Magnetization Compression Heating Status and Progress on Magnetized Liner Inertial Fusion Daniel Sinars, Sandia National Laboratories Associates Meeting Dec. 6-7, 2017 Washington, D.C.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineerin g Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-00035 25. Magnetized Liner Inertial Fusion (MagLIF) relies on three stages to produce fusion relevant conditions

Laser Applied Applied Amplified B-field B-field B-field

Current

Current- generated B-field

Compress the heated Apply axial magnetic field Laser-heat the magnetized fuel and magnetized fuel

S.A. Slutz et. al., PoP (2010) M.R. Gomez, et. al., PoP (2015) S.A. Slutz and R. A. Vesey, PRL (2012) S.B. Hansen, et. al. , PoP (2015) M.R. Gomez et. al., PRL (2014) P.F. Knapp et al., PoP (2015) P. F. Schmit et. al., PRL (2014) A.J. Harvey-Thompson et al., PoP (2015) A.B. Sefkow, et. al. ,PoP (2014) R.D. McBride, et. al., PoP (2016) 2

S. A. Slutz, et al., Phys. Plasmas 17, 056303 (2010). Magnetized Liner Inertial Fusion (MagLIF) can also be studied on laser facilities such as Omega

Laser Applied Applied Amplified B-field B-field B-field

Current

Current- generated B-field

Can replace Apply axial magnetic field Laser-heat the magnetized fuel magnetic pressure with laser ablation pressure

J.R. Davies et. al., PoP (2017) D.H. Barnak et. al. ,PoP (2017) 3 A joint collaboration between Sandia and Rochester is exploring magneto-inertial fusion science & scaling

Sandia National Laboratories Laboratory for Laser Energetics

§ 80-TW, 20 MJ § 60-beam, 30-TW, 30 kJ, OMEGA laser facility Initial Conditions Z pulsed power facility • Be liner § 1-TW, multi-kJ Z- § 4-beam, TW to PW, • ρDT~ 1-4 mg/cc multi-kJ OMEGA-EP laser • Bz0~ 10-30 T (~0.1 Backlighter laser MG) § § 20 T B-field systems 30 T B-field system Laser Heating (900 kJ stored energy) (200 J stored energy) • Elaser ~ 2-6 kJ @.53μm • TDT ~ 0.2 KeV • ωτ ~ 2-5 • Research on Z, ZBL, Omega, Omega-EP

Implosion/stagnation • Vimp~ 70-100 km/sec • PDT ~ 5 Gbar • Tion > 5 keV • ωτ ~ 200 (B~100 MG) • Research on Z, Omega We have verified that good performance on Z, using our initial parameters, requires both applied B-field and laser heating

No B-field B-field Without With B-field B-field No Pre- 10 10 heat 0.3x10 1x10

Pre- 4x1010 300x1010 heat

DD yield

5 Rochester’s laser-driven MagLIF uses targets 10x smaller than Z to study scaling and basic physics with a high shot rate and good diagnostic access

40 compression beams 14 kJ in 1.5 ns Coils: 4 turns per side 18 kV, 26 kA, Bz = 10 T

Preheat beam 180 J in 1.5 ns CH cylinder Starts at -1 ns filled with D2 gas

1 mm

6 Rochester’s laser-driven MagLIF uses targets 10x smaller than Z to study scaling and basic physics with a high shot rate and good diagnostic access Optimized beam Optimized preheating timing configuration to drive cylindrical compression

Integrated experiments appear to show effect of preheating & magnetization

J.R. Davies et. al., PoP (2017) D.H. Barnak et. al. ,PoP (2017) 7 Last year we reported on progress using a new laser protocol based on phase plates and lower laser intensity

SBS backscatter Spot profile Laser power Shadowgraphy imaging 900 J

B16062201 60 ) - 2237 J 2 End of main pulse 1.0 50 -2 Old protocol 40

No DPP 30 0 0.5

Power (TW) 20 Distance (mm) Distance 2 10 B16062201

Intensity (x1e13 W/cm 0.0 0 -4 -2 0 2 4 0 2 4 6 8 10 12 Time (ns) Distance (mm)

20 J B16082404 12 ) 1.0 - 1585 J 2 End of main pulse 10 -2 New protocol 8 0 6 1100 µm DPP 0.5

Power (TW) 4 Distance (mm) Distance 2 2 B1608240

Intensity (x1e13 W/cm 0.0 0 0 2 4 6 4 8 10 12 -4 -2 0 2 4 Distance (mm) Time (ns)

Bulbous features could be Filament beam spray/filamentation or SRS sidescatter or ???

8 We have clarified that while more energy is coupled, this protocol also injects window material deeper into the fuel

1 nm Co coating Z3057 1100 μm DPP: Z3085 – no DPP: XRS3 spectrum XRS3 spectrum

Fe Ni He-α 10 He-β + sats. 10

Co extends 8 8 LEH material over >1/2 imploding pushed in 6 6 Co He-α lights up at region + sats. stagnation 4 4 Co He-α Distance from cathode (mm) + sats. Distance from cathode (mm) 2 Co 2 Ly-α Fe Kα Fe He-α + Ni Kα 1,2 sats. 1,2 0 0 6400 6600 6800 7000 7200 7400 7600 7800 8000 7000 7200 7400 7600 Photon energy (eV) Photon energy (eV) We have also shown that while the new protocol has produced higher yields, its reproducibility is a concern

z3040 Z3041 z3057 Laser 70 + 1460 J 73 + 1534 J 103 + 1283 J energy

YDD 4.1e12 ± 20% 3.2e11 ± 20% 2.0e12 ± 20% ~50% of Direct repeat Co coating on Comments clean 2D of z3040. LEH

10 Other MagLIF configurations can also have variability

AR6 z2839 AR6 z2850 AR6 z2851 AR6 z2852 AR6 z2976 AR6 z2979

4 4 4 4 4 4 3 3 3 3 3 3 2 2 2 2 2 2 1 1 1 1 1 1 0 0 0 0 0 0 -1 -1 -1 -1 -1 -1 -2 -2 -2 -2 -2 -2 -3 -3 -3 -3 -3 -3 -4 -4 -4 -4 -4 -4

-0.4 0 0.4 -0.4 0 0.4 -0.4 0 0.4 -0.5 0 0.5 -0.4 0 0.4 -0.4 0 0.4

§ Stagnations structures vary between experiments § Helices, bright spots § Yield can vary an order of magnitude § The source of the variations is poorly understood § Laser heating variations (non-uniform mix, dust?) § Implosion variations (too high convergence, 3D effects) 11 Data indicate a trend in wavelength and amplitude with aspect ratio (liner thickness); consistent with feedthrough

Aspect Ratio 4.5 Aspect Ratio 6 Aspect Ratio 9 AR4.5 z3017 AR6 z2839 AR9 z3018

4 4 4

3 3 3 3.0 2.5 2 2 2 2.0 1 1 1 1.5 0 0 0 1.0 0.5 Uncoated

-1 -1 -1 Helix Wavelength (mm) 0.0 4.5 6.0 7.5 9.0 -2 -2 -2 Aspect Ratio -3 -3 -3 -4 -4 -4

-0.4 0 0.4 -0.4 0 0.4 -0.4 0 0.4

12 Applying a coating to the outside of liners appears to enhance implosion stability and affects the in-flight mass distribution

K.J. Peterson et al., PoP (2012) K.J. Peterson et al., PoP (2013) T.J. Awe et al., PRL (2013) K.J. Peterson et al., PRL (2014) T.J. Awe et al., PoP (2014) T.J. Awe et al., PRL (2016) 13 Stagnation data appears to confirm the impact of dielectric coatings improving the stagnation uniformity and structure

100 Uncoated Coated (3 shots) m) µ 80 60 40 23 µm

Helix Radius ( 20 22 µm 17 µm 0 3.0 4.5 6.0 7.5 9.0 Aspect Ratio 3.0 2.5 2.0 1.5 1.0 Uncoated

Helix (mm) Pitch 0.5 Coated 0.0 4.5 6.0 7.5 9.0 Aspect Ratio While coatings don’t appear to improve our average stagnation conditions, they do appear to improve our reproducibility

3019 3075 3135 Mean Variation DD 3.0e12 2.6e12 3.1e12 2.9e12 9% DT 4.8e10 4.1e10 5.5e10 4.8e10 15% DD/DT 62.5 63.4 56.4 60.8 6%

Tion (nTOF) 2.5 keV 2.2 keV 2.2 keV 2.3 keV 8%

Te (continuum) 3.0 keV 3.3 keV No data 3.15 7%

12 4x10 4.0 3.5 3x1012 3.0 2.5 2x1012 2.0 1.5

12 Electron Yield (DD) 1x10 1.0 Uncoated 0.5 Uncoated Coated (keV) Coated 0 0.0 3.0 4.5 6.0 7.5 9.0 4.5 6.0 7.5 9.0 Aspect Ratio Aspect Ratio 15 After ~1.5 years of work, we now have a new laser pulse shape that more gently disassembles the window and allows the density to drop for ~20 ns

Independently timed prepulse More uniform and deeper penetration 0.5 B17072619 ) ZBL pulse 2 0.4 4 Co-injected pulse W/cm

0.3 13 1229 J 0.2 2 Power (TW)Power

B17072619, +25 ns, 90 psi, 1.1 mm DPP, 1.77um LEH 0.1 24 J Intensity (x10

0.0 0 -25 -20 -15 -10 -5 0 5 10 3 B17012524 - ~700 J Time (ns) B17072619 (coinjected) - ~1100 J 2

1 Energy kJ/cm 0 0 2 4 6 8 10 12 Height / mm 16 Overlay of x-ray and and optical blast wave images illustrates the difference in the laser configurations 1100µm Phase Plate 1100µm Phase Plate 90 psi D2 90 psi D2 Pre-pulse 80 J “Foot”: 190 J Main pulse 1270 J Main pulse 1230 J (X-ray image: 60psi, 60/1060 J) Co-Injection 24 J

17

(D2 capability recently added) The MagLIF effort has a lot of moving parts proceeding in parallel, which are being integrated in 2018-2020 § We are advancing new hardware platforms on Z capable of delivering higher current to the targets to facilitate scaling studies § These hardware platforms will allow higher magnetic fields, which are generally predicted to improve performance at our present scales § Our laser capabilities have been improved, which has already resulted in dramatically improved laser heating. Work will continue on these platforms with an emphasis on heating higher-density fills. § We have made progress in improving the stability of our stagnation plasmas, which has so far produced more reproducible results. § Implementing higher magnetic fields and higher preheat should reduce the convergence ratio of our implosions, which should further improve stability. § Upcoming Omega MagLIF tests will look at the impact of increasing magnetization

18