Applications for energy recovering free electron lasers

Science, 2001

A free-electron laser consists of an electron beam propagating through a periodic magnetic field. Today such lasers are used for research in materials science, chemical technology, biophysical science, medical applications, surface studies, and solid-state physics. Free-electron lasers with higher average power and shorter wavelengths are under development. Future applications range from industrial processing of materials to light sources for soft and hard x-rays.

Physical Review Letters, 2000

Jefferson Laboratory's kW-level infrared free-electron laser utilizes a superconducting accelerator that recovers about 75% of the electron-beam power. In achieving first lasing, the accelerator operated "straight ahead" to deliver 38-MeV, 1.1-mA cw current for lasing near 5 mm. The waste beam was sent directly to a dump while producing stable operation at up to 311 W. Utilizing the recirculation loop to send the electron beam back to the linac for energy recovery, the machine has now recovered cw average currents up to 5 mA, and has lased cw with up to 1720 W output at 3.1 mm.

1995

Advanced concepts of electrostatic accelerator free-electron lasers (EA-FELs) are discussed. The capabilities of electrostatic accelerators to produce continuous high energy electron-beams enable construction of efficient FELs, for generation of high average power of radiation at a wide range of the electromagnetic spectrum. Employing RF linacs for charging electrostatic accelerators provides transport of larger e-beam currents, and correspondingly producing even higher power. The unique features of EA-FELs make them excellent sources for applications, which require high-power radiation.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1987

Experiments to demonstrate recovery in conjunction with the Los Alamos free electron laser are reported in this paper. Deceleration of the electron beam greater than 70% has been observed. Beam transport through the system down to 3.5 MeV has been obtained and power flow measurements have been made that demonstrate the conversion of beam energy back into rf power. The resonant bridge couplers appear to function as designed. Predicted instabilities in the beam transport system have been observed.

1989

The free-electron laser (FEL) has been developed to the point where projections of its high-power capbility have made it an important component of the directed-energy research program within the Strategic Defense Initiative. To achieve the desired near-visible wavelength and high intensity, stringent demands are placed on the electron beam that drives the FEL. Typical requirements are high peak current (0.2 to 2 kA) at a kinetic energy of 100 to 150 MeV, small energy spread «1 %), small diameter «3 mm), and low divergence «0.1 mrad). Either an induction linac or an rf linac may be a suitable candidate to provide the electron beam. In this review, we describe the technical issues and technology needed to build a visible-light FEL driven by an rf linac. A recently installed rf linac at Boeing Aerospace is used as the principal illustrative example.

European Physical Journal D, 2006

Many scientific disciplines ranging from physics, chemistry and biology to material sciences, geophysics and medical diagnostics need a powerful X-ray source with pulse lengths in the femtosecond range . This would allow, for example, time-resolved observation of chemical reactions with atomic resolution. Such radiation of extreme intensity, and tunable over a wide range of wavelengths, can be accomplished using high-gain free-electron lasers (FEL) [5-10]. Here we present results of the first successful operation of an FEL at a wavelength of 32 nm, with ultra-short pulses (25 fs FWHM), a peak power at the Gigawatt level, and a high degree of transverse and longitudinal coherence. The experimental data are in full agreement with theory. This is the shortest wavelength achieved with an FEL to date and an important a Present address:

Proceedings of the IEEE, 1999

Vacuum electronic sources have shown marked improvement since the invention of the magnetron before World War II, and dramatic increases in both average powers and frequencies have been achieved. Of course, many of these gains have been achieved by the development of different devices. The typical development pattern for a given device exhibits an initial period of rapid improvement followed by a plateau determined by technological or physical limitations on the concept. Slow wave devices such as magnetrons and/or klystrons operate efficiently at frequencies up through X-band or somewhat higher. Helix or coupled cavity traveling-wave tubes are used for various applications at frequencies ranging up through W-band. At still higher frequencies, fast wave devices such as gyrotrons and free-electron lasers are required for high-power operation. The free-electron laser concept is unique in that the mechanism is applicable across the entire electromagnetic spectrum; free-electron lasers have been built at wavelengths from microwaves through the ultraviolet, and plans are under development for X-ray systems. Our purpose in this paper is to describe the principal directions of free-electron laser research at the present time. To this end, we first give a brief tutorial of the physics underlying the concept and then describe the principal development paths under way.

Physical Review Letters, 1996

AIP Conference Proceedings, 2009

A design of a compact free-electron laser (FEL), generating ultra-fast, high-peak flux, XUV pulses is presented. The FEL is driven by a high-current, 0.5 GeV electron beam from the Lawrence Berkeley National Laboratory (LBNL) laser-plasma accelerator, whose active acceleration length is only a few centimeters. The proposed ultra-fast source (∼10 fs) would be intrinsically temporally synchronized to the drive laser pulse, enabling pump-probe studies in ultra-fast science. Owing to the high current (10 kA) of the laser-plasma-accelerated electron beams, saturated output fluxes are potentially greater than 10 13 photons/pulse. Devices based both on self-amplified spontaneous emission and high-harmonic generated input seeds, to reduce undulator length and fluctuations, are considered.