Stopping Vehicles With Directed
Energy
Source: Martin’s Page
Below are excerpts of a report from The Pursuit
Management Task Force dealing with all aspects of stopping vehicles
during chases involving law enforcement. I cut all the non energy
related stuff out and left the parts detailing the use of
radiative/directed energy devices.
Radiated electrical techniques fall into two main
classes: radio frequency (RF)/microwave (MW) and ultrawideband
(UWB)/electromagnetic pulse (EMP). Both types are totally
electromagnetic, with no "hard" or inherently dangerous ionizing
radiation (x-ray or nuclear) types being proposed or investigated at
this time.
(Electromagnetic (EM) waves, however, still can be
emitted to an unsafe degree if safe exposure standards are exceeded).
RF/MW and UWB/EMP differ only in frequency range and pulse rise and
fall times, leading to different frequency coverage or "content" in
the pulse. RF/MW frequencies are generally considered to fall in the
several hundred megahertz (MHz) to several hundred gigahertz (GHz)
range, with the pulses or continuous waves (CW) usually considered
"narrowband"; i.e., with a small range (less than 10 percent) around a
single frequency.
UWB/EMP pulses, on the other hand, are very wideband or
"ultra" wideband, containing a large range of frequencies in each
pulse, but generally considered in the overall lower range up to 100 -
200 MHz. The frequency content leads to differences in how the
electromagnetic waves "couple," or penetrate, the outer metal skin and
the electronic engine control, ignition, or other electronics of the
vehicle. High frequency or short wavelength EM waves couple better
with the small electronic components within the vehicle’s electronic
engine control boxes, but are highly attenuated when passing through
metal joints and other ports-of-entry such as windows to reach those
components. Long wavelength, low frequency EM waves, however, couple
better with the larger metal structures, allowing less attenuation in
penetrating a vehicle’s body, after which they cause "resonant" EM
field buildups that, in turn, induce currents to flow in the
electronic engine controls and their electronic components through
their connecting cables or wires. The latter, low RF/MW, EM waves
(i.e., less than a few GHz, such as those that power microwave ovens),
appear to work better for most radiated engine-stopping techniques
evaluated so far, but more testing remains before final conclusions
can be reached.
The safety and effectiveness of all the currently
proposed electrical methods, whether direct injection or radiated,
were intensively investigated by the Army Research Laboratory (ARL) in
partnership with the National Institute of Justice(NIJ). In their
investigation, ARL utilized a number of target vehicles obtained from
the Federal drug asset forfeiture program of the Immigration and
Naturalization Service (INS) and U.S. Border Patrol (through the Chief
of the U.S. Marshal’s Service) and some vehicles previously purchased
by ARL. These vehicles were gasoline-powered commercial sedans, vans,
and small trucks, made by most major U.S. and foreign carmakers,
giving a good sample of the different electronic engine controls in
current use around the world. During each participant’s test and
evaluation EM field levels were measured by EM probes placed at
various points both inside (at the driver’s and passenger’s positions)
and outside the various test vehicles. The field levels measured were
then compared with the Institute of Electrical and Electronic
Engineers’ safety standards(the basis for the American National
Standards Institute / Occupational Safety and Health Administration
(ANSI/OSHA) standards). The results of this ARL/NIJ study, presented
to NIJ as a separate report by the ARL, compared the relative safety
and effectiveness of the various electrical techniques evaluated. The
ARL’s report concludes with a recommendation for additional phases of
testing on some of the technologies tested, including outdoor testing
in simulated field conditions. The PMTF concurs with the ARL’s
recommendation.
Electrical Systems
The Army Research Laboratory (ARL) in Adelphi, Maryland,
conducted tests on electronic vehicle-stopper technologies concurrent
with the work of the PMTF. Dr. Edward Scannell, director of the study,
who also serves as a member of the PMTF, has kept the PMTF advised of
the progress in testing. It appears, based upon the ARL testing, that
electrical vehicle-stopping is a viable option, but much more research
and development is required before a usable product emerges. The
PMTF’s surveys showed strong support for electrical vehicle stoppers
among members of the public and officers surveyed. The PMTF recommends
that resources be allocated for additional testing and
proof-of-principle demonstrations of electrical vehicle stoppers that,
hopefully, will lead to a marketable product. One concern with the use
of any electrical system is the potential for loss of vehicle systems
that impact driver control (e.g., power steering and braking) and that
occur when engines stop operating. Although this is often likened to
running out of gas, it is nonetheless a potential liability concern.
Radiative Systems
Radiative electrical vehicle stoppers differ from their
direct injection counterparts in that no actual contact between the
vehicle and energy source is required. This, in theory, removes the
necessity to place objects on the roadway in the path of a fleeing
vehicle or to launch a projectile at it. The potential ability to stop
a vehicle without actually contacting it greatly interests the PMTF.
The PMTF is aware of prior research conducted by ARL on a high-power
microwave vehicle stopper. Although not fully tested or developed, the
system appeared to be able to disrupt electronic engine controls.
Radiative systems would have the same impact upon the fleeing vehicle
as their direct injection counterparts. Only the delivery system is
significantly different. If target dwell times can be condensed and
targeting itself enhanced to avoid collateral damage, such systems
appear to have great potential at fixed-point locations. If
portability could be enhanced by creating smaller and more lightweight
systems, their use in typical police pursuits would be enhanced.
Finally, if a device could be mounted on the front of a chase vehicle
and pre-targeted for a distance directly in front of the chase
vehicle, such a system could be most significant in minimizing the
risks associated with pursuits. Difficulties encountered with
radiative vehicle stoppers are significant, however. They include
problems associated with collateral impact on other electronic devices
in common use, and requirements for hardening (or shielding) the
deployment platform from its effects. Nonetheless, radiative systems
appear to have significant promise for use in typical police pursuits,
and the PMTF recommends additional research and testing for such
devices.
Another concept for an electrical vehicle stopper came
to the attention of the PMTF in late June 1997. A company proposed a
plasma beam technology concept that could have applications for
stopping fleeing vehicles. In theory, high-voltage RF currents could
be directed at a fleeing vehicle, resulting in disruption or
destruction of electronic components. The potential for enhanced
target specificity of such a system, coupled with the potential for
deployment from a chase vehicle platform, interests the PMTF. This
technology is in its early conceptual state and requires significant
work prior to prototype testing. Pending proof-of-concept
demonstration, the PMTF does not yet have the requisite information to
make a specific recommendation regarding this concept.
http://www.geocities.com/CapeCanaveral/Lab/7919/Empstop.htm