Figure 4. A representative plot of fringe shift (vertical axis) versus time and position on the slit from data obtained on the time-resolved Mach-Zehnder interferometer.

Figure 5.

Variable thickness dye apodizer.

Some versions use two curved windows and have slight curvatures on the outer surfaces as well to correct for index mismatch between the dye and window material.

Figure 6. Propagation calculations for two intensity profiles of the form Ioexp(-r/a) N. The left-hand curves are the input profiles for

N = 5 and 10. The right-hand curves are the developing beam-shapes after propagating 7.8 meters at design intensities into the LLL developmental glass amplifier chain.

Figure 7. Small scale beam breakup at 20 GW/cm2 in an unpumped 24 cm long glass rod. The photograph at the bottom shows the type of filamentary damage which results.

13

Normalized gain coefficient (g/9max)

Figure 8.

Normalized wave number (K/Kmax)

The variation of the exponential gain coefficient for the growth of small-scale intensity modulations as a function of modulation wave number as predicted by the simplest form of linearized instability theory.

Figure 9. Beam photographs and densitometer scans showing the growth of shear-plate interference fringes spaced 2 mm apart (K = 119 cm-1) on a pulse with a peak intensity of 5 GW/cm2.

Figure 10.

Comparison of the beam breakup caused by propagation through a rod with that caused by propagation through a series of disks.

Figure 11.

Laser disk

Schematic drawing of the behavior of various bumps when propagating through a series of disks.

Figure 12. Energy collection at a distant calorimeter as a function of
input energy density. For this plot "relative energy" is defined as that
fraction of the energy exiting the rod which is still within the fixed
1.6 cm aperture of the calorimeter after propagating 6 meters.

COMMENTS ON PAPER BY BLISS

A number of points regarding the experimental setup used in the work described in this paper were clarified. The question was asked regarding the use of saturable dyes in the dye apolizers. The speaker commented that generally saturable dyes were used, but under the circumstances in which they responded in a linear fashion. With regard to the analysis of the experiment on the growth of the small self focusing, the importance of treating the initial conditions of the problem realistically, that is say, of reproducing in the analysis the relative phase of the intensity and phase modulation introduced at the entrance face of the glass sample by the shearing plate interferometer was emphasized. It was pointed out that the introduction of the appropriate initial conditions led to extremely good agreement between calculation and theory and that the analytic model was further substantiated by detailed numerical computation.