Abstract:
An apparatus and method for testing electromagnetic effects. In one advantageous embodiment, the apparatus has a chamber, a door connected to the chamber, a gas supply system attached to the chamber, a plurality of electrical connectors attached to the chamber, a removable platform, and a specimen holding. The chamber has an opening into an interior space located in the chamber. The door closes to seal the opening and prevents a flammable gaseous mixture in the interior space from leaking out of the interior space of the chamber. The gas supply system is configured for connection to the gas supply system to allow introduction of the flammable gaseous mixture into the interior space. The removable platform is moveable into and out of the interior space of the chamber through the opening. The specimen holding system located on the removable platform and is configured to hold a specimen and is electrically connected to the plurality of electrical connectors when the removable platform is placed into the chamber, wherein an electrical current travels through the specimen when the electrical current is supplied by an electrical current source that is connected to the plurality of electrical connectors.

Description:
BACKGROUND INFORMATION 
   1. Field 
   The present invention relates to a method and apparatus for performing electromagnetic tests on components in an enclosed chamber. 
   2. Background 
   Aircraft are occasionally struck by lightning when traveling near or through a thunderstorm. Because, until recently, most aircraft structure was aluminum, these strikes did little or no damage. With more aircraft structure being fabricated from composite material, the electromagnetic effects of lightning strikes have taken on greater significance. In particular, an electrical strike may cause arcing between different components in the aircraft. This type of arcing is undesirable because an arc may cause flammable vapors or liquids in the aircraft to ignite. 
   In designing an aircraft, the different designers and engineers take into account electromagnetic effects, such as lightning. For example, cables and equipment are protected from damaging surges or transients through techniques such as shielding, grounding, and the application of surge protection or suppression devices. As another example, fuel systems and other systems that carry flammable liquids or vapors are an area of concern because even a tiny spark or arc may be disastrous. Extreme precautions are taken to assure that currents caused by lightning strike cannot cause sparks in any portion of an aircraft&#39;s fuel system. All of the structural joints and fasteners are designed to prevent sparks as lightning current passes from one section to another section of the aircraft. Other components such as access doors, fuel filler caps, and vents are designed to withstand lightning. All of the fuel lines that carry fuel into the engines are verified to be protected against lightning. Similar design concerns are made with respect to other systems that carry flammable fluids or vapors. 
   In verifying these designs, tests are performed on the various components to ensure that simulated lightning strikes do not cause arcing. These same concerns are also present in other environments in which high voltages or large electrical currents may occur. 
   Currently, testing is performed in a number of different ways. Electrical arcing may be determined to have occurred using photographic paper in a darkened chamber or by the ignition of a flammable mixture that has been introduced into an enclosed chamber. When using the ignition method, the particular component is placed into a chamber and the component is connected to an electrical source. A flammable gas mixture is introduced into the chamber and the electrical source is activated to simulate an electromagnetic event, such as a lightning strike. Should an ignition event be observed, it is assumed that arcing of sufficient energy to initiate the ignition has occurred. 
   Large chambers are currently used to test the many different possible components that go into an aircraft. Further, the existing testing systems require the test setup to be dismantled and reassembled between tests. These types of testing systems are time consuming and expensive because of the time and amount of gas required for each test. The individual setups for each test require a great deal of time and effort between each test and most test programs involve many separate tests. Added up these multiple tests require a great deal of time to setup, disassemble, and reassemble. In addition, the large chamber volume requires additional gas mixture and the time required to fill the chamber multiple times. 
   SUMMARY 
   The advantageous embodiments of the present invention provide an apparatus and method for testing electromagnetic effects. In one advantageous embodiment, the apparatus has a chamber, a door connected to the chamber, a gas supply system attached to the chamber, a plurality of electrical connectors attached to the chamber, a removable platform, and a specimen holding system. The chamber has an opening into an interior space located in the chamber. The door closes to seal the opening and prevents a flammable gaseous mixture in the interior space from leaking out of the interior space of the chamber. The gas supply system is configured for connection to the chamber to allow introduction of the flammable gaseous mixture into the interior space. The removable platform is moveable into and out of the interior space of the chamber through the opening. The specimen holding system located on the removable platform and is configured to hold a specimen and is electrically connected to the plurality of electrical connectors when the removable platform is placed into the chamber, wherein an electrical current travels through the specimen when the electrical current is supplied by an electrical current source that is connected to the plurality of electrical connectors. 
   In another advantageous embodiment, the apparatus has a chamber, an electrical interface in the chamber, a platform, a port, and a specimen mounting apparatus. The platform is moveable into and out of the chamber. The port allows introduction of a flammable gaseous mixture into the interior of the chamber. The specimen mounting apparatus is located on the platform to which the actual test specimen may be attached. Inserting the platform into the chamber provides an electrical connection between the electrical interface and a specimen mounted on the mounting apparatus. An electrical current applied to the electrical interface travels from the electrical interface to the mounting apparatus and through the specimen. 
   In yet another advantageous embodiment, a method is used to test specimens. The method includes connecting a current source to an electrical interface in the test chamber, connecting a gas supply to a port in the test chamber, and mounting a specimen on a platform. The platform with the specimen is placed into the test chamber. The test chamber is sealed after placing the platform into the test chamber. A flammable gaseous mixture is introduced into the interior of the test chamber after sealing the test chamber. An electrical current is supplied from the current source to the electrical interface to simulate an electromagnetic effect on the specimen. 
   The features, functions, and advantages can be achieved independently in various embodiments of the present invention or may be combined in yet other embodiments in which further details can be seen with reference to the following description and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an advantageous embodiment of the present invention when read in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a diagram illustrating an isometric view of a fluid fitting electromagnetic test chamber in accordance with an advantageous embodiment of the present invention; 
       FIG. 2  is a diagram of a top plan view of a test chamber in accordance with an advantageous embodiment of the present invention; 
       FIG. 3  is a bottom view of a test chamber in accordance with an advantageous embodiment of the present invention; 
       FIG. 4  is a side view of a test chamber in accordance with an advantageous embodiment of the present invention; 
       FIG. 5  is a rear view of a test chamber in accordance with an advantageous embodiment of the present invention; 
       FIG. 6  provides a front view of a test chamber in accordance with an advantageous embodiment of the present invention; 
       FIG. 7  is a side view of a tray and the specimen clamping system in accordance with an advantageous embodiment of the present invention; 
       FIG. 8  is a bottom view of a tray in accordance with an advantageous embodiment of the present invention; 
       FIG. 9  is a top view of a tray in accordance with an advantageous embodiment of the present invention; 
       FIG. 10  is a view of an end of a tray and the specimen clamping system in accordance with an advantageous embodiment of the present invention; 
       FIG. 11  is a more detailed illustration of the specimen clamping system in accordance with an advantageous embodiment of the present invention; 
       FIG. 12  is a diagram illustrating a connection of a cable to a pin in accordance with an advantageous embodiment of the present invention; 
       FIG. 13  is a cross sectional view of the complete hardware described in accordance with an advantageous embodiment of the present invention; 
       FIG. 14  is a cross sectional view of the complete hardware described in accordance with an advantageous embodiment of the present invention; and 
       FIG. 15  is a flowchart of a process for testing specimens in accordance with an advantageous embodiment of the present invention; and 
       FIG. 16  is an isometric view of a tray and specimen support system with a representative specimen installed. 
   

   DETAILED DESCRIPTION 
   With reference now to the figures, and in particular with reference to  FIG. 1 , a diagram illustrating an isometric view of a fluid fitting electromagnetic test chamber is depicted in accordance with an advantageous embodiment of the present invention. In this particular example, test chamber  100  is an example of one implementation for an electromagnetic effects test chamber. Test chamber  100 , in the different advantageous embodiments of the present invention, reduces the time required to perform testing of specimens. 
   Box  102  has footers  104 ,  106 , and  108  on bottom side  110  of box  102 . These footers are used to clamp or attach test chamber  100  to a structure, such as a table or a cart. Box  102  also contains windows  112 ,  114 ,  116 , and  118 . Window  112  is found on end  120  of box  102 . Windows  114  and  116  are found on side  122  of box  102 . Window  118  is found on top side  124  of box  102 . The windows may be replaced with blanking plates or camera mounts should the need to use the “Light on Film” technique arise. Box  102  also contains port  126  on side  122 . Port  126  provides a connection to introduce gas into the interior of box  102 . Windows also are present on the side opposite side  122 , which are not visible from this view. Door  128  provides a mechanism to place test components into the interior of box  102  of test chamber  100 . 
   Further, door  128  is magnetically latched to prevent an over pressure condition. An over pressure condition is a condition in which the pressure in test chamber  100  may increase to a level such that damage to test chamber  100  may occur. For example, if the pressure increases too rapidly with the occurrence of an ignition event, a window could crack or shatter if door  128  was secured such that it could not open when pressure increased. An over pressure condition could occur if an improper gas mixture is used. 
   Reaction ball  130  and exhaust hole  132  provide an escape valve for gasses within the interior of box  102  during filling operations. Reaction ball  130  will pop up or move away from exhaust hole  132  to allow gasses to escape in the event that an ignition of gasses occurs within box  102 . In these examples, sockets  134 ,  136 , and  138  provide an electrical connection into the interior of box  102 . These sockets provide a connection between an electrical source and the components within box  102  to simulate an electromagnetic event. Ignition unit  140  provides a spark of known energy to ignite gasses within the interior of box  102  verifying the gaseous mixture was flammable and was present inside test chamber  100  during the test. 
   Test chamber  100  provides an apparatus for testing components or parts such as fluid fittings for arcing or other electromagnetic effects in a flammable gas mixture. This chamber provides for electromagnetic effects testing with a flammable gas mixture, allows the introduction of electrical currents simulating lightning strikes, and provides a high degree of reliability to the testing. Further, test chamber  100  also provides an ability to increase the number of tests that may be performed within a period of time. 
   Test chamber  100  includes a platform or tray (not shown) that is to be placed into the test chamber. Specimens are to be mounted on this platform or tray. Multiple trays may be used to increase the speed at which components may be tested. After testing of one component in one tray, that tray may be removed from test chamber  100 . A second tray may then be placed into test chamber  100 . The second specimen on the second test tray may be tested while the specimen attached to the first tray is removed and a third specimen is attached to the first tray. The tray used within test chamber  100  is illustrated and described with respect to  FIGS. 7-13  below. 
   Also, test chamber  100  has a size that requires a smaller volume of flammable gas mixtures for testing specimens in the illustrative examples. In particular, this smaller volume is especially useful for smaller specimens, such as connectors in the form of a joint, sleeve, or clamp that connects tubes, hoses, or other types of conduits to one another. This type of test chamber may also be used to test types of specimens other than the ones described in these examples. 
   For example, the different illustrative embodiments may be applied to test electrical components or other parts. As a result, less time is required to fill test chamber  100  as compared to other currently available test chambers. Further, the amount of flammable gas mixture required for each test also is reduced. Test chamber  100  also includes flexible nozzle  1312  designed to ensure proper flow of flammable gases into and around the test parts. This feature is accessed through port  126  in these examples. 
   Thus, the different advantageous embodiments of the present invention provide improved reliability and repeatability of testing as well as reducing the time required to perform each test. Further, the amount of gas needed for each test also is reduced. With the use of multiple trays, test setups may be accomplished outside of the test chamber. With the use of these trays, the specimens being tested can be quickly positioned in the chamber for each test. 
   This advantage is provided in one advantageous embodiment through the clamping system in the tray and the electrical connection provided between the test chamber and the tray that lead to the test specimens. For example, the test chamber, in these advantageous embodiments, is capable of running a test every 10 minutes, as compared to the 3 to 4 hours per test that can be run with existing chambers, designed to house larger components. 
   In these examples, test chamber  100  is fully wired to provide electrical test currents to test specimens when the tray is placed into test chamber  100 . Further, the gaseous mixture provided to the test specimens is provided through port  126 , which contains a flexible tube within test chamber  100 . Port  126  is connected to a gas supply system. 
   Test chamber  100  also provides another advantage through fixed and isolated electrical connections to interface laboratory equipment. These connections do not have to be disconnected and then reconnected between each test specimen. 
   Turning now to  FIG. 2 , a diagram of a top plan view of a test chamber is depicted in accordance with an advantageous embodiment of the present invention. In this example, windows  200  and  202  are located on side  204  on box  102  of test chamber  100 . Additionally, in this view of box  102 , window  206  can be seen on door  128 . 
   With reference next to  FIG. 3 , a bottom view of a test chamber is depicted in accordance with an advantageous embodiment of the present invention. In this example, door  128  is attached to box  102  of test chamber  100  using hinge  300 . 
   Turning now to  FIG. 4 , a side view of a test chamber is depicted in accordance with an advantageous embodiment of the present invention. In this example, door  128  may move along line  400  to allow for a tray to be placed into and removed from the interior of box  102 . 
   Turning now to  FIG. 5 , a rear view of test chamber  100  is depicted in accordance with an advantageous embodiment of the present invention. Next,  FIG. 6  provides a front view of test chamber  100  in accordance with an advantageous embodiment of the present invention. 
   With reference now to  FIGS. 7-13 , different views and cross sections of a tray are depicted in accordance with an advantageous embodiment of the present invention. In these examples, the tray provides another advantage by allowing different specimens to be tested without having to take time to mount or connect and dismount or disconnect each specimen for a test. This type of feature is provided in these examples through using multiple trays. Specimens may be attached or mounted on the different trays prior to testing or while testing occurs. 
   As a result, while a specimen is being tested in test chamber  100 , another specimen may be mounted on another tray while the testing occurs. As a result, time is saved by not having to wait for testing to finish before mounting another specimen. When one specimen has been tested, the tray with that specimen may be removed from test chamber  100  and another tray with another specimen may be promptly inserted. 
   With reference first to  FIG. 7 , a side view of a tray is depicted in accordance with an advantageous embodiment of the present invention. Tray  700  is an example of a tray that may be placed into box  102  of test chamber  100 . In this view of tray  700 , specimen clamps  702 ,  704 , and  706  extend from surface  710  of planar section  708  of tray  700 . These specimen clamps are used to physically mount specimens. Further, these specimen clamps provide electrical connections to connect the specimen mounted with a power electrical source. The mounting posts help center the test specimen in the test chamber interior. 
   In these illustrative examples, planar section  708  is made of an insulator material, such as, for example, polycarbonate. Of course, any insulating material may be used depending on the particular examples. Planar section  708  has a configuration that is designed to slide into the interior of box  102 . In this example, tray  700  also includes beam  712 . Beam  712  is a planar section that is mounted perpendicular to surface  714  of tray  700 . 
   Tray  700  is an example of a platform that may be used to mount and test specimens. The illustration of tray  700  is only meant to illustrate one embodiment. For example, other embodiments may use other numbers of specimen clamps or other mechanisms to hold specimens other than using clamps. 
   Turning next to  FIG. 8 , a bottom view of tray  700  is depicted in accordance with an advantageous embodiment of the present invention. As can be seen, in addition to beam  712  extending perpendicular from surface  714  of tray  700 , beams  800 ,  802 , and  804  also are present. These beams also extend in a direction perpendicular from surface  714  of tray  700 . 
   Additionally, in this view, tray  700  includes hole  806 , which is oval in shape. Hole  806  in tray  700  provides a handle or grip for a user to insert and remove tray  700  from box  102 . In these examples, section  808  of tray  700  is covered with a rubber gasket to provide additional sealing between the top of box  102  in  FIG. 1  and the volume below tray  700 . The sealing prevents the flammable gaseous mixture from reaching the bottom of box  102  in amounts that can cause an ignition by the components under tray  700 . 
   Beams  712 ,  800 ,  802 , and  804  are configured to support tray  700  when outside test chamber  100  in  FIG. 1 , preventing electrical connections, fasteners and other hardware from contacting the supporting surface. In these examples, cables  810 ,  812 , and  814  are used to provide an electrical connection between mounting posts  702 ,  704 , and  706 , and pins  816 ,  818 , and  820 , respectively. 
   When tray  700  is placed into box  102  in the test chamber, pins  816 ,  818 , and  820  fit into sockets  134 ,  136 , and  138 . In this manner, an electrical connection may be quickly made to the specimen without having to connect and disconnect laboratory equipment. The connections to sockets  134 ,  136 , and  138  do not have to be connected and disconnected each time a new specimen is tested. In this example, beams  822  and  824  also are present to provide for additional structural rigidity in these examples. Further, these beams also serve to separate cables  810 ,  812 , and  814  in these examples. Cables  810 ,  812 , and  814  may be any type of cable that has a conductive core of sufficient current carrying capacity for simulating a lightning strike and an insulated exterior capable of electrically insulating the voltage required by the test. 
   With reference to  FIG. 9 , a top view of tray  700  is depicted in accordance with an advantageous embodiment of the present invention. 
   Turning now to  FIG. 10 , a view of an end of tray  700  is depicted in accordance with an advantageous embodiment of the present invention. In this example, a more detailed illustration of mounting post  702  is shown. 
   In these examples, mounting post  702  includes riser  1000 , cradle  1002 , and cap  1004 . Riser  1000  extends from surface  710  of planar section  708  in tray  700 . Cradle  1002  is attached to riser  1000 . Cap  1004  covers cradle  1002  to clamp a test specimen in place. In this illustrative example, opening  1006  is formed when cap  1004  is attached to cradle  1002 . Further, insulator  1008  is present within the step or groove formed within cap  1004  and cradle  1002 . A portion of a specimen may be secured between cradle  1002  and cap  1004 . A test specimen, such as a tube or hose may be secured between these two components. 
   Turning now to  FIG. 11 , a more detailed illustration of a specimen clamp is depicted in accordance with an advantageous embodiment of the present invention. Section  1100  is a more detailed illustration of specimen clamp  702  in cross section along line B-B. In this example, cradle  1002  and cap  1004  are made of a conductive metal, such as aluminum. Of course, other types of conductive materials may be used. Copper, bronze, or steel are other examples of conductive materials that may be used. 
   Riser  1000  also is made of a conductive material in these examples. Alternatively, riser  1000  may be made from a non-conducting material. In this particular example, riser  1000  may be made of just about any material with sufficient strength, conductive or non-conductive. Terminal assembly  1105  is attached to surface  714  of planar section  708 . Terminal assembly  1105  includes mounting post  1104  and plate  1102  both of which should be made from a highly conductive material such as copper. Mounting post  1104  may be made as part of terminal assembly  1102  or may be a separate component that is welded or brazed to terminal  1102 . Mounting post  1104  provides a connector for cable  810 , which is fastened to mounting post  1104  with a nut and washer (not shown). Planar section  708  is disposed between terminal assembly  1105  and riser  1000 . 
   Electrical connection is made between terminal assembly  1105  and specimen cradle  1002  through connectors  1106  and  1108 . In these examples, connectors  1106  and  1108  extend through terminal assembly  1105 , through planar section  708 , and through riser  1000  into cradle  1002 . This connector serves to physically connect terminal assembly  1105 , riser  1000 , and cradle  1002  to each other. 
   Further, connectors  1106  and  1108  serve to provide a conductive path for current that may run between cable  810  and cradle  1002 . In these examples, connectors  1106  and  1108  take the form of a copper rod that has been threaded on both ends and a nut brazed to one end. Of course, any highly conductive material may be used. 
   Connectors  1110  and  1112  are used to connect cap  1004  to cradle  1002 . Cap  1004  and cradle  1002  must come in contact face to face to provide a current path and eliminate a possible site of arcing that may result in false positive test results. Connectors  1110  and  1112  are removable to allow cap  1004  to be removed from and then reattached to cradle  1002 . A portion of a specimen may be placed between cap  1004  and cradle  1002 . Then, connectors  1110  and  1112  may be tightened to hold the specimen in place. In this manner, a portion of the specimen is now rigidly fixed in place and connected in a manner that allows for electrical currents to be run through the specimen. 
   Turning now to  FIG. 12 , a diagram illustrating a connection of a cable to a socket pin is depicted in accordance with an advantageous embodiment of the present invention. The illustrated connection is a cross section along lines A-A in  FIG. 8 . In this example, pin  816  uses a highly conductive material and provides a connection to cable  810 . Pin  816  connects with a socket, such as socket  138  when tray  700  is placed into box  102 . 
   Turning now to  FIG. 13 , a cross sectional view of a test chamber is depicted in accordance with an advantageous embodiment of the present invention. In this particular example, the illustration in  FIG. 13  is taken along lines C-C in  FIG. 4 . In this illustrative example, tray  700  has been placed into interior  1300  of box  102 . As can be seen, planar section  708  of tray  700  serves to create section  1304  within interior  1300 . Section  1304  is isolated from the electrical connections located on surface  714  by the planar section  708 . Surface  714  rests on the flanges  1301  and  1303  of box  102 . This configuration results in seals around the periphery of tray  700 , and a flap covering the handle of tray  700 . The flanges and flaps serve to reduce the amount of gas that may move from section  1304  into section  1306  and section  1308 . In other words, the seal between sections  1308  and  1304  is made between tray  708 , the flanges on bottom  110  of box  102  and the two seals, one on the front of the box and one on the door. 
   These different enclosed sections do not need to be air tight in these examples but must be resistant to air movement. The sections are designed to prevent gas from moving within section  1304  into section  1308  in an amount that could cause an ignition of the gases and false positive result. All connections in areas  1306  and  1308  are made to be non-arcing but sealing the gas from these areas is further insurance against false positive test results. 
   In this example, flexible conduit  1312  is attached to port  126 . Flexible conduit  1312  provides a mechanism to introduce gas into section  1304  in interior  1300  of box  102  from a gas supply system. The flexible conduit is to be oriented such that the exiting gas is directed down the center of the test specimen ensuring the gas mixture is evenly distributed both inside and outside the test specimen. 
   Turning next to  FIG. 14 , a cross sectional view of a test chamber is depicted in accordance with an advantageous embodiment of the present invention. In this particular example, the cross section is taken along lines AA in  FIG. 5 . In this illustrative example, the volume in section  1304  of interior  1300  is approximately 2550 cubic inches. 
   Further, in this illustration, the electrical connection between tray  700  and socket  134  is seen in more detail. Tip  1400  of pin  816  fits into socket  134  allowing pin  816  to form an electrical connection between these two parts. Socket  134  may be connected to a power supply to supply current to cable  810  through pin  816 . This is duplicated at the other pin and socket pairs. In this manner, connections between laboratory equipment, such as a gas supply and a current source do not have to be connected and disconnected each time a test is run. 
   With reference now to  FIG. 15 , a flowchart of a process for testing specimens is depicted in accordance with an advantageous embodiment of the present invention. The process illustrated in  FIG. 15  may be implemented using the test chamber illustrated in  FIGS. 1-14 . 
   The process begins by connecting the test chamber to an electrical source (operation  1500 ). In these examples, the electrical source is connected to sockets  134 ,  136 , and  138 . Thereafter, the test chamber is connected to a gas supply (operation  1502 ). In these examples, the gas supply is connected to port  126  in  FIG. 1 . 
   Next, specimens are mounted using the specimen mounting clamps,  702 ,  704 , and  706  to trays, such as tray  700  in  FIG. 7 . In these examples, the specimens may be, for example, connectors in the form of a joint, sleeve, or clamp that connects tubes, hoses, or other types of conduits to each other. The specimens also may be an assembly of connectors with conduits. For example, a sleeve may connect two hoses together. An example of specimens mounted on a tray is described in more detail below with reference to  FIG. 16 . 
   Thereafter, an untested tray is selected for testing (operation  1506 ). The selected tray is placed into the test chamber (operation  1508 ) thereby making an electrical connection between  816 ,  818 ,  820  and  134 ,  136 , and  138  respectively. Next, the test chamber is sealed (operation  1510 ). The test chamber is sealed by closing the door to the test chamber in these examples. 
   A gas mixture is then introduced into the test chamber (operation  1512 ). Test specifications, may require a volumetric exchange of three to five times the chamber volume. The number of exchanges differs depending on test requirements. Because the chamber operates at atmospheric pressure, any gas entering the chamber must be matched by an equivalent volume of gas leaving the chamber. The exiting gas leaves the chamber through the reaction ball opening. When the gas supply is shut off, the reaction ball, acting as a check valve, seals this opening. 
   Afterwards, an electromagnetic effect is simulated in the test chamber (operation  1514 ). In these examples, the simulation is performed by applying the current to the sockets  134 ,  136 , and  138 . The electrical current travels through the sockets, pins, cables, terminal assembly connectors, specimen cradles, and through the specimens themselves, creating a circuit. Current may be routed to different components in different directions by applying current to the different external sockets  134 ,  136 ,  138 . Thereafter, any results, i.e. ignition events, are recorded (operation  1516 ). 
   If no ignition event was noted, spark generator  140  is charged and fired (operation  1518 ). At this point an ignition should occur indicating there was a flammable gas mixture present. 
   Then, a determination is then made as to whether untested trays are present (operation  1520 ). If untested trays are not present, the process terminates. Otherwise, the process returns to operation  1506  to select another tray for testing. In this manner, multiple trays may be prepared with specimens for testing. 
   In this manner, after one specimen is tested, the tray for that specimen may be removed and another tray with a different specimen may be promptly placed into the test chamber for immediate testing. This is opposed to having to wait for the specimen to be removed and for a new specimen to be mounted in the test chamber itself. Further, while a specimen is being tested in the test chamber, another specimen may be placed on an empty tray such that the new specimen is ready for testing when testing has been completed on the current specimen. 
   The different blocks illustrated in  FIG. 15  are presented in a particular order for purposes of providing one illustrative embodiment. Different operations may be performed in different orders depending on the particular implementation. For example, the electrical source may be connected to the test chamber after the gas supply is connected to the test chamber. Further, these specimens may be mounted before these other operations occur. In these examples, operations  1506 - 1514  are performed in a particular order for the test procedure being used in these examples. 
   With reference now to  FIG. 16 , a diagram of an isometric view of two specimens mounted on a tray is depicted in accordance with an advantageous embodiment of the present invention. In this example, tray  1600  is an example of tray  700  in  FIG. 7 . Tray  1600  includes specimen clamps  1602 ,  1604 , and  1606 . Specimen clamp  1602  includes cradle  1608  and cap  1610 . Specimen clamp  1604  includes cradle  1612  and cap  1614 . In a similar fashion, specimen clamp  1606  includes cradle  1616  and cap  1618 . 
   In these examples, specimens  1620  and  1622  are couplings used to connect tubes  1624 ,  1626 , and  1628 . In this example, specimen  1620  connects tubes  1624  and  1626 , while specimen  1622  connects tubes  1626  and  1628 . Tube  1624  is placed onto cradle  1608 ; tube  1626  is placed onto cradle  1612 ; and tube  1628  is placed onto cradle  1616 . 
   After the tubes have been placed onto cradles  1608 ,  1612 , and  1616 . After specimen  1620  has been placed onto these cradles, caps  1610 ,  1614 , and  1618  are secured to cradles  1608 ,  1612 , and  1616  to secure specimen  1620  in place for testing. As discussed above, specimen clamps  1602 ,  1604 , and  1606  conduct currents to simulate an electromagnetic event, such as a lightning strike. 
   One of specimen clamps  1602 ,  1604 , and  1606  acts as a current source while another one of these clamps acts as a ground. The remaining specimen clamps may be configured to function as a source or ground depending on the implementation. For example, specimen clamp  1604  may act as a ground while specimen clamps  1602  and  1606  are current sources. In another example, specimen clamp  1604  may function as a current source with specimen clamps  1602  and  1606 , functioning as ground. Other configurations are possible by changing the connections to the test chamber. 
   Also, the shape or configuration of specimen clamp  1602 ,  1604 , and  1606  may differ depending on the type of specimens that are to be tested. Further, depending on the implementation, a different cap and cradle setup may be mounted onto tray  1600  depending on the test to be performed. 
   The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Further, different advantageous embodiments may provide different advantages as compared to other advantageous embodiments. The embodiment or embodiments selected are chosen and described in order to best explain the principles of the invention, the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.