Demonstration of an optical mixing technique to drive Kinetic Electrostatic Electron Nonlinear waves in laser produced plasmas

摘要

A nitrogen gas Raman cell system has been constructed to shift a 70 J 527 nmlaser beam to 600 nm with 20 J of energy. The 600 nm probe and a 200J, 527 nmpump beam were optically mixed in a laser produced (gas jet) plasma. Thebeating of the two laser beams formed a ponderomotive force that can driveKinetic Electrostatic Electron Nonlinear (KEEN) waves discovered inVlasov-Poisson simulations by Afeyan et al [1,2]. KEEN waves were detected inthese experiments where traditional plasma theory would declare there to be aspectral gap (ie no linear waves possible). The detection was done usingThomson scattering with probe wavelengths of both 351 nm and 263.5 nm.