Annular plasma injector

This disclosure relates to a plasma generation device particularly adapted to an electrothermal-chemical propulsion system. The device comprises a membranous conductive substance having structural compositions which enable the formation of a continuous and volumetrically distributed plasma arc. The membranous substance is versatile and operates, inter alia, as a fuse wire, plasma incubator, plasma container, plasma distributor, plasma infusion and permeation media as well as a fuel container.

FIELD OF THE INVENTION 
The present invention relates to annular and cylindrical plasma injector 
device which in cooperation with a membranous element provides stable 
discrete and continuous plasma arcs in a current path to enable 
equilibrated distributions, infusion and permeation of the plasma into a 
combustible mass. 
SUMMARY OF THE INVENTION 
The annular and cylindrical plasma injector device of the present invention 
enables the creation of an equilibrated non-shorting distribution, 
infusion and permeation of plasma throughout the extent of a combustible 
mass. Heretofore, plasma distributions into a combustible mass, 
particularly in applications where the plasma is generated across a fuse 
wire between an anode and cathode terminals, have experienced shorting of 
the plasma due to ionic plasma arc flowing via the ground return from the 
terminal. Consequently, the plasma arc is discharged into the combustible 
mass pre-maturely and is readily extinguished because of quenching and or 
uncontrolled combustion. The present invention overcomes these problems 
and provides a reliable and consistent plasma arc and distribution, 
infusion and permeation of same into a contiguous combustible mass. 
More particularly, the membranous element enables the formation of annular 
and or cylindrical plasma which could be permeatively distributed and 
infused inwardly, outwardly or delivered into a desired location 
irrespective of the geometric shape, position and orientation of the 
combustible mass. Further, the membranous element proffers significant 
advances, inter alia, in that it acts as a fuel containment medium, a fuse 
wire and annular or cylindrical plasma arc source. Several embodiments of 
the membranous element may be used depending upon the contemplated 
application and desired results. The annular and cylindrical plasma 
injector device disclosed herein provides distinguished advances over 
prior practice. Included in these advances are enablement of reliable 
formation and delivery of plasma as well as enabling to strike a 
consistent arc across a slender capillary span thereby increasing plasma 
reach and surface area coverage within a containment cartridge. Further, 
because the need for an intermediate plasma distribution structure, such 
as a perforated tube, is eliminated significant weight and volume savings 
are realized over the prior art. 
Specific advances, features and advantages of the present invention will 
become apparent upon examination of the following description and drawings 
dealing with several specific embodiments thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The annular and cylindrical plasma injector device of the present invention 
provides an efficient and directable distribution, infusion and permeation 
of high energy plasma into a combustible mass. Specifically, the present 
invention provides annular and or cylindrical plasma formation, incubation 
and permeative injection devices which can be integrated with a 
combustible mass container cartridge and a projectile, comprising a round. 
The embodiment of the present invention is supplied with each round of an 
electrothermal-chemical gun system and is generally spent with each 
firing. The present invention provides a significant advance in the art 
and is distinguished from earlier systems in that it enables the creation 
of annularly or cylindrically arranged continuous plasma arcs in 
cooperation with a membranous element which serves as a fuel storage, a 
fuse and a plasma distribution, infusion and permeative media. 
Accordingly, as will be discussed herein below, the annular or cylindrical 
geometry of the membranous element provides a large surface area for 
plasma discharge, distribution, infusion and permeation while eliminating 
plasma arc instabilities and shorting. 
An embodiment of the annular plasma injector device is shown in FIG. 1. 
Cartridge housing 10, comprising a stub case 12 and insulator 14 
(polyethylene, polyurethane or equivalent), is integrally attached to 
projectile 16. Power supply 24 is disposed at the center of rim insulator 
14 and is isolated by insulation means from power supply 24 and is 
connected to power rod 28 and anode 30. Annular capillary 32 forms an 
annular enclosure around cathode 26, power rod 28 and anode 30. Annular 
capillary 32 comprises membranous element 38 and internal dielectric liner 
43. Annular capillary 32 is attached to cathode 26 at stub case 12 and 
cantilevers out into combustible mass 42 which is contained in cartridge 
housing 10. As indicated hereinabove, the central core of annular 
capillary 32 comprises power rod 28. Insulator sheath 43 separates annular 
capillary 32 and power rod 28. Cathode 26 is connected to anode 30 via 
membranous element 38. Further, annular capillary 32 is internally and 
externally covered with insulator sheath 43 and 44, respectively. FIG. 1A 
depicts capillary 32 having a tapered membranous element 38a, an example 
of an alternate structure. In the interest of simplicity cartridge housing 
10 is not shown. 
FIG. 1B is a detail section of annular capillary 32 where intermediate 
electrode 46 is shown. As will be discussed hereinbelow, one or more of 
this type electrodes can be used to effect segmentation of arcs and 
creation of serial arcs within a cartridge. 
Turning now to FIG. 2, a detail segment of membranous element 38 is shown 
wherein a foam like structure, and in the alternate a foil, comprise the 
structure of element 38. Further, the assembly is shown disposed in a gun 
chamber 52 with projectile 16 situated in gun tube 54. Membranous element 
38 or foil membrane 70 shown in FIG. 2A form an outer annulus situated 
between cartridge 10 and combustible mass 42. This is a typical embodiment 
in which membranous element 38 is structured to serve as a fuse wire as 
well as a container for combustible mass. Isolation sheaths 43 and 44 are 
used to separate membranous element 38 from combustible mass 42 and case 
of cartridge 10 respectively. FIG. 2A shows foil membrane 70 replacing 
element 38. Foil 70 may be preferred in some applications where 
combustible mass 42 needs to be contained in a non-porous media or the 
vaporization rate of the membrane needs to be slower. Further, the 
structure enables an increase in surface area of plasma/propellant 
interface while promoting a significant intrusion of projectile 16 into 
cartridge 10. 
Considering now FIG. 3, another embodiment of the plasma injector is 
depicted with chamber 52 comprising a number of unicharge modules in 
chambers 56 which enable artillery velocity zoning. The assembly is shown 
in a gun chamber 52 with projectile 16 situated in gun tube 54. A power 
rod 28 extends to the base of the modules making contact with cylindrical 
membranous element 38 which is segmentally structured enabling a modular 
assembly capable of velocity zoning by varying charge mass and electric 
energy throughout the length or partial length of chamber 52. Each 
compartment section in charge modules 56 may contain varying composition, 
architecture and structure of charges and dividers 72 act as separators 
between the modules. 
FIGS. 4A, 4B and 4C are graphical representations of operational and 
performance data obtained using an open air test fixture wherein, the 
performance of annular or cylindrical membranous elements 38 or 38a are 
tested and the results compared with that for a fuse wire. The open air 
test fixture (not shown) allows testing of plasma injection systems under 
atmospheric conditions to evaluate electrical stability and plasma 
distribution patterns. The sets of graphs are discussed hereinbelow to 
clearly identify some of the distinguishing performance and operational 
parameters of the present invention. 
The disclosure hereinabove relates to some of the most prominent structural 
features of the present invention. The operation and the cooperative 
aspects of the structures, under a best mode scenario, is described herein 
below. 
Referring to FIG. 1, sufficient power is supplied from a high energy pulse 
forming network or equivalent power supply source (not shown) and 
connected to the annular or cylindrical plasma injection device at power 
supply connection 24. Current flows to anode 30 via isolated power rod 28. 
From here the current flows to cathode 26 via membranous element 38. 
Accordingly, element 38 serves as an initial current path bridging cathode 
26 and anode 30. One of the unique structural organizations of the present 
invention includes directing current to a remote anode 30 and returning 
the current to cathode 26 such that prior art limitations such as short 
circuiting which occur due to plasma flow past a conductive outer 
structure, for example a perforated tube, are eliminated. More 
particularly, by positioning anode 30 axially forward in combustible mass 
42 with cathode 26 back near stub case 12, the requirement for a grounded 
cathode current return path is eliminated. Accordingly, this structure 
attenuates shorting through the cathode return and eliminates the problem 
of shorting which has hitherto made electrothermal-chemical cartridges 
susceptible to failure and malfunction. The current is grounded at ground 
66 via stub case 12. When the current path is sufficiently established, 
membranous element 38 vaporizes allowing sufficient gas conductivity to 
establish a plasma between anode 30 and cathode 26, annularly about power 
rod 28. Insulator sheaths 43 and 44 are consumed thereby providing 
additional fuel for the plasma. Further, the consumption of sheath 44 
allows plasma to interact with the surrounding combustible mass 42. 
Although a small portion of insulator sheath 43 may be eroded, generally, 
power rod 28 and its insulation (sheath 43) remain intact. Thus, annular 
plasma arc develops across the extent of annular capillary 32. 
Particularly, membranous element 38 provides a significant advance in that 
it performs multi-functions. Primarily, element 38 acts as a fuse wire and 
is a current path as discussed hereinabove. In the preferred embodiment, 
membranous element 38 is made of a conductive element such as aluminum 
comprising spatially distributed random size pores interconnectively 
layered forming a foam-like woolly tubular structure. In some applications 
the size and orientation of the pores is decidedly uniform and 
symmetrical. This structure enables the formation of a transparent 
configuration with a loose open weave having an intertwined mesh 
construction with an inner and outer surface defining a layer. The ullage 
volume contained in the layer of element 38 enables a plasma expansion 
space. When element 38 vaporizes an annular plasma ring is formed 
extending through the length between anode 30 and cathode 26. Further, 
element 38 provides a containment region for plasma to be formed. Thus, 
the matted-type woolly labyrinthine foam structure having random or 
uniform size pores and orientation extending throughout the tubular layers 
of element 38, enables a continuous and volumetrically distributed 
formation of annular plasma. The resulting plasma is stable and yields a 
higher power profile than that of a typical solid fuse wire (see FIGS. 4A, 
4B and 4C). Moreover, the random size/uniform size interconnected, 
internetted pores extending throughout the annularly homogenous foam 
layers of element 38 act as plasma distribution outlets through which 
plasma is discharged into the contiguous combustible mass 42. The ullage 
volume, inherent in element 38, may be used to store an energetic fluid to 
create a fuel-impregnated, more volatile plasma front for distribution. 
Accordingly, element 38 and the unique porous structure defining capillary 
32 provides a gauze-like fibrous tube comprising layers with a 
predetermined volumetric capacity and performs as a fuse wire, annular 
plasma incubator, a plasma container, a plasma distributor, plasma 
infusion and permeation media as well as a fuel containment chamber. 
In reference to FIG. 1, power supply connection 24 protrudes into stub case 
12 forming an extended tip therein. Stub case 12 is isolated from power 
rod 28 which supports and connects with anode 30. As indicated 
hereinabove, element 38 connects anode 30 with Cathode 26. Cathode 26 is 
annularly disposed and coaxial with and isolated from power rod 28. Stub 
case 12 is isolated from power rod 28 and provides a ground contact with 
cathode 26. Further dielectric liners 43 isolate power rod 28 from the 
internal surface of element 38. Similarly, insulator sheath 44 separates 
membranous element 38 from combustible mass 42. As stated hereinabove, in 
some applications, voids and cavities of labyrinthine membranous element 
38 can be filled with a combustible fuel or fuel/ oxidizer combination. 
This arrangement utilizes the ullage volume of element 38 and provides an 
initial combustion chamber which promotes a rapid distribution and 
infusion of plasma-impregnated burning fuel into combustible mass 42. 
FIG. 1A depicts an exemplary arrangement in which capillary 32 comprising 
membranous element 38a is tapered. The arrangement of FIG. 1A may be 
preferred in cartridges where the composition, architecture and density of 
combustible mass 42 (See FIG. 1) vary. More particularly, the tapered 
structure of membranous element 38a provides a varying spacial and 
temporal plasma discharge throughout the volumetric extent of annular 
capillary 32 thus enabling a plasma infusion and permeation rate which 
translates into controllable and efficient combustion. It should be noted 
that other shapes and configurations can be used depending upon the 
geometry and orientation of combustible mass 42 and the need to distribute 
plasma in a pre-determined direction and rate. 
Similarly, FIG. 1B shows an exemplary variation of capillary 32. The 
distinguishing feature of this structure includes an intermediate anode 
46. In very slender cartridges, where very long plasma discharge lengths 
are needed, this approach is preferred to create segmented serial annular 
arcs. Segmented serial annular arcs have proven to be more stable and 
provide manageable sets of discreet plasma arcs. In this particular 
application, the location of intermediate electrode 46 may be varied to 
provide plasma arc segments having varying length. Alternately, several 
intermediate electrodes 46 can be used to create a number of segmented 
plasma arc regions throughout combustible mass 42. This arrangement 
enables to maintain varying levels of plasma segments throughout the 
length of capillary 32. Particularly, membranous element 38 can be filled 
with fuel or oxidant having varying quantities and types of fuels in every 
segment as defined by intermediate electrodes 46. As noted hereinabove, 
each segment can be varied by varying the distance between intermediate 
electrodes 467. This feature enables to introduce a tailored amount of 
plasma into a combustible mass having variable volumes, chemical 
composition or architecture. Thus, intermediate electrode 46 and the 
associated structures of the present invention can be arranged to effect 
and accommodate variable plasma distribution and combustion rate 
requirements at different segments of a cartridge. 
FIGS. 2 and 2A depict a specialized embodiment of the present invention 
showing the versatility of membranous element 38 and foil membrane 70. 
Primarily, membranous element 38 contains combustible mass 42 forming an 
outer annulus. In the alternate, foil membrane 70 is used as a container. 
In this arrangement, membranous element 38 or foil membrane 70 make up the 
innermost layer of cartridge 10 with a non-conductive layer between them. 
Thus, in addition to being a fuse wire, plasma container, plasma arc 
generator and fuel container membranous element can be used to house 
combustible mass 42. Power is supplied at power supply 24 which is 
connected to anode 30. Membranous element 38 or foil 70 is annularly 
connected to anode 30. On the farther end, cathode 26 is annularly 
connected to element 38 or foil 70. Evidently, the embodiment provides a 
compact and structurally efficient cartridge system. The structure 
provides simplicity in manufacturing while maintaining the advantages of 
multi-functionality proffered by membranous element 38. Further, this 
geometry allows for significant projectile intrusion into the cartridge 
case. Furthermore, the structure provides a maximum interaction surface 
area between combustible mass 42 and membranous element 38 or foil 70. 
When sufficient power is supplied, membranous element 38 or foil 70 heat 
up and vaporize to form annular plasma surrounding combustible mass 42. 
Consequently, plasma implosively infuses and permeates combustible mass 42 
thereby promoting efficient combustion to produce the requisite pressure 
and temperature to accelerate projectile 16. 
FIG. 3 shows another embodiment of the present invention. A series of 
uni-charge modules 56 of individual charge are shown within a slender 
artillery chamber wall 52. A segmented membranous element 38 extends 
across charge modules 56. Each module chamber 56 is a discreet package 
containing propellant mass and membranous element 38 isolated from the 
others by means of dielectric dividers 72. When the high energy current is 
supplied via power supply connection 24, membranous element 38 starts to 
heat up in each of charge modules 56. Eventually, membranous element 38 
vaporizes allowing formation of a plasma which spans the filled length of 
the chamber 52. The plasma consumes sheath liner 44 and invades 
combustible mass 42 contained in each module chamber 56. Dividers 72 act 
as temporary separators preventing plasma from shorting to chamber wall 
52, and are later consumed during the combustion cycle. The process 
enables a near instantaneous development of a balanced combustion pressure 
and temperature throughout chamber wall 52. Thus, modules can be assembled 
extending from one to complete chamber length thereby enabling velocity 
zoning. 
FIGS. 4A, 4B, 4C are graphical data for the results of an open air test 
using an Aluminum fuse wire, membranous aluminum cylindrical rod and 
membranous aluminum annular rod, respectively. The test results of FIGS. 
4A, 4B, 4C are obtained by applying high energy current via power supply 
connection 24. Primarily, the test is focused on measuring current and 
voltage thereby determining power and resistance. These parameters are 
determinative of performance for a plasma generation system. Typical open 
air test data for power in Mega Watts (MW) and Resistance in milli-Ohms 
(mOHM) against time in milli seconds (ms) are shown in FIGS. 4A, 4B, 4C. 
From these relations it can be observed that aluminum fuse wire (see FIG. 
4A) experiences a power spike at about 0.4 milli seconds, the power 
reaches its highest peak and drops off rapidly after 2.0 milli seconds. 
Thereafter, the power decreases gradually and diminishes to zero at about 
8 milli seconds. Generally, a power spike of this type imparts shock to 
the propellant and is undesirable. The resistance readings vary with time 
as well. Initially, after about 0.2 milli seconds a resistance spike 
develops showing that the initial flow of current through the fuse to be 
rather low. However, after about 0.3 milli seconds, the resistance starts 
to drop off quickly. Further, after about 8 milli seconds, the resistance 
increases rapidly and subsequently becomes erratic showing instability and 
deterioration of the arc which eventually leads to plasma arc 
extinguishment. In comparison, FIG. 4B shows resistance and power readings 
taken for membranous aluminum cylindrical rod. At about 0.05 milli 
seconds, the power reaches its highest peak and drops off rapidly until 
0.2 milli seconds. Thereafter, the power increases gradually to about 0.8 
milli seconds. The power then decreases gradually to zero at about 5.5 
mill seconds. The resistance readings vary with time as well. Initially, 
at about 0.05 milli seconds the resistance increases rapidly. The 
resistance then falls off and exhibits a near constant reading from about 
0.2 milli seconds to about 5 milli seconds. Similarly, readings for the 
power show a substantial rise in power at about 0.01 milli seconds 
followed by a drop at about 0.2 milli seconds. Thereafter, the power rises 
gradually to about 2.00 milli seconds to be followed by a gradual decent 
to zero at about 5.5 milli seconds. A comparison of the resistance and 
power curves of FIG. 4B with that of FIG. 4A confirms that the cylindrical 
membranous fuse provides significant advances and advantages over a 
standard fuse wire. First, the resistance spike in the fuse wire (see FIG. 
4A) is comparatively high. This translates into high voltage and power 
spikes. Power spikes impart shock to the propellant and or combustible 
mass. Such shocks inhibit efficient combustion and therefore limit the 
development of constant pressure in the gun chamber. Consequently, the 
performance of the electrothermal- chemical gun system is severely 
curtailed. Second, as indicated hereinabove, a power spike develops in the 
case of the fuse wire (see FIG. A) and the curve shows a quick rise and 
fall thus yielding a small area under the curve. The power curve for the 
cylindrical membranous element exhibits a comparatively low spike and a 
curve profile having a gradual rise and fall, thus providing a large area 
under the curve. 
Referring now to FIG. 4C, which shows resistance and power readings for 
membranous annular rod, the resistance readings show a subdued spike at 
0.5 milli seconds. The readings fall immediately after 0.5 milli seconds 
and indicate a progressive increment thereafter showing a generally smooth 
increase in the resistance. This results in higher average power yield. As 
can be seen from the power graph, the power spike is much lower and the 
curve shows a smooth transition between the rise at 0.4 milli seconds and 
the gradual fall thereafter. 
Accordingly, from these comparative graphs it can be shown that the 
membranous annular rod yields the highest power output for a given 
electrical energy input. Further, the membranous cylindrical rod yields 
the second highest power output with a typical fuse wire yielding the 
lowest power output. It should be noted that the open air test data was 
obtained for all three types of fuses under similar conditions. A general 
conclusion to be inferred from the open air test is that the membranous 
element, which is one of the significant aspects of the present invention, 
enables the annular plasma injection device to be electrically efficient 
and imparts less shock to the propellant or combustible mass. Further, 
because of a lower voltage spike than the fuse wire, the chances for 
dielectric breakdown are minimized thus eliminating short circuiting 
problems. 
Thus, the annular plasma injector device disclosed herein enables formation 
and distribution of a confinable annular plasma arc chain to promote 
efficient burning of a combustible mass to thereby yield high muzzle 
velocity. Heretofore, plasma injection systems use exploding wires and 
electrodes to create a generally linear plasma arc source. Further, prior 
art distribution devices include perforated tube or equivalent devices 
which discharge plasma radially or in a vectored manner into a propellant 
or combustible mass chamber. The transfer of plasma for distribution from 
a fuse wire to a capillary by means of a perforated tube or an equivalent 
means resulted in the development of large resistance spikes as well as 
electrically unstable plasma thus posing insurmountable operability and 
reliability problems in the prior art practice. More importantly, a 
centrally located plasma generated from exploding fuse wires randomly 
attaches to the ground return through the distribution capillary, such as 
a grounded perforated tube, and creates a short which results in 
unpredictable ignition, poor power transfer and potentially uncontrollable 
detonation. The annular plasma injector disclosed herein enables a 
reliable formation, incubation and containment of plasma, as well as 
distribution, infusion and permeation of plasma into a combustible mass 
while overcoming all the limitations and problems encountered in the prior 
art. Particularly, the present invention provides a significant advance in 
the art by utilizing capillary 32 as a plasma source disposed proximate to 
combustible mass 42. This eliminates the need for intermediate members, 
such as a perforated tube, to transfer and distribute plasma from a 
discharge source. As discussed hereinabove, plasma is directly infused and 
permeated into combustible mass 42 from membranous element 38. Moreover 
unlike perforated tubes, annular capillary 32 consumably ablates with the 
added advantage of eliminating the likelihood of plasma attaching to the 
ground and short circuiting the electrothermal chemical combustion. 
Further, unlike fuse wires, the present invention provides a large surface 
area for plasma distribution and direct infusion of same into a contiguous 
combustible mass. More particularly, as discussed hereinabove with 
reference to FIGS. 2 and 2A, membranous element 38 or foil member 70 may 
be used to contain fuel to enhance plasma effects on combustible mass 42 
or provide for fuel/oxidizer stratification. Additionally, by 
strategically placing intermediate electrodes 46 (See FIG. 1B), the 
present invention enables the creation of serially segmented plasma arcs 
to allow differentiated ignition and combustion patterns. In another 
embodiment, discrete charge modules incorporate a consumbable plasma 
generating device. The charge modules are connected along a chamber length 
to allow for velocity zoning. 
As indicated in the best mode embodiments disclosed hereinabove, annular 
plasma formation, incubation, segmentation, distribution, infusion and 
permeation is effectuated by the elements and cooperation thereof of this 
invention. Particularly, membranous element 38 with a labyrinthine, 
woolly, foam-like, gauzy and annularly layered capillary and or 
cylindrical formed rod provides a significant advance over the prior 
practice. Element 38 with its randomly and or uniformly oriented cavities 
and pores contains an ullage volume in which, as discussed hereinabove, 
fluid or fuel may be stored to impregnate the plasma with a 
preconditioning fluid, such as a HAN (HydroxylAmmoniumNitrite). In the 
alternate, a foil membrane may be used to provide the advantages noted 
hereinabove. 
While a preferred embodiment of the annular plasma injection device has 
been shown and described, it will be appreciated that various changes and 
modifications may be made therein without departing from the spirit of the 
invention as defined by the scope of the appended claims.