NRL Explores Plasma Mirror's Potential for High-Frequency Radar Director

4/19/1996 - 34-96r
Contact: Public Affairs Office, (202) 767-2541

Dr. Robert Meger, Head of the Charged Particle Physics Branch, Plasma Physics Division at the Naval Research Laboratory (NRL), delivered a seminar on March 1 summarizing the current status of the development of the plasma mirror.

The plasma mirror, called Agile Mirror, is a multipurpose, microwave beam director. It has advantages over existing director technology including size, weight and cost, but especially electronic steering, wide bandwidth operation, and high-power capability, Dr. Meger explained.

"Because a plasma mirror is electronically steerable with no moving parts, it possesses the ability to move very fast from one point to another," Dr. Meger said.

Agile Mirror consists of a smooth plasma sheet formed in a low-pressure chamber by a gas discharge, Dr. Meger said. The present laboratory system measures 60 centimeters x 60 centimeters x 1 centimeter thick. The plasma acts just like a conducting metal sheet to the microwaves. It is possible to turn the plasma mirror on and off repeatedly and very rapidly (less than 10 microseconds) and change the orientation of the mirror in between pulses. Multiple high-power microwave sources with the same or different frequencies could use a single Agile Mirror beam director, in sequence or simultaneously.

"Its beauty is that it could allow a radar system to follow many targets simultaneously while continuing to search for more," Dr. Meger said.

Agile Mirror is being developed at NRL's Plasma Physics Division in collaboration with the Radar Division.

Dr. Meger explained that radar redirection (crucial for finding targets) originally depended on moving antennas mechanically. This limited response time. A substantial improvement in response time was achieved with phased arrays, which are used on Aegis cruisers.

Phased array radar, which is steered electronically by changing the relative phase of individual elements in the array, is costly and has frequency limitations. Broadband frequency capability is important because a target invisible in one frequency may be readily visible in another, Dr. Meger explained.

Agile Mirror differs significantly because it separates the beam generator from the means of electronically directing the high-frequency microwaves to a target. This allows use of multiple or broadband high-power microwave sources with a single mirror.

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