Abstract:
A plasma generation process that is more optimized for vapor deposition processes in general, and particularly for directed vapor deposition processing. The features of such an approach enables a robust and reliable coaxial plasma capability in which the plasma jet is coaxial with the vapor plume, rather than the orthogonal configuration creating the previous disadvantages. In this way, the previous deformation of the vapor gas jet by the work gas stream of the hollow cathode pipe can be avoided and the carrier gas consumption needed for shaping the vapor plume can be significantly decreased.

Description:
RELATED APPLICATIONS 
     This application is a national stage filing of International Application No. PCT/US2010/025259, filed Feb. 24, 2010, which claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/154,890, filed Feb. 24, 2009, entitled “Coaxial Hollow Cathode Plasma Assisted Directed Vapor Deposition and Related Method Thereof and U.S. Provisional Application Ser. No. 61/248,082, filed Oct. 2, 2009, entitled “Coaxial Hollow Cathode Plasma Assisted Directed Vapor Deposition and Related Method Thereof” the disclosures of which are hereby incorporated by reference herein in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Coatings applied by physical vapor deposition (PVD) processes—typically performed in a vacuum—are widely used in various applications such as in creating barrier layers for packaging films, metalizing plastics for flexible electronics and EMI shielding purposes, depositing scratch-proof, corrosion protection or decorative layers on various raw materials, or for controlling the electrical, optical and tribological properties of components, tools and machine parts. Usually, different techniques may be capable of depositing the desired layers, but business economics favor processes which create the coatings quickly and efficiently. This means, the process must be able to generate large amounts of vapor rapidly, and to transport and deposit it to the substrate with low losses and at the right atomic scale structures needed for the given application. 
     Electron beams are established as a known tool for evaporating materials at highly achievable rates. For coating of large-area substrates, like plastic or metal films and sheets, extended evaporators heated by scanned high-power electron beams are available. It is well known that deposition rates ranging up to 10 μm/s can be achieved with this technology, i.e. the rates are several orders of magnitude higher than with sputter technology. Without applying additional aids, however, the layers grown at high rates are usually of poor quality. 
     Another drawback of conventional thermal evaporators—the fairly low utilization of the evaporant material when coating smaller substrates such as tools, engine parts or fibers—stems from the inherently divergent propagation characteristic of the vapor particles. 
     To address these issues, the development of a new coating technology, which is now called “Directed Vapor Deposition” (DVD) was started several years ago. The basic idea of the DVD concept is to evaporate the coating material by an electron beam and then to capture, transport and focus the vapor particles by a flowing carrier gas stream. This approach, fully described and disclosed in the U.S. Pat. No. 5,534,314 (of which is hereby incorporated by reference), combines the advantages of conventional EB evaporation (high vaporization rate, clean and uncontaminated material evaporation, easy alloy deposition by co-evaporation of the pure constituents from individual crucibles) with the advantages of known jet evaporators (high material utilization efficiency, possibility to vary adatom energy and spatial distribution of the vapor stream, natural mixing of vapor and reactive gas components). 
     In a number of applications, such as coating of fibers and metal foams, or formation of “zig-zag” structured thermal barrier coatings (TBC&#39;s) for jet engines, the DVD process demonstrated unique capabilities (non-line-of-sight coating, vapor utilization efficiency) beyond those known from established PVD technologies. However, it was also found in the course of investigations that DVD at this stage was restricted to deposition of porous or columnar microstructures. As in conventional EB-PVD, this is caused by the limited kinetic energy of the thermally generated vapor atoms. In the case of TBC&#39;s, a columnar structure is desired by the engineering purpose. For other applications or also for certain layers in the multilayer systems required in turbine blade coating, however, dense structures are demanded. 
     Extensive development work previously done in conventional PVD has shown that this goal can be achieved by combining the thermal evaporation process with a plasma activation of the vapor. The plasma facilitates that a remarkable fraction of the neutral vapor particles will get ionized. The ions can then be accelerated towards the substrate by the electrical fields within the plasma sheath between the bulk plasma and the substrate&#39;s surface. These fields are generally caused by the intrinsic self-bias potential of the plasma but may also be enforced by an external bias voltage. The enhanced kinetic energy of condensing particles results in densification and improved adherence of the deposited layers. By changing the plasma density, a wide range of layer modifications can be created. Further, the plasma promotes the chemical activity of reactive gases involved in deposition of compounds. 
     Calculations and experiments have revealed that only arc sources deliver plasma, which is sufficiently dense and capable of efficiently ionizing the vapor flux prevalent in high-rate coating. For instance, an apparatus for plasma-assisted high-rate coating has been described in the U.S. Pat. No. 5,635,087 (of which is hereby incorporated by reference). It combines electron beam evaporation with a plasma activation utilizing a transverse hollow cathode arc discharge. The process appeared to be well suited even for reactive deposition of insulating layers (oxides, nitrides) onto cold plastic substrates. 
     This approach has been adopted for creating a plasma-activation tool for the DVD process, too. Details of this innovation have been fully described and disclosed in the U.S. Pat. No. 7,014,889 (of which is hereby incorporated by reference). The plasma-activated DVD process has proven to be capable of high-efficient deposition and precise control of deposited coatings&#39; composition and morphology in a great variety of applications including coatings of aircraft engine components and semiconductor wafers, among other items. In aircraft applications, coatings can be applied for both thermal and environmental barriers, as well as oxidation and hot corrosion mitigation coatings. Directed vapor deposition methods are also used to apply titanium alloy coatings to silicon carbide monofilaments to make titanium matrix composites, and to infiltrate silicon carbide fiber performs with SiC to make (SiC/SiC) ceramic matrix composites. The use of plasmas also greatly enhances vapor phase reaction rates enabling the synthesis of hard materials such as titanium carbide and various nitrides. 
     The conventional plasma assisted deposition process has several drawbacks, however. First, the plasma source&#39;s working gas emitted from the hollow cathode forms a high speed jet whose axis is at right angles to the direction of vapor transport. Slow moving or light (i.e. low momentum) vapor particles can be scattered away from the substrate by the working gas jet of the hollow cathode. Second, the conventional approach requires the use of high argon working gas flow rates which has adverse economic consequences. It also requires a more powerful vapor transporting gas jet which has economic consequences because of the greater use of the helium gas and need for higher capacity pumping systems. Third, there is no means for sweeping the vapor plume from side to side (i.e. paint spraying a large area surface) in the conventional arrangement without significantly effecting the plasma properties. Fourth, the conventional plasma generation approach provides inadequate cleaning, etching, and heating properties for some applications (i.e. the deposition of high temperature materials onto large area substrates). 
     SUMMARY OF THE INVENTION 
     An embodiment of the present invention provides, among other things, a plasma generation process that is more optimized for vapor deposition processes in general, and particularly for directed vapor deposition processing. An embodiment of the present invention provides, among other things, the process of plasma generation that is stable across a very wide range of background pressures and in coexistence with the supersonic gas-vapor-jet. An embodiment of the present invention is applicable to, among other things, a very wide range of source materials and operates in the presence of many different gases (both reactive and nonreactive) including, but not limited to, inert gases, and inert gases doped with nitrogen, methane, borane, etc. 
     In addition to these features, an embodiment of the present invention provides, among other things, the approach that enables a robust and reliable coaxial plasma capability in which the plasma generating discharge is coaxial with the vapor plume, rather than the orthogonal configuration creating the previous disadvantages. In this way, the previous deformation of the vapor gas jet by the work gas stream of the hollow cathode pipe is avoided and the carrier gas consumption needed for shaping the vapor plume is significantly decreased. Second, instead of only one large hollow cathode pipe or slot, an annular arrangement of many small pipes can be used. Individual control of working gas flow and current for each pipe will enable the desired sweeping of the plasma plume in sync with the vapor jet. Third, some of the design variants described herein will contain means for magnetic tuning of the discharge. This is aimed at further increasing the particle energy as well as optimizing the spatial density distribution. Fourth, the components of the new plasma system can be designed with enhanced electric insulating capability up to the kV range. This will allow for biasing the plasma source with respect to the chamber (and/or substrate) and hence, performing heating or etching steps conveniently. 
     An aspect of an embodiment of the present invention provides an apparatus for applying at least one coating onto at least one substrate. The apparatus may comprise: a deposition chamber; at least one evaporant source, at least one energetic beam for impinging the evaporant source; at least one hollow cathode aligned at least substantially coaxially with the evaporant source for delivering a discharge current; at least one plasma-forming gas emitted from the hollow cathode; and at least one anode for electrostatically attracting the discharge current from the hollow cathode. 
     An aspect of an embodiment of the present invention provides a method for depositing at least one evaporant onto at least one substrate. The method may comprise: providing at least one substrate; providing at least one evaporant source impinging the at least one evaporant source with an energetic beam; discharging a current that is aligned with the evaporant source; emitting a plasma forming gas that is at least substantially aligned with the evaporant source; electrostatically attracting the discharge current; and interacting the plasma with the substrate. 
     An aspect of an embodiment of the present invention provides a method or apparatus for depositing at least one evaporant onto at least one substrate. The method may comprise (or the apparatus may be configured for) the following: providing at least one substrate; providing at least one evaporant source; impinging the at least one evaporant source with an energetic beam, providing a plasma source and discharging a current that is at least substantially coaxially aligned with the evaporant source; emitting a plasma forming gas that is at least substantially coaxially aligned with the evaporant source; electrostatically attracting the discharge current; and interacting the plasma with the substrate. 
     An aspect of an embodiment of the present invention provides a method or apparatus for depositing at least one evaporant onto at least one substrate. The method may comprise (or the apparatus may be configured for) the following: providing at least one substrate; providing at least one evaporant source; impinging the at least one evaporant source with an energetic beam to generate a vapor plume; generating a plasma and discharging a current that is aligned with said vapor plume; emitting the generated plasma that is at least substantially aligned with the vapor plume; electrostatically attracting the discharge current; and interacting the plasma with the substrate. Further, the discharge current may be changed as desired to modulate and/or control the plasma density. 
     An aspect of an embodiment of the present invention provides a method or apparatus for depositing at least one evaporant onto at least one substrate. The method may comprise (or the apparatus may be configured for) the following: providing at least one substrate; providing at least one evaporant source; impinging the at least one evaporant source with an energetic beam to generate a vapor plume; generating a plasma and discharging a current that is aligned with the vapor plume; emitting at least one plasma forming gas in a direction that is at least substantially aligned with the vapor plume; electrostatically attracting the discharge current towards at least one anode; and interacting the plasma with the substrate. 
     These and other objects, along with advantages and features of various aspects of embodiments of the invention disclosed herein, will be made more apparent from the description, drawings and claims that follow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated into and form a part of the instant specification, illustrate several aspects and embodiments of the present invention and, together with the description herein, serve to explain the principles of the invention. The drawings are provided only for the purpose of illustrating select embodiments of the invention and are not to be construed as limiting the invention. 
         FIG. 1  is a longitudinal sectional schematic view of an embodiment of the coaxial vapor deposition apparatus and assembly. 
         FIG. 2  is a sectional schematic view of an embodiment of the evaporation and plasma generation aspect of the plasma deposition system. 
         FIG. 3  is a sectional schematic view of an embodiment where the anode is positioned above the substrate. 
         FIG. 4  is a sectional schematic view of an embodiment where the anode is positioned in the plane of the hollow cathode pipe exits into the deposition chamber. 
         FIG. 5  is a sectional schematic view of an embodiment where the anode is segmented to force individual discharges across the central axis. 
         FIG. 6  is a sectional schematic view of an embodiment where individual gas lines to each hollow cathode pipe are shown and a coil is used for magnetic enhancement of the plasma. 
         FIG. 7  is a longitudinal schematic cross sectional view of an embodiment of the coaxial vapor deposition apparatus and assembly in a working form. 
         FIG. 8  is a sectional schematic view of an embodiment where the anode is positioned above the substrate. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the drawings, an aspect of an embodiment of the present invention, as shown in  FIGS. 1-2 , is a method and apparatus  10  for applying at least one coating onto at least one substrate  20  (e.g., sample), utilizing a plasma assisted directed vapor deposition process. The apparatus  10  may include a deposition chamber  30 , having an upstream area  33 , and downstream area  35 , at least one evaporant source  40 , at least one energetic beam  50  for impinging the evaporant source  40 , at least one hollow cathode  60  aligned at least substantially coaxially with the evaporant source  40  for delivering a discharge current (not shown), at least one plasma-forming gas  70  (e.g., working gas) emitted from the hollow cathode  60 , and at least one anode  80  for electrostatically attracting the discharge current from the hollow cathode  60 . At least some of the elements included in the apparatus  10  may comprise a “nozzle”  15 , which may participate in applying at least one coating to at least one substrate  20 . 
     The energetic beam  50  may be produced by an electron beam gun, a laser source, or any other device now or later appreciated in the art. In the case of an electron beam gun, it may be operated in either a low vacuum state, or at a reduced background pressure (i.e. a high vacuum state). The electron beam gun may be approximately a 70 kV/10 kW type, but not necessarily. 
     The anode  80  may be ring-shaped or annular, and may be placed in an elevated position above the hollow cathode  60 , which may be inside a downstream chamber area  35  from the nozzle  15 . This positioning may prevent the anode  80  from being coated by vapor from the vapor plume  90 . Additionally, the anode  80  may be positioned at an inclined angle, facing away from the vapor plume  90 , which may advantageously prevent contamination from the vapor plume  90 . Additionally, the elevated positioning of the anode  80  may advantageously aid in attracting plasma in the direction of the substrate  20 , thus enhancing the overall efficiency of the vapor deposition process. 
     A vapor plume  90  may be created by evaporation, via the energetic beam  50 , of a source material (the evaporant source)  40  which may be contained in a cooling device  42  for cooling the evaporant source  40 . The cooling device  42  may be a crucible, or any other means now known or later appreciated in the art. While the evaporant source  40  may generally be a solid, it should be appreciated that it could also be in the form of a liquid. As a solid, the evaporant source  40  may turn locally into a liquid upon impingement of the energetic beam  50 . Then, vaporization may occur from a resulting “melt pool” (not shown). Some solid materials may be vaporized by sublimation directly (i.e. without forming a melt pool), and may not require a cooling device  42 . Possible modifications to the evaporant source  40  may include wires, bars, granulates, or any other modification now known or later appreciated. In a case where more than one evaporant source  40  may be used, the evaporant source  40  may consist of different materials in order to deposit compounds onto the substrate  20  via “co-evaporation.” Additionally, multiple evaporant sources  40  may also exist if necessary. 
     Still observing  FIGS. 1-2 , the hollow cathode  60  may be designed as the source of plasma, and may be designed to operate in a high-current, low voltage arc mode and may be additionally designed to emit electrons forming a low-voltage electron beam (also known as the “cathode effect”). The cathode effect may be created by arranging two or more hollow cathodes  60  substantially coaxially around at least one evaporant source  40 . In other words, one or more evaporant sources  40  may be substantially coaxially integrated inside the perimeter outlined by the two or more hollow cathodes  60 . The two or more hollow cathodes may be positioned in an annular configuration around at least one evaporant source. For example, the annular configuration may be any desired array. It should be appreciated that the hollow cathodes may be a variety of structures, including, but not limited to any one of the followings: pipes, conduits, tubes, channels, hose, stems, ducts, ports, grooves, passages, tunnels, ports, or the like as desired. 
     In an embodiment (not shown), the hollow cathode  60  and its cathode effect in the present invention may be realized by positioning two coaxial cylinders, an inner cylinder (not shown), and outer cylinder (not shown) of slightly different diameters to form a continuous annular slot (not shown) from which a plasma jet  100  could be emitted. One or more evaporant sources  40  may be substantially coaxially integrated inside the inner cylinder (not shown). For example, referring to an embodiment as shown in  FIG. 8 , which is an alternative to  FIG. 3  (discussed below), it should be appreciated that such an approach may be applied to any of the embodiments disclosed or referenced herein. Still referring to  FIG. 8 , the hollow cathode  360  and its cathode effect in an embodiment of the resent invention ma realized by positioning two coaxial cylinders, an inner cylinder  362 , and outer cylinder  363  of slightly different diameters to form there between a continuous annular slot  364  from which a plasma jet  300  could be emitted. One or more evaporant sources (not shown) may be substantially coaxially integrated inside the inner cylinder  362 . 
     The plasma forming gas  70 , when emitted from the hollow cathode  60 , may form a plasma jet  100  (e.g., plasma region), which may stream off of the hollow cathode&#39;s orifice  61 . The axis  101  and/or momentum of the plasma jet  100  as well as the axis and/or momentum of the hollow cathode&#39;s low voltage electron beam (not shown) may be at least substantially aligned with the axis  64  of the hollow cathode  60 . When the hollow cathode  60  and corresponding axis  64  are aligned with the evaporant-source-to-substrate vector  66 , the plasma jet  100  may at least partially assist the axisymmetric entrainment and transport of the vapor plume  90  to the substrate  20 , which may allow for the total gas that must be pumped in the system (for high efficiency deposition) to be significantly reduced. As discussed above, the plasma jet  100  may at least partially entrain the vapor plume  90  and may at least partially assist in transporting the vapor plume  90  towards the substrate  20 . The plasma jet  100  may also partially shape the vapor plume  90 . At least some of the vapor plume  90  may be ionized by the plasma jet  100  and by the hollow cathode&#39;s low voltage electron beam (not shown). 
     An aspect of an embodiment of the present invention may also include a bias voltage  57  applied to the substrate  20 . By applying a bias voltage  57  to the substrate  20 , plasma particles from the vapor plume  90  can be accelerated toward the substrate  20  to enhance or perform various kinds of beneficial interactions with the substrate  20 . The bias voltage  57  may be DC, AC, unipolar or bipolar pulsed voltage, or any other means now known or later appreciated in the art. 
     A negative potential difference between the substrate  20  and the plasma bulk will accelerate ions towards the substrate  20 . During a vapor deposition process and with the bias voltage  57  in the range of approximately 0 V to approximately 250 V, one can increase the mean energy of condensing particles aimed at improved adhesion and quality (as measured, e.g., by packing factor, density, degree of crystallinity) of the grown layer (plasma activated deposition). When applied prior to a physical vapor deposition (PVD), for example, coating process in a suitable gas atmosphere (mostly Ar at approximately 0.5 Pa, for example) and with the bias voltage  57  in the range of approximately 500 to approximately 1000 V, sputtering occurs and removes impurities or adsorbed layers thus cleaning the substrate surface (ion etching). With specific parameter combinations, however, it is also possible to embed (reactive) gaseous species into near-surface layers of the substrate thus forming special interfaces for subsequent coating (ion implantation). 
     If the substrate  20  is positively biased, plasma electrons may be accelerated toward the substrate  20 , providing a power source for advantageous heating of the substrate  20 . 
     The apparatus  10  may also comprise a means for initiating the emission of a plasma jet  100  from the hollow cathode&#39;s orifice  61 . The means may comprise a heat source based on Ohmic heating of a current conductor, a heat source based on an auxiliary gas discharge, a “kicker” circuit to ignite the hollow cathode plasma emission via a high voltage impulse, or any other means now known or later appreciated. 
     The desired arc discharge from the hollow cathode  60  may be significantly sustained by thermionic and thermally-assisted field emission of electrons from the hollow cathode  60 . These means for initiating plasma emission may require a high work temperature of the hollow cathode  60  which may be established first to enable the operation in arc mode afterwards. Initial heating of the cathode may be achieved by resistive heating of the hollow cathode  60  itself or of an auxiliary radiation heater (not shown). 
     Alternatively, the hollow cathode  60  may be heated slowly by a glow discharge which may burn at voltages comparable to or slightly higher than the later arc mode voltage. Glow discharge may require high plasma gas flows or an elevated pressure within the deposition chamber  30  during the ignition phase. 
     Alternatively, the arc discharge from the hollow cathode  60  may also be initiated via a glow discharge heating phase at a later desired gas flow and chamber pressure. There, the discharge may be ignited by applying a voltage significantly higher (kV range) than the final burning voltage in the arc mode. After ignition, the transition to the low-voltage arc mode may occur rapidly. In that situation, the high voltage usually may be provided as a short impulse. This procedure may generally be referred to as a “kicker” circuit. In that situation, after ignition, the cathode temperature may be maintained by the arc discharge itself, and the additional means for heating may be turned off. 
     As shown in  FIGS. 1, 2 and 6 , the apparatus  10  may further comprise a solenoid  55  (e.g., solenoid coil) positioned coaxially and at least partially proximal to the at least one hollow cathode  60 . The solenoid  55  may be capable of at least partially bending the energetic beam  50 , and most effectively if the energetic beam is, for example, an electron beam. The solenoid  55  may be positioned and energized such as to magnetically enhance the efficiency of the hollow cathode  60 . Additionally, the solenoid  55  may at least partially increase plasma density and facilitate an axial potential gradient for accelerating positive ions of the plasma jet  100 , or the vapor plume  90 , or both toward the substrate  20 . The solenoid  55  may also provide the ability to alter the beam impingement points for the energetic beam  50  among one or more evaporant sources  40 . The use of a solenoid coil  55  may allow the evaporation geometry to be changed to advantageously increase the space available for positioning and manipulating complex shaped substrates  20  and auxiliary heating  59  and biasing  57  subsystems. Additionally, the placement of the solenoid  55  near the anode  80  may advantageously enhance the discharge voltage, and hence, the particle energy. An embodiment of the apparatus  10 , as shown in  FIG. 6 , is arranged whereby individual gas lines providing the plasma forming gas  70  (e.g., working gas) to each hollow cathodes  60  are shown and a coil  55  is used for magnetic enhancement of the plasma. 
     Overall, the use of a solenoid coil  55  at least partially proximal to at least one hollow cathode  60  may allow for an increased ion saturation current at low gas flow through the hollow cathode  60 . The use may also provide elevated discharge voltages, and therefore, higher electron temperatures, which is generally advantageous for low-vacuum applications. Additionally, by adjusting the current in the solenoid  55 , it may be possible to manipulate not only the ion saturation current, but also the spatial distribution of the ions in the deposition chamber  30 . 
     An aspect of an embodiment of the present invention may also comprise means for the inlet of at least one secondary gas forming at least one jet positioned at least substantially coaxially with said at least one evaporant source and at least one hollow cathode. The at least one secondary gas jets may at least partially assist in shaping and transporting the vapor plume to the substrate. The at least one secondary gas jets may also introduce reactant gases for creating compounds with the evaporated material. Possible embodiments include, but are not limited to, concentric arrangement around the hollow cathode slot/multi jets, multi jet array where plasma and secondary gas jets alternate along a common circle line around the evaporant sources, or slot-type or multi jet gas nozzles integrated into the annular anodes. 
     In an embodiment of the apparatus  310  having a nozzle  315 , shown in  FIG. 3 , the anode  380  may be annular, and may be configured in an elevated position above the at least one hollow cathodes  360 . The plasma forming gas  370  (e.g., working gas), when emitted from the hollow cathode  360 , may form a plasma jet  300  (e.g., plasma region). A source material (not shown) such as the evaporant source, may be contained in a cooling device  342 . Furthermore, the anode  380  may be positioned above the substrate  320  (for example, as shown), or between the substrate  320  and hollow cathode  360  (not shown). This later configuration may allow for the anode  380  to be advantageously shielded from the vapor plume  390  by the substrate  320 . 
     In an embodiment of the apparatus  410  having a nozzle  415 , shown in  FIG. 4 , the anode  480  may be annular, and may be positioned at least coaxially and in the same plane as the at least one hollow cathode  460 . The plasma forming gas  470  (e.g., working gas), when emitted from the hollow cathode  460 , may form a plasma jet  400  (e.g., plasma region). A source material (not show), such as the evaporant source, may be contained in a cooling device  442 . Also shown are a substrate  420  and vapor plume  490 . Additionally, turning to an embodiment of the apparatus  510 , as shown in  FIG. 5  for use with a substrate  520 , the anode  580  may be bisected radially, forming anode segments  581 . The anode  580  may be bisected into the same number (but not necessarily) of anode segments  581  as the number of hollow cathodes  560 . This may allow for the emissions from the hollow cathodes  560  to burn diametrically across the vapor plume  590  between each one of the hollow cathodes  560  and the corresponding anode segment  581  situated at the opposite position. This diametric burning may drive the emission of the hollow cathode  560  across the center of the nozzle  515 , which may increase the plasma density in regions where the concentration of the vapor plume  590  is the highest. The plasma forming gas  570  (e.g., working gas), when emitted from the hollow cathode  560 , may form a plasma jet  500  (e.g., plasma region). A source material (not shown), such as the evaporant source, may be contained in a cooling device  542 . 
     The above configurations may provide the ability to control the relative intensity of the plasma jets  100  generated by the hollow cathodes  60  for optional directional aerodynamic sweeping either of the plasma jet  100 , or vapor plume  90 , or both, from side to side (i.e. spray coat a large surface area or different areas) without significantly affecting the plasma properties. This directional aerodynamic sweeping may be accomplished by systematically controlling the pressure or gas flow rates individually in each hollow cathode  60 , or any other means now known or later appreciated in the art. 
     In an embodiment of the apparatus  710 , as shown in  FIG. 7 , the anode  780  may further comprise a means for magnetic plasma confinement by creating a magnetic field (not shown) and guiding a magnetic flux (not shown) such that the magnetic field lines in front of the anode  780  may be substantially parallel to its surface and radially directed. This is an exemplary embodiment of a working form wherein two or more hollow cathode pipes are positioned in the upstream chamber of a directed vapor deposition apparatus and the annular anode comprises a magnetic circuit facilitating an anodic plasma layer. The described magnetic field arrangement together with the electric field strength directed substantially normal to the surface of the anode  780  may produce a circular Lorentz force parallel to the anode&#39;s surface  785  (F=E×B) which may advantageously create a closed circumferential electron drift track. Along this track, intensive ionization of the gas and vapor particles may occur. In the vicinity of the anode  780 , the magnetic field (not shown) will diverge and may facilitate via ambipolar diffusion an axial potential gradient for accelerating positive ions toward the substrate (not shown). Furthermore, the use of magnetic plasma confinement may advantageously provide for enhanced discharge voltage resulting in an increase in the mean energy of the discharge electrons to values which are close to the maximum in the energy dependence of the cross section for electron impact ionization. Suitable inclination angle of the anode  780 , appropriate shielding (not shown) and use of a clear gas flow (not shown) shall ensure protection against contamination of the anode surface  785  by stray vapor. As discussed previously, this embodiment may include a deposition chamber  730 , at least one evaporant source  740 , at least one energetic beam  750  for impinging the evaporant source  740 , at least one hollow cathode  760  for delivering a discharge current (not shown), and at least one anode  780  for electrostatically attracting the discharge current from the hollow cathode  760 . At least some of the elements included in the apparatus  710  may comprise a “nozzle”  715  acting as a flow resistor which pressure-wise separates the upstream area  733  from the downstream area  735 , thus facilitating the generation of a directed carrier gas stream as needed for vapor entrainment and for applying at least one coating to at least one substrate  20 . The plasma forming gas  770  may be emitted from the hollow cathode  760 . 
     Two or more hollow cathodes  760  of the plasma source may be arranged around the evaporant source  740  as an annular multi jet array and placed below the nozzle  715  inside the upstream area  733 . The plasma forming gas  770  streaming off the hollow cathode  760  is released into the upstream area  733  and acts then as a carrier gas for vapor plume shaping upon directed expansion downstream into the deposition chamber  730 . 
     Also provided may be any of the following modules  795 : power cable, water cooling, purging gas and coil current. Also provided may be any of the following modules  797 : power cable and water cooling. 
     It should be appreciated that aspects of various embodiments of the present invention system and method may be utilized for applying a large variety of coatings, barriers, layers, films, packaging, or other desired materials, or structures for, but not limited thereto, the following: electronics, optics, engine components, rotors, blades, desired structures or components, packaging films, metalizing plastics for flexible electronics or EMI shielding purposes, nanostructures, for depositing scratch-proof, corrosion protection or decorative layers on various raw materials, for controlling the electrical, optical and tribological properties of components, tools and machine parts, coatings of aircraft (or land or watercraft) engine components and semiconductor wafers, among other items. In aircraft (or sea or land crafts) applications, coatings can be applied for both thermal and environmental barriers. Further, aspects of various embodiments of the present invention system and method may be utilized for: metalizing ceramic or other non-metallic (organic) metal matrix composite reinforcing fibers; coating nanomaterials (particles, rods, wires, and fibers, or the like); and growing nanowires for opto-electric sensors. 
     The devices, systems, compositions, apparatuses, and methods of various embodiments of the invention disclosed herein may utilize aspects disclosed in the following references, applications, publications and patents and which are hereby incorporated by reference herein in their entirety:
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     In summary, while the present invention has been described with respect to specific embodiments, many modifications, variations, alterations, substitutions, and equivalents will be apparent to those skilled in the art. The present invention is not to be limited in scope by the specific embodiment described herein. Indeed, various modifications of the present invention, in addition to those described herein, will be apparent to those of skill in the art from the foregoing description and accompanying drawings. Accordingly, the invention is to be considered as limited only by the spirit and scope of the following claims, including all modifications and equivalents. 
     Still other embodiments will become readily apparent to those skilled in this art from reading the above-recited detailed description and drawings of certain exemplary embodiments. It should be understood that numerous variations, modifications, and additional embodiments are possible, and accordingly, all such variations, modifications, and embodiments are to be regarded as being within the spirit and scope of this application. For example, regardless of the content of any portion (e.g., title, field, background, summary, abstract, drawing figure, etc.) of this application, unless clearly specified to the contrary, there is no requirement for the inclusion in any claim herein or of any application claiming priority hereto of any particular described or illustrated activity or element, any particular sequence of such activities, or any particular interrelationship of such elements. Moreover, any activity can be repeated, any activity can be performed by multiple entities, and/or any element can be duplicated. Further, any activity or element can be excluded, the sequence of activities can vary, and/or the interrelationship of elements can vary. Unless clearly specified to the contrary, there is no requirement for any particular described or illustrated activity or element, any particular sequence or such activities, any particular size, speed, material, dimension or frequency, or any particularly interrelationship of such elements. Accordingly, the descriptions and drawings are to be regarded as illustrative in nature, and not as restrictive. Moreover, when any number or range is described herein, unless clearly stated otherwise, that number or range is approximate. When any range is described herein, unless clearly stated otherwise, that range includes all values therein and all sub ranges therein. Any information in any material (e.g., a United States/foreign patent, United States/foreign patent application, book, article, etc.) that has been incorporated by reference herein, is only incorporated by reference to the extent that no conflict exists between such information and the other statements and drawings set forth herein. In the event of such conflict, including a conflict that would render invalid any claim herein or seeking priority hereto, then any such conflicting information in such incorporated by reference material is specifically not incorporated by reference herein.