Stimulated brillouin backscatter of a short-pulse laser

Conference · Thu Nov 03 04:00:00 EST 1994

OSTI ID:207420

Hinkel, D E; Williams, E A; Berger, R L

Stimulated Brillouin backscattering (SBBS) from a short-pulse laser, where the pulse length is short compared to the plasma length, is found to be qualitatively different than in the long pulse regime, where the pulse length is long compared to the plasma length. We find that after an initial transient of order the laser pulse length transit time, the instability reaches a steady state in the variables x{prime} = x {minus} V{sub g}t, t{prime} = t, where V{sub g} is the pulse group velocity. In contrast, SBBS in a long pulse can be absolutely unstable and grows indefinitely, or until nonlinearities intervene. We find that the motion of the laser pulse induces Doppler related effects that substantially modify the backscattered spectrum at higher intensities, where the instability is strongly coupled (i.e. , has a growth rate large compared to the ion acoustic frequency).

• Research Organization: Lawrence Livermore National Lab., CA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 207420
• Report Number(s): UCRL-JC--117056; CONF-941101--15; ON: DE96005401
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BACKSCATTERING
BRILLOUIN EFFECT
LASER RADIATION
LASER-PRODUCED PLASMA
MATHEMATICAL MODELS
PLASMA INSTABILITY
PULSES