Evolution of a finite pulse of radiation in a high-power free-electron laser. Memorandum report

Technical Report · Thu Jun 20 04:00:00 EDT 1991

OSTI ID:5334582

Ting, A; Hafizi, B; Sprangle, P; Tang, C M

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)

• Research Organization: Naval Research Lab., Washington, DC (United States)
• OSTI ID: 5334582
• Report Number(s): AD-A-237427/0/XAB; NRL-MR--6844
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
426002* -- Engineering-- Lasers & Masers-- (1990-)
AMPLIFICATION
COMPUTER CODES
COMPUTERIZED SIMULATION
CROSS SECTIONS
ELECTRICAL EQUIPMENT
ELECTROMAGNETS
EQUIPMENT
FOCUSING
FREE ELECTRON LASERS
GAIN
LASERS
MAGNETS
MODULATION
OPTICAL PROPERTIES
OPTIMIZATION
PARTICLES
PHYSICAL PROPERTIES
PULSES
SIMULATION
STABILITY
TIME DEPENDENCE
WIGGLER MAGNETS