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Power Beaming using FELs

Power beaming from ground-based systems to space-based platforms has been proposed by a number of researchers as a means of delivering energy to orbiting satellites and stations. Our work considers the use of a seeded high-gain high-efficiency Free-Electron Laser (FEL) amplifier based on a conventional linac as the source for power beaming. While the wall-plug efficiency of a single pass FEL is likely to be considerably lower than a recirculating system, electrical efficiency is unlikely to be a serious consideration for first-generation power-beaming systems. Moreover, the simplicity of the proposed scheme scales well from existing and completed experiments.

The concept of power beaming has been around since the 1960’s but technical and economic hurdles prevented implementation [ ]. The Free Electron Laser has been examined as a possible source for ground-based beaming already. This work takes advantage of recent progress in photoinjectors and high average-power lasers. We consider a system capable of delivering 1 KW of electrical power to a platform in geo-stationary orbit.

Table: Selected initial parameters for study
Parameter Value
Central Wavelength 840 nm
Beam Energy 226 MeV
Beam Current 500 A
Beam Emittance (norm. rms) 5 µm
Beam Energy Spread 0.15%
Undulator Period 6 cm
Undulator Parameter 3.0
Focusing (betafunction) 87 cm

Study Considerations:

Figure: Measured output of a standard silicon solar cell as a function of incident wavelength . The dashed line indicates the ideal (unity quantum efficiency) spectral response.

Seed Laser


We used Genesis 1.3 to simulate the FEL process in 3D including important effects such as diffraction and slippage.


20m undulator
40m undulator

Efficiencies as high as 13% were achieved, but with an unrealistically long (150 m) undulator. One can assume a denser beam, with peak currents of 1 - 2kA, and achieve much higher efficiencies.


Optimization of a high-gain FEL yielded a system capable of producing 1 KW of electric power in space using a 40 m undulator and a &Mac197;100 KW electron beam. This design relies on improvements to photoinjectors and lasers that may allow for high repetition-rate, high-brightness beam production and for high-power seeding of the FEL.

A paper was published on this study and is available for download:

C. Muller and G. Travish, Design Considerations for a High-Efficiency High-Gain Free-Electron Laser for Power Beaming, Proc. FEL 2003 (to be published).

A poster presented at the same conference (FEL2003) is also available as a PowerPoint slide.

Selected References:

FEL Power Beaming:
Laser Space Power:
Microwave Beaming:
Atmospheric Absorption:
High Power FEL:
Genesis 1.3: