Patent Publication Number: US-10760881-B2

Title: Systems and methods for modifying and enhancing pyrotechnic emissions and effects by irradiating pyrotechnic emissions using electromagnetic radiation sources with programmable electromagnetic radiation profiles

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims the benefit of U.S. Provisional Application No. 62/485,088, titled SYSTEMS AND METHODS FOR MODIFYING AND ENHANCING PYROTECHNIC EMISSIONS AND EFFECTS BY IRRADIATING PYROTECHNIC EMISSIONS USING ELECTROMAGNETIC RADIATION SOURCES WITH PROGRAMMABLE ELECTROMAGNETIC RADIATION PROFILES, filed Apr. 13, 2017, the disclosure of which is expressly incorporated by reference herein. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     The invention described herein includes contributions by one or more employees of the Department of the Navy made in performance of official duties and may be manufactured, used and licensed by or for the United States Government for any governmental purpose without payment of any royalties thereon. This invention (Navy Case 200,410) is assigned to the United States Government and is available for licensing for commercial purposes. Licensing and technical inquiries may be directed to the Technology Transfer Office, Naval Surface Warfare Center Crane, email: Cran_CTO@navy.mil. This invention was made with government support under grant nos. FA9550-15-1-0195 and FA9550-15-1-0481 awarded by the United States Air Force Office of Scientific Research. The government has certain rights in the invention. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to systems and methods for modifying the emissions and effects output of a pyrotechnic device by exposing the pyrotechnic device&#39;s emissions to electromagnetic radiation. 
     Most pyrotechnic devices rely on exothermic chemical interactions created by combining an oxidizer with a fuel source, known as a pyrotechnic composition. The chemical reactions can create a combination of heat, light, sounds, and gas based on the pyrotechnic composition within the device. Photonic emissions are released in the flame of a pyrotechnic device as a result of the relaxation of excited electrons returning to their ground state and releasing their quantized energy. A pyrotechnic composition can be adjusted to meet individual performance requirements such as desired light emissions across the electromagnetic spectrum, adiabatic flame temperature, dominant wavelength, and spectral emission purity. However, the process of adjusting the pyrotechnic composition is time intensive; additionally, the possible emission and effect profiles of pyrotechnic devices are limited by the electronic transition energies of atomic and molecular emissions produced by the chemical reactions. Adjusting the pyrotechnic composition cannot efficiently augment or amplify electron excitation pathways or access new excitation pathways, severely limiting the variety of emission and effect profiles. Once a pyrotechnic composition has been created, changes to the emission and effect profile cannot be made without changing the pyrotechnic composition. 
     To solve these problems, embodiments of this invention disclose the application of electromagnetic radiation (EMR) to the flame of a pyrotechnic device to allow much greater variety in emission and effect profiles without the need to change the pyrotechnic composition. Irradiating pyrotechnic emissions causes additional excitation of electrons within the irradiated area (e.g. additional excited electrons or further excitation of previously excited electrons). When these electrons relax to a lower state, the resulting photons can augment or amplify the normal pyrotechnic emissions. By irradiating the emissions with specific frequencies and durations of EMR, the size of emission flames and plasma, the electromagnetic emissions, the dominant wavelength of emissions, and spectral purity of emissions can be discretely controlled. Applying a series of varying EMR can produce a multitude of effects over the course of a single pyrotechnic event. 
     According to an illustrative embodiment of the present disclosure, a pyrotechnic device can be irradiated by an external EMR source which is not coupled to the pyrotechnic device. The external EMR source can generate EMR directed towards a specific point with a discrete EMR source (e.g. a laser) or towards a region with an area of effect EMR source (e.g. a RF transmitter). Varying the frequency, amplitude, and/or flux of the generated EMR can affect the pyrotechnic emissions (e.g. dominant wavelength, spectral purity, brightness) of the pyrotechnic device while varying the duration of transmission (e.g. continuous transmission for a particular duration, a series of pulses) of the EMR can affect the pyrotechnic effects (e.g. creating patterns or designs). To tailor EMR output to create a desired emission and effect profile, programmable hardware within the external source can transmit a plurality of EMR of various frequencies, power levels, and durations of transmission. 
     According to a further illustrative embodiment of the present disclosure, an EMR source can be coupled to a pyrotechnic device. A coupled EMR source can include an independent power source to allow the system to remain portable. In some embodiments, the coupled EMR source creates a localized electromagnetic field (EMF) across the pyrotechnic emissions to irradiate the emissions. 
     Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description of the drawings particularly refers to the accompanying figures in which: 
         FIG. 1  shows an exemplary system for irradiating pyrotechnic emissions with an external EMR source. 
         FIG. 2  shows an exemplary system for irradiating airborne pyrotechnic emissions with an external EMR source. 
         FIG. 3A  shows an exemplary pre-ignition system for irradiating pyrotechnic emissions with an EMF inducing coil. 
         FIG. 3B  shows an exemplary post-ignition system for irradiating pyrotechnic emissions with an EMF inducing coil. 
         FIG. 4  shows an exemplary system for irradiating pyrotechnic emissions with a pair of EMF inducing plates. 
         FIG. 5  shows an exemplary system for irradiating pyrotechnic emissions with a waveguide directing EMR from an EMR source to a flame. 
         FIG. 6  shows an exemplary component structure of an exemplary EMR source. 
         FIG. 7  shows an exemplary method for irradiating pyrotechnic emissions. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The embodiments of the invention described herein are not intended to be exhaustive or to limit the invention to precise forms disclosed. Rather, the embodiments selected for description have been chosen to enable one skilled in the art to practice the invention. 
     Referring initially to  FIG. 1 , an exemplary system for irradiating pyrotechnic emissions is shown. A pyrotechnic device  11  (e.g., a flare, a firework, a match) generates pyrotechnic emissions  13  (e.g. a flame, plasma, secondary EMR) and an external EMR source  15  (e.g. a microwave magnetron or an RF antenna) generates output EMR  17  (e.g. microwaves, radio waves, ultraviolet radiation, visible light. In some embodiments, the pyrotechnic device  11  includes a casing or body and a pyrotechnic composition. The pyrotechnic composition can include an alkali, alkaline-earth, or transition-metal compound (e.g. potassium nitrate), a halogen compound (e.g. polytetrafluoroethylene), or other combustible compositions. An EMR source  15  can direct output EMR  17  towards the pyrotechnic emissions  13  of the pyrotechnic device  11  to irradiate the emissions. An EMR source  15  can direct output EMR  17  through a cross sectional or volumetric area of pyrotechnic emissions  13  or to a discrete point within pyrotechnic emissions  13 . In reaction to output EMR  17 , the properties of pyrotechnic emissions  13  change, including an increase in the size of a flame or plasma (e.g. 50% increase in length), a change in the dominant frequency of visible light released (e.g. changing the dominant color of a flame from 700 nm light to 400 nm light) in the pyrotechnic emissions  13 , a decrease in unwanted frequencies of secondary EMR to improve spectral purity of the pyrotechnic emissions  13 , and prolongation of the duration of pyrotechnic emissions  13  (e.g. maintaining bright emissions for a longer period of time, sustaining plasma after a pyrotechnic device  11  ceases to produce emissions). An EMR source  15  can generate output EMR  17  continually for predetermined periods of time (e.g. constant generation over the lifetime of a pyrotechnic device&#39;s chemical reactions), for predetermined pulses (e.g. bursts of EMR generation for 10 ms with 10 ms pauses between each pulse), or other combinations of varying durations. Generated output EMR  17  can be a uniform wavelength or plurality of wavelengths (e.g. three predetermined and distinct electromagnetic frequencies) and can vary over time (e.g. cycle through a series of different frequencies). An EMR source  15  can generate output EMR  17  at a variety of power level (e.g. 1 kW, 50 kW) and can change the power output during operation to create different effects (e.g. rapid increases and decreases in power to create flashing or shimmering effects). Higher power levels can be used to increase the number of interactions between EMR  17  and pyrotechnic emissions  13  or to make up for photons scattered away from the pyrotechnic emissions  13  prior to interaction. Pluralities of wavelengths can be cycled for varying durations of time to create a dynamic system of changes to pyrotechnic emissions  13 . A dynamic system of changes can cause a variety of effects (e.g., rapidly changing visible light wavelengths, varying brightest across pyrotechnic emissions  13  to cause changing shapes and patterns within the emissions) which can be stored in the EMR source  15  as an emission and effect profile. 
       FIG. 2  shows another exemplary system for irradiating pyrotechnic emissions. Pyrotechnic devices (e.g., see  11 ,  FIG. 1 ) are launched into the air and activated to release airborne pyrotechnic emissions  21  from the said pyrotechnic devices. An external EMR source  15  can irradiate airborne pyrotechnic emissions  21  to excite the electrons present within the airborne pyrotechnic emissions  21  to create augmented airborne pyrotechnic emissions  23 . Augmented airborne pyrotechnic emissions  23  will then release photons when the electrons relax. Exemplary embodiments can use the system as shown in  FIG. 1 , including EMR source  15  and output EMR  17 . 
       FIG. 3A  shows an exemplary pre-ignition system for using an inductive coil  31  as a source of EMR. In an exemplary embodiment, a power source  35  is coupled to a pyrotechnic device  11  and is electronically coupled to an inductive coil  31  with electrical cables  33 . The inductive coil  31  forms rings around the emission path of the pyrotechnic device  11 . The power source  35  creates a current through the inductive coil  31  which causes a localized electromagnetic field (EMF) to be created through an axis connecting the approximate centers of the loops or rings of the inductive coil  31 . The inductive coil  31  can be positioned such that an EMF created by the inductive coil  31  can irradiate pyrotechnic emissions  13 , as shown in  FIG. 3B .  FIG. 3B  shows an exemplary embodiment of the same system after the pyrotechnic device  11  has been ignited. In exemplary embodiments, the coil can form loops in either a clockwise or counter-clockwise direction. In additional embodiments, the thickness of and spacing between the rings can vary. In an exemplary embodiment, the inductive coil  31  begins at the boundary between the pyrotechnic device  11  and the pyrotechnic emissions  13  and occupies the first ten percent of the height of pyrotechnic emissions  13  beyond that boundary. 
       FIG. 4  shows an exemplary system for using conductive plates  41  as a source of EMR. In an exemplary embodiment, a power source  35  is coupled to a pyrotechnic device  11  and is electronically coupled to a pair of conductive plates  41  with electrical cables  33 . The power source  35  creates a positive charge in a first plate and a negative charge in a second plate which causes a localized EMF to form between the two plates. In exemplary embodiments, the conductive plates  41  are positioned such that the EMF can pass through and irradiate the pyrotechnic emissions  13 . 
       FIG. 5  shows an exemplary system for using a waveguide  51  (e.g., a hollow metallic pipe, a fiber optic cable) to transfer EMR (not shown) from a coupled EMR source  15  to pyrotechnic emissions  13 . In an exemplary embodiment, a coupled EMR source  15  (e.g. microwave generator, RF generator, laser generator) is coupled to a pyrotechnic device  11  and a waveguide  51 . EMR created by a coupled EMR source  15  enters and exits a waveguide  51  such that the EMR is directed into the pyrotechnic emissions  13 . 
       FIG. 6  shows an exemplary component structure of an EMR source  15  that can be used in exemplary embodiments (e.g., as shown in  FIGS. 1, 2, and 5 ). A power supply  61  can provide power to the systems and subsystems. A storage medium  65  (e.g. a HDD, flash memory) can be configured to store programmed emission and effect profiles (e.g. desired wavelength, desired luminous intensity, required output to create desired results, etc.) and tracking identification profiles (e.g. wavelengths of light to be tracked). A user interface  69  can be configured to allow an operator to enter an emission and effect profile and a tracking identification profile into the storage medium  65 . A tracking sensor system  71  can detect and identify wavelengths of EMR with an EMR sensor (e.g. a RF receiver, a video camera) and generate a plurality of tracking signals identifying the location or direction of the source of the EMR (e.g. the direction from which the EMR was received) and the wavelength of the corresponding EMR (e.g. 700 nm light, 50 mm microwaves). In some embodiments, a processor  63  can be configured to compare a plurality of tracking signals to a tracking identification profile from the storage medium  65  to determine whether detected EMR matches a tracking identification profile, generate a plurality of directional control signals if a tracking signal matches a tracking identification profile, and transfer the plurality of directional control signals to a directional control system  73  (e.g. a two-axis rotational system capable of aiming along a 2π steradian solid angle). A directional control system  73  receiving directional control signals can use the signals to orient the EMR source  15  towards a location identified by a plurality of tracking signals. In additional embodiments, the directional control system  73  can avoid particular targets (e.g. a human, a stage prop) by including an optical sensor (e.g. a video camera) in the tracking sensor system  71  and including avoidance targets in a plurality of tracking signals for comparison against an avoidance profile. The processor  63  can be configured to generate a plurality of output signals corresponding to an emission and effect profile if a tracking signal matches the emission and effect profile, and transfer the plurality of output signals to an EMR generator  67 . An EMR generator  67  receiving output signals can use the signals to generate output EMR (e.g., see  17 ,  FIG. 1 ) specified in a corresponding emission and effect profile. In other embodiments, an operator can manually control a directional control system  73  to direct an EMR source  15  towards a chosen target. 
       FIG. 7  shows an exemplary method of irradiating pyrotechnic emissions. In step  101 , a system including a pyrotechnic device (e.g., see  11 ,  FIG. 1 ) and an EMR source (e.g., see  15 ,  FIG. 1 ) is provided. In step  103 , a desired pyrotechnic emission and effect output is identified, including a first at least one wavelength of EMR (e.g., both 700 nm and 475 nm visible light), a first at least one luminous intensity of EMR (e.g. 100 cd), and a first at least one duration of time (e.g. a 5 second duration, 200 cycles of 5 ms with 10 ms between each cycle). In step  105 , an emission and effect profile, including a second at least one wavelength of EMR (e.g., 2.45 GHz), at least one power output of EMR (e.g. 1 kW), and a second at least one duration of time, is designed such that irradiating the pyrotechnic emissions of a pyrotechnic device with the emission and effect profile will create the desired pyrotechnic emission and effect output. In step  107  the emission and effect profile is loaded onto the EMR source (e.g., see  15 ,  FIG. 1 ) (e.g. uploading the profile to a storage medium (e.g., see  65 ,  FIG. 6 )). In step  109 , the pyrotechnic device (e.g., see  11 ,  FIG. 1 ) is ignited. In step  111 , the said EMR source is operated (e.g. by human control, by automatic programming) to generate EMR according to the emission and effect profile. In step  113 , the EMR is directed (e.g. a human manually changing the trajectory of a laser by moving the EMR source (e.g., see  15 ,  FIG. 1 ), a processor (e.g., see  63 ,  FIG. 6 ) controlling an automated directional control mechanism to shift an RF transmitter) towards the pyrotechnic emissions. In an exemplary embodiment, at step  101  a user provides a pyrotechnic device (e.g., see  11 ,  FIG. 1 ) with a pyrotechnic composition including Mg/PTFE, wherein the said pyrotechnic device normally releases emissions with primary wavelengths between 600 nm and 800 nm. At step  103 , a user identifies a desired output wavelength of about 400 nm. At step  105 , the user creates a pyrotechnic emission and effect profile including a 1 kW 2.45 GHz microwave, which will turn the non-irradiated red/orange pyrotechnic emissions into blue pyrotechnic emissions. 
     Although the invention has been described in detail with reference to certain preferred embodiments, additional variations and modifications exist within the spirit and scope of the invention as described and defined in the following claims.