fig1 shows a lamp strobe sub - assembly 10 , similar to the lamp unit of the &# 39 ; 666 patent , with the electromagnetic suppressor units in accordance with the invention . lamp sub - assembly 10 contains three flash tubes 12 , each having an anode 14 and a cathode 16 . wires 18 connect anode 14 of one tube to cathode 16 of an adjacent tube . wires 18 are coated with a high - voltage insulating covering and / or covered with electrical tape . terminals 20 couple the completed circuit to a trigger transformer ( not shown ). the primary of the trigger transformer is connected to a power cable , which , in field applications , is frequently extremely long and may tend to attenuate the primary trigger voltage . also shown in fig1 are two pairs of ferrite suppression core assemblies 22 . each core assembly 22 surrounds a segment of one of wires 18 adjacent to tube anode 14 or cathode 16 . heat - shrink tubing 24 assists in holding cores 22 in place along wires 18 . fig2 shows details of the core assemblies 22 . cores 25 are comprised of grain ferrite or another suitable magnetic material . cores 25 are illustrated as having a generally square cross - section , but any other shape is suitable , including any polygon or a circle . round and hexagon shapes , for example , are common on the market . in addition , cores 22 may have one - piece or multi - piece construction . for example , u . s . pat . no . 5 , 355 , 109 shows two semi - cylindrical ferrite parts held in an insulating case , u . s . pat . no . 5 , 343 , 184 shows two parts that together have a square perimeter ( in cross - section ) and a circular interior edge , and u . s . pat . no . 5 , 287 , 074 shows a package containing two pairs of hemi - cylindrical cores disposed along the wire . the term &# 34 ; core &# 34 ; is intended to encompass any of those shapes , which have in common that the material is formed into a shape continuously surrounding an axial hole . foil 26 , of copper or another suitable metal or conductor , creates a continuous cover for the bulk of the exterior of core 25 . a thin strip of foil 26 ( 2 mils thickness has been found suitable ) is wrapped around core 25 , with the ends overlapped by a few millimeters , and a solder joint connects the overlapping ends of the strip . foil 26 is positioned so as to leave the edges 28 of the exterior surface of core 25 uncovered , and high - voltage insulating tape ( not shown ) is placed over the edges of the metal foil , to prevent arcing . similarly , ends 30 of core 25 and the interior hole should not be covered with foil . push - on terminal 32 is soldered to foil 26 , completing core assembly 22 . assemblies 22 can be formed around wire 18 or completed separately and slipped over wires 18 before the wires are connected to both anode 14 and cathode 16 of adjacent flash tubes 12 . fig2 a shows a side ( elevation ) view of the ferrite core assembly 22 of fig2 . core 25 has an axial hole 27 visible , through which wire 18 can pass , which forms the inner surface of the ferrite core . fig2 b shows an exemplary alternate embodiment of core 25 of fig2 and 2a , based on u . s . pat . no . 5 , 287 , 074 , in which hemi - cylindrical core elements 25a , 25b are fitted together by rotating them , as indicated by the broken line in the figure , around a hinge at point 29 - which is likely part of an external case ( not shown )- to form a completed core 25 having an axial hole 27 . fig3 shows a side view of one of tubes 12 , including wire 18 and one of core assemblies 22 . in a preferred embodiment , grounding wire 34 electrically connects terminal 32 of core assembly 22 to reflector 36 positioned behind tube 12 . although any form of grounding is suitable , the disclosed embodiment is particularly preferred because grounding wire 34 can be quite short , which reduces the arcing and the consequential risk of shorting the circuit . fig4 is a top view of the assembly , showing reflectors 36 , core assemblies 22 , and wires 18 , as previously described . preferably , wires 18 are bent as shown , allowing terminals 32 to abut reflectors 36 , thus further shortening the distance between foil 26 and ground . fig4 also shows wires 38 , which connect terminals 40 attached to the several reflectors 36 . thus , in the preferred embodiment shown in fig4 reflectors 36 are grounded together , further increasing the mass of the ground . reflectors 36 are composed of metal , such as aluminum , and ( as seen in fig3 ) are themselves grounded to the base of the lamp assembly . fig5 shows a perspective view of the overall flash lamp , similar to that disclosed in the &# 39 ; 666 patent . the elements of the lamp assembly are as described and shown above in connection with fig4 and previous figures . the core assemblies 22 and wires 18 described above are omitted from fig5 for clarity . shown in fig5 but not previously is transparent cover 42 and base plate 44 . base plate 44 is adapted to fit on , or comprise part of , a base assembly that may house electrical connectors to the power source , such as a trigger transformer and the end of the cable connecting the beacon to a power source , or in some applications , an isolation transformer . as the components of the base assembly are of conventional design or as shown in the &# 39 ; 666 patent , they are not shown in the drawings here . fig6 is a circuit diagram showing the electrical function of the inventive design . the circuit essentially operates as an rlc low - pass filter . the resistive and inductive components are implemented by the ferrite core , and the capacitive component by the conductive foil surrounding the ferrite core . the conductive foil serves as one plate of the capacitor and is connected to chassis ground . the other &# 34 ; plate &# 34 ; of the capacitor is the wire connected to the electrode of the flashtube . in fig6 two capacitors are shown , illustrating the function of two adjacent core assemblies 22 with a wire 18 between them . the conductive foil also serves as a grounded electrostatic shield to attenuate the radiated high - voltage trigger pulse . the inventive apparatus is surprisingly more effective in reducing emissions than systems without the combination of ferrite cores and grounded conductive shields . fig7 - 11 show the qualitative results of one set of example measurements , for both magnetic ( h ) and electrical ( e ) fields , expressing the noise level in decibels referenced to one milliwatt . the h field was measured with a near - field probe placed adjacent to the base assembly and oriented so as to maximize the signal , and the e field was measured by an omni - directional probe placed adjacent to cover 42 . with the exceptions noted below , each figure displays measurements taken on the same beacon unit with a long cable ( approximately 150 meters ). in each figure , the lower plot line represents the background noise with the beacon turned off ( which includes noise from the transducer ), and the top plot line represents the noise with the beacon activated . fig7 and 9 show the measured h and e fields ( respectively ) without any suppression apparatus installed . fig8 and 10 show the measured h and e fields ( respectively ) with a suppressor in accordance with this invention as described in fig1 - 6 , above . as comparison of those figures reveals , the inventive assembly is effective to reduce both fields , across a wide range of frequencies including those measured , from zero khz ( that is , direct current ) to 1 , 000 mhz . peak emissions at those frequencies were reduced by about 1 - 20 db in the h field , and essentially all significant peaks were removed . for the e field , peak emissions were reduced by similar levels , the ranges of high - noise frequencies were sharply reduced , and the noise spectrum was significantly leveled . fig1 shows the measured e field with the inventive apparatus installed but with the foils 26 left ungrounded . thus , fig1 shows the effect of the ferrite cores by themselves . although use of the ferrite cores alone ( fig1 ) attenuates the noise level as compared to the unprotected lamp ( fig9 ), grounding the foils ( fig1 ) provides a significant additional improvement over the use of ungrounded ferrite cores ( fig1 ). although the apparatus shown above is illustrated in a strobe lamp assembly , the inventive system can be used to shield any other sort of wire from which it is desired to reduce the emissive characteristics across a wide range of frequencies both in the e - field and the h - field . broadly , it is contemplated that the apparatus can be used in any application where there are high - voltage switching circuits that generate harmonic emissions over a wide frequency spectrum . in particular , the invention can be applied in the following types of systems : strobe lights , arc welders , carbon arc lights , automobile ignition systems , switching power supplies , relays and contactors , other electronic spark ignitors , and discharge lighting . although the invention has been described with reference to specific embodiments , many modifications and variations of such embodiments can be made without departing from the innovative concepts disclosed . thus , it is understood by those skilled in the art that alternative forms and embodiments of the invention can be devised without departing from its spirit and scope . the foregoing and all other such modifications and variations are intended to be included within the spirit and scope of the appended claims .