Electra is an R & D program at the U. S. Naval Research Laboratory (NRL) to develop a rep-rate, reliable, and efficient, high energy, high average power Krypton Fluoride (KrF) laser. A primary motive for this program is to develop a driver for inertial fusion energy (IFE). For IFE, the ultimate goals are: overall efficiency: 6-7%; cost: $10.00/ e beam Joule; durability: 2x108 shots.
The program will use advanced scientific research to develop the necessary technologies. These technologies will then be integrated into a single 5 Hz, 700 J rep-rate laser. This size is small enough to be manageable, but large enough to demonstrate that the technology would scale to higher energy (30-100 kJ) systems. The laser technologies that need development are: a durable, efficient pulsed power system; a durable electron beam emitter; a long life pressure foil structure ("hibachi"); a recirculator to quiet the laser gas between shots; and long life optical windows. In the course of developing these technologies advanced research will be performed in the fields of: large area electron beam propagation, advanced gas kinetics, 3-D radiation and laser transport, hydrodynamics, solid state electronics, pulsed power, materials, and advanced optics.
Electra wil be pumped by two 500 kV, 110 kA, 100 nsec, electron beams. The durable and efficient pulsed power system that will eventually be needed will require several years of advanced R & D. To provide a test bed to start addressing the other laser issues right away, a First Generation Pulsed Power System that is based on existing technology is being built. This system uses existing spark gap technology, and has been designed and built by Pulse Sciences, Inc (PSI). It has two identical and independent sides. One side was sent to NRL for installation, the other kept at PSI for testing.
The tests at PSI showed the pulsed power system can run at 5 Hz, at full voltage, for 90,000 shots. This five hour run exceeds the original lifetime specification by a factor of nine, and is unprecedented for a spark gap based system. (After 180,000 shots the output electrodes need to be replaced. This is a two hour job.) The run time is more than enough for the initial laser research. Both sides are expected to be installed, working, and ready for electron beam studies by June, 2000.
For further information, contact: John Sethian (sethian@this.nrl.navy.mil); (202) 767-2705.