Converging wave detonator

A detonator fuze train combination utilizes a thin centrally initiated disc haped lead azide primer's detonation waves reflected from interior walls of a circumambient metal cup shaped housing member to peripherally detonate a secondary output charge. The output charge produces a detonation wave which converges radially inwardly to generate an enhanced jet output. The resultant jet output is capable of initiating a remotely positioned, RDX, high explosive acceptor.

BACKGROUND OF THE INVENTION 
Various means have been used in prior art to provide for detonation of a 
high explosive. Prior art explosive detonators generally utilize an impact 
type primer or an electrically activated primer to initiate a lead azide 
train or a pyrotechnic delay train to ignite a booster charge and in turn 
to fire the main high explosive charge. One problem with these prior art 
devices was that the primer-lead azide train-detonator size requirements 
were frequently too large to be accommodated within the space limitations 
imposed by fuzes. The problem of space limitation is particularly vexing 
in applications where the munition has a plurality of sub-munitions 
contained therein. Another problem with the abovementioned prior art 
detonators was that they frequently were unreliable and unsafe because of 
their sensitivity to stray electrical currents, the failure of any one of 
a multitudinous of electrical connections, failure in movement or function 
of an essential part because of the influence of a high acceleration 
environment, or a failure due to contamination or corrosion caused by loss 
of hermeticity. 
SUMMARY OF THE INVENTION 
The present invention relates to a converging wave detonator of TO-104 to a 
TO-5 size which utilizes a metal housing welded to a lead-header assembly 
to hermetically enclose a thin disc shaped layer of lead azide 
intermediate an electrical igniter assembly and a thin disc shaped layer 
of secondary output charge such as, cyclotetramethylenetetranitramine, 
HMX. The present invention is designed so that the thin lead azide layer 
is too short to initiate an output charge such as HMX directly. A plot of 
average denting ability, %, detonator output, versus lead azide thickness 
in thousandths of an inch are shown in FIG. 1. From test results and the 
plot, it has been empirically determined that for detonators having lead 
azide layers less than 0.040 thousandths of an inch thick, the denting 
ability is less than 5% of the full detonator output and that this impact 
force is insufficient to directly initiate a secondary high explosive such 
as HMX or cyclonite, RDX. 
An object of the present invention is to provide a detonator which has a 
very short overall length so that it can be efficiently used in a 
submunition. 
Another object of the present invention is to provide a small size 
detonator which has an output capability of effectively jumping a 
substantial distance gap to initiate a high explosive such as RDX which is 
proximately disposed therefrom. 
Another object of the present invention is to provide a detonator having a 
primer member which, because of its thickness, is not capable of directly 
initiating a secondary output charge in the center. 
Another objective of the present invention is to provide a detonator and 
integrated igniter which is effective in initiating an RDX explosive and 
which fits into the top of an integrated circuit enclosure having a TO-104 
to TO-5 size. 
Another object of the present invention is to provide a combined detonator 
and igniter assembly in a hermetically sealed container which is not 
influenced by stray electrical signals. 
Another object of the present invention is to provide a combined converging 
wave detonator and igniter assembly in a hermetically sealed container 
which is of reduced size and cost. 
Another object of the present invention is to provide a combined detonator 
and igniter assembly which has increased resistance to spin and setback 
acceleration environments. 
A further object of the present invention is to provide a combined 
converging wave detonator and igniter assembly in a container which is 
hermetically sealed against ambient environmental conditions. 
For a better understanding of the present invention, together with other 
and further objects thereof, reference is made to the following 
descriptions taken in connection with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now in FIG. 2 a disc shaped metal header 10 has an axial 
transverse insulator bore 12 therein which hermetically contains a tubular 
insulator 14 and a lead post 16 which passes through the insulator 14 and 
is hermetically sealed thereto. A bridge wire 18 is fixedly electrically 
connected on one end to the top of axially disposed lead post 16 and on 
its other end to header member 10. A hemispherical ignitor spot charge 20 
made of material such as, lead styphnate, is operatively positioned on top 
of the igniter bridge wire 18. A disc shaped layer of primer charge member 
22, made of material such as lead azide, approximately 0.015 of an inch 
thick, is disposed on top of the igniter-header assembly aforedescribed. A 
disc shaped secondary output charge member 24, made of material such as 
HMX, approximately 0.040 of an inch thick, is positioned on top of the 
primer member 22. A circumambient metal housing 26 of 0.2 to 0.3 of an 
inch in diameter, is hermetically sealed to header member 10 at the solder 
circular fillet 28. The metal header 26 serves as the ground connection 
for the device. 
FIG. 3 shows an alternate embodiment of the converging wave detonator 
design described in FIG. 2. In this design a multiple lead metal header 30 
has a number of header insulator holes 32 therein. Tubular insulators 34 
having header leads 36 therein are sealed into header 30 to make a leak 
tight header assembly. An electrical igniter integrated circuit chip 38 is 
centrally positioned on the interior surface of the header 30 so that an 
igniter hot spot 40 is axially positioned on the header 30. Header leads 
36 are electrically connected to the igniter integrated circuit chip by 
means of electrical conductors 42. The electronic igniter integrated 
circuit chip includes R.F. bypass means, an electronic logic system, and 
switching means to enable generation of a hot spot 40 only upon 
application of an intended input signal to leads 36. A disc shaped 
insulator element 44 having an axial hole 46 therein is axially aligned 
with the igniter-header assembly and positioned thereon. A lead styphnate 
cylindrical igniter charge element 48 is positioned within the axial hole 
46 so that it is in direct contact with the igniter hot spot 40. The 
insulator 44 has an annular groove 50 therein which permits clearance 
between the bottom wall surface of the insulator 44 and the interior 
surface of the header 30 so that the electrical conductors 42 and 
integrated circuit chip 38 are not disturbed by the positioning of 
insulator 44 thereover. 
In a similar fashion to the detonator of FIG. 2, a thin disc shaped primer 
charge member 22, made of such material as lead azide, is positioned on 
top of the insulator 44 and the lead styphnate igniter, and a disc shaped 
secondary output charge member 24, made of such material as HMX is 
positioned on top of the primer charge 22. A cup shaped metal housing 52 
having a flange 54 thereon is ring welded to header shoulder 56 to form a 
hermetic sealed detonator. 
In operation, the detonators of FIGS. 2 and 3 are initiated when the lead 
styphnate 20 and 48 is ignited by a hot wire or an integrated circuit hot 
spot respectively after application of a proper input voltage to the lead 
16 and 36 respectively. Other initiating sources that would be suitable 
for use as an igniter are an exploding wire, a conductive mixture, or a 
mild detonating cord. The initial detonation wave produced in the lead 
azide primer charge layer 22, because of the thin cross-section, is not 
sufficient to initiate the secondary output charge 24 directly. The 
detonation wave propagates radially outward from the center until it hits 
the interior walls 27 and 53 of housings 26 and 52, respectively. The 
reflected shock waves causes pressure to increase to a level which causes 
annular initiation of secondary output charges 24 at their outer edges. 
The detonation of the secondary output charges 24 then propagates in a 
converging detonation wave which collides in the center of the device 
producing an axial jet of explosion materials whose energy is effective in 
initiating a high explosive, RDX, acceptor (not shown) across an air gap 
of approximately 3/8 of an inch. In the specific embodiments illustrated 
in FIGS. 2 and 3 of the metal housings 26 and 52 are made of steel with a 
wall thickness of at least 0.010 inch. The secondary output charges 24 are 
made of 80 mg. HMX material pressed at 25,000 psi to give the desired 
thickness of 0.040 inch. The primer charges 22 are made of 60 mg lead 
azide charge pressed at 25,000 psi to give the desired thickness of 0.015 
inch. 
While there has been described and illustrated specific embodiments of the 
invention, it will be obvious that various changes, modifications and 
additions can be made herein without departing from the field of the 
invention which should be limited only by the scope of the appended 
claims.