FELs are being developed in a number of laboratories in the world for application as industrial lasers. Conventional high-powered lasers of average power are capable of generating only thousands of watts, and most of them do not operate continuously, but rather in short pulses. These devices cannot operate at high powers continuously because of heat damage to the core material in the laser --gas, crystal or liquid -- that emits the light beam.

FELs, by contrast, radically reduce the problem of heat damage because the technology involves free (unbound) electrons traversing in vacuum. No core materials are used. Instead, a beam of electrons is accelerated through a magnetic structure that extracts their energy in the form of light, and then the electrons are recycled for more passes through a loop.

Another limitation of most conventional lasers is that they can only operate at one frequency -- or what the eye sees as one color -- in the electromagnetic spectrum. FELs, however, are "tunable"; they can operate at almost any frequency, from x-rays to microwaves. This flexibility allows for a greater range of industrial applications.

Most regular lasers, especially tunable ones, are not highly efficient, converting only something in the order of 1% of their energy into light and losing all the rest in the form of heat. FELs have a potential efficiency rate of 10%, while the Israeli kind of FEL may even be able to reach 50%.

Continuous power

Of the 50 FELs being constructed or in operation worldwide, just four, including Israel's, are electrostatic accelerator FELs (EA-FELs) with internal resonator - the only type that can potentially move beyond pulsed energy to continuous energy. The Israeli team made the first breakthrough when they demonstrated with a 1,000-watt pulse that this kind of EA-FEL technology works.

"Granted, our laser generated only a short pulse of relatively low energy," clarified Prof. Gover, "but the experiment behaved exactly according to our calculations and expectations. The FEL research community views this result as an important milestone on the way to realizing high power continuous lasers. Now, we're working on increasing the power and duration of the laser beam."

Star Wars survivor

Electron-optical elements of the Free Electron Laser inside the tandem accelerator

Super lasers were originally envisioned by the US's Star Wars weapons program as "death rays" for felling ballistic missiles attacking via outer space. Today, scientists' aspirations are more peaceable though no less impressive. Potential uses for FEL laser energy are igniting non-polluting nuclear reactors; powering communications unmanned airborne vehicles (UAVs); and remote sensing of pollutants in the atmosphere.

The most immediate application of FELs may be in the materials processing industry. Commercially manufactured, rugged and economical, FELs could be deployed for strengthening metal surfaces, producing light-weight high-temperature ceramics, and processing artificial and synthetic fibers - among other industrial uses.

The TAU-led project, carried out at a modified van de Graff accelerator at the Weizmann Institute of Science, was funded by the Israeli government, the Israeli Academy of Sciences, the US-Israel Binational Science Foundation, and the Meyer Foundation.

The Israeli FEL consortium maintains close scientific collaboration with leading research laboratories in the field in the US, the Netherlands, and Russia. The Dutch research group, with early contributions by the Israeli consortium, is in the process of constructing a similiar EA-FEL which is expected to operate with continuous power at the level of one million watts.