chemical or nuclear reactions. 
A further object of this invention is to provide two or more or such 
oscillating plasma streams reciprocating in mutually opposite directions, 
for inciting energetic collisions of entrained plasma ions at the 
junctions of said reciprocating plasma streams. 
Another object of our invention is the reduction of lateral expansion of 
the plasma stream during its acceleration by the traveling magnetic field 
as caused by thermal motions of the plasma ions and random collision 
effects. This is achieved by magnetostatic or electrostatic fields of 
relatively small intensities for deflecting any deviating plasma ions 
toward the preselected flow path of the plasma stream. 
Another inportant object of this invention is the generation of a dense 
mono-energetic plasma stream of predominantly laminar flow along a 
preselected open-ended path by injecting the plasma intermittently at the 
start of the open-ended path, and timing the plasma injection in a 
synchronous phase relationship to the traveling magnetic field applied to 
said path. 
A very important object of our invention is the utilization of the very 
large mass flow rates achievable by plasma accelerators according to this 
invention, in which the plasma stream densities are not limited by the 
space charge effects of ion accelerators. These large mass flow rates can 
be applied in certain effective processing configurations for producing 
chemical compounds at fast rates, for the controlled excitation of nuclear 
fusion of hydrogen isotopes as a source of neutrons and thermal power, and 
for generating mechanical reaction forces for the propulsion of space 
vehicles. 
SUMMARY OF THE INVENTION 
Our invention is based upon the realization that the trajectory of a 
charged particle overtaken by a traveling magnetic field of constant 
intensity and velocity, whose vector is perpendicular to its line of 
motion, is a cycloid whose vertices have tangents parallel to this line of 
motion and whose cusps are spaced from these tangents by a distance 2R 
where R is the radius of a circle which the particle describes about the 
central field vector of its zone of entrainment as seen by an observer 
moving with that field vector. As is well known per se, a charged particle 
of mass m and charge g, entering a stationary and constant magnetic field 
of intensity B at a linear speed v perpendicular to the field, is 
deflected into a circular path whose radius R is given by 
EQU R = vm/gB 
where R, v, m, q and B are measured in compatible units (e.g. meters, 
meters per second, kilograms, coulombs and webers per meter.sup.2, 
respectively). If, now, the particle is substantially stationary and a 
magnetic field of intensity B moves past it with velocity v, the foregoing 
formula still applies but the path of the particles as seen from a fixed 
observation point is now a cycloid of pitch 2.pi.R and height 2R. This 
height 2R represents the extent of the lateral excursion of the entrained 
particle, transversely to the line of field motion, and must evidently be 
less than the internal width of the vessel (i.e. its dimension 
perpendicular to the line of motion and to the field vector) if collisions 
between the particle and the wall of the vessel are to be avoided. Since 
the radius R depends (with v and B constant) on the ratio m/q, this width 
must be so chosen as to accommodate those particles whose mass/charge 
ratio is the greatest among those introduced into the vessel for magnetic 
entrainment. 
In the practical realization of our invention as described hereinafter, 
fluctuations of magnetic-field intensity and/or velocity lead to 
deviations of the particle trajectories from an exactly cycloidal shape. 
The actual trajectories, therefore, may be described as quasi-cycloidal. 
If the charged particles are randomly introduced into or generated within 
the accelerator vessel, they will be spread out on both sides of the 
centerline of the vessel so that some of them may start out in a position 
relatively close to the sidewall facing the convex side of their cycloid. 
In order to prevent even particles on the "wrong" side of the centerline 
from striking a sidewall, the distance between that sidewall and the 
centerline should be well in excess of 2R as defined above with reference 
to the particles with widest excursion. 
In principle, a traveling magnetic field adapted to entrain charged 
particles along cycloidal trajectories could be uniform over the entire 
path length; thus, a toroidal vessel might be bracketed between two 
concentric annular pole shoes of a permanent or electrically excited 
constant magnet mechanically rotated at high speed about its axis. Such a 
system, however, is not very practical since for mechanical reasons the 
traveling speed of the magnetic field must be kept rather low. We 
therefore envisage as a preferred solution the generation of a traveling 
field with the aid of a set of electromagnets spaced along the particle 
track and excited in staggered phase relationship by a source of 
high-frequency current. The time-variant magnetic field gradients thus 
generated by the set of electromagnets produce the equivalent effect of a 
moving magnetic field, whose peaks and valleys of field intensity are 
moving along the set of electromagnets in form of a "magnetic wave" in the 
direction of the gradients. 
These electromagnets have cores trained upon the vessel wall, but, for 
closer spacing, could also be designed as overlapping wire coils supported 
on a common ferromagnetic yoke. Such a mode of energization, similar to 
that of the field windings of a polyphase electric motor, enables 
selective reversal of the direction of field travel (and therefore of the 
mean direction of particle motion) by a switching of the phase leads in 
the supply circuit. With rapid switching, advantageously by electronic 
means, the particles may be made to shuttle back and forth along the same 
or complementary quasi-cycloidal trajectories for an indefinite period 
during which their kinetic energy is available for the intended purpose. 
This feature of our invention may be utilized, for example, to promote 
sustained collisions between two groups of particles reciprocating in 
mutually opposite directions in adjoining vessel sections. If the system 
comprises only two magnets alternately excited with unidirectional 
current, or with alternating current in the presence of a biasing field, 
reversal of motion is automatic. 
In accordance with another important feature of our invention, the driving 
electromagnets generating the travelling field may have their polar axes 
-- which are trained upon the centerline of the tubular vessel -- 
angularly offset from one another, the offset between adjoining 
electromagnets being less than 180.degree. so as to vary the spatial 
orientation of the magnetic field vector as it progresses along the track; 
the relative tilting of these polar axes then constrains the particles to 
follow a trajectory that is twisted about the centerline whereby the 
driving field becomes successively effective in different planes to 
control the movement of the particles and to prevent them from straying. 
By this means, the need for an axially oriented magnetostatic focusing 
field -- as disclosed in the concurrently filed Ress application for a 
toroidal vessel -- is obviated while positive omnidirectional guidance for 
and confinement of the particles is achieved even with vessels of linear 
or other noncircular configuration. 
Nevertheless, the provision of such magnetostatic focussing means may be 
beneficial in some instances even in the presence of a helicoidally or 
otherwise twisted trajectory. In the case of a tubular vessel, in 
particular, such focusing means may take the form of a coil wound about 
the vessel and traversed by direct current to set up a steady magnetic 
field in the direction of its centerline. Such a field does, however, have 
a distoring effect upon the cycloidal trajectory of the particles and 
should therefore be limited in its intensity in order to minimize 
turbulence. Focusing fields may also be generated by one or more elongate 
magnetic members flanking the vessel, these members advantageously having 
a permeability of approximately unity so as not to interfere with the 
traveling field. Thus, they may be constituted by coreless flat coils of 
copper or other nonmagnetic conductive wiring; they may also be 
permanently magnetized strips of substantially nonparamagnetic material, 
i.e. material with a permeability near unity. A suitable material of this 
description is a bariumferrite composition marketed under the name INDOX I 
(permeability 1.15) or INDOX VI (permeability 1.06) by Indiana General 
Corporation of Valparaiso, IN. 
The excitation of a set of spaced-apart electromagnets in staggered phase 
relationship produces a magnetic driving field in the form of a traveling 
wave with distinct peaks of alternating magnitude +B and -B. The internal 
width of the vessel will then have to be well in excess of 4R, as defined 
above, in order to accommodate both types of cycloids. According to 
another feature of our invention, however, this width may be reduced by 
energizing the driving electromagnets with a unipolar pulsating current, 
obtained by raw rectification of an alternating current, so that the lines 
of force of all these magnets are codirectionally polarized. Thus, all 
particles with common polarity will follow quasi-cycloidal paths bulging 
in one sense whereas those of the opposite polarity will bulge in the 
other sense; as the particles of the greatest mass/charge ratio are 
usually positive ions, the vessel may be dimensioned to accommodate their 
excursions without much regard to the relatively minor excursions of the 
accompanying electrons. In fact, the electrons will generally be drawn 
away from the adjoining vessel wall by the electrostatic attraction of the 
ion cloud gravitating toward the opposite wall. 
Whether the traveling magnetic field consists of a train of moving 
magnetic-flux waves of alternating or unipolar character, we prefer to 
adapt the physical spacing of the generating electromagnets to the "pitch" 
of the cycloid described by the dominant particles of largest mass/charge 
ratio. Thus since a cycloid of height 2R has a "pitch" equal to 2.pi.R, 
magnets separated by a distance 2.pi.R (with R satisfying the aforestated 
relationship) should be cophasally excited to keep these dominant 
particles in step with the field. This is particularly desirable in very 
dense plasma streams, in which the codirectional entrainment of all 
particles -- regardless of their masses and charges -- is impeded by space 
charges and collisions. With angular offsetting of the electromagnets to 
establish a helicoidal mean path, the pitch of the helix may also be made 
equal to to this distance 2.pi.R. 
If the driving magnets are all excited by alternating instead of 
unidirectional pulsating currents, the intensity of the traveling field 
may be modified by superimposing a codirectional steady but advantageously 
adjustable biasing field upon the moving magnetic vector. This technique 
of field control is available as long as the steady biasing field is of 
sufficient strength to override the opposing polarity of the moving field. 
If the entry of a particle (especially an ion) into the traveling magnetic 
field is timed to coincide with a particular phase of the field, the path 
followed by the particle upon initial acceleration by the magnetic field 
can be predetermined. Thus it becomes possible, pursuant to a further 
feature of our invention, to position successive electromagnets along the 
line of acceleration of the particles by the field of the immediately 
preceding electromagnets for establishing a path which will be 
substantially identical for all simultaneously injected particles of like 
mass/ charge ratio which therefore will follow more or less parallel 
trajectories so as to give rise to an essentially laminar plasma flow. As 
will be shown in detail hereinafter, such a path will have the general 
shape of a half-cycloid if the direction of field travel does not change 
along the track, i.e. if the field gradients move parallel to a fixed line 
which constitutes the base line of the half-cycloid. However, by changing 
the direction of the field gradient between consecutive electromagnets we 
can modify the shape of the trajectory and, in a limiting case, even 
approach a rectilinear path. 
In order to establish the desired direction of field gradient, it is 
advantageous to provide the electromagnets with pole shoes adjoining one 
another along boundaries intersecting the centerline of the vessel which 
preferably is a flattened tube of substantially rectilinear cross-section 
carrying these pole shoes on its major surfaces. With the magnetic field 
substantially uniform on either side of the boundary, the field gradient 
is perpendicular thereto. Near the starting point of the track, these 
boundaries should be generally parallel to the centerline of the vessel in 
order to let the injected particles be accelerated in the proper 
direction. With increasing distance from the starting point, these 
boundaries progressively approach perpendicularly to the centerline with 
resulting reduction of acceleration but continued guidance of the particle 
stream. At the terminal point the cumulative acceleration brings the 
particle velocity to a value of about twice the speed of the traveling 
field. 
This aspect of our invention, which virtually eliminates losses due to ion 
collisions and radiation effects, enables the generation of monoenergetic 
beams powerful enough to initiate nuclear reactions, especially if several 
such beams from a plurality of like accelerators are combined in a common 
reaction vessel. A reactor of this kind may serve as a neutron source and 
may also be used as a generator of thermal power. 
Other uses of a system according to our invention include the stimulation 
of chemical reactions by accelerating at least one of the reactants to 
moderate velocities at which it can be injected into another enclosure 
filled with an unexcited reactant fluid; alternatively, ions of the 
several reactants may be brought into mutual collisions by being 
accelerated in different sections of a common vessel, with the aid of 
separate sets of driving magnets as described above, so as to move in 
opposite directions. As our system affords close control of the ion 
energies, end products of high purity may be obtained without the 
simultaneous generation of unwanted compounds. This includes, for example, 
the selective conversion of atmospheric constituents into nitrogen oxides 
(NO, NO.sub.2), the synthesis of ammonia (NH.sub.3) from its constituents, 
or the conversion of oxygen (O.sub.2) into ozone (O.sub.3); transformation 
of methane (CH.sub.4) or ethane (C.sub.2 H.sub.6) into acetylene (C.sub.2 
H.sub.2) plus hydrogen is also possible. Higher plasma velocities, readily 
realizable with our improved accelerator, make it possible to synthesize 
compounds not obtainable by conventional heating methods. 
A system according to our invention may be also used for ion implantation 
into solid objects for useful and/or ornamental modification of their 
surface characteristics, e.g. hardness, corrosion resistance, or 
electrical conductivity. 
The very large plasma flow rates achievable by accelerators according to 
our invention makes it possible to employ them as reaction motors for 
sustained propulsion and directional control of inter-planetary space 
vehicles. 
In all embodiments of this invention the ions and electrons of a plasma are 
propelled with equal mean velocity along their tracks. As a consequence, 
the energy imparted to the electrons amounts to a negligible fraction of 
the energy transferred to the dominant ions. This characteristic feature 
of our invention is of fundamental importance for nuclear fusion 
reactions, since it greatly reduces the turbulence and radiation losses of 
dense plasma streams of hydrogen isotopes; it is also important for the 
stimulation of chemical reactions by the availability of low-energy 
electrons for the intended reaction.

Reference will first be made to FIGS. 1 and 2 diagrammatically illustrating 
the principles underlying our invention. A traveling magnetic field, 
advancing along a centerline C of a nonillustrated vessel, consists of an 
alternation of north poles N and south poles S of flux density B with 
intervening neutral areas O. For purposes of illustration the boundaries 
between the polar and neutral areas have been sharply drawn, with the 
field strength assumed to be uniform throughout each polar zone; in 
reality, such uniformity may exist only in the transverse dimension 
(perpendicular to line C) with gradual reduction and eventual reversal of 
field strength between zones N and S. 
Let us consider a positive particle P.sub.1 .sup.+, such as a heavy ion of 
large mass/charge ratio, introduced into the vessel in the vicinity of 
centerline C and substantially without motion of its own at the instant 
when the zone N sweeps past it with a velocity v. Since this situation is 
tantamount to an injection of the particle at speed -v into a static 
magnetic field of like intensity, the particle will be deflected into a 
circular orbit of radius R = vm/qB about an axis V.sub.1 ' which is 
parallel to the lines of force and which for purposes of this discussion 
may be considered a field vector. The linear motion of this vector at 
speed v converts this circle into a cycloidal undulation of pitch Z = 
2.pi.R and height 2R as measured between its vertex and a baseline 
interconnecting its cusps. The absolute velocity of the particle in the 
direction of centerline C is zero at the cusps and 2v at the vertex, for 
an average of v over the entire period. 
A similar particle P.sub.2.sup.+, located in the same general area of the 
vessel at the instant when a zone S sweeps by, is deflected onto a 
cycloidal trajectory symmetrical to the one of particle P.sub.1.sup.+. In 
this case, too, the mean particle speed in the direction of line C is that 
of the associated field vector V.sub.2 ', namely v. 
A negatively charged particle P.sub.1.sup.-, such as an electron, entrained 
by zone N is similarly deflected but in the opposite direction with 
reference to particle P.sub.1.sup.+, with a reduced pitch z = 2.pi.r, r 
being the radius of a circle traced by that particle about a field vector 
V.sub.1 ". Another such particle P.sub.2.sup.- swept along by a zone S 
traces a cycloid centered on a field vector V.sub.2 ", this cycloid 
bulging in the same direction as particle P.sub.1.sup.+. The mean velocity 
of these negative particles in the direction of field propagation is also 
v. 
The relative sizes of cycloids for ions and electrons shown in FIG. 1 do 
not represent the true proportions of their orbits, and are intended for 
showing the principle only. The real ratio of cycloid dimensions of the 
lightest ion -- the proton -- to the electron cycloid would be equal to 
the proton-electron mass ratio of 1836 to 1. 
It may be assumed that, at a particular instant represented by the diagram 
of FIG. 1, zones S and N coincide with the locations of respective 
electromagnets energized in phase opposition as more fully described 
hereinafter, with other electromagnets in intermediate phases of 
excitation disposed therebetween. With the field strength at any one of 
these electromagnets varying harmonically between +B and -B, the 
instantaneous field values are sinusoidally related; at the gaps between 
these magnets, however, the stray field generated by the adjoining magnets 
has an amplitude appreciably below that of the sine wave so that the 
traveling polar zones fluctuate in intensity on passing from one magnet to 
the next. It is for this reason that we prefer to make the spacing of 
these magnets equal to an aliquot fraction of the pitch Z of the cycloid 
of the dominant particles P.sup.+ (cf. FIG. 1), thereby insuring that 
each of these particles is subjected to the same acceleration at every 
cusp. The electrons P.sup.-, whose cycloids generally do not span a whole 
number of magnet spacings, are more or less forced to keep pace with the 
large ions by electrostatic attraction. Smaller positive ions in the 
plasma may fall periodically out of step with the field, but since this 
may occur at points where their velocity component in the direction of 
propagation is either smaller or larger than that of the field, the net 
effect may substantially cancel so that their mean speed is approximately 
that of the dominant particles. 
The particle accelerator shown in FIGS. 3 and 4 comprises a toroidal vessel 
100 of refractory material (e.g. quartz) closed against the atmosphere. A 
multiplicity of electromagnets 101 - 116 bracket the vessel 100 at 
locations angularly equispaced along its centerline C. Each of these 
electromagnets, as best illustrated for magnet 103 in FIG. 4, has a core 
117 with pole faces 117', 117" and an exciter winding 118 connected across 
a high-frequency oscillator 119, common to all the electromagnets, by way 
of a phase shifter 120; this phase shifter may be common to several 
electromagnets which are cophasally excited as described below. 
An inlet 121 provided with a stopcock 122 serves to admit electrically 
charged gas (e.g. an ionized reactant entering into the formation of a 
compound) into the vessel 100; an outlet for the reaction products has 
been shown at 123. 
The pole faces 117', 117" have an axis Q which passes through the 
centerline C of the vessel 100 and includes an angle .gamma. with the 
plane P of that centerline which is perpendicular to the axis A of the 
toroid. The angle of inclination varies from one electromagnet to the next 
and changes progressively, by increments of 45.degree., for the 
odd-numbered magnets 101 (.phi. = 0), 103 (.phi. = 45.degree.), 105 (.phi. 
= 90.degree.) . . . as well as for the even-numbered magnets 102 (.phi. = 
270.degree.), 104 (.phi. = 315.degree.), 106 (.phi.= 0) . . . It is seen, 
therefore, that each even-numbered magnet is offset by 90.degree. from the 
preceding odd-numbered one. 
Electrically, the annular array of magnets is divided into four sectors 
S.sub.1, S.sub.2, S.sub.3, S.sub.4 in which the phases of the 
corresponding magnets recur identically except for a reversal of polarity 
between adjoining sectors. Thus, the first two magnets of each sector such 
as 101, 102 or 105, 106 are cophasally excited with a phase shift .phi. = 
0 (sectors S.sub.1, S.sub.3) or .phi. =180.degree. (sectors S.sub.2, 
S.sub.4) with reference to the output of the common current supply 119; 
the phase shifter 120 of FIG. 4 may therefore be omitted in these 
instances, with simple crossing of the wires in the case of the 
even-numbered sectors. The last magnets of each sector such as 103, 104 or 
107, 108 also form a cophasally excited pair, with .phi. = 90.degree. 
(sectors S.sub.1, S.sub.3) or .phi. = 270.degree. (sectors S.sub.2, 
S.sub.4). It should be noted, however, that this simplified relationship 
is not critical and that the phase angle could also vary progressively 
from one electromagnet to the next, exceeding, for example, by 30.degree. 
the phase angles of the immediately preceding magnets. 
The arrangement just described generates, in effect, two interleaved 
magnetic fields transverse to the circular centerline C and traveling 
along that line with a velocity equal to .pi. radians per cycle of the 
polyphase current from source 119 energizing the electromagnets 101 - 116. 
At the same time, on traversing a full circle, the orientation of the 
field vector with reference to the orbital plane P varies progressively, 
in 45.degree. increments, by 360.degree.. 
Except for the negative and positive particles which recombine during the 
time of the movement of the field through 2.pi.radians (two cycles of 
alternating current in the arrangement just described), each particle 
moves a full 360.degree. in the course of every field revolution. 
Cycloidal undulations generally paralleling the centerline C are described 
by each particle, positive and negative, as discussed above. 
If the axes Q of the driving electromagnets were coplanar, e.g. 
perpendicular to the vessel axis A as disclosed in the concurrently filed 
Ress application, focusing means generating a magnetostatic field would 
have to be provided for constraining the movement of the particles so that 
their cycloidally undulating trajectories remain confined to the interior 
of the toroidal vessel 100. This is required because the magnetic driving 
field is unable to counteract drift forces effective in the direction of 
this field. Such drift forces, liable to let the particles collide with 
the walls of the reactor, may be caused by mutual repulsion of individual 
particles, by inertial forces, by the effects of elastic collisions 
between the particles, or by interaction between space charges of groups 
of particles. 
With the array of angularly offset driving magnets shown in FIGS. 3 and 4, 
however, any particle-velocity component directed toward the walls of the 
toroidal vessel 100 in one phase of the travel of that particle is 
transformed into a component parallel to the walls of the vessel in a 
later phase of its travel on account of the fact that the vectors of the 
driving field at that later phase of travel are inclined with reference to 
those previously effective. Thus, the cycloidal undulation of any particle 
is helically twisted about centerline C at the pitch of an imaginary 
helicoidal surface containing the polar axes Q. 
FIG. 5 shows a tubular vessel 200 which differs from vessel 100 by being 
linear rather than toroidal, the associated electromagnet having been 
designated 201 - 216. The mode of operation is the same as for the 
toroidal vessel 100 except, of course, that the particles move only once 
past each electromagnet if the direction of field travel is not changed. 
The inlet and outlet ports for the reactant are shown as the open ends of 
tubular vessel 200. The reactant gas entering the inlet port may be 
ionized by auxiliary ionization means not illustrated in FIG. 5. 
In those applications in which prolonged containment of moving particles 
within the vessel 200 is desired, the phasing of the current feeding the 
electromagnets 201 - 216 may be periodically inverted, by switch means of 
the type shown in FIG. 15, to reverse the directions of travel of the 
magnetic field. Such periodic reversal causes reciprocation of the 
particles along the axis of the vessel 200; naturally, the length of a 
reciprocating cycle should be so chosen that the distance covered by the 
particles is less than the length of the vessel. 
FIG. 6 shows part of the vessel 100 of FIG. 3 with omission of the drive 
magnets 101 - 116 for the sake of clarity. The containment of the charge 
in vessel 100 is aided by the provision of a pair of main direct-current 
coils 124', 124", centered on the toroid axis A (FIG. 3), and two pairs of 
relatively inclined ancillary coils 125', 126' and 125", 126" which 
generate a steady supplemental field in the vicinity of centerline C 
whereby the central field of coils 124', 124" may be reduced in intensity. 
The coils 125', 126' and 125", 126" form a pair of flat, elongate magnetic 
members flanking the vessel 100 and generate relatively inclined fluxes 
inside the vessel. Since these coils do not have any ferromagnetic cores, 
their permeability is the same as that of the surrounding space so as to 
leave unaffected the field generated by the driving magnets. It will be 
evident that similar coils, linear instead of annular, can also be used 
(without coils 124', 124") in a straight-line accelerator of the type 
shown in FIG. 5. In a toroidal vessel equipped with sufficiently strong 
focusing means 125', 126' and 125", 126", the coaxial coils 124', 124" can 
also be omitted. 
In FIG. 7 we have shown an equivalent arrangement in which the flat, 
elongate focusing members are in the form of permanently manetized strips 
with similar relative inclination. These magnets, which in modified form 
could also be used with a linear accelerator, are advantageously made from 
low-permeability material as described above. 
FIG. 8 shows a coil 128, likewise traversed by direct current, enveloping 
the tube 100 in order to help contain the charge thereof. While such an 
enveloping coil would not be practical as a sole containment means, for 
the reasons already pointed out, it may also be used as a supplemental 
focusing element for a linear accelerator of the type shown in FIG. 5. The 
axially oriented coils 124', 124" may again be omitted in some instances. 
The coil 128 need not directly envelop the tube, as shown, but could be 
large enough to surround the driving electromagnets 101 - 116 or 201 - 216 
of FIG. 3 or FIG. 5, or electromagnets 301 - 309 of FIG. 10 described 
hereinafter. 
The focusing assemblies of FIGS. 6 - 8 could also be used in a particle 
accelerator with coplanar polar axes perpendicular to the vessel axis as 
described and claimed in the concurrently filed Ress application. 
FIG. 9 illustrates a linear reaction vessel 200, similar to that of FIG. 5, 
axially divided into four sections along transverse planes X, Y, Z. These 
sections are controlled by respective subsets of drive magnets similar to 
those shown at 201 - 216 and collectively designated 300a, 300b, 300c and 
300d. The outer drive-magnet assemblies 300a and 300d are energized in 
mutual phase opposition from a first oscillator 219', the inner magnet 
assemblies 300b and 300c being also energized in mutual phase opposition 
from a second oscillator 219". The latter oscillator is periodically 
reversible, under the control of an electronic switch 230, whereby the 
charges in the sections controlled by assemblies 300b and 300c can be made 
to shuttle back and forth as indicated by the double-headed arrows. The 
charges in the outer sections of the vessel move toward each other as 
indicated by single-headed arrows. At the junctions X, Y, Z, therefore, 
these charges collide at a predetermined energy level. Such collisions may 
be utilized for nuclear fusion to generate heat which can be carried off 
by a fluid circulating through a heat exchanger (not shown) for 
utilization elsewhere, or the momentum of the colliding particles may be 
so chosen as to initiate a desired chemical reaction. 
If the reactor is employed for nuclear fusion, rarefied deuterium and/or 
tritium is drawn into the right-hand end of tube 200 via an inlet 221, 
having a shut-off valve 222 in series with a throttle valve 231, from a 
reservoir 232 via a vacuum pump 233 connected to an outlet 223 at the 
left-hand end of the tube, this outlet being closable by a valve 236. 
These devices can also be used for handling the reactants and the end 
products of a chemical reaction taking place inside the vessel. 
In FIG. 10 we have shown details of a driving assembly 300 for a linear 
accelerator, this assembly being representative of any of the sections 
300a - 300d of FIG. 9. It comprises a subset of electromagnets 301 - 309 
with angularly offset polar axes, similar to either of the two interleaved 
series of magnets 201, 203, . . . 215 and 202, 204, . . . 216 in FIG. 5. 
Their exciting coils, not shown, are energized from a source of polyphase 
alternating current with staggered phase angles varying monotonically, 
over a pitch length Z, in 45.degree. increments equaling the relative 
offset of their polar axes; thus, magnets 301 and 309 are geometrically 
parallel and cophasally excited to generate codirectional fluxes. 
FIGS. 11 and 12 illustrate a cylindrical vessel 400, coaxially surrounded 
by a biasing coil 424 energized with direct current, in which the 
particles are reciprocatingly entrained along a diametrical line D by a 
pair of coplanar electromagnets 401', 401" whose windings 417', 417" are 
excited from an alternating-current source 419. The two windings are 
energized via respective full-wave rectifiers 440', 440" supplying them 
with raw-rectified currents whose pulsations are in quadrature owing to 
the insertion of a 90.degree. phase shifter 420 between source 419 and 
rectifier 417". A similar effect, but at half the frequency, can be 
obtained without rectifiers and phase shifter by feeding the two windings 
from source 419 in phase opposition and superimposing upon the alternating 
current a direct current of a magnitude equal to the a-c peak amplitude. 
The resulting alternate excitation of magnets 401' and 401" with the same 
polarity has the effect of setting up a traveling field shuttling back and 
forth between their polar axes Q' and Q", with reciprocation of entrained 
particles along symmetrical cycloids. Advantageously, for reasons 
explained above, the separation of the polar axes Q' and Q" equals the 
pitch Z of the cycloid described by the dominant ion. 
A generally similar structure for the acceleration of charged particles 
along a diametrical line D within a cylindrical vessel such as that shown 
at 400 in FIGS. 11 and 12 has been shown in FIGS. 13 and 14. In FIG. 14, 
however, the vessel has been omitted for the sake of clarity. A yoke 501 
of ferromagnetic material, extending in the direction of diameter D, 
brackets a biasing focusing coil 524 coaxially surrounding the vessel and 
is provided with slots 541, 542 along its lower and upper inner surfaces 
confronting the broad sides of the vessel, these slots lying in planes 
perpendicular to the diameter D. The slots are divided into three 
overlapping groups, here of eight slots each, occupied by respective phase 
windings .phi..sub.1, .phi..sub.2 and .phi..sub.3 energized from 
respective phase leads of a nonillustrated three-phase current source. The 
input ends of these windings have been indicated in FIG. 13 at .phi..sub.1 
', .phi..sub.2 ', .phi..sub.3 ' whereas their output ends have been 
designated .phi..sub.1 ", .phi..sub.2 ", .phi..sub.3 ". Each phase winding 
forms several wire loops constituting cophasally and antiphasally excited 
electromagnets; the spacing of the cophasal loops along line D again 
corresponds to the pitch D of the cycloid described by the dominant ion. 
By periodically switching the phases of two of these windings, e.g. 
windings .phi..sub.2 and .phi..sub.3 (cf. FIG. 15), the sense of 
propagation can be reversed so that the entrained particles will be 
reciprocated within the confines of the vessel if the period of thse 
reversals is less than the transit time of the particles along diameter D. 
In a system of the type shown in FIGS. 11 - 14, the energization of d-c 
coil 424 or 524 may be varied (or completely cut off) to modify the effect 
of the traveling field upon the trajectory of the charged particles moving 
in an equatorial plane of vessel 400. In FIGS. 11 and 12, in which the 
traveling field is unipolar, energization of biasing coil 424 in aiding 
relationship with that field increases the effective value of B so as to 
reduce the radius R whereby particles of larger mass/charge ratio can be 
accommodated. In fact, selection of the proper amperage enables precise 
adjustment of the pitch of the cycloid of the dominant ion to correspond 
to the magnet spacing Z. In the system of FIGS. 13 and 14, the static 
field of coil 524 may be made equal to the traveling field B so as to 
suppress the negative magnet poles -B existing between positive poles +B, 
thereby effectively rectifying the magnetic wave; further intensification 
of the static field can then again be used to change the pitch of the 
cycloid and the lateral excursion 2R of the dominant ion. A source of 
adjustable direct current for coil 524 has been illustrated schematically 
as a battery 545 is series with a variable resistor 546. 
Since in the accelerators of FIGS. 11 -14 there is no magnetic force 
restraining the drift of particles in axial direction electrostatic 
repulsion may be used to prevent such drift by particles of a selected 
polarity, i.e. those most essential to the desired reaction. Thus, as 
shown in FIG. 12, the upper and lower end faces (which may be coated both 
internally and externally with thin conductive films) can be connected to 
a voltage source 450, here positive, acting capacitively from the outer 
faces upon the inner faces which thereby acquire a high potential of the 
proper polarity to keep the reactant ions away. 
In FIG. 15 we have shown a set of electromagnets 601A, 601B, 601C whose 
windings 618A, 618B, 618C are energized, with phase differences of 
120.degree., from a three-phase source having phase leads 619x, 619v and 
619z respectively connected to these windings via full-wave rectifiers 
640A, 640B, 640C. A reversing switch 630 is operable, manually or 
automatically, to interchange the connections between windings 601B, 601C 
and phase leads 619v, 619z for reversing the direction of travel of a 
magnetic field along a particle track formed by a vessel 600. This vessel, 
illustrated only in part, is shown to be toroidal but could also be linear 
or of any other configuration. The polar axes of the magnets all lie in a 
plane transverse to the axis of the toroid, as in the concurrently filed 
Ress application, and an axially oriented focusing field may be supplied 
by a coil not shown in this Figure and/or by annular magnetic members of 
the type illustrated in FIGS. 6 and 7. The group of magnets 601A - 601C 
may be duplicated along other sectors of the vessel, with cophasal 
excitation of correspondingly positioned magnets of the several groups; in 
the illustrated switch position, the order of excitation is 601A, 601B, 
601C so that particles are entrained in the direction indicated by the 
arrow. The raw rectification of the phase currents establishes an 
invariable polarity for the pulsating magnetic fields of all magnets, 
their north poles having been shown disposed on the convex side of the 
vessel. Thus, as explained above, the dominant ions will have trajectories 
curving only in one direction (for a given sense of propagation) so that 
the width of the vessel may be less than would be otherwise necessary. 
If desired, the vessels shown in the various Figures may be provided with 
electrodes for ionizing the injected gas molecules as is well known per 
se. In FIGS. 16 and 17 we have shown an accelerator in accordance with our 
invention designed to produce a laminar plasma flow. This accelerator 
comprises a vessel 700 in the shape of a flattened tube of rectilinear 
cross-section curved along a half-cycloid in a plane parallel to its major 
surfaces. These major surfaces are overlain by flat, plate-shaped pole 
shoes 747 of a series of electromagnets 717 provided with energizing 
windings 718. The pole shoes adjoin one another along boundaries 748 which 
lie in mutually parallel planes (vertical in the presentation of FIG. 16); 
these planes include progressively larger angles with the centerline C of 
the vessel 700 with increasing distance from an inlet 721 serving for the 
injection of charged particles into the vessel. In the vicinity of that 
inlet, the planes of boundaries 748 are almost parallel to centerline C so 
that the field gradient thereacross, and hence the direction of field 
travel, is nearly perpendicular to the direction of particle injection; 
this injection is controlled by an electromagnetic valve 749 which is 
periodically opened by a pulse generator 750, in response to signals from 
a programmer 751 which also activates a high-frequency power source 752 
connected to a pair of ionization electrodes 753 embracing the inlet 721. 
Programmer 751 further controls the staggered energization of coils 718 in 
such a way that the magnetic-field vector traverses each boundary 748 at 
the instant when the injected particles cross the plane of that boundary. 
The instant of vector crossover coincides with the disappearance of the 
field gradient across the boundary, occuring thus when the fields on 
opposite sides of the boundary are equal. 
If the particles reached the first boundary proximate to inlet 721) with 
zero velocity (with the instantaneous magnetic field assumed to be 
directed downwardly into the plane of the paper in FIG. 16) the absolute 
speed v.sub.f of the field would deflect the particles upwardly, i.e. on a 
line tangent to centerline C. However, the particles are injected with an 
initial speed v.sub.P so that the relative field velocity v.sub.r includes 
with the direction v.sub.f an angle .delta. causing a corresponding 
inclination of the particle trajectory. The progressive acceleration of 
the particles calls for a corresponding increase in the spacing of the 
boundary intersections with the centerline in the direction away from 
inlet 721. The last boundary, at the vertex of the half-cycloid, is 
substantially perpendicular to the centerline so that the traveling field 
at that point has only a focusing effect. 
If the coils 718 are energized with alternating current, particles are 
injected in a single burst per cycle; with a raw-rectified driving current 
a burst occurs at the beginning of each half-cycle. 
Vessel 700 discharges at an outlet 723 into a reaction chamber 754 which 
the generated plasma stream enters at a velocity equal to twice the speed 
of the traveling magnetic field. 
By diviating from the parallelism of consecutive pole-shoe boundaries, as 
illustrated in FIG. 18, we can modify the trajectory of the particles to 
change their path from a substantially semi-cycloidal one to an 
approximately rectilinear one so that they can pass axially through a 
straight vessel 800 otherwise similar to vessel 700 of FIGS. 16 and 17. 
The first boundary 848 between pole shoes 847, energized in the 
aforedescribed manner by electromagnets 817 with coils 818, is nearly 
parallel to the vessel axis or centerline C whereby the particles, in view 
of their initial injection velocity, move substantially axially toward the 
next boundary. The progressively increasing angle included between 
successive boundaries and the centerline C straightens the trajectory of 
the particles to let them exit at the opposite (right-hand) end of vessel 
800 with a velocity again equaling about double the speed of the traveling 
field. 
It will be evident that other track configurations, intermediate those of 
FIGS. 16 and 18, could be realized with different orientation of the 
pole-shoe boundaries. Moreover, the intensity of the driving field should 
be adjustable for the purpose of accelerating plasmas with dominant ions 
having different mass/charge ratios. Since the transit time of the plasma 
also depends on the mass/charge ratio of the dominant ion, the frequency 
of the driving current should likewise be adjustable. 
The reaction chamber 754 of FIG. 16 may contain a liquid or gas with which 
the charged particles accelerated in vessel 700 (or 800) are to interact; 
these particles could also be trained upon a solid object to modify its 
surface characteristics as discussed above. 
An accelerator of the type shown in FIGS. 16 - 18 may be used, for example, 
to generate deuterium-plasma beams with ion energies exceeding 20,000 
electron-volts. such beams, on impinging upon a cold metal target coated 
with lithium deuteride or lithium tritide, induces nuclear collisions 
which cause neutrons to be emitted from the target at a rate depending 
upon the amplitude of the deuterium-plasma current. controlled neutron 
sources of this kind are useful in neutron radiography and for the 
conversion of stable elements into radioactive isotopes. 
In FIGS. 19 and 20 we have illustrated another aspect of our invention, 
i.e. a reactor for the excitation of large-scale nuclear fusion as a 
source of thermal power. This system comprises an annular vessel 960 
forming a closed loop for the circulation of charged particles produced at 
peripherally spaced locations by four branch channels 961, 962, 963, 964 
each similar to the half-cycloidal accelerator of FIG. 16. (In 
contradistinction to the schematic showing of vessel 700, these branch 
channels are shown to converge from their input ends to their output ends, 
which affords more room to accommodate the nonillustrated driving 
magnets.) The charged particles injected by these branch channels into 
vessel 960 circulate therein under the control of a magnetostatic field 
parallel to the vessel axis, this field being generated by a peripheral 
array of permanent magnets 965 which are bracketed by annular pole pieces 
966 and 967. The intensity of this magnetostatic field is so chosen that 
the particles, at their laminar flow velocities, do not strike the walls 
of their circular track. 
One or more ancillary inlets 968 (only one shown) serve for the admission 
of small amounts of gas whose molecules collide with the circulating 
high-energy particles to relese neutrons and to generate heat. The heat is 
carried off by a cooling fluid in a conduit system 969 passing through the 
walls or reactor vessel 960 and is transferred in a heat exchanger 970 to 
a secondary coolant circuit 971 for delivery to a load 972, e.g. to a 
generator of steam or electric power. The use of heat exchanger 970 
isolates the load against radioactive contamination as is well known per 
se. 
In a specific instance, the plasma beams introduced into reactor vessel 960 
via branch channels 961 - 964 contain a large concentration of deuterium 
ions accelerated to 40,000 electron-volts at the point of their tangential 
entry into the circular storage loop. In order to achieve a flow density 
in vessel 960 substantially exceeding that of its feeder streams, the 
accelerators 961 - 964 are simultaneously operated at full power to 
injection of additional deuterium via inlet 968. Following the initiation 
of nuclear fusion, the plasma flow in the accelerators 961 - 964 is 
reduced to a sustaining level designed to compensate for the relatively 
small radiation and turbulence losses of the nearly laminar flow in vessel 
960 and for the acceleration and ionization energy consumed by the 
relatively minor quantities of cold deuterium gas fed in at 968. 
The boundaries 748, 846 in FIGS. 16 - 18 may be formed by small airgaps or 
by strips of nonmagnetic material inserted between the pole shoes.