1.0-MJ CH-Foam Ignition Targets on the NIF Using 1-D MultiFM SSD with 0.5 THz of Bandwidth

Transcription

1 -MJ CH-Foam Ignition Targets on the NIF Using 1-D MultiFM SSD with.5 THz of Bandwidth -MJ CH-foam target; end of acceleration 4 1-D SSD, 1.8 Å 1-D MultiFM, 6 Å (1/2 THz) 2-D SSD, 11 Å Density (g/cm 3 ) z (nm) J. A. Marozas University of Rochester Laboratory for Laser Energetics 5th Annual Meeting of the American Physical Society Division of Plasma Physics Dallas, TX November 28

2 Summary DRACO simulations of -MJ CH-foam targets using 1-D MultiFM SSD achieve ignition on the NIF Can be designed for a bandwidth of Do UV =.5 THz (Dm IR = 6 Å). Only a single frequency-conversion crystal is needed. Takes advantage of multiple color cycles without detrimental resonant features that are present in single modulator systems. The 1-D MultiFM SSD system could be installed in the NIF fiber front end within a small rack-mounted unit. This concept will be tested on OMEGA EP. TC8326

3 Collaborators T. J. B. Collins J. D. Zuegel University of Rochester Laboratory for Laser Energetics

4 MultiFM is produced by applying multiple FM modulators in a single dimension Do 1 Do 2 E-O bandwidth Do n E (t) E(t) Time delay (y direction) Disperse (y direction) Correct time delay (y) Total bandwidth and divergence are distributed across the modulators. TC8327

5 MultiFM is produced by applying multiple FM modulators in a single dimension Do 1 Do 2 E-O bandwidth Do n E (t) E(t) No pre-shear grating on NIF s 1 st SSD dimension Disperse (y direction) Total bandwidth and divergence are distributed across the modulators. MultiFM could be implemented in the NIF fiber front end. TC8327

6 The inverse coherence time is a 2-D function of the far-field spatial frequency 1-D SSD Inverse coherence time 2-D SSD Inverse coherence time k yff /(2rD/fm UV ) k yff /(2rD/fm UV ).5..5 k yff /(2rD/fm UV ) t 1 c (THz) TC8328

7 The inverse coherence time is a 2-D function of the far-field spatial frequency t 1 c (THz) D SSD Inverse coherence time t 1 c (THz) D SSD Inverse coherence time k yff /(2rD/fm UV ) t 1 c (THz) t 1 c (THz) The traditional SSD systems have large regions with very low values of t 1 c. TC8328

8 The inverse-coherence-time distribution for MultiFM does not go to zero (except along the central horizontal axis) 1-D MultiFM SSD Inverse coherence time k yff /(2rD/fm UV ) k yff /(2rD/fm UV ) t 1 c (THz) TC8329

9 The inverse-coherence-time distribution for MultiFM does not go to zero (except along the central horizontal axis) t 1 c (THz) D MultiFM SSD Inverse coherence time k yff /(2rD/fm UV ).5..5 Smoothing results at all spatial wavelengths except along the central horizontal axis t 1 c (THz) TC

10 The inverse-coherence-time model used in DRACO accurately mimics the results of far-field simulations The resultant time dependent power spectra from far-field simulations are fit to a simple model of the nonuniformity, psd ~ psd t c /t D SSD, eight color cycle TC833 t 1 c (GHz) , mode FF sim. data fit to simple model

11 The inverse-coherence-time model used in DRACO accurately mimics the results of far-field simulations The resultant time dependent power spectra from far-field simulations are fit to a simple model of the nonuniformity, psd ~ psd t c /t. DRACO employs an analytic model that accurately estimates the inverse coherence time for each, mode as a function of time D SSD, eight color cycle TC833 t 1 c (GHz) 1 5 DRACO analytic model 1 1 1, mode FF sim. data fit to simple model

12 DRACO simulations show that 1-D MultiFM SSD significantly reduces imprint using less bandwidth 3 nm CH 9 nm 14 nm CH foam DT ice DT vapor 15 nm TC8331a

13 DRACO simulations show that 1-D MultiFM SSD significantly reduces imprint using less bandwidth -MJ CH-foam target 4 1-D SSD, 1.8 Å 1-D MultiFM, 6 Å (1/2 THz) 2-D SSD, 11 Å Density (g/cm 3 ) z (nm) Broken shell v rms ~ 2 nm 2 3 nm CH 9 nm 14 nm 15 nm CH foam DT ice DT vapor 4 v rms, $ 6 = 3.3 nm 2 v rms, $ 6 = 1.5 nm 4 2 End of acceleration phase, t = 8.25 ns 4 TC8331

14 DRACO simulations show that 1-D MultiFM SSD significantly reduces imprint using less bandwidth -MJ CH-foam target 4 1-D SSD, 1.8 Å 1-D MultiFM, 6 Å (1/2 THz) 2-D SSD, 11 Å Density (g/cm 3 ) z (nm) Broken shell v rms ~ 2 nm 2 3 nm CH TC nm 14 nm 15 nm CH foam DT ice DT vapor 4 v rms, $ 6 = 3.3 nm 2 v rms, $ 6 = 1.5 nm 4 2 End of acceleration phase, t = 8.25 ns Includes sources of nonuniformity imprint, = 2:1 inner/outer shell roughness mistiming 3-ps rms power imbalance 8% 4

15 The 1-D MultiFM case achieves a gain of seven, whereas the 1-D SSD case fails to ignite -MJ CH-foam target; near peak compression, t = 8.9 ns 1 1-D SSD, 1.8 Å 1-D MultiFM, 6 Å (1/2 THz) 2-D SSD, 11 Å Density (g/cm 3 ) z (nm) Gain = Gain = 7, = 6 dominates Gain = 33 TC8332

16 Summary/Conclusions DRACO simulations of -MJ CH-foam targets using 1-D MultiFM SSD achieve ignition on the NIF Can be designed for a bandwidth of Do UV =.5 THz (Dm IR = 6 Å). Only a single frequency-conversion crystal is needed. Takes advantage of multiple color cycles without detrimental resonant features that are present in single modulator systems. The 1-D MultiFM SSD system could be installed in the NIF fiber front end within a small rack-mounted unit. This concept will be tested on OMEGA EP. TC8326