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Compact single and nested tungsten-wire-array dynamics at and applications to inertial confinement fusiona)
a)Paper QI2 2, Bull. Am. Phys. Soc. 50, 260 (2005).
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View: Figures


Image of FIG. 1.
FIG. 1.

(Color) This is a conceptual layout of the double -pinch driven hohlraum ICF concept. The design is symmetric about the midplane. Shown here are the (1) upper MITL power feed, (2) lower MITL power feed, (3) outer wire array, (4) inner wire array, (5) foam pulse shaping target, (6) high-yield scale cryogenic fusion capsule, (7) upper primary hohlraum, (8) lower primary hohlraum, (9) secondary hohlraum, (10) beryllium spokes for coupling to secondary (two places), and (11) axial shine shield to prevent pole hot capsule drive (two places).

Image of FIG. 2.
FIG. 2.

(Color) Implosion dynamics data from 20-mm-diam, 6 mg/cm array showing (a) array trajectories vs normalized time from four methods. Trajectories are from a radial optical streak (ROS, red triangles), the edge of the x-ray pinhole framing camera radial profile (axial XRPHC edge, green circles), the peak of the moving shell from the radial profile (XRPHC peak, blue circles), and from the inductance unfolds (, orange line), compared with a thin-shell model (black line). (b) x-ray radiograph obtained prior to peak x-ray power. The position of the individual bubbles (circles) and spikes (triangles) are shown, as well as the averages that were plotted in (a) (blue lines).

Image of FIG. 3.
FIG. 3.

(Color) Implosion dynamics data (left axis) for a 2.5 mg/cm array: ROS (red triangles), radiography (light blue bars), shadowgraphy (black bars), effective current radius (orange line), and radial soft x-ray power (right axis/black line). The time of acceleration or the end of the ablation period is shown.

Image of FIG. 4.
FIG. 4.

(Color) X-ray radiographs of different regions of nested wire arrays at : (a)–(c) on , wires. The inner array is slightly twisted on this shot. (c) is a blowup of two wires from (b). (d)–(f) on , wires. (f) is a blowup of several wires from (e), plotted on a logarithmic color scale to enhance the detection of the inner wires. (g)–(i) on , wires. (j)–(l) on , wires. A transmission scale for these radiographs is given in Fig. 8.

Image of FIG. 5.
FIG. 5.

(Color) Trajectory data (left axis) for a on nested array (ROS, blue triangles) and effective current radius (, blue line), and radial power (right axis/black line). The outer array acceleration or ablation time , interaction pulse produced by the interaction of the outer and inner array (IP), the inner array ablation period , and inner array acceleration time are all defined on the plot. (b) A comparison of single and nested array powers (right axis), and radii of the inductance : orange lines (single array, , green line (, , power not shown), blue line from (a) (, ).

Image of FIG. 6.
FIG. 6.

(Color) Ablation time of single (red) or outer (blue) array versus array mass from electrical (circles) and streak data (squares). Rocket model of the ablation time with (black line).

Image of FIG. 7.
FIG. 7.

(Color) Ablation time of inner array versus inner mass from electrical data for three different outer array masses: (, , ). All data have , except where noted. Rocket models (for ) of the ablation time with (black line, including current transfer time/broken black line). Wire array currents at the peak of the IP are given in the legend.

Image of FIG. 8.
FIG. 8.

X-ray radiographs of different regions of nested wire arrays at : (a) on on foam, . (b) on on foam, . (c) on on foam, .

Image of FIG. 9.
FIG. 9.

(Color) Laser shadowgraphs of nested arrays: (a)–(e) on . (f)–(h) on on foam. Times are with respect to the peak of the interaction pulse ( for (a)–(e), for (f)–(h). Lines denote the initial position of the outer array (red), of the inner array (purple), and of the effective current (solid white).

Image of FIG. 10.
FIG. 10.

(Color) Array implosion dynamics data and models: (a) Outer array trajectory data from array in Fig. 11(a) ( on ): effective current radius (blue line), shadowgraphy bubbles (black diamonds) and spikes (open triangles), radiography bubbles (blue diamonds) and spikes (blue triangles). The time of maximum outer array , of the peak of the IP , of the inner array acceleration , and of array final stagnation are marked with vertical dotted lines. Current switching may begin at . The inner array ablation period [(, see Figs. 5(a), 7] is the difference between and . The inner array implosion time is the difference between and . (b) Inner array trajectory data for array from Fig. 11(d) ( on on foam), except with radiography. Trajectory models in (a) and (b): outer array ablation models (red lines), inner array ablation models (orange lines), inner array thin-shell trajectory with no ablation (green line). Numbers marked near trajectory endpoint is the fraction of trailing mass for that trajectory.

Image of FIG. 11.
FIG. 11.

(Color) (a)–(c) Single (black) and nested (color) array power pulses for various single , outer , and inner array masses, noted on the plots in units of . (d) Nested array results that use foam targets on axis. Multiple tests with identical setups are shown as dashed lines. When dashed lines show multiple tests, the solid lines are the average. (a)–(c) are obtained with high inductance () feed, (d) low .

Image of FIG. 12.
FIG. 12.

(Color) The inner array implosion time vs for different , compared to models with , 25%, 100%.

Image of FIG. 13.
FIG. 13.

(Color) (a) Comparison of single power pulse (black) with nested array power pulses (color) showing the interaction pulse (IP), and possible signature of the outer array striking the axis (OS). These experiments used fixed outer (or single array mass) or , and varied the inner array mass . Power pulses are not corrected for diagnostic slot collimation. (b) Comparison of the normalized interaction pulse shapes. (c) Comparison of the net power produced by the outer-inner interaction as is varied (1.16, 2.4, 2.5, and ) and fixed . Data is corrected for diagnostic slot collimation.

Image of FIG. 14.
FIG. 14.

(Color) (a) Peak of the net interaction power from Fig. 13(c), and the measured outer array bubble velocity from shadowgraphy plotted versus . (b) The net interaction pulse energy [black lines, the integral of the pulses in Fig. 13(c)] plotted vs , compared with a collisional model (red lines). is the geometric interaction fraction. (c) Comparison of the interaction pulse for two shots with 30 inner wires (orange) and two shots with 180 inner wires (blue), for fixed outer and inner array masses (, ), not corrected for collimation.

Image of FIG. 15.
FIG. 15.

(Color) (a) Predicted power pulses for single (black) and nested arrays (color) from a 2D-MHD simulation of the implosions in the plane. (b) Partition of the predicted power pulse into parts resulting from PdV (kinetic energy) and Ohmic heating. (c) Comparison of the model to data. Data is as described in Fig. 14(c), but corrected for diagnostic slot collimation in this plot.

Image of FIG. 16.
FIG. 16.

(Color) (a) Capsule drive temperature for a -pinch high-yield design (red). (b) Predicted for accelerator (solid lines) for tests Z1178 [red, on , two pulses overlay in Fig. 11(a)], Z1331 [green, 2.5 on 2.5 on foam, two pulses overlay in Fig. 11(d)], Z1396 [blue, 2.5 on 5.3 on foam, from Fig. 11(d)], and Z985 [orange, 2.5 on 7.5, two pulses overlay in Fig. 11(b)], scaled version of the pulse shape from part (a) (broken lines).


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Compact single and nested tungsten-wire-array dynamics at 14–19MA and applications to inertial confinement fusiona)