Inverse Bremsstrahlung Stabilization of Noise in the Generation of Ultra-short Intense Pulses by Backward Raman Amplification

Berger, Richard L. ; Solodov, Daniel S. Clark Andrei ; Valeo, Ernest J. ; Fisch, Nathaniel J.

Princeton University. Plasma Physics Laboratory.

关键词: 25 Energy Storage;    Amplification;    Bremsstrahlung;    Laser-Plasma Interactions;    Temperature Gradients Laser-Plasma Interactions;   

DOI  :  10.2172/820122
RP-ID  :  PPPL-3898
RP-ID  :  AC02-76CH03073
RP-ID  :  820122

美国|英语

来源: UNT Digital Library

【 摘 要 】

Inverse bremsstrahlung absorption of the pump laser beam in a backward Raman amplifier over the round-trip light transit time through the sub-critical density plasma can more than double the electron temperature of the plasma and produce time-varying axial temperature gradients. The resulting increased Landau damping of the plasma wave and detuning of the resonance can act to stabilize the pump against unwanted amplification of Langmuir noise without disrupting nonlinear amplification of the femtosecond seed pulse. Because the heating rate increases with the charge state Z, only low-Z plasmas (hydrogen, helium, or helium-hydrogen mixtures) will maintain a low enough temperature for efficient operation.