| United States Patent |
5,952,600
|
|
Herr
|
September 14, 1999
|
Engine disabling weapon
Abstract
A non-lethal weapon for disabling an engine such as that of a fleeing car
by means of a high voltage discharge that perturbs or destroys the
electrical circuits. The transmission of the disabling voltage to the
distant target is via two channels of electrically conductive air. The
conductive channels are created by multi-photon and collisional ionization
within the paths of two beams of coherent (laser) or collimated incoherent
ultraviolet radiation directed to the target. A single beam may be used
when the high voltage source and the target are grounded. The high-voltage
current flows from electrodes at the origin of the beams along the
channels of free electrons within them.
| Inventors:
|
Herr; Jan Eric (P.O. Box 15044, San Diego, CA 92175)
|
| Appl. No.:
|
806014 |
| Filed:
|
February 24, 1997 |
| Current U.S. Class: |
89/1.11; 361/213; 361/232 |
| Intern'l Class: |
H01T 023/00 |
| Field of Search: |
89/1.11
42/1.08
361/213,232
307/149
|
References Cited [Referenced By]
U.S. Patent Documents
Primary Examiner: Jordan; Charles T.
Assistant Examiner: Montgomery; Christopher K.
Attorney, Agent or Firm: Charmasson; Henri J. A., Buchaca; John D.
Parent Case Text
PRIOR APPLICATION
This is a continuation-in-part application of application Ser. No.
08/597,395 filed Feb. 8, 1996, now U.S. Pat. No. 5,675,103, issued Oct. 7,
1997.
Claims
What is claimed is:
1. An apparatus for generating an electrical circuit disabling high-voltage
electrical discharge at a first point proximate to a distant target
circuit which comprises:
means for generating a high-voltage pulsed alternating electrical current
adjusted to induce secondary disabling currents in said circuit;
wherein said current has periodic positive and negative voltages;
means for ionizing at least one channel of ambient air between said means
for generating and said first point; and
means for applying said electrical current to said ionized channel.
2. The apparatus claimed in claim 1, wherein said means for generating
comprise
a high-voltage pulse-creating electronic circuit;
and wherein said means for ionizing comprise means for emitting a first
beam of ultraviolet radiation.
3. The apparatus claimed in claim 2, wherein said means for applying
comprises an electrically conductive mirror placed in the path of said
ionized channel, said mirror being connected to a first output terminal of
said high-voltage pulse-creating electronic circuit.
4. The apparatus claimed in claim 2, wherein said means for applying
comprise a plate of electrically conductive, transparent material placed
in the path of said beam, said plate being connected to a first output
terminal of said high-voltage pulse-creating electronic circuit.
5. The apparatus claimed in claim 2 wherein said first beam has a
wavelength of approximately 193 nanometers.
6. The apparatus claimed in claim 2 wherein said means for ionizing
comprises a laser operated in a pulsed mode.
7. The apparatus claimed in claim 6 which further comprises means for
synchronizing said high-voltage pulsed electrical current with said beam
of ultraviolet radiation.
8. The apparatus claimed in claim 6 which further comprises means for
emitting a second beam of ultraviolet radiation between said means for
generating and a second point proximate to said target and a means for
connecting a second output terminal of opposite polarity to said first
terminal of said high-voltage pulse-creating electronic circuit to said
second beam of ultraviolet radiation.
9. The apparatus of claim 8, wherein said target circuit is housed within
an electrically conductive body, and wherein said first point is located
on a first part of said body, and said second point is located on a second
part of said body.
10. The apparatus claimed in claim 2, wherein said beam has a wavelength
within one of the ranges from approximately 190.6 through 192.8 and from
193.2 through 195.4 nanometers.
11. The apparatus claimed in claim 2, wherein said high-voltage
pulse-creating electronic circuit comprises a Marx generator having an
output voltage of at least 400 kilovolts.
12. The apparatus of claim 1, wherein said target circuit is housed within
an electrically conductive body, and wherein said first point is located
on a part of said body.
13. A method for generating an electrical circuit disabling high-voltage
electrical discharge about a distant target which comprises:
generating a high-voltage pulsed alternating primary electrical current;
wherein said current has periodic positive and negative voltages;
repetitively ionizing at least one channel of ambient air between a source
of said current and a point proximate to said target by emitting a beam of
ultraviolet radiation of sufficient energy to cause multi-photon
ionization, said beam impinging upon both said source and said point; and
discharging said source though said channel.
14. The method claimed in claim 13 wherein, said step of emitting a beam
comprises using an ultraviolet source having an energy level sufficient to
cause multi-photon ionization through said channel.
15. The method claimed in claim 13, wherein the frequency of said
high-voltage pulses is selected between 1 and 10,000 hertz.
16. The method claimed in claim 13, wherein the step of emitting a beam
comprises using an ultraviolet source having a wavelength of approximately
193 nanometers.
17. The method claimed in claim 13, wherein the step of emitting a beam
comprises using an ultraviolet source having a wavelength within one of
the ranges from 190.6 through 192.8 and from 193.3 through 195.4
nanometers.
18. The method of claim 13, wherein said target has an electrically
conductive body and wherein said point is located on a part of said body.
Description
FIELD OF THE INVENTION
This invention relates to weapons and more particularly to a type of
non-disabling weapon which may be used by military personnel or law
enforcement agents for the temporary immobilization of a target subject or
subjects. The invention also relates to muscle tissue involuntary
contraction by application of electric current identical to or closely
approximating the physiological neuroelectric impulses which control
muscle movements. This weapon may further be used to stop an automobile or
other vehicle by disabling the electronic circuits which control its
engine.
BACKGROUND OF THE INVENTION
To this date, the known non-lethal and sub-lethal electrical weapons that
have been designed to render a target subject less than completely
functional have relied on low-frequency, high-voltage currents to shock,
stun, or disorient said target subject. An early example of such a device
is disclosed in U.S. Pat. No. 3,803,463, to Cover. This device is a
handheld weapon from which two small projectiles are fired at the target
subject. Each projectile is attached to a fine conductive wire so as to
deliver an electrical current to stun said target subject. The principal
drawback of this type of device is that only a single shot can be fired
without reloading. The weapon is thus of little value if it must be used
against multiple targets, if one or both projectiles misses the target, or
if the target subject is able to dislodge one or both of the projectiles
or their wires before the stunning current is activated. Further, the
weapon is classified as a firearm because the projectiles are propelled by
nitrocellulose powder charges, and it is therefore subject to all the
legal restrictions applied to firearms.
To overcome these difficulties, several non-lethal weapons have been
proposed which project two parallel streams of electrically conductive
liquid at the target subject. These streams are maintained at different
potentials so as to complete a circuit when they contact a target subject
and thereby stun said target subject with a series of very low frequency
electrical pulses of about 10,000 volts each. Such weapons are disclosed,
for example, in U.S. Pat. No. 3,971,292, Paniagua; U.S. Pat. No.
4,486,807, Yanez; U.S. Pat. No. 4,846,044, Lahr; U.S. Pat. No. 4,852,454,
Batchelder; U.S. Pat. No. 4,930,392, Wilson; and U.S. Pat. No. 5,103,366,
Battochi. The main disadvantage of these weapons is that they can be fired
only a few times without reloading. A second disadvantage is that, like
the earlier projectile-and-wire device, all these weapons create painful
muscle spasms in the target subject that may cause injury, and invite
legal action against the users. A third disadvantage is that capillary
instability causes the liquid streams to break up into droplets after a
short distance. A fourth disadvantage is that gravity quickly pulls such
liquid streams into a ballistic arc, thus making aiming difficult. A fifth
disadvantage is that the ionic flow within liquid electrolytes provides
only weak electrical conductivity. A sixth disadvantage is that the target
subject may be wetted by the liquid streams so that the current is
short-circuited and unable to stun the subject. A seventh disadvantage is
that the electro-mechanical nature of these devices and the corrosive
liquids they employ tend to shorten their useful life.
Tetanization is the stimulation of muscle tissue by a rapid series of
electrical impulses of such frequency as to fuse individual muscle
contractions into a single sustained contraction. Tetanization is a
well-known phenomenon: see Offner, "Stimulation With Minimum Power,"
Journal of Neurophysiology, Vol. 9, pp. 387-390, 1946; Dalziel, "Effect of
Wave Form on Let-go Currents," AIEE Transactions, Vol. 62, pp. 739-744,
1943; Dalziel and Lee, "Lethal Electrical Currents," IEEE Spectrum, Vol.
6, pp. 44-50, 1969; Dalziel, Ogden, and Abbott, "Effect of Frequency on
Let-go Currents," AIEE Transactions, Vol. 62, pp. 745-750, 1943;
Kouwenhoven, Hooker and Lotz, "Electrical Shock Effects of Frequency,"
Electrical Engineering, Vol. 55, pp. 384-386, 1936; and Ferris et al.,
"Effects of Electrical Shock on the Heart," Electrical Engineering, Vol.
55, pp. 498-515, 1936.
The present invention also results from prior experiences in the
laser-induced ionization of air as described by Koopman and Wilkerson,
"Channeling of Ionizing Electrical Streamer by a Laser Beam," Journal of
Applied Physics, Vol. 42, pp. 1883-1886, 1971, and Koopman and Saum,
"Formation and Guiding of High-Velocity Electrical Streamers by
Laser-Induced Ionization," Journal of Applied Physics, Vol. 44, pp.
5328-5336, 1973. Prior applications of laser-induced ionization can be
found in U.S. Pat. No. 3,719,829, Vaill and U.S. Pat. No. 3,775,638,
Tidman which disclose methods of creating a conductive path in a gas, U.S.
Pat. No. 4,017,767 Ball and U.S. Pat. No. 4,453,196 Herr which disclose
the transmission of electricity via laser-ionized air channels, and U.S.
Pat. No. 5,175,664 Diels et al. which discloses methods of creating
conductive paths of ionized air by means of laser beams toward the goal of
discharging storm clouds.
This invention also relates to devices used to damage or destroy electronic
circuits at a distance. Because such circuits now control many internal
combustion engines, high-voltage currents or pulses which damage those
circuits necessarily disable the engines they govern. One commercial
application is the stopping of fleeing automobiles quickly without causing
injury to the passengers or bystanders. High voltages are required because
the current must reach ground across a gap of about ten centimeters
between the automobile's wheel rims and the roadbed. Because the breakdown
voltage of dry air is about 32 kV cm-.sup.1, the potential difference
between the wheel rims and the ground is approximately 320 kv. As
disclosed by U.S. Pat. No. 5,503,059, prior means of stopping an
automobile with an external electric current include placing a conductive
pad in its path. As the vehicle passes over, the pad delivers a powerful
electric impulse to it and thus to its electronic components. This method
has the obvious disadvantage of the user having to choose and reach an
effective location before the automobile's arrival. The same U.S. Patent
also discloses two other means of conveying an electric current to a
moving vehicle. The first is by contacting its undercarriage with metal
rods that project from the pursuing police car. The second is by firing
into the fleeing auto a harpoon with trailing wires which then transmit
electric pulses to it. Each of those methods lacks satisfactory range and
the ability to continuously target a moving vehicle. Another prior means
utilizes microwave pulses that are directed toward the automobile from an
antenna on the pursuing police car. According to U.S. Pat. No. 5,293,527,
the width of the beam intended to achieve this goal is approximately
50.degree.. A microwave pulse of this width would not only dissipate too
rapidly to be effective at any reasonable distance, but would probably
affect other vehicles as well.
The instant invention results from a search for a weapon that would be more
efficient in conducting electrical discharges to a distant vehicle within
a greater range for a more precise and continuous targeting.
SUMMARY OF THE INVENTION
The principal object of the instant invention is to provide a non-lethal
immobilizing weapon for use by military or law enforcement personnel.
A second object of this invention is to provide a non-lethal, immobilizing
weapon which is inherently safe in its operation.
A third object of this invention is to provide a non-lethal weapon which is
capable of temporarily immobilizing a target subject without causing pain,
shock, disorientation, or loss of consciousness.
A fourth object of this invention is to provide a non-lethal weapon which
is capable of temporarily immobilizing a target subject without his being
aware of the cause.
A fifth object is to provide a non-lethal, immobilizing weapon whose range
is substantially greater than prior related weapons that use wires or
conductive liquid streams.
A sixth object is to provide a non-lethal, immobilizing weapon which can be
fired from a remote location without requiring the physical impact of
solid or liquid matter upon the target.
A seventh object is to provide a non-lethal, immobilizing weapon which can
be directed continuously and swept across an indefinitely large number of
target subjects.
An eighth object is to provide a non-lethal, immobilizing weapon which can
rapidly be fired toward a specific location on a single target subject, or
to a specific target subject among many because of the highly directional
nature of its current-conducting means.
A ninth object is to provide a non-lethal, immobilizing weapon which has a
significantly longer service life than prior related weapons.
These and other objects are achieved by transmitting relatively high
frequency electrical impulses to the target by means of one or two
electrically conductive channels of ionized air produced within one or two
beams of intense ultraviolet radiation aimed at the target, and by placing
a high-voltage field of the opposite polarity across the path of each
beam.
The present invention functions by immobilizing the target person or animal
at a distance. It performs this function by producing skeletal muscle
tetanization in the target subject. Tetanization is the stimulation of
muscle tissue by a series of electrical impulses of such frequency as to
merge individual muscle contractions into a single sustained contraction.
The immobilizing tetanization is maintained as long as the weapon
continues to produce an electrical current within a major portion of the
skeletal musculature of the subject, and for a brief time thereafter due
to paralysis caused by the temporary inhibition of neuromuscular impulses.
The optimum current and frequency required to create and maintain
immobility while avoiding impairment of cardiac or respiratory activity
are 25 milliamperes and 100 hertz, respectively. Currents in the range of
20 to 50 milliamperes and 1 to 10,000 hertz may also be employed, with the
higher frequencies requiring higher currents. A frequency of about 2 hertz
may ultimately be used to produce painful spastic contractions. A minimum
electrical potential of approximately 600 volts is required to overcome
skin resistance without producing burns.
The most effective current waveform in producing tetanization is that which
most closely duplicates the physiologically produced neural impulse. As
Offner points out, this waveform is an exponentially rising pulse. The
second most effective waveform is a square wave, whereas the least
effective is a sine wave. Due to their rapid rise-times, square waves
allow the greatest penetration through the clothing and skin of the target
subject.
Further, the differences in the effectiveness of various waveforms
constitute an inherent safety factor in the operation of the instant
weapon. This safety factor is a result of the rapid absorption by
biological tissue of the harmonic frequencies within complex waveforms
such as square waves. A 20 to 50 milliampere current is thus able to
stimulate only the target subject's skeletal muscles, and cannot penetrate
to the autonomically-controlled internal muscles such as the heart.
A lethal variation of the present weapon could be implemented by increasing
the current above approximately 250 milliamperes. A sine wave current
having a density of about 5 milliamperes per square centimeter that flows
through cardiac muscle for more than about two seconds may initiate
ventricular fibrillation. The duration of the current needed to cause
ventricular fibrillation is inversely proportional to the current density
within the cardiac muscle.
The current carried by the ionized air channel is limited by the number of
free electrons within the ultraviolet beam. A minimum 20 milliampere
current required to induce skeletal muscular tetanization can be carried
by a gaseous channel with a concentration of 10.sup.8 ions per cubic
centimeter. This concentration is most efficiently achieved in air by
ionizing molecular oxygen with coherent or collimated incoherent
ultraviolet radiation having a wavelength of approximately 193 nanometers.
Shorter wavelengths may be employed as optical technology progresses.
At its normal operating intensity and a wavelength near 193 nanometers, the
ultraviolet beam is safe to the skin because it cannot produce more than
mild erythema akin to a sunburn unless it is directed at the same location
for many minutes. Moreover, it is safe to the eyes because wavelengths
near 193 nanometers cannot penetrate the cornea to reach internal ocular
structures such as the lens and retina.
At this wavelength, molecular oxygen has a two-photon ionization cross
section of 1.times.10.sup.-34 cm.sup.4 /watt. Because of its low
ionization threshold, the number of photons required for ionization, and
its large proportion in the atmosphere, it is easily able to create
sufficient electron density.
The most efficient source of 193-nanometer radiation presently available is
the argon fluoride discharge-pumped excimer laser. A reasonable power
density, pulse duration, and pulse repetition rate for this laser is 5
megawatts per square centimeter, 10 nanoseconds, and 200 pulses per
second, respectively.
An argon fluoride laser with an aperture of 1 square centimeter has a power
density (energy output) of 10 millijoules per pulse or 1 megawatt per
square centimeter. Each pulse liberates 6.3.times.10.sup.6 electrons, or
6.3.times.10.sup.14 electrons per second in the air immediately outside
the aperture. A power density of 50 millijoules per pulse or 5 megawatts
per square centimeter liberates 1.6.times.10.sup.8 electrons during each
pulse, which is equivalent to 1.6.times.10.sup.16 electrons per second.
A narrow beam of ultraviolet radiation may also be generated from the
collimated emission of an ultraviolet lamp.
The electron density in the channel of ionized air is a function of the
ratio between the electron production and loss rates. In both the two-body
and three-body electron attachment processes, the delay time between the
end of the laser pulse and the beginning of the high-voltage tetanizing
pulse determines the number of available electrons. When the electron
energy is only 0.1 electron volt, for example, the three-body attachment
is rapid, and the steady-state electron density for a 193 nanometer, 5
megawatt per square centimeter beam falls to 8.times.10.sup.7 per cubic
centimeter.
The range of the present weapon is determined by the rate at which the
laser beam is absorbed by the atmosphere. A 193-nanometer wavelength beam
is attenuated in dry air at about 1.times.10.sup.-4 per centimeter. It
will thus propagate approximately 100 meters before its intensity is
decreased to l/e of its initial value. As a consequence, the
1.6.times.10.sup.8 electron density at the aperture of an argon fluoride
laser with a power density of 5 megawatts per square centimeter falls to
2.2.times.10.sup.7 after 100 meters. Because the minimum electron density
required to transmit a current is between 10.sup.6 and 10.sup.8 per cubic
centimeter, the above ionized channel should conduct the tetanizing
current at least 100 meters. The range of this weapon could be increased,
however, by the use of a more efficient ultraviolet source.
Various techniques, including those suggested in U.S. Pat. No. 4,017,767
Ball and U.S. Pat. No. 5,175,664, Diels et al. which are incorporated
herein by reference, may be used in order to enhance the multi-photon and
collisional ionization along the laser beams. These techniques are well
known to persons skilled in the electrical arts.
The engine-disabling application of the invention creates high voltage
discharge in the proximity of a vehicle engine either by using the vehicle
body as a shorting means between either voltage-carrying beam and the
ground or a pair of voltage-carrying beams.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a diagrammatical illustration of a first embodiment of the
invention;
FIG. 2 is a diagrammatical illustration of a second embodiment of the
invention;
FIG. 3 is a diagrammatical illustration of an ultraviolet beam generating
system using a UV lamp;
FIG. 4 is a diagrammatical illustration of a third embodiment of the
invention; and
FIG. 5 is a diagrammatical illustration of a fourth embodiment of the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
Referring now to the drawings and more specifically to FIG. 1, there is
illustrated a first embodiment of the invention. A high-intensity source
of coherent or collimated incoherent ultraviolet radiation, typically
operating in a pulsed mode such as a pulsed laser 1, directs a photon beam
6 having a wavelength of preferably and approximately 193 nanometers
toward a grounded human or animal target 2. A channel of ionized air is
created within the photon beam 6 according to multi-photon, collisional,
and other ionization processes. A high-voltage tetanizing pulse generator
3 has one of its output terminals connected to an electrically conductive
mirror 5 or an electrically conductive transparent plate 5a, interposed in
the path of the photon beam 6 or 6a. The second terminal of the
high-voltage pulse generator 3 is connected to ground. A variable resistor
7 is mounted in series with one of the terminals of the high-voltage pulse
generator 3 and controlled by a feedback circuit to maintain a constant
current through the target 2. A clocking circuit 4 produces the
synchronized triggering signals for both the pulsed laser 1 and the
high-voltage pulse generator 3.
Assuming that a sufficient number of free electrons are created by the
multi-photon, collisional, and other ionization processes between the
mirror 5 or plate 5a and the target 2, an electrical path for the
high-voltage pulses issuing from the generator 3 is provided to the body
of the human or animal target 2.
In the second embodiment of the invention illustrated in FIG. 2, a second
laser 8 is used to create the return path of the electrical circuit in
place of the ground connection. The second terminal of the high-voltage
pulse generator 3 is connected to a second electrically conductive mirror
9 or electrically conductive transparent plate 9a interposed in the path
of the second laser beam 10. The laser beams 6 and 10 are directed to
impinge upon the human or animal target 2 in two locations 11 and 12
between which the high-voltage tetanizing current is to flow. Assuming
that sufficient free electrons are created in each of the ionized air
channels between the mirror 5 or plate 5a and the location 11 on the
target on one part, and the mirror 9 or plate 9a and the location 12 on
the target on the other part, an electrical path for the high-voltage
pulsed current is provided. This electrical path includes a portion of the
target subject 2. The firing of the lasers 1 or 8 and the activation of
the high-voltage pulse generator 3 are synchronized by means of the
clocking circuit 4.
FIG. 3 is a diagrammatical illustration of a ultraviolet beam generating
system wherein the radiation from a UV lamp 13 is focused by a parabolic
reflector 14 on the focal center of a lens 15. The beam 16 of parallel
ultraviolet rays is used to ionize an air channel.
FIG. 4 illustrates a third embodiment of the invention. This embodiment
uses the high-voltage (not the tetanizing) aspect of the invention against
electronic circuits, especially those of vehicles. A high-intensity source
of coherent or collimated incoherent ultraviolet radiation, typically
operating in a pulsed mode such as a pulsed laser 1, directs a photon beam
6 having a wavelength of preferably and approximately 193 nanometers
toward a vehicle 22. A channel of ionized air is created within the photon
beam 6 according to multi-photon, collisional, and other ionization
processes. A high-voltage capacitor bank or Marx generator 17 has its
output terminal connected to either an electrically conductive mirror 5,
or an electrically conductive transparent plate 5a, interposed in the path
of either the photon beam 6 or 6a respectively.
Assuming that a sufficient number of free electrons are created by the
multi-photon, collisional, and other ionization processes between the
mirror 5 or plate 5a and the vehicle 22, an electrical path for the
high-voltage direct current pulses issuing from the capacitor bank or Marx
generator 17 is provided to the vehicle 22. These pulses travel through
the metal portions of the vehicle 22 to its wheel rims and thence to
ground. The return path of the circuit is through ground to the opposite
terminal of the capacitor bank or Marx generator 17. Because of their high
potential and changing nature, the pulses induce secondary currents in the
vehicle's electronic circuits, thus damaging their voltage-sensitive
components. The photon beam 6 or 6a is directed automatically, as by a
radar-controlled servomechanism 19 (not shown), or by the manual alignment
of a beam of visible light 20 that is coaxial with the ultraviolet photon
beam 6 or 6a.
FIG. 5 illustrates a fourth embodiment of the invention for use against
electronic circuits, especially those of vehicles. A second laser 8 is
used to create a return path for the electrical current. Each of the
terminals of a high-voltage alternating current generator 18 are connected
either to electrically conductive mirrors 5 and 9, or to electrically
conductive transparent plates 5a and 9a that are interposed respectively
in the paths of the photon beams 6 and 10. The photon beams 6 and 10 are
directed to impinge upon the target vehicle 22 in two locations 23 and 24
between which the high-voltage alternating current is to flow. Assuming
that sufficient free electrons are created between the mirror 5 or plate
5a and the location 23 on one part of the vehicle 22, and the mirror 9 or
plate 9a and the location 24 on another part of the vehicle, an electrical
path for high-voltage alternating current is provided. This electrical
path should include the greater portion of the vehicle 22, which
presumably would contain the majority of its electronic circuits. Because
of its high potential and changing nature, the primary alternating current
induces secondary currents in the vehicle's electronic circuits, thus
damaging their voltage-sensitive components. Therefore, the primary
current is adjusted to cause these secondary currents through electrical
induction. The primary current may be further adjusted to maximize the
disabling nature of the secondary currents depending on known or suspected
characteristics of the target circuit. The photon beams 6 and 10 are
directed automatically, as by a radar-controlled servomechanism 19 (not
shown), or by the manual alignment of beams of visible light 20 and 21
that are coaxial with the ultraviolet photon beams 6 and 10.
Alternately, the photon beams 6 and 10 are directed to converge in the air
above the engine compartment of the vehicle 22. The high-voltage
alternating current is therefore conducted to a point immediately above
that part of the vehicle 22 in which the majority of its electronic
circuits are located. Because of its high potential and changing nature,
the alternating current induces transient currents in the automobile's
electronic circuits, thus damaging their voltage-sensitive components.
Because a return path is provided, this embodiment may be employed from an
ungrounded platform such as a helicopter or other aircraft.
It should be noted that an ultraviolet laser wavelength of 193 nanometers
yield the most intensive ionization and therefore the widest channel. In
most of the above-disclosed applications where distance rather than
intensity is the prime requirement, it is advantageous to operate the
laser at wavelenths slightly to either side of the optimal one. Typically,
the laser is preferably operated within the ranges from 190.6 through
192.8 or from 193.2 through 195.4 nanometers.
It may be useful in damp weather to reduce the amount of water vapor or
water droplets in the path of the ultraviolet beam. As described in U.S.
Pat. No. 5,175,664 Diels et al., a more optically transparent path is
created through the use of a coaxial beam of infrared radiation. This
coaxial infrared beam may be produced by any of several commonly-available
carbon dioxide lasers.
While the preferred embodiments of the invention have been described,
modifications can be made and other embodiments may be devised without
departing from the spirit of the invention and the scope of the appended
claims.
* * * * *