Refractive Index Seen by a Probe Beam Interacting with a Laser-Plasma System

A plasma amplifier to combine multiple beams at NIF

“…(1)- (4) and the analysis that generated them, stems from comparison to experimental observations of power transmission in cases where the pump and seed beams had linear polarizations that were either aligned 14 or had their polarizations components measured separately. 28,29 The close agreement with observations in cases where the ion wave response was linear confirmed the Vlasov model of the plasma in predicting a linear plasma response that is applicable in a wider range of situations. Still, there have been numerous observations of the amplification of beams by CBET in conditions where the plasma response was either inferred to be non-linear by comparison of seed amplification with linear models 10,11,18,[20][21][22] or directly demonstrated to be non-linear via the scaling of transmitted amplified seed power with incident seed power.…”

“…The closest agreement of this measurement with predictions was obtained by varying the fraction of H in the mixed C and H plasma to fit the observations at which point the difference with the model was within a few % at all seed wavelengths. 28 Further, the measurements confirmed the expected phase shift in the polarization components that were both aligned and transverse to the pump field. 27 This effect was used to demonstrate that a beam plasma system can be a polarizer for the seed beam, 29 which is another successful use of plasma optics to control a laser beam's performance.…”

“…27 The models of CBET by beams with arbitrary polarization have received further validation with increased accuracy by a very recent set of experiments studying both the power and polarization of a seed beam transmitted through a CH plasma illuminated by a single linearly polarized pump beam. 28,29 These experiments studied the relative seed gain produced by the plasma in each polarization component of a linearly polarized seed interacting with a linearly polarized pump that was rotated 45 with respect to the seed. The ratio of the transmission of the two components was studied for seed wavelengths varying across the ion wave response function, producing a measurement of the gain profile for the aligned polarization of the seed relative to that of the crossed polarization as a function of frequency to compare with the predictions of kinetic models shown in Eqs.…”

“…[20][21][22][23][24][25][26][27] These models have shown encouraging correspondence with observations, both in early experiments, 9,10,13,14 and in more recent experiments at the NIF [15][16][17] and have undergone their most precise validation yet in recent experiments with smaller lasers and precise measurements. 28 The development of a robust technology of controlling optical power flow in plasmas now benefits from careful comparison of these models to the existing data base. Producing CBET models that conform to existing standards of validation and verification (V&V) 30 will also depend on close comparisons with this database.…”

Influence of coupling on thermal forces and dynamic friction in plasmas with multiple ion species

“…In particular, it has been suggested that strong background gradients introduced during the implosion can separate fusion fuel constituents, resulting in yield degradation [1][2][3][4][5][6][7][8][9][10][11][12][13]. The same ion diffusion mechanisms that govern species separation in the fuel underlie mixing at the shell/fuel interface [14][15][16][17][18][19][20], as well as at the inner boundary of the hohlraum [21].…”