Page 433 - High Power Laser Handbook

400 So l i d - S t at e La s e r s The National Ignition Facility Laser 401

0.20

15%
0.15
RMS variation from the mean 0.10 10% 10%

6%

0.05
3%

0.00
0 2 4 6 8 10 12 14
Time (ns)
Ignition point design
requirement
Measured 16 shot
RMS variation
Point design temporal
pulse shape

Figure 14.39 The time-dependent root mean square variation among a set
of 16 nominally identical shots (red), compared with the Rev. 2 power-balance
requirement (green); the temporal pulse shape (blue) is for reference.

on a single shot, this test predicted that NIF would meet its power-
balance specifications with a comfortable margin. Further, assuming
that shot-to-shot power variations are correlated within a quad, but
uncorrelated between quads, we would expect the maximum shot-to-
shot variation for the full NIF to be ∼9%/ 48 = 1 3%, which is also
.
significantly less than the 3 percent Rev. 2 requirement. Two direct
60
measurements of the achievable full-system power balance are repre-
sented in Fig. 14.40. Data from the 96-beam, 500-kJ project-completion
shot on December 21, 2008 (Fig. 14.40a), verify that the quad-to-quad
rms power variation is well below the Rev. 3.1 requirement through-
out the pulse, including the 3 percent requirement at the peak of the
pulse (compare with 8 percent in the 1994 Functional Requirements
and Primary Criteria ). The 1-MJ, 192-beam shot fired on March 9,
25
2009 (Fig. 14.40b), had a known error in the request sent to the MOR