U.S. patent number 3,724,383 [Application Number 05/111,473] was granted by the patent office on 1973-04-03 for lasser stimulated ordnance initiation device.
This patent grant is currently assigned to The United States of America as represented by the Secretary of the Navy. Invention is credited to Ronald W. Benson, Bertil V. Carlson, John A. Gallaghan.
United States Patent |
3,724,383 |
Gallaghan , et al. |
April 3, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
LASSER STIMULATED ORDNANCE INITIATION DEVICE
Abstract
A device for generating a high order detonation by using fiber
optics and a pherical glass focusing head to distribute the
initiating light pulse and a low energy laser to initiate the
explosive material. Potassium Hexanitro Diphenylamine (KHND), a
secondary explosive, is initiated by the device to a low order
detonation which in turn sets off Pentaerythrital Tetranitrate
(PETN), another secondary explosive material, to give a high order
detonation.
Inventors: |
Gallaghan; John A. (Ben Lomond,
CA), Benson; Ronald W. (Cupertino, CA), Carlson; Bertil
V. (Santa Cruz, CA) |
Assignee: |
The United States of America as
represented by the Secretary of the Navy (N/A)
|
Family
ID: |
22338757 |
Appl.
No.: |
05/111,473 |
Filed: |
February 1, 1971 |
Current U.S.
Class: |
102/201;
102/275.9; 385/88 |
Current CPC
Class: |
F42B
3/113 (20130101); G02B 6/421 (20130101) |
Current International
Class: |
F42B
3/113 (20060101); F42B 3/00 (20060101); G02B
6/42 (20060101); F42b 009/00 () |
Field of
Search: |
;149/92
;102/70.2,28,7.2A,46 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Engle; Samuel W.
Claims
What is claimed is:
1. A device for initiating an explosive charge including an optical
transmission means and laser means, said device comprising in
combination:
a. a hollow detonator assembly;
b. said detonator comprising a first interior chamber, a second
interior ball chamber and an explosive storage chamber;
c. said second ball chamber having first and second openings, said
first opening communicating with said first interior chamber and
said second opening communicating with said explosive storage
chamber;
d. said explosive storage chamber containing a first explosive
material located adjacent a second explosive material wherein said
second explosive material is compressed in a gradient of increasing
density away from said first material to form an explosive
train;
e. a spherical shaped bead focusing means positioned inside said
second ball chamber and in direct contact with said first explosive
material;
f. a hollow collet positioned inside said first chamber;
g. said optical transmission means positioned inside the hollow
portion of said hollow collet; and
h. said laser means operatively connected to said optical
transmission means and adjacent said collet.
2. The device recited in claim 1 wherein the major portion of said
storage chamber contains said second explosive material.
3. The device recited in claim 1 wherein said first explosive
material is Potassium Hexanitro Diphenylamine (KHND) and said
second explosive material is Pentaerythrital Tetranitrate (PETN) to
be initiated by said laser device.
Description
The invention described herein may be manufactured and used by or
for The Government of the United States of America for governmental
purposes without the payment of any royalties thereon or
therefor.
BACKGROUND OF THE INVENTION
The present invention relates generally to a device for initiating
a high order explosion by utilizing a laser device and fiber optic
transmission system and more particularly to the use of Potassium
Hexanitro Diphenylamine (KHND), a low order detonation material
adjacent to a glass focusing bead and a low energy laser device to
initiate the Potassium Hexanitro Diphenylamine (KHND), which in
turn initiates another secondary explosive material thereby causing
a high order detonation.
The present day ordnance systems may be grouped roughly into three
catagories:
A. A LOW VOLTAGE EXPLOSIVE DEVICE THAT HAS AS ITS INITIATING CHARGE
A PRIMARY EXPLOSIVE, WHICH REACTS TO A HOT WIRE WHICH IN TURN IS
STIMULATED BY A LOW VOLTAGE DISTRIBUTOR SYSTEM. The primary charge
initiates the secondary explosive charge.
B. An exploding bridgewire--device that initiates a secondary
explosive directly, thus eliminating the need for a primary
explosive. The objections to the sensitivity of the low voltage
system using primary explosives in a low voltage systems led to the
development of the exploding bridgewire systems.
C. A confined detonating cord that replaced the electrical
initiation distributor used in the low voltage system and the
exploding bridgewire device. The confined detonating cord system
uses an explosive cord shielded with a fiberglass braid to
distribute the initiating event.
It has been found that the laser with its unique optical
characteristics is a very safe and reliable method for initiating
explosive charges in that none of the usual hazards such as
electromagnetic radiation, X-ray, and the like, would provide the
proper stimulus for initiator. The primary advantage of this new
device is the unique method of initiating the explosive. The
distribution system is extremely simple and presents none of the
problems or hazards caused by the use of electrical or explosive
distribution systems.
The major object of the invention is to provide an explosive system
initiated by the output of a low energy laser device.
A more particular object of the invention is to provide a high
order detonation by using a secondary explosive charge.
Another object of the invention is to provide a safe and reliable
method of explosive initiation.
Other objects and features will be apparent from the following
description of the invention and from the accompanying drawings of
the preferred embodiment of the present invention wherein:
FIG. 1 is a sectional view of the assembled detonator; and
FIG. 2 is an exploded view, partially in section, of the detonator
assembly .
Explosive material and explosive train. The explosive device or
detonator is shown in both of FIGS. 1 and 2. The success or failure
of the overall detonation system lies in the design of the
detonator assembly and the explosive train. It has been found that
the choice of explosive upon which the laser beam impinges is a
critical factor in success or failure of the system. None of the
commonly used secondary explosives performed satisfactorily,
apparently having a too low melting point as well as other more
subtle characteristics relating to the manner of energy
absorption.
A potassium salt of Hexanitro Diphenylamine, hereafter referred to
as KHND, for various technological reasons was found to react in
the desired manner under laser stimulation. Although KHND is a
high-energy, temperature-insensitive high explosive, it did not
itself give a high order event herein, but when the KHND was
followed by a column of Pentaerythrital Tetranitrate, hereafter
referred to as PETN, a high order detonation was obtained.
Several alternative explosive materials have been found equally
successful; namely, salts of Hexanitro Diphenylamine, either sodium
or Strontium and pyrotechnic compounds such as Hafnium/Copper Oxide
and Zirconium/Copper Oxide. All of these explosive materials were
tested in laser fired devices and yielded adequate output evidence
of detonation in steel dent plates.
Detonator device. Referring to FIG. 1, where the detonator assembly
consists of body 1, spherical washer 3, spherical shaped glass
focusing bead 4, and threaded collet 2.
The detonator body 1 has a long drilled cavity 12 extending back
and opening into ball end mill section 5. Cavity 12 acts as a
storage chamber for the explosive material. The ball end mill
section 5 extends to the bottom tap 6. The bottom tap section is
threaded to accept the threaded detonator screw or collet 2. The
threaded collet 2 has a hollow portion 7 with slot 8 at one end.
The hollow threaded collet 2 holds the fiber optics transmission
line or bundle 9 in close proximity to the glass bead 4. Referring
to FIG. 2, fiber optics capsule 9 is inserted into the hollow
chamber 7 of the collet 2. Glass focusing bead 4 is inserted in the
ball end mill opening 5 and is in turn held back by the spherical
washer 3 and threaded collet 2. There is an aperture between cavity
12 containing explosive materials 10 and 11 and ball end mill
section 5, to allow spherical glass bead 4 to come in contact with
explosive material 11. The function of the focusing bead 4 is
twofold; first to provide optimum containment of the explosive
event; second to provide optical focusing and to concentrate
instant energy of the laser beam, thus encouraging hot spot
initiation of the KHND charge 11 as hereinafter explained.
Detonator and detonator screw. Referring to FIG. 1, body 1 is made
of stainless steel or equivalent. The detonator washer 3 is made
from annealed brass and has a curved interior surface and a 0.045
inch diameter opening. The detonator glass sphere lens 4 is of the
proper diameter to fit the open ball end mill 5 of the detonator
body 1 and washer 3.
Fiber optics assembly and laser pulse supply. Referring to FIG. 2,
fiber optics bundle 9 is enclosed in a hollow jacket assembly 9a.
Outer jacket 9a is then inserted into the opening 7 of the threaded
collet 2. Threaded collet 2 holds the fiber optics transmission
line 9 in close proximity to the glass bead 4. A stainless steel
cap nut 13 is placed on the threaded portion of the fiber optic
assembly.
Neodymium laser device 14 is used as the source of initiated
energy. The energy levels used were 0.3 and 0.5 Joules. It should
be noted that both the fiber optics and the laser device are
standard apparatus used in the art.
Method of loading the detonator device. Referring again to FIG. 1,
KHND charge 11, having a weight of about 5 milligrams, is pressed
against the spherical shaped glass focusing bead 4 which in turn is
held in the ball mill section 5 by the spherical washer 3 and the
threaded collet 2. The explosive charge PETN 10 is then loaded into
the long cavity 12. The PETN is loaded in a gradient of increasing
density from right to left, filling the major portion of the
cavity. The final increment of PETN is compressed to about 40,000
psi whereas the initial increment is compressed to 4,000 psi. Laser
14 is attached to the open end of the fiber optics cap nut 13 and
the explosive event is as follows: The laser pulse from the supply
passes through the fiber optic bundle 9, focusing bead 4, and
impinges upon the KHND charge 11. The KHND charge is set into low
order detonation, thereby setting the adjacent PETN into low order
detonation. As this event progresses from right to left, the
pressure and temperature increases rapidly because the density of
the gradient loaded pETN column increases from right to left. In
this manner the velocity of the reaction front increases very
rapidly, reaching a detonation velocity of 7,000 to 8,000 meters
per second. Thus the result is a high order explosion.
In summary, the primary advantage of this new system is the unique
method and apparatus of initiation of the explosive. The usual
dangers which cause accidental initiation are not present in the
present invention. For example, only secondary explosives are used.
In addition, it has been found that the loaded laser detonator did
not result in initiation when it was subjected to the spark of a
100 KV Tesla coil generator.
A single laser source may be used to provide stimulus to many
devices, either simultaneously or in programmed sequence. The
distribution system is extremely simple and presents none of the
inherent problems of high voltage EBW or CDR explosives
distribution systems.
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