Use of incoherence to produce smooth and controllable irradiation profiles with KrF fusion lasers

Journal Article · Fri May 01 04:00:00 EDT 1987 · Fusion Technology; (United States)

OSTI ID:5687638

Lehmberg, R H; Goldhar, J ^[1]

---

1. US Naval Research Lab., Washington, DC 20375

A technique called echelon-free induced spatial incoherence is proposed for producing smooth, controllable target beam profiles with large KrF fusion lasers. The idea is basically an image protection technique that projects the desired time-averaged spatial profile F(x) onto the target via the laser system, using partially coherent broadband light. The information needed to reproduce F(x) is transported through the system by a multitude of independent coherence zones, whose diameters are small compared to scalelengths of linear aberration and gain nonuniformities; as a result, F(x) remains relatively insensitive to these effects. An analysis is carried out to evaluate the pertubations of F(x) due to linear aberration, self-focusing, gain saturation, and diffraction. It shows that under conditions applicable to large KrF lasers, the pertubations will result in a small broadening and smoothing of F(x), whose functional form should be controllable to within a few percent. The ability of this technique to generate smooth focal profiles is demonstrated using a small KrF discharge oscillator-preamplifier system.

• OSTI ID: 5687638
• Journal Information: Fusion Technology; (United States), Journal Name: Fusion Technology; (United States) Vol. 11:3; ISSN 0748-1896; ISSN FUSTE
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700208* -- Fusion Power Plant Technology-- Inertial Confinement Technology
BEAM PROFILES
COHERENT RADIATION
DIFFRACTION
DISTURBANCES
FOCUSING
GAIN
INERTIAL CONFINEMENT
IRRADIATION
KRYPTON FLUORIDE LASERS
LASER FUSION REACTORS
LASER TARGETS
OSCILLATORS
PREAMPLIFIERS
PRODUCTION
SPACE DEPENDENCE
TIME DEPENDENCE