Top: NIF Hohlraum, with electron density profile from a Lasnex simulation superimposed on the right half. Bottom: overlapped intensity of the 24 incoming laser quads in the transverse (X,Y) plane, at the three indicated Z-positions (, 4.2, and 5.2 mm; 4.2 mm is the LEH position). The intensity is defined with the Poynting vector in the Z-direction; in this case the crossed beam transfer was turned off in the calculations for illustration purpose.
Hydrodynamic profiles for an emulator Hohlraum with (top halves) and without (bottom halves) a LEH liner. The Z contours show the boundaries between the gas ( in both cases), the LEH liner material (CH), the ablator (Be or CH), the gold Hohlraum wall, and its Au–B liner (designed to reduce to amount of SBS from the outer beams); the triangles on the plot on the left are vector-plot representations of the plasma flow. The hydrodynamics profiles for the lined LEH Hohlraum are from Lasnex simulations, while the unlined are from Hydra; both are taken at the time of peak laser power.
(a) Relative energy gain from crossed-beam transfer averaged over the inner cones and the outer cones going through one LEH, for the Hohlraum emulator with (dashed) and without (solid) a LEH liner (there is about twice as much energy in the outer cone than in the inner). (b) Intensity profiles for all the beams as they reach the Hohlraum walls, for a wavelength separation of 0, 1.5, and 3 Å between the inner and outer cones (with ). This is for a Hohlraum without LEH liner ( is the point of best symmetry).
Left: GXD images of the capsule for three wavelength separations between the inner and outer beams: 1.5, 2.3, and 3.9 Å (the Hohlraum axis is vertical on these images). Right: P2/P0 (pole-waist asymmetry) for the corresponding three shots as measured in the experiments (diamonds), and as calculated in preshot (upper line) and postshot (lower line) simulations.
Calculated average energy transfer between the inner and outer cones as a function of the wavelength separation between the cones. The net transfer is zero for a nonzero wavelength separation due to the flow at the LEH. The curves flatten near the peaks due to laser depletion. The separation between the peaks is proportional to the ion acoustic velocity.
Article metrics loading...
Full text loading...