Evolution of a Finite Pulse of Radiation in a High-Power Free-Electron Laser
Abstract
The development of an optical pulse of finite axial extent is studied by means of an axisymmetric, time-dependent, particle simulation code for different rates of tapering of the wiggler field. The results illustrate a number of the physical phenomena underlying the free-electron laser mechanism. These include: suppression of the sideband instability; the role of gain focusing versus that of refractive guiding; efficiency enhancement; and pulse slippage. It is found that a significant reduction in the sideband modulation of the optical field can be achieved with a faster tapering of the wiggler parameters. Increasing the tapering rate also reduces refractive guiding, causing the optical wavefronts to become more convex, thus spreading the optical field into a large cross-section. The corresponding enhancement of the peak output power is associated with an increased lateral extent of the optical field rather than an increase in the field amplitude. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 20, 1991
- Accession Number
- ADA237427
Entities
People
- Antonio Ting
- Bahman Hafizi
- Chai AMei Tang
- Phillip A. Sprangle
Organizations
- United States Naval Research Laboratory