Pulse powerUsing pulse power to stop cars in their tracks

Published 15 November 2007

A beam of microwave energy could stop vehicles in their tracks; good solution for perimeter defense, security check points, and police car chases; problem is, it may disable electronic systems in the neighborhood

Remember the movie “2 Fast 2 Furious”? Researchers at Pasadena, California-based Eureka Aerospace are now turning a fictional concept from that movie into reality: They are creating an electromagnetic system that can stop a vehicle in its tracks (the company calls it high-power electromagnetic system, or HPEMS) . The system, which can be attached to an automobile or aircraft carrier, sends out pulses of microwave radiation to disable the microprocessors that control the central engine functions in a car. The device could be used by law enforcement to stop fleeing and noncooperative vehicles at security checkpoints, or as perimeter protection for military bases, communication centers, and oil platforms in the open seas. Technology Review’s Brittany Sauser writes that the system has been tested on a variety of stationary vehicles and could be ready for deployment in automobiles within eighteen months, says CEO James Tatoian, who is also the project’s leader.

This is how it works: To bring an opposing vehicle to a halt, the 200-pound device is attached to the roof of a car. The car’s alternator serves as the system’s power source, the direct-current (DC) power of which feeds into a power supply. This generates a stream of 50-nanosecond-duration pulses of energy. These pulses are amplified to 640 kilovolts using a 16-stage Marx generator. The 640 kilovolts of DC power are then converted into microwaves using an oscillator which consists of a pair of coupled transmission lines and several spark-gap switches. Finally, a specially designed antenna beams the microwave energy toward an opposing vehicle through a part of the car, such as the windshield, window, grill, or spacing between the hood and main body, which is not made of metal (metal acts as a shield against microwave energy). The radiated microwave energy will upset or damage the vehicle’s electronic systems, particularly the microprocessors which control important engine functions such as the ignition control, the fuel injector, and the fuel-pump control. Note that electronic control modules were not built into most cars until 1972, so the system will not work on automobiles made before that year.

The concept of disabling vehicles’ electronic system with microwaves was first tested in 1997 by the U.S. Army using bulky and heavy military equipment. The Eureka Aerospace system is only six to eight feet long (antennae included) and not quite three feet wide. “It is much more efficient and compact than anything previously used in military vehicles,” says Tatoian. The device’s peak power output is two gigawatts, although the average power emitted in a single shot is about 100 watts. Each radiated pulse lasts about 50 nanoseconds. All the test cars’ engines were shut off using a single pulse at a distance of approximately fifteen meters, making the total energy output 100 joules, says Tatoian. Eureka is currently developing a more compact high-power microwave pulse system with the goal of disabling engines at ranges from as far away as 200 meters. “I have no doubt that if you set up a microprocessor and get a high-powered, well-focused beam of energy on [a car], you can disrupt its operation,” says Peter Fisher, a professor of physics and the division head in particle and nuclear experimental physics at MIT. To be able to deploy such a system safely, however, will take some work, he says. Just imagine if a police officer is in a high-speed chase near a shopping mall or an office building and turns on one of these systems to stop a car driven by a fleeing criminal: Many of the elevators have microprocessor controls, so if the officer is pointing the device in the direction of the mall, he or she could end up trapping dozens people in elevators, says Fisher. Many other electronic systems, such as an automated teller machine or a security system, could also be disrupted. Fisher also cautions that, while the system may seem like an easier and more efficient solution than spike strips, it could still cause a huge accident if a car is disabled and a driver loses steering control. The system could pose a safety concern as well: Radiation can burn human skin, and microwaves have long been suspected of being a cancer-causing agent.

Sauser quotes Fisher to say that at the moment, the most practical application for the system would be in the U.S. military for perimeter protection of areas that are generally remote. Initial funding for the project came from the U.S. Marine Corp, but now Eureka Aerospace is looking to other governmental agencies for financial support as the company continues to work to make the device smaller, lighter, and more efficient. Tatoian says that details regarding future work with the military are confidential.