Improving electron beam quality of the Boeing free electron laser

doi:10.1016/0168-9002(91)90881-P

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

Volume 304, Issues 1–3, 1 July 1991, Pages 336-341

https://doi.org/10.1016/0168-9002(91)90881-P Get rights and content

Abstract

The successful operation of any free electron laser (FEL) is critically dependent upon electron beam quality. In a radiofrequency (rf) accelerator the micropulse or instantaneous beam emittance and peak current is established by the injector, however, it is important to maintain this beam's quality as it is accelerated and transported to the wiggler. In the past year, work has continued to enhance the electron beam of the Boeing FEL. The previous year's improvements in levelling the gun charge during the macropulse and rf power flatness were reported in the 1989 FEL conference. More recent work has concentrated upon the rf master oscillator and electron beam transport, which have lead to reduced macropulse energy spread, as well as decreased position and angle jitter. Also some electron beam diagnostics have been upgraded. The result has been lower macropulse emittance at the entrance to the wiggler.

References (5)

A.H. Lumpkin et al.
J.C. Goldstein et al.

There are more references available in the full text version of this article.

Cited by (6)

An FEL beam injection system with adjustable isochronism
1996, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
A design study is presented for a beam injection system suitable for a free-electron laser (FEL) and other purposes, which in its normal mode is isochronous to second order in the particle co-ordinates, yet which may be progressively shifted from the isochronous condition by alteration of the strengths (and for larger deviations the locations) of some of its magnetic elements. The system uses a minimum number of magnetic components (3–4 dipoles and 2 quadrupole triplets), and can produce both positive and negative deviations from isochronism within the range ±30 ps/% momentum deviation. The major second-order chromatic and geometric aberrations are minimised by the use of sextupoles. Use of the system for electron bunch compression in an FEL is discussed.
Final results of the Boeing and Los Alamos grazing incidence ring-resonator free electron laser experiment
1992, Nuclear Inst. and Methods in Physics Research, A
Initial test results for the Boeing and Los Alamos grazing incidence ring-resonator FEL were presented at the 1990 FEL Conference. This work showed that the resonator pointing alignment accurcy required improvements to the resonator diagnostics to increase the alignment accuracy. The alignment technique was described, but lasing results with the more accurate alignment were not available at that time. This paper discusses more recent and final test results from the grazing-incidence ring-resonator experiment. With the new alignment techniques, the extraction was approximately seven times greater, and the FEL output exhibited much reduced temporal structure. Measurements show that FEL output and wavelength are sensitive to electron beam energy variations.
Optical measurements on the Boeing free electron laser ring resonator experiment
1991, Nuclear Inst. and Methods in Physics Research, A
The Boeing free electron laser is presently operating with a stable semiconfocal ring optical cavity surrounding a 5 m wiggler. The resonator consists of two grazing-incidence reflective telescopes each formed by a grazing-incidence hyperboloid and its companion off-axis paraboloid. The resonator is closed by two flats: one used for dynamic jitter correction and the other used to outcouple some of the circulating beam. It is critical to lasing that the alignment of the resonator be maintained, the focus of the optical mode be at the midpoint of the wiggler, and the wavefront quality of the propagating beam be maintained. Measurements of the focus position, power loss, and wavefront quality are made before operation of the electron accelerator to diagnose whether the conditions required for lasing exist.
First operation of a free electron laser using a ring resonator
1991, Nuclear Inst. and Methods in Physics Research, A
During the past year the Boeing free electron laser optical cavity was changed from a simple concentric cavity using two spherical mirrors to a much larger ring resonator. The new resonator is made up of two-mirror telescopes located at each end of the wiggler with a round-trip path length of approximately 133 m. Each telescope consists of a grazing-incidence hyperboloid and a paraboloid. First lasing operation at 0.63 μm occurred on March 23 and 24, 1990. The lasing output was approximately seven orders of magnitude above the outcoupled spontaneous emission. The characteristics of the ring resonator are discussed. Lasing data is analyzed for the electron beam and ring resonator effects. Optical alignment techniques for the ring resonator are presented.
Development of an XUV-IR free-eIecron laser user facility for scientific research and industrial appilcations
1991, Proceedings of SPIE - The International Society for Optical Engineering
Tests of a Grazing-Incidence Ring Resonator Free-Electron Laser
1991, IEEE Journal of Quantum Electronics

View full text