Progress in demonstrating magneto-inertial fusion science and scaling Dr. Daniel Sinars for the MagLIF team Sandia National Laboratories ARPA-E Annual Meeting August 29-31, 2017

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & Engineering 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-NA0003525. 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 -heat the magnetized fuel and magnetized fuel 2 S. A. Slutz, et al., Phys. Plasmas 17, 056303 (2010). 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

Can replace magnetic Compress the heated Apply axial magnetic field Laser-heat the magnetized fuel pressure with laser and magnetized fuel ablation pressure 3 S. A. Slutz, et al., Phys. Plasmas 17, 056303 (2010). Our project utilizes existing capabilities* at two institutions to demonstrate magneto-inertial fusion science & scaling

Initial Conditions Sandia National Laboratories Laboratory for Laser Energetics • Be liner § 80-TW, 20 MJ § 60-beam, 30-TW, 30 kJ, • ρDT~ 1-4 mg/cc Z pulsed power facility OMEGA laser facility • Bz0~ 10-30 T (~0.1 MG) § 1-TW, multi-kJ Z-Backlighter § 4-beam, TW to PW, multi-kJ laser facility OMEGA-EP laser facility Laser Heating § 30 T B-field system § 20 T B-field systems • Elaser ~ 2-6 kJ @.53μm (900 kJ stored energy) (200 J stored energy) • 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

* All facilities are multi-user, multi-program facilities funded by the NNSA Work at Sandia is focused on improving the laser preheating over the parameters used in the initial 2013-2014 Z experiments (10 T, 2.5 kJ laser energy, and 17 MA) Laser pulse Magnets Bz 2 kJ 0.5 kJ

Extended 2.5 to 0.45 mm power 3.5 µm feed Anode MagLIF implosion history 3 mm 0.465 mm Outer liner boundary 7.5 mm 7.5

Target B-field 4.65 mm Inner liner pulse boundary

D2 gas ~2 ms rise time to 10 T Cathode

M.R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014). We have verified that good performance on Z, using our initial parameters, requires both applied B-field and laser heating

Without With No B-field B-field B-field B-field

No Laser 3x109 1x1010 Heating (near- background)

Laser 4x1010 3x1012 Heating

3x1012 is a DT-equivalent yield of ~0.6 kJ 6 Rochester’s laser-driven MagLIF uses targets 10× smaller than Z to study scaling and basic physics with a higher shot rate and better 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

7 Laser-driven MagLIF data indicate that magnetization and preheating increase yield and ion and reduce convergence

2 Type YDD Ti ρR (mg/cm ) ρR/ρR0 (108) (keV)

Compression-only 11 atm D2 (3) 10.0±0.74 2.27±0.40 (2) 1.41±0.28 (2) 27.3±5.4

Compression+Preheat 11 atm D2 (2) 14.4±2.7 2.49±0.34 0.71±0.21 (1) 14.1±4.2

Compression+Field 11 atm D2 (2) 16.9±0.85 2.36±0.29 0.71±0.15 13.9±2.9

Integrated 11 atm D2 (1) 15.7±0.16 2.67±0.5 - -

Compression-only 7 atm D2 (2) 3.93±0.28 2.14±0.17 - -

Compression+Field 7 atm D2 (2) 5.54±0.91 2.42±0.35 1.29±0.25 39.2±7.4

§ Lower convergence leads to higher yields § Confirmed that magnetization and preheat provide a practical

route to low convergence inertial confinement fusion 8 Z: A new laser protocol was developed for Z-Beamlet that uses phase plate smoothing & lower laser intensity to reduce LPI and modeling uncertainties

SBS backscatter Spot profile Laser power Shadowgraphy imaging 900 J

B16062201 60

) End of main pulse - 2237 J 2 1.0 50 -2

Old protocol 40 0 No DPP 30 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/filamentati on or SRS sidescatter or ??? With such huge amounts of energy being diverted into LPI in old configuration, no hope for HYDRA to accurately model preheat consistently While more energy is coupled using DPP smoothed laser configuration, it also appears to inject window material deeper into the stagnation column

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

Fe Kα Fe He-α + Ly-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)

XRS3 – axially resolved spherical crystal spectrometer Z: The new laser preheat configuration has produced the highest MagLIF yields in integrated experiments, but questions remain about reproducibility

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 We are presently investigating hypotheses for the shot-to-shot variations

Dust on the laser windows Clean 50 um 100 um § Dust particles >50 microns can significantly change laser energy deposition in simulations § Some evidence that dust of this 0.1 mm size can occur under nominal conditions on Z

§ However, laser-only tests 8 mm appear reproducible

Variability in fuel convergence § New high-resolution x-ray images show considerable sub- structure—will reducing the convergence ratio help?

12 A new laser pulse shape more gently disassembles the window and allows the density to drop for ~ 20 ns, minimizing interaction with steep density gradients

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

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

0.0 0 -25 -20 -15 -10 -5 0 5 10 3 B17012524 - ~700 J Time (ns) B17072619 (coinjected) - ~1100 J 2 First integrated Z 1 shot on August 31 Energy kJ/cm 0 0 2 4 6 8 10 12 Height / mm Over the next year, we expect to scale MagLIF on Z to higher drive conditions and to further improve our quantitative measurements on Omega

§ Our main near term goal for Z is to reduce the § Our main near term goal for Omega is to convergence of the system to produce a more improve our diagnosis of the stagnation reliable and easily-diagnosable stagnation conditions, including measurements of the § Increase the energy density of the fuel through compressed magnetic field more effective laser coupling, higher initial fuel § Increase the level of magnetization by density, and increased inhibition of thermal using two coils instead of one transport § Use protons to measure the BR increase Proton Tracing 10 T Integrated Shot § We have been operating at 10 T, 0.2-1 kJ, and 17 MA (no stopping in coil) ⎯ 9 T ⎯ 10 T ⎯ 11 T § We expect to be operating at 15-20 T, 1-2 kJ, and 19- 20 MA within the next year

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