Journal of Plasma Physics

Papers

Observation of amplification of light by Langmuir waves and its saturation on the electron kinetic timescale

R. K. KIRKWOODa1, Y. PINGa1, S. C. WILKSa1, N. MEEZANa1, P. MICHELa1, E. WILLIAMSa1, D. CLARKa1, L. SUTERa1, O. LANDENa1, N. J. FISCHa2, E. J. VALEOa2, V. MALKINa2, D. TURNBULLa2, S. SUCKEWERa2, J. WURTELEa3, T. L. WANGa4, S. F. MARTINSa4, C. JOSHIa4, L. YINa5, B. J. ALBRIGHTa5, H. A. ROSEa5 and K. J. BOWERSa5

a1 Lawrence Livermore National Laboratory, Livermore, California 94550, USA

a2 Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA

a3 Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA

a4 Department of Electrical Engineering, University of California at Los Angeles, Los Angeles, California 90095, USA

a5 Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

Abstract

Experiments demonstrate the ~77× amplification of 0.5 to 3.5-ps pulses of seed light by interaction with Langmuir waves in a low density (1.2 × 1019 cm−3) plasma produced by a 1-ns, 230-J, 1054-nm pump beam with 1.2 × 1014 W/cm2 intensity. The waves are strongly damped (kλD = 0.38, Te = 244 eV) and grow over a ~ 1 mm length, similar to what is experienced by scattered light when it interacts with crossing beams as it exits an ignition target. The amplification reduces when the seed intensity increases above ~1 × 1011 W/cm2, indicating that saturation of the plasma waves on the electron kinetic time scale (<0.5 ps) limits the scatter to ~1% of the available pump energy. The observations are in agreement with 2D PIC simulations in this case.

(Received October 19 2010)

(Accepted November 16 2010)

(Online publication December 21 2010)