C. Bibeau, D. R. Speck, R. B. Ehrlich, C. W. Laumann, D. T. Kyrazis, M. A. Henesian, J. K. Lawson, M. D. Perry, P. J. Wegner, and T. L. Weiland, "Power, energy, and temporal performance of the Nova laser facility with recent improvements to the amplifier system," Appl. Opt. 31, 5799-5809 (1992)
High-powered glass-laser systems with multiple beams, frequency-conversion capabilities, and pulse-shaping flexibility have made numerous contributions to the understanding of inertial confinement fusion and related laser-plasma interactions. The Nova laser at Lawrence Livermore National Laboratory is the largest such laser facility. We have made improvements to the Nova amplifier system that permit increased power and energy output. We summarize the nonlinear effects that now limit Nova’s performance and discuss power and energy produced at 1.05-, 0.53-, and 0.35-μm wavelengths, including the results with pulses temporally shaped to improve inertial confinement fusion target performance.
J. K. Lawson, D. R. Speck, C. Bibeau, S. C. Burkhart, M. A. Henesian, C. W. Laumann, T. L. Weiland, and R. B. Wilcox Appl. Opt. 31(24) 5061-5068 (1992)
G. J. Linford, B. C. Johnson, J. S. Hildum, W. E. Martin, K. Snyder, R. D. Boyd, W. L. Smith, C. L. Vercimak, D. Eimerl, and J. T. Hunt Appl. Opt. 21(20) 3633-3643 (1982)
Stephen Obenschain, Robert Lehmberg, David Kehne, Frank Hegeler, Matthew Wolford, John Sethian, James Weaver, and Max Karasik Appl. Opt. 54(31) F103-F122 (2015)
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Listed for each stage is the small-signal gain (G0), energy stored in the upper laser level, input and output energies and fluences, extraction efficiency η, fill factor, square-pulse distortion SPD, and the accumulated B integral at the end of the pulse (ΔB).
Fill factor is defined as energy in the beam divided by the product of the aperture area and the maximum locally averaged fluence. A central disk split in the 46-cm amplification stage accounts for the lower fill factor value.
SPD is defined as the ratio of the gain seen by the first photon in the pulse to that seen by the last photon.
ΔB is the phase retardation in radians accumulated because of the nonlinear index of refraction n2.
Table 2
Test Shots Done After the Glass in the Output Section of the Laser Is Replaceda
Pulse Duration
Shot Number
10-Arm Average (
) (kJ)
(%)
Max Deviation (%)
(2.5 ns)
40307
7.0
10
15
40408
7.7
5.5
9.3
40414
8.1
1.9
3.4
40418
9.8
2.5
4.1
40503
9.8
1.5
2.7
40508
12.5
1.7
2.7
41105
12.0
1.2
2.0
(1 ns)
40605
5.9
2.6
5.0
40709
7.1
2.1
3.5
41205
8.2
3.5
6.9
41213
7.8
4.0
6.6
41307
8.2
1.0
1.8
(0.1 ns)
41310
1.04
6.9
12
41313
0.97
5.7
9.7
41405
1.04
3.8
6.2
41411
1.14
2.1
3.4
41803
1.33
2.1
3.6
In this series of shots, the 1.05-μm energy was gradually increased for 2.5-, 1-, and 0.1-ns pulse durations. The table gives for each shot the average beam-line energy and the standard deviation and maximum deviation in energy among the 10 beam lines in percent.
Table 3
Maximum and Future Capabilities Based on Single Beam-Line Performances Extrapolated to 10-Arm Performancesa
Nova can routinely produce second- or third-harmonic energies with two segmented arrays of 1-cm-thick type-II–type-II crystal plates.
Harmonic energies are expected energies at the target and include losses that are due to target chamber optics.
Tables (3)
Table 1
Characteristics of the Amplification Stages in a Nova Beama
Listed for each stage is the small-signal gain (G0), energy stored in the upper laser level, input and output energies and fluences, extraction efficiency η, fill factor, square-pulse distortion SPD, and the accumulated B integral at the end of the pulse (ΔB).
Fill factor is defined as energy in the beam divided by the product of the aperture area and the maximum locally averaged fluence. A central disk split in the 46-cm amplification stage accounts for the lower fill factor value.
SPD is defined as the ratio of the gain seen by the first photon in the pulse to that seen by the last photon.
ΔB is the phase retardation in radians accumulated because of the nonlinear index of refraction n2.
Table 2
Test Shots Done After the Glass in the Output Section of the Laser Is Replaceda
Pulse Duration
Shot Number
10-Arm Average (
) (kJ)
(%)
Max Deviation (%)
(2.5 ns)
40307
7.0
10
15
40408
7.7
5.5
9.3
40414
8.1
1.9
3.4
40418
9.8
2.5
4.1
40503
9.8
1.5
2.7
40508
12.5
1.7
2.7
41105
12.0
1.2
2.0
(1 ns)
40605
5.9
2.6
5.0
40709
7.1
2.1
3.5
41205
8.2
3.5
6.9
41213
7.8
4.0
6.6
41307
8.2
1.0
1.8
(0.1 ns)
41310
1.04
6.9
12
41313
0.97
5.7
9.7
41405
1.04
3.8
6.2
41411
1.14
2.1
3.4
41803
1.33
2.1
3.6
In this series of shots, the 1.05-μm energy was gradually increased for 2.5-, 1-, and 0.1-ns pulse durations. The table gives for each shot the average beam-line energy and the standard deviation and maximum deviation in energy among the 10 beam lines in percent.
Table 3
Maximum and Future Capabilities Based on Single Beam-Line Performances Extrapolated to 10-Arm Performancesa
Nova can routinely produce second- or third-harmonic energies with two segmented arrays of 1-cm-thick type-II–type-II crystal plates.
Harmonic energies are expected energies at the target and include losses that are due to target chamber optics.