Patent Publication Number: US-10760887-B2

Title: Detonation transfer assembly

Description:
FIELD 
     The present disclosure relates generally to thermally-initiated venting systems, and more particularly, to detonation transfer assemblies. 
     BACKGROUND 
     Thermally-initiated venting systems may be implemented in energetic systems and configured to reduce the violence of the reaction of an energetic assembly in response to a known threat, for example, a propellant in a rocket motor exposed to an external heat source, such as a fire. Thermally-initiated venting systems may comprise a detonation transfer assembly configured to transfer a detonation or energy from one part of a thermally-initiated venting system to another, in order to cause a reaction, such as the ignition of an explosive material. Detonation transfer assemblies should be able to be exposed to fast cook-off (i.e., direct, immediate exposure to high heat, such as a fire) and/or slow cook-off (i.e., the exposure to gradually increasing temperature over an extended period of time) without ignition or detonation and without thermal degradation. 
     SUMMARY 
     In various embodiments, a detonation transfer assembly may comprise an external casing comprising an input end and an output end axially opposite the input end, an explosive column spanning axially inside the external casing, a primary explosive disposed within the explosive column, and/or a secondary explosive disposed within the explosive column axially between the primary explosive and the output end. The primary explosive and/or the secondary explosive may thermally insensitive initiation material that may resist detonation and/or thermal degradation in response to a temperature increase rate of 3.3° C. per hour over at least twenty hours. 
     In various embodiments, the primary explosive may comprise lead azide and/or copper(I) 5-nitrotetrazolate. In various embodiments, the secondary explosive may comprise hexanitrostilbene and/or nonanitroterphenyl. In various embodiments, the primary explosive may comprise the same thermally insensitive initiation material as the secondary explosive. In various embodiments, the detonation transfer assembly may comprise a primer comprised within the external casing between the explosive column and the input end. In various embodiments, a column height of the explosive column may be less than one-third of a casing height of the external casing. In various embodiments, a column height of the explosive column may gradually increase from a first portion of the explosive column to a second portion of the explosive column. 
     In various embodiments, a thermally-initiated venting system may comprise a first stage pyrotechnic, a detonation transfer assembly coupled to the first stage pyrotechnic and configured to be actuated by the first stage pyrotechnic, and/or an energetic transfer line coupled to the detonation transfer assembly, wherein the energetic transfer line is configured to be ignited by the detonation transfer assembly. The detonation transfer assembly may comprise a primary explosive and a secondary explosive disposed axially-adjacent to the primary explosive. The primary explosive and/or the secondary explosive may comprise a thermally insensitive initiation material that resists detonation and/or thermal degradation in response to a temperature increase rate of 3.3° C. per hour over at least twenty hours. In various embodiments, the primary explosive and/or the secondary explosive may comprise a thermally insensitive initiation material that resists detonation and/or thermal degradation in response to a temperature increase rate of 3.3° C. per hour over at least 48 hours. 
     In various embodiments, the primary explosive may comprise lead azide and/or copper(I) 5-nitrotetrazolate. In various embodiments, the secondary explosive may comprise hexanitrostilbene and/or nonanitroterphenyl. In various embodiments, the primary explosive may comprise the same thermally insensitive initiation material as the secondary explosive. 
     In various embodiments, a method of igniting a thermally-initiated venting system may comprise igniting a first stage pyrotechnic, igniting a primary explosive in a detonation transfer assembly in response to the igniting the first stage pyrotechnic, igniting a secondary explosive in the detonation transfer assembly in response to the igniting the primary explosive, igniting an energetic transfer line in response to the igniting the secondary explosive, and/or damaging a vessel comprising a propellant in response to the igniting the energetic transfer line. The secondary explosive may comprise hexanitrostilbene and/or nanonitroterphenyl. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures. 
         FIG. 1A  illustrates a block diagram of a thermally-initiated venting system coupled to a motor, in accordance with various embodiments; 
         FIG. 1B  illustrates a thermally-initiated venting system, in accordance with various embodiments; 
         FIG. 2  illustrates a schematic view of a detonation transfer assembly, in accordance with various embodiments; 
         FIGS. 3A-3C  illustrate detonation transfer assemblies, in accordance with various embodiments; and 
         FIG. 4  illustrates a method of igniting a thermally-initiated venting system, or other explosive material, in accordance with various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     All ranges may include the upper and lower values, and all ranges and ratio limits disclosed herein may be combined. It is to be understood that unless specifically stated otherwise, references to “a,” “an,” and/or “the” may include one or more than one and that reference to an item in the singular may also include the item in the plural. 
     The detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical, chemical, and mechanical changes may be made without departing from the scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full, and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. 
     Referring to  FIG. 1A , a block diagram of a thermally-initiated venting (“TIV”) system  100  is depicted, in accordance with various embodiments. In various embodiments, TIV system  100  may comprise a thermal sensor  110 , a first stage pyrotechnic  120  coupled to thermal sensor  110 , a detonation transfer assembly  200  coupled to first stage pyrotechnic  120 , and/or an energetic transfer line  130  coupled to detonation transfer assembly  200 . TIV system  100  may be coupled to a motor  50 , or any other device comprising a propellant or other explosive that may benefit from hazard mitigation in response to being exposed to a thermal threat. For instance, TIV system  100  may prevent motor  50  from propelling a missile (which comprises motor  50 ) in response to being exposed to a thermal threat, such as a fire. In various embodiments, energetic transfer line  130  may be coupled to motor  50 . 
     In various embodiments, thermal sensor  110  may be any thermally-sensitive ignition device that reacts at an actuation temperature (e.g., chemically reacts), and in response, actuates and/or ignites first stage pyrotechnic  120 . In various embodiments, thermal sensor  110  may comprise a melting alloy, which gives an output energy in response to achieving an actuation temperature. The output energy may ignite first stage pyrotechnic  120 . In various embodiments, thermal sensor  110  may comprise a shape memory alloy. The shape memory alloy may comprise titanium (Ti), Nickel (Ni), Zirconium (Zr), Hafnium (Hf), Palladium (Pd), Gold (Au), Platinum (Pt), Aluminum (Al), Niobium (Nb), and/or Tantalum (Ta). For example, the shape memory alloy may comprise a Ti—Ni alloy, a (Ti—Zr)—Ni alloy, a (Ti—Hf)—Ni alloy, a Ti—(Ni—Pd) alloy, a Ti—(Ni—Au) alloy, a Ti—(Ni—Pt) alloy, a Ti—Al alloy, a Ti—Nb alloy, Ti—Pd alloy, and/or a Ti—Ta alloy. The shape memory alloy may be configured to transition from a first geometry to a second geometry, or from the second geometry to the first geometry, in response to the shape memory alloy achieving an actuation temperature. Therefore, the actuation temperature may cause thermal sensor  110  to change geometry, in response to thermal sensor  110  comprising a shape memory alloy, which may ignite first stage pyrotechnic  120 . In various embodiments, thermal sensor  110  may be a reactive material configured to give an output energy in response to reaching an actuation temperature, and the output energy be configured to ignite first stage pyrotechnic  120 . 
     In various embodiments, first stage pyrotechnic  120  may be ignited by the energy produced by thermal sensor  110 . First stage pyrotechnic  120  may comprise any reactive material capable of being ignited by the energy output of thermal sensor  110 , and capable of creating an output energy from the reactive material. For example, first stage pyrotechnic  120  may comprise black powder and/or boron potassium nitrate (BKNO 3 ). The output energy from first stage pyrotechnic  120  may ignite detonation transfer assembly  200 . In various embodiments, the output energy from first stage pyrotechnic  120  may comprise heat, expanding gases, a shock wave, and/or any other energy capable of actuating and/or igniting detonation transfer assembly  200 . For example, first stage pyrotechnic  120  may chemically react and produce expanding gas. The expanding gas may mechanically act on an ignition device, such as a firing pin, causing the firing pin to strike and actuate, initiate, and/or ignite detonation transfer assembly  200 . 
     In various embodiments, with combined reference to  FIGS. 1A and 2 , detonation transfer assembly  200  may comprise a primary explosive  210  and a secondary  220  adjacent to primary explosive  210 . In operation, input energy  205  may include, for example, the mechanical energy from first stage pyrotechnic  120  (e.g., movement of a firing pin), and/or energy produced by the actuation or ignition of an initiator  303  (depicted in  FIGS. 3A-3C ), such as a primer. Input energy  205  may, in response, ignite primary explosive  210 . Primary explosive  210  may ignite and/or detonate, creating transfer energy  215 . Transfer energy  215  produced by primary explosive  210  may provide the energy necessary to ignite and/or detonate secondary explosive  220  and cause secondary explosive  220  to detonate. The detonation of secondary explosive  220  may produce transfer output energy  225 , which may be configured to ignite energetic transfer line  130 . 
     In various embodiments, detonation transfer assembly  200  may be configured to withstand slow cook-off without primary explosive  210  and/or secondary explosive  220  igniting, detonating, or otherwise actuating, and/or without primary explosive  210  and/or secondary explosive  220  thermally degrading. Thermal degradation may entail a material, such as primary explosive  210  and/or secondary explosive  220 , degrading in response to exposure to heat such that the material will no longer actuate, ignite, and/or detonate when desired and/or triggered. Slow cook-off is the exposure to gradually increasing temperature over an extended period of time. Slow cook-off may comprise a temperature, starting at 50° C. (122° F.), and a temperature increase rate of 3.3° C. (5.9° F.) per hour for at least 20 hours. In various embodiments, the slow cook-off may comprise a temperature increase rate of 3.3° C. (5.9° F.) per hour for at least 40 hours or 48 hours. In various embodiments, the slow cook-off may comprise a temperature increase rate of 3.3° C. per hour for at least 60 hours. Accordingly, primary explosive  210  and/or secondary explosive  220  may comprise thermally insensitive initiation materials, which are materials having the chemical stability to withstand mechanical or energetic shocks, the rapid and/or slow increase in temperature, and/or impact by a physical object, without igniting, detonating, and/or actuating. More specifically, primary explosive  210  and/or secondary explosive  220  may comprise thermally insensitive initiation materials capable of resisting detonation, ignition, and/or thermal degradation in response to exposure to slow cook-off, and/or prolonged exposure to temperatures ranging from 116° C. (240° F.) to 177° C. (350° F.). In various embodiments, primary explosive  210  and/or secondary explosive  220  may comprise thermally insensitive initiation materials capable of withstanding prolonged exposure to temperatures ranging from 116° C. (240° F.) to 204° C. (400° F.), or temperatures ranging from 177° C. (350° F.) to 204° C. (400° F.). 
     In various embodiments, primary explosive  210  may comprise lead azide (molecular formula: Pb(N 3 ) 2 ), a lead-free alternative to lead azide such as copper(I) 5-nitrotetrazolate, which is know in industry as “DBX-1” (molecular formula: C 2 Cu 2 N 10 O 4 ), and/or any other suitable primary explosive  210  that can withstand slow cook-off in conjunction with secondary explosive  220 . Lead azide has an auto-ignition temperature of 300° C. (572° F.). The auto ignition temperature is the temperature at which a reactive material will spontaneously ignite under normal atmospheric conditions without an external source of ignition, such as a spark. The chemical structure of DBX-1 is show in Diagram 1 below, which has an auto-ignition temperature of about 340° C. (644° F.) to 360° C. (680° F.). As used only in this context, the term “about” refers to plus or minus 10° C. (18° F.). Therefore lead azide and DBX-1 do not have a risk of igniting without an external ignition source until temperatures reach about 300° C. (572° F.) or above, wherein the term “about” as used in this context only, means plus or minus 10° C. 
     
       
         
         
             
             
         
       
     
     In various embodiments, secondary explosive  220  may comprise hexanitrostilbene (“HNS”), nonanitroterphenyl (“NONA”), and/or any other suitable secondary explosive  220  that can withstand slow cook-off in conjunction with primary explosive  210 . HNS has an ignition onset temperature of about 320° C. (608° F.), which is preceded by an endothermic melt that occurs at about 317° C. (603° F.). NONA is very thermally stable, having a melting point of 440° C. (824° F.). As used only in this context, the term “about” refers to plus or minus 10° C. (18° F.). In various embodiments, primary explosive  210  and secondary explosive  220  may comprise the same thermally insensitive initiation material. In various embodiments, primary explosive  210  and secondary explosive  220  both may comprise, for example, lead azide, DBX-1, HNS, and/or NONA. 
     In various embodiments, energetic transfer line  130  may be configured to be actuated and/or ignited by transfer output energy  225  created by detonation transfer assembly. Energetic transfer line  130  may be, for example, a linear shape charge comprising an explosive material configured to weaken and/or rupture a metal casing coupled to the linear shape charge. For example, energetic transfer line  130 , such as a linear shape charge, may be disposed adjacent to a motor  50 , such as a rocket motor. In operation, energetic transfer line  130  may be actuated and/or ignited by transfer output energy  225 , causing the explosive material in energetic transfer line  130  to detonate. Such a detonation may result in the damaging of, i.e., the weakening or destruction of, a portion of a vessel, such as a motor case, which may house a propellant. The propellant may be ignited by the explosion of the explosive material in energetic transfer line  130 . In various embodiments in which the vessel is a motor case, the motor case may be weakened by the explosion of the explosive material in energetic transfer line  130 , and the propellant within the motor case may ignite without an external ignition source, but instead, the propellant may ignite as a result of heat and pressure around the motor case. The detonation of the explosive material in energetic transfer line  130  may mitigate a potential hazard, such as exposure to a thermal threat such as a fire, by venting energy from the propellant to prevent the rocket or missile comprising the propellant from moving and/or exploding. Otherwise, the thermal threat may cause an explosion of the propellant, causing the rocket or missile comprising the propellant to be propelled in a direction or explode. In various embodiments, energetic transfer line  130  may transfer an energetic signal to another component within TIV system  150  or to a separate system. 
       FIG. 1B  depicts a TIV system  150 , in accordance with various embodiments. TIV system  150  may comprise a thermal sensor  111 , a first stage pyrotechnic  121  coupled to thermal sensor  111 , a detonation transfer assembly  200  coupled to first stage pyrotechnic  121 , and/or an energetic transfer line  131 . As depicted in  FIG. 1B , energetic transfer line  131  is a linear shape charge. TIV system  150  may further comprise a system casing  105 , which may house the other components of TIV system  150 . System casing  105  may be coupled to a motor  50  such that at least energetic transfer line  131  (e.g., linear shape charge) is coupled to the motor and/or motor case. In response to energetic transfer line  131  being coupled to the motor and/or motor case, in operation, in response to actuation, ignition, and/or detonation of energetic transfer line  131 , a propellant in motor and/or motor case may be ignited, and/or the motor case may be damaged, i.e., weakened or ruptured, as described herein. 
       FIGS. 3A-3C  depict detonation transfer assemblies  300 A- 300 C, respectively, in accordance with various embodiments. An A-R-C axis has been included in the drawings to illustrate the axial (A), radial (R) and circumferential (C) directions. In various embodiments, detonation transfer assemblies  300 A- 300 C may comprise an external casing  306 A- 306 C, respectively. External casing  306 A- 306 C may be comprised of any suitable material, such as stainless steel. Detonation transfer assemblies  300 A- 300 C and/or external casings  306 A- 306 C may comprise an input end  301  and an output end  302  axially opposed of input end  301 . In various embodiments, detonation transfer assemblies  300 A- 300 C may comprise an initiator  303  adjacent to input end  301 . With brief reference to  FIGS. 2 and 3A-3C , initiator  303  may be a device configured to create input energy  205  to ignite primary explosive  210 . In various embodiments, initiator  303  may be a primer comprising a primer mix of explosive material which is configured to detonate in response to being triggered, but also configured to avoid detonation in environments including temperatures of 204° C. (400° F.) and above. 
     In various embodiments, an explosive column  317 A- 317 C in detonation transfer assemblies  300 A- 300 C, respectively, may be disposed axially-adjacent to initiator  303  and span axially between initiator  303  and output end  302 . In various embodiments, within explosive columns  317 A- 317 C, there may be a column void  304 A- 304 C, respectively, adjacent to initiator  303 . A primary explosive  310 A- 310 C may be disposed axially-adjacent to column voids  304 A- 304 C, respectively, in explosive columns  317 A- 317 C, respectively. A secondary explosive  320 A- 320 C may be disposed axially-adjacent to primary explosives  310 A- 310 C, respectively, and output end  302 . 
     In various embodiments, explosive columns  317 A- 317 C may comprise various dimensions depending on the explosive materials used as primary and/or secondary explosives. In various embodiments in which a primary and/or secondary explosive is used that has a detonation energy that is less than tradition explosive materials used in detonation transfer assemblies such as hexogen (C 2 H 6 N 6 O 6 ) (“RDX”) or octogen (C 4 H 8 N 8 O 8 ) (“HMX”), more of the primary and/or secondary explosive will be required to achieve the same detonation energy as the traditional explosive materials. For example, HMX has an energy of detonation of 10.87 KJ/cc, while HNS has an energy of detonation of 8.08 KJ/cc. Therefore, in order to achieve the same amount of detonation energy with HNS as would have been produced by HMX, a greater mass of HNS should be used than HMX in the explosive column, which is associated with an adjustment of the dimensions of explosive column  317 A- 317 C. In various embodiments, a column height, such as column height  322 A of explosive column  317 A, may be uniform across the axial length of the explosive column. With reference to  FIG. 3A , in various embodiments, a column height  322 A of explosive column  317 A may be less than one-third the height of detonation transfer assembly  300 A, and/or less than one-third the height of external casing  306 A. With reference to  FIG. 3B , in various embodiments, a column height  322 B may be greater than one-third the height of detonation transfer assembly  300 B, and/or greater than one-third the height of external casing  306 B. Accordingly, explosive column  317 B may have a larger cross-sectional area than explosive column  317 A. 
     Referring to  FIG. 3C , in various embodiments, the column height of an explosive column may not be uniform across the axial length of the explosive column. In various embodiments, column height  322 C may increase from a first portion of explosive column  317 C to a second portion of explosive column  317 C. In various embodiments, the first portion may be at the portion of secondary explosive  320 C that is closest to primary explosive  310 C. In various embodiments, the first portion may be the portion of explosive column  317 C adjacent to column void  304 C, and/or adjacent to initiator  303 . In various embodiments, the second portion may be output end  302  or adjacent to output end  302 . In various embodiments, the second portion may be adjacent to secondary explosive  320 C, primary explosive  310 C, and/or column void  304 C. As depicted in  FIG. 3C , the first portion is point  321 , and the second portion is at output end  302  such that column height  322 C increases throughout the axial span of secondary explosive  320 C. Therefore, the second portion of explosive column  317 C at output end  302  has a larger cross-sectional area than the first portion of explosive column  317 C at point  321 . Such a configuration may be to allow more of the primary and/or secondary explosive into detonation transfer assembly  200  to achieve a desired transfer output energy  225  (depicted in  FIG. 2 ). 
     In various embodiments, the lengths  324 A- 324 C of different sections of explosive columns  317 A- 317 C, respectively, may vary. As depicted in  FIGS. 3A-3C , the lengths  324 A- 324 C of primary explosives  310 A- 310 C, respectively, may vary depending on the desired volume of primary explosive  310 A- 310 C within explosive columns  317 A- 317 C, respectively. The desired volume of primary explosive  310 A- 310 C may depend on the column height  322 A- 322 C, respectively, throughout explosive columns  317 A- 317 C, respectively. The lengths of secondary explosives  320 A- 320 C and/or column voids  304 A- 304 C may also vary depending on the desired volume of primary explosives  310 A- 310 C, secondary explosives  320 A- 320 C, and/or column voids  304 A- 304 C, respectively, which may also depend on the column height  322 A- 322 C throughout explosive columns  317 A- 317 C, respectively. As discussed herein, the desired volume of primary explosives  310 A- 310 C and/or secondary explosives  320 A- 320 C may depend on a desired detonation energy to be achieved by primary explosives  310 A- 310 C and/or secondary explosives  320 A- 320 C. 
     In various embodiments, primary explosives  310 A- 310 C and/or secondary explosives  320 A- 320 C may comprise thermally insensitive initiation materials, as described herein. For example, primary explosives  310 A- 310 C may comprise lead azide, DBX-1, and/or any other suitable primary explosive. Secondary explosives  320 A- 320 C may comprise, for example, HNS, NONA, and/or any other suitable secondary explosive. 
     In operation, with reference to  FIGS. 1A, 1B, 2, and 3A-3C , initiator  303  may receive the output energy from first stage pyrotechnic  120 , via a firing pin, for example. Initiator  303  may be a primer, and the primer mix within the primer may ignite and cause energy to flow through column void  304 A- 304 C. In response, primary explosive  310 A- 310 C may be ignited, which may result in secondary explosive  320 A- 320 C igniting, and in response, transfer output energy  225  may be created. 
     In various embodiments, referring back to  FIG. 2 , primary explosive  210  may comprise the same thermally insensitive initiation material as secondary explosive  220 , such that there is one thermally insensitive initiation material in the explosive column (such as explosive columns  317 A- 317 C in  FIGS. 3A-3C ) in detonation transfer assembly  200 . In various embodiments, primary explosive  210  and secondary explosive  220 , i.e., the one thermally insensitive initiation material, may comprise, for example, lead azide, DBX-1, HNS, and/or NONA. In various embodiments, in which primary explosive  210  and secondary explosive  220  comprise the one thermally insensitive initiation material, the one thermally insensitive initiation material may be ignited by an exploding foil initiator, which may be comprised in initiator  303  (depicted in  FIGS. 3A-3C ). In various embodiments, the exploding foil initiator may not be a component of detonation transfer assembly  200 . An exploding foil initiator may comprise a metal foil which is explosively vaporized, for example, by applying a high voltage (i.e., several thousand volts) of electric current to the metal foil, and in response, a projectile may be propelled at a high velocity (e.g., thousands of meters per second) toward the one thermally insensitive initiation material. A high-velocity impact by of the projectile with the one thermally insensitive initiation material may ignite the one thermally insensitive initiation material, causing the one thermally insensitive initiation material to detonate and create transfer output energy  225 . In various embodiments, in which primary explosive  210  and secondary explosive  220  comprise the one thermally insensitive initiation material, the TIV system  100  (depicted in  FIG. 1A ) may or may not comprise thermal sensor  110  and/or first stage pyrotechnic  120 . 
     Referring to  FIG. 4 , a method  400  of igniting a TIV system, in accordance with various embodiments. With combined reference to  FIGS. 1A, 1B, 2, and 4 , a thermal sensor  110  may be actuated and/or ignited (step  402 ). In response to the actuation and/or ignition of thermal sensor  110 , a first stage pyrotechnic  120  may be ignited (step  404 ). First stage pyrotechnic  120  may produce an output energy, which may mechanically act on an ignition device, such as a firing pin. The output energy from first stage pyrotechnic  120  may result in actuating and/or igniting a detonation transfer assembly  200 . Actuation and/or ignition of detonation transfer assembly  200  may comprise activating and/or igniting an initiator (such as initiator  303  in  FIGS. 3A-3C ), for example a primer or an exploding foil initiator, igniting a primary explosive  210  (step  406 ) in response to initiator activation, and/or igniting a secondary explosive  220  (step  408 ) in response to the primary explosive  210  ignition. Ignited secondary explosive  220  may produce a transfer output energy  225 , which may ignite an energetic transfer line  130  (step  410 ). Energetic transfer line  130  may be coupled to a vessel holding propellant, or any other detonatable material, for instance within a motor case comprising propellant. Energetic transfer line  130  may detonate in response to being ignited, and may damage, i.e., weaken and/or rupture, the vessel (step  412 ). Damaging the vessel holding the propellant may cause the propellant or other detonatable material within a rocket motor or other device to ignite. In various embodiments, primary explosive  210  and/or secondary explosive  220  may be any suitable thermally insensitive initiation material, as described herein. In various embodiments, primary explosive  210  and secondary explosive  220  may comprise the same material, as described herein. 
     Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials. 
     Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment”, “an embodiment”, “various embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments. 
     Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.