Boeing has a complete 100 kilowatt free electron laser (FEL) design which will operate by passing a beam of high-energy electrons through a series of powerful magnetic fields, generating an intense emission of laser light that can disable or destroy targets
The Boeing news release does not mention the 100 Kilowatt power level, but the $163 million program is working to a 100 kilowatt FEL laser demonstrator and eventually megawatt class FEL that will be deployed on navy ships.
Photonics – Two companies are competing to develop the laser, The Boeing Co.’s Directed Energy Systems Div. in West Hills, Calif., and Raytheon Co.’s Integrated Defense Systems Div. in Tewksbury, Mass. Each has been awarded a 12-month, $6.9 million contract from the Office of Naval Research. The project is estimated to reach $163 million to fully complete a 100-kW demonstration prototype.
Defenseupdate – The Office of Naval Research (ONR) is investing nearly $25 million in the FEL program during fiscal year 2009. In April, ONR awarded Raytheon and Boeing $6.9 million to complete the preliminary design of the electric-powered Free Electron Laser; additional $156 million are earmarked or the system’s development and demonstration in realistic tests at sea. Boeing will partner with U.S. Department of Energy laboratories, academia and industry partners to design the laser. According to the Navy’s request the weapon class FEL demonstrator will be a 100kW device, designed to operate at the 1.6 micron near infrared (NIR). A follow-on Megawatt class FEL could be an element of the full fledged weapon system test bed to follow the current development, that would include a beam director, beam control and fire control elements for eventual introduction into the Fleet.
The FEL based weapon system is promising to transform future naval warfare capability by providing an ultra-precise, speed-of-light capability and unlimited magazine depth to defend ships against new, challenging threats, such as hyper-velocity cruise missiles. Furthermore, the future weapon could be employed in different levels, from non lethal to lethal effects. Other benefits of FEL include its ability to engage multiple targets at light speed, reduced dependency on explosive magazine, provide counter-surveillance at sea, flexible defense of the battle group, advanced maritime situational awareness and high-resolution imagery. FEL is expected to be deployed with the Navy’s future all-electric ship architecture.
Free-electron lasers work by injecting a number of electrons into a linear accelerator, where they are amplified to very high energy levels. Directed through a sequence of powerful electromagnetic fields, the electrons emit energy, creating an intense laser beam. “The FEL is the only all-electric laser that is capable of producing megawatt-and-above powers,” said Gary Fitzmire, vice president and program director of Boeing’s Directed Energy Systems.
To enhance energy, two variables of the system must be changed. The first includes increasing the number of times an electron group is injected into the accelerator, and the second, increasing the number of electrons.
One of the key benefits of the free-electron laser is that it is tunable in both its power levels and its wavelengths. To facilitate a successful and powerful laser beam that propagates through the atmosphere and that will not become absorbed, various wavelengths must be available – depending on environmental conditions – on a day-to-day basis. In addition, adjusting the power allows for fully destroying a target or for merely disabling it. The laser also provides a point-defense capability that uses high-resolution imaging and a beam director to pinpoint a specific spot on a target quickly and accurately.
There are three phases to the 100 KW demonstrator. The first, 1A, will involve a year of constructing an introductory design proposal for the 100-kW prototype FEL system, while the second phase, 1B, will be to create a detailed design. The third, phase 2, will be the fabrication, integration and testing of the FEL prototype.
Technical Design from 2006 of a 100 KW Free Electron Laser
The challenges of a 100-kW free-electron laser (FEL) are not insurmountable but nevertheless require technological solutions beyond the incremental refinements of mature technologies. Efforts are underway to develop technologies that will enable a new level of FEL performance, e.g. 100-kW average power or greater. These technologies include high-gain amplifiers driven by high-brightness electron beams, high-average-current
electron injectors, spoke resonator cavities for energy recovery linac, beam-break-up (BBU) suppression, and new concepts of high-efficiency tapered wigglers.
* High-average-current Injectors
Three candidates for the high-average-current injectors are being developed. They are the DC gun-SRF booster combination, the SRF gun and the normalconducting radio-frequency (NCRF) gun. The DC gun has been the workhorse of the Jefferson Lab FEL. It has achieved 10-mA average current.
* Spoke Resonators
A relatively new design of superconducting RF cavities called the spoke resonators offer a number of advantages: mechanical rigidity to resist vibrations, small transverse dimension, strong cell-to-cell coupling and the potential for high BBU limits. At the same diameter, the spoke resonator’s operating frequency is about one-half that of elliptical cavities. This means that a 350-MHz spoke cavity has the same diameter as a 700-MHz elliptical cavity but can operate at 4.5 K.
*A new concept of a tapered wiggler called the stair-step wiggler has the potential of delivering the same extraction efficiency as, but not the complexity of, a convention a linearly tapered wiggler.
* Beam-break-up Suppression
A very innovative way to significantly increase the multi-pass, multi-beam BBU limit in an ERL is by modifying the recirculation transfer matrix using skewed quadrupole magnets. This modification could be either a rotation or a reflection in such a way that BBU cannot develop or develops at a much higher current. This novel approach has quadrupled the measured BBU limit at the Jefferson Lab FEL. With refinements, it is conceivable
that much higher BBU limits can be achieved.