MIT Research using High-Energy Density Plasmas at OMEGA and the NIF

Transcription

1 MIT Research using High-Energy Density Plasmas at OMEGA and the NIF 860 μm 2.3 μm SiO 2 D 3 He gas D-D 3 He D-D T Yield D-D p D- 3 He Energy (MeV) D- 3 He p Hans Rinderknecht Wednesday, Jan 15 th 2:00 pm IAP PSFC

2 The High Energy Density Physics Division at MIT and Collaborators Scientists Johan Frenje Maria Gatu Johnson Chikang Li Fredrick Séguin Richard Petrasso Grad Students Hans Rinderknecht Mike Rosenberg Alex Zylstra Hong Sio Staff Robert Frankel Ernie Doeg

3 The HEDP division at MIT performs cutting-edge research using laser-generated plasmas Recent research addresses outstanding issues in Inertial Confinement Fusion (ICF), Plasma Nuclear Science, and basic plasma physics. This work was facilitated by unique nuclear spectral, imaging, and time resolved diagnostics, which have been developed using the Linear Electrostatic Ion Accelerator (LEIA) at the PSFC. Come back Thursday 3:15 for a tour of the HEDP Diagnostic Development lab!

4 Outline I. What is High-Energy Density Physics? II. HEDP Facilities The National Ignition Facility (NIF) OMEGA laser MIT Diagnostic Development Laboratory III. A Selection of Recent Experiments: I. Stopping Power in plasmas II. Plasma Nuclear Physics III. Kinetic Effects IV. Multiple ion-fluid Effects V. Non-hydrodynamic mix VI. Studies of Inertial Confinement Fusion (ICF) implosions VII. Proton Radiography

5 High Energy Density Physics studies matter under extreme states of pressure, temperature, and density Temperature (ev) Density (m -3 ) (1 Mbar) Density (g/cc) from Frontiers in High Energy Density Physics: The X-Games of Contemporary Science 2003

6 High Energy Density Physics studies matter under extreme states of pressure, temperature, and density Temperature (ev) Density (m -3 ) (1 Mbar) Density (g/cc) from Frontiers in High Energy Density Physics: The X-Games of Contemporary Science 2003

7 High Energy Density Physics studies matter under extreme states of pressure, temperature, and density Temperature (ev) Density (m -3 ) (1 Mbar) Density (g/cc) from Frontiers in High Energy Density Physics: The X-Games of Contemporary Science 2003

8 To create these environments in the lab, high-power lasers deliver energy impulses to targets NIF Target: NIF Laser impulse: 192 beams, 2 MJ, 500 TW ~ 10 mm Plasmas are very shortlived: they are confined only by their inertia. Duration: <10 ns ~ 10 m

9 Outline I. The High-Energy Density Physics division at MIT II. HEDP Facilities The National Ignition Facility (NIF) OMEGA laser MIT Diagnostic Development Laboratory III. A Selection of Recent Experiments: I. Stopping Power in plasmas II. Plasma Nuclear Physics III. Kinetic Effects IV. Multiple ion-fluid Effects V. Non-hydrodynamic mix VI. Studies of Inertial Confinement Fusion (ICF) implosions VII. Proton Radiography

10 The National Ignition Facility (NIF) is a three football field-sized laser, which delivers ~1.8 MJ to a cm-scaled target. ~ 1 shot per day Hohlraum target 10

11 The OMEGA laser at Laboratory for Laser Energetics is a highly versatile resource for HEDP studies 240 feet Capsule diameter ~1 mm A direct-drive implosion 60 laser-beam facility, up to 30 kj on capsule in ~1 ns 12 shots per day Direct or indirect drive 11

12 Nuclear reactions generate many products that can be used for studying ICF and HEDP MIT has developed several charged particle and neutron spectrometers, imagers, and time-resolved diagnostics for studies of HED plasmas. Primary Fusion reactions D + D T (1.01 MeV) + p (3.02 MeV) n (2.45 MeV) + 3 He (0.8 MeV) D + T (3.5 MeV) + n (14.1 MeV) D + 3 He (3.6 MeV) + p (14.7 MeV) T + T + 2n MeV 3 He + 3 He + 2p MeV Secondary Fusion reactions 14.1-MeV neutron knockons 3 He (0.82 MeV) + D ( MeV) + p ( MeV) T (1.01 MeV) + D ( MeV) + n ( MeV) n (14.1 MeV) + p n + p ( 14.1 MeV) n (14.1 MeV) + D n + D ( 12.5 MeV) n (14.1 MeV) + T n + T ( 10.6 MeV) n (14.1 MeV) +? n ( 14.1 MeV) Tertiary Fusion reactions D ( 12.5 MeV) + 3 He + p ( 30.8 MeV)

13 MIT Accelerator PhD work by Nareg Sinenian (2013) The heart of the MIT-HEDP lab is the accelerator used to develop and test nuclear diagnostics for OMEGA, NIF and HED science...and is appreciated by our guests Stefano Atzeni and Wolf Seka Primary products: D + D t (1.01 MeV) + p (3.02 MeV) D + D n (2.45 MeV) + 3 He (0.82 MeV) D + 3 He α (3.6 MeV) + p (14.7 MeV) 13

14 D 3 He implosions provide a compelling physics platform The magnet-based charged-particle spectrometer on OMEGA D-D 3 He D-D T 2.5 mm SiO 2 15 atm D 3 He Yield D-D p There are several monoenergetic fusion products, all observable D- 3 He Energy (MeV) D- 3 He p Hydroequivalence (equal mass & number density) can be established for different ratios of D to 3 He In last 2 decades, many diagnostics using D 3 He products have been developed. 14

15 Outline I. The High-Energy Density Physics division at MIT II. HEDP Facilities The National Ignition Facility (NIF) OMEGA laser MIT Diagnostic Development Laboratory III. A Selection of Recent Experiments: I. Inertial Confinement Fusion II. Stopping Power in plasmas III. Plasma Nuclear Physics IV. Kinetic Effects V. Multiple ion-fluid Effects VI. Non-hydrodynamic mix VII. Proton Radiography

16 ICF ICF seeks to generate a dense plasma (~10 26 cm -3 ) through which a fusion burn can propagate Drive laser (DIRECT DRIVE) or laser-generated x-rays (INDIRECT DRIVE) Solid Fuel Target (DT) Fuel Vapor Fuel (DT) (DT) Ablating CH shell ρr ~ 1 g/cm 2 T core ~ 3 kev 14.1 MeV neutrons escape 3.5 MeV α heat fuel 1. Ablation of the outer part of the shell propels remaining shell and solid fuel inward 2. Cryogenic fuel assembles into dense, cold mass where fusion can propagate 3. Timed shocks converge at the center, initiating the hot-spot burn. 4. PdV work continues to heat the central hot spot, and *initiates a fusion burn wave through the cold dense fuel. *still working on this part

17 ICF The MRS neutron spectrometer was developed to measure the DT neutron spectrum, from which ρr, T i and Y n are determined Implosion Neutrons Deuterons CD 2 foil CR-39 detector 3-18 MeV (deuterons) MRS PhD work by Dan Casey (2012) 17

18 Counts / MeV ICF The MRS, implemented by MIT, LLNL and LLE, has played an important role in the ICF programs at OMEGA and the NIF MRS spectrum for NIF shot on Aug 2, Yield (Y n ) Density (ρr) Temperature (Ti) Neutrons Deuterons 10 3 CD 2 foil CR-39 detector Yn = ± 5% R = 1.05 ± 0.05 g/cm 2 Ti = 2.5 ± 1.2 kev Deuteron energy (MeV) 3-18 MeV (deuterons) 18

19 Counts / MeV ICF The MRS, implemented by MIT, LLNL and LLE, has played an important role in the ICF programs at OMEGA and the NIF MRS spectrum for NIF shot on Aug 2, Yield (Y n ) Density (ρr) Temperature (Ti) Yn = ± 5% R = 1.05 ± 0.05 g/cm 2 Ti = 2.5 ± 1.2 kev Deuteron energy (MeV) High adiabat: Lower convergence more stable 1D in nature Low adiabat: High convergence Unstable 3D in nature 19

20 Stopping Power Understanding how rapidly fusion alphas stop ( stopping power ) in the hot-spot is important for attaining ignition Energy loss/distance (MeV/cm) 15 Models of alpha stopping power ne = cm MeV / cm kev 1.0 kev 3.0 kev MeV / cm MeV Energy (MeV) MeV Models can differ by ~ 30%, but alpha stopping (alpha heating) is the key to ignition.

21 Stopping Power Experimental measurements of stopping power are made using multiple fusion products from a single implosion 2.2 μm SiO 2 18 atm D 3 He D + D t (1.01 MeV) + p (3.02 MeV) D + 3 He (3.71 MeV) + p (14.63 MeV) Counts / bin D 3 He-α spectrum T i = 6.6 kev Birth energy [MeV] - E i / Z i α t DDp T e = 0.6 kev D 3 Hep MeV E /A [ MeV] i J. Frenje, presented at IFSA 2013

22 Stopping Power Experimental measurements of stopping power are made using multiple fusion products from a single implosion 2.2 μm SiO 2 18 atm D 3 He D + D t (1.01 MeV) + p (3.02 MeV) D + 3 He (3.71 MeV) + p (14.63 MeV) Counts / bin D 3 He-α spectrum T i = 6.6 kev T i = 14.1 kev Birth energy [MeV] - E i / Z i α t DDp T e = 0.6 kev T e = 4.1 kev D 3 Hep MeV E /A [ MeV] i J. Frenje, presented at IFSA 2013

23 Nucleosynthesis ICF plasmas can also be used to study other fusion reactions in thermal environments relevant to stellar nucleosynthesis 2.2 µm SiO 2 30 kj 12 atm 3 He 3 He + 3 He 4 He + 2p ( MeV) 3 He + 3 He 5 Li + p (9.2 MeV) 3 He + 3 He 5 Li* + p T i ~ 12 kev ( 10 6 ) p+ 5 Li resonance 1.5 Yield / MeV p+p+ 4 He A. Zylstra, PhD thesis Proton energy [MeV] This is the first 3 He+ 3 He spectrum obtained in a plasma setting Experiments with T + 3 He have recently been performed as well.

24 Nucleosynthesis Future work: the p+d reaction will be studied using implosions on OMEGA D + p 3 He + g (5.5 MeV) Primary energy source p+d generates energy in in protostars and brown dwarfs. 24

25 Kinetic physics Shock-driven exploding pusher experiments generate plasmas where kinetic effects are important Radius (µm) Simulation of D 3 He exploding pusher from A. Zylstra (HYADES) SiO 2 [2.3μm] Kinetic regime: λ ii ~ R implosion ρ gas = 0.4 mg/cm 3 D 3 He This is important to study because mainline ICF simulations are hydrodynamic, and do not include kinetic effects. M shock ~ λ ii ~ 100 μm 25

26 Kinetic physics Radius (µm) Conditions very similar to the kinetic shock phase of hot-spot ignition implosions are generated Radius (µm) 1000 Simulation of Hot-spot ignition from H. Robey Simulation of D 3 He exploding pusher from A. Zylstra (HYADES) SiO 2 [2.3μm] ρ gas = 0.3 mg/cm 3 ρ gas = 0.4 mg/cm 3 D 3 He 400 M shock ~ M shock ~ λ ii ~ 100 μm λ ii ~ 100 μm Time (ns) Unmodeled kinetic physics early in the ignition implosions could affect the implosions later in time. 26

27 Aside: Simulations allow us to rapidly investigate important aspects of the relevant physics in close detail SIMULATION EXPERIMENT but nature can be a little different.

28 Fuel density (mg/cc) Kinetic physics Two parameters fuel pressure and ion mixture were varied to explore scaling of nuclear yield with λ ii and ion ratio Pressure scan kinetic effects 10 Selected densities and mixtures of D 3 He fuel Deuterium: 3 He ratio scan multi-ion fluid effects Deuterium fraction, f D

29 Kinetic physics The transition between hydrodynamic and kinetic regimes in ICF has been studied Fuel density (mg/cc) 2.3 μm SiO mg/cm 3 D 3 He Hydro regime λ ii < R fuel (at bang time) 10 1 Selected densities and mixtures of D 3 He fuel 0.14 mg/cm 3 D 3 He Kinetic regime λ ii >> R fuel (at bang time) Deuterium fraction, f D 29

30 Kinetic physics Near the shock, ion-ion mean-free-paths can be comparable to the scale of the implosion λ ii ~ T i2 /n ln(λ) Hydro regime 3.1 mg/cc D 3 He λ ii / R 3 < λ ii > / R ~ 0.3* * Burn averaged, at shock BT 30

31 Kinetic physics Ion-ion mean-free-path increases as initial gas density is reduced λ ii ~ T i2 /n ln(λ) Kinetic regime 0.14 mg/cc D 3 He Hydro regime 3.1 mg/cc D 3 He λ ii / R 3 λ ii / R 3 * Burn averaged, at shock BT < λ ii > / R ~ 10* < λ ii > / R ~ 0.3* How do the plasma conditions differ in the hydro and kinetic regimes, and how do they impact ICF? 31

32 Kinetic physics The yield was found to drop off sharply in the kinetic/low density limit 1E λ ii /R fuel 1E+11 D 3 He 1E+10 DD-n 1E+09 1E+08 Kinetic regime Hydro regime Initial Density (mg/cm 3 ) Mike Rosenberg, submitted to PRL 32

33 Kinetic physics 1D hydrodynamic simulations strongly over-predict the yields in the kinetic regime 1E λ ii /R fuel 1E+11 1E+10 D 3 He DD-n Clean 1D simulations 1E+09 1E+08 Kinetic regime Hydro regime Initial Density (mg/cm 3 ) Mike Rosenberg, submitted to PRL 33

34 Kinetic physics Ions on the high-energy tail of the energy distribution may be lost due to long mean-free-paths, reducing fusion yield 1E+00 1E-01 Maxwell-Boltzmann distribution D ~ 30 kev λ ii ~ 0.14 L 1E-02 1E-03 1E-04 D 3 He cross section (barns) 1E-05 Gamow peak Plasma: D 3 He Ti = 4 kev ni = 3e22 cm^-3 L ~ 100 um *K. Molvig, et al. PRL 109, (2012) 1E-06 1E-07 1E COM energy (kev) λ ii /L:

35 Kinetic physics Ions on the high-energy tail of the energy distribution may be lost due to long mean-free-paths, reducing fusion yield D ~ 30 kev λ ii ~ 0.14 L 1E+00 1E-01 1E-02 1E-03 1E-04 Maxwell-Boltzmann distribution Tail-ion loss * D 3 He cross section (barns) 1E-05 Gamow peak 1E-06 Plasma: D 3 He Ti = 4 kev ni = 3e22 cm^-3 L ~ 100 um *K. Molvig, et al. PRL 109, (2012) 1E-07 1E-08 Tail-ion loss Gamow peak COM energy (kev) λ ii /L:

36 Multi-ion physics A related study explored the transition between single- and multi-ion fluid regimes Initial fuel density (mg/cc) Multi-ion fluid: Single Fluid: 10 Selected densities & mixtures of D 3 He fuel 2.3 μm SiO 2 D 3 He D 1 Fuel density: 3.3 or 0.4 mg/cc Deuterium fraction, f D 36

37 Multi-ion physics In equal-density mixtures of D and 3 He, yields become anomalously low relative to pure D 2 DD-neutron Yield-over-Simulation mg/cc Deuterium Fraction expected scaling H. Rinderknecht, Invited Talk, APS 2013 and PhD Thesis HYADES simulations by Alex Zylstra. Points artificially spread out in f D What is causing this anomaly?

38 Density (cm -3 ) Multi-ion physics Strong gradients in pressure, electric potential or temperature can cause separation of the ion species Multi-ion-fluid vs single-ion-fluid simulation: DT Multi-ion fluid: Single-fluid DT shock Radius (µm) All main-line simulations, including ignition simulations, assume single-fluid. These effects will impact DT as well as D 3 He. Simulation by C. Bellei, LLNL *P. Amendt, et al. PRL 109, (2012)

39 Multi-ion physics Such a separation is likely to manifest as differences in fusion burn histories, as compared to single-fluid hydro predictions Burn histories: Single-fluid LSP simulation Burn histories: Two-ion-fluid LSP simulation D 3 He DD D 3 He DD *LSP simulations by C. Bellei, P. Amendt, S. Wilks 39

40 Kinetic and Multi-ion physics Measurement of D 3 He-p and DD-n burn history on a single diagnostic has been developed at OMEGA 2.3 µm SiO 2 Particle Temporal Diagnostic streak D 3 He signal lineout D 3 He-p DD-n Time D3He-p deconvolved signal DD-n This diagnostic will explore detailed effects of kinetic and multi-ion physics on fusion burn. Current relative accuracy: ± 20 ps Goal relative accuracy: ± 10 ps Hong Sio, PhD student 40

41 Kinetic mix A study to examine fuel-shell mix in exploding pushers was performed by imploding deuterated shells filled with 3 He CD[5.1μm] CD[5.1μm] 50:50 D 3 He 0.49 mg/cc 3 He 0.49 mg/cc D 3 He-proton yield from gas D 3 He-proton yield from mix only H. Rinderknecht, Invited APS talk, submitted to PRL and POP 41

42 Kinetic mix Equivalent D 3 He and 3 He fills in CD shells generated the same D 3 He yield, indicating kinetic mix Measured Yield CD[5.1μm] CD[5.1μm] 5E+10 50:50 D 3 He 0.49 mg/cc 3 He 0.49 mg/cc 4E+10 3E+10 2E+10 D 3 He-protons 1E+10 0 Shock-yield from gas Mix yield only H. Rinderknecht, Invited APS talk, submitted to PRL and POP 42

43 Kinetic mix Ion Density (cm -3 ) Ion diffusion can explain the observations, by generating a mix layer prior to shock burn Ion Density (cm -3 ) 14 x He Ion density profiles* with ion diffusion shock Clean 1D simulation Radius mm Radius (μm) t=0.7 ns D C *Post-processed HYADES 1D-simulation shown 43

44 Kinetic mix Ion Density (cm -3 ) Ion diffusion can explain the observations, by generating a mix layer prior to shock burn Measured Yield Measured Yield Ion Density (cm -3 ) 14 x He Ion density profiles* with ion diffusion shock Radius mm Radius (μm) t=0.7 ns Clean 1D simulation D C x E E E E E CD[5.1μm] 50:50 D 3 He CD[5.1μm] 3 He D 3 He-protons DD-neutrons 0 30 kj 1 30 kj 2 23 kj 3 x **1D-sim with Ion diffusion model *1D-sim without ion diffusion *Post-processed HYADES 1D-simulation shown **simulation by Peter Amendt, LLNL 44

45 Proton Radiography Particle Yield per MeV Monoenergetic fusion products can be used to probe other HED plasmas of interest D 3 He and DD Fusion Products HED Plasma of Interest CR-39 Nuclear Track Detector 10 Temporal Resolution ~120 ps *10 Spatial Resolution ~40 μm 10 D-D Proton Charged particles are sensitive to E and B fields in the plasma! 5 0 D- 3 He Alpha Energy (MeV) D- 3 He Proton The Lorentz Force F = qe + qv B

46 Magnetic reconnection in asymmetric plasma bubbles has been studied with monoenergetic proton radiography Proton Radiography D 3 He backlighter Laser-driven foil (top beam delayed) 15-MeV Proton radiographs high Protons / area Inferred B-field maps 0 Mike Rosenberg APS invited talk to be submitted to PRL & PoP 0.1 ns 0.4 ns 0.7 ns Interaction time A very fast reconnection rate is inferred, similar to symmetric experiments, due to B field pileup. 46

47 Proton Radiography D 3 He radiographs of astrophysically relevant plasma plume collisions show fine filamentary structures CR-39 imager Proton fluence images 3-MeV Protons 15-MeV Protons High 0 Protons Planar Foils Drive Side-on Plasma plume Work at OMEGA by C. Huntington, H.S. Park (LLNL) and MIT; submitted to Nature Physics D 3 He backlighter 47

48 Proton Radiography Monoenergetic-proton radiographs of hohlraum implosions illuminate fields, plasma flows, & RT instabilities 2.5 mm SiO 2 15 atm D 3 He D 3 He backlighter 0.5 ns 1 ns 1.5 ns 1.8 ns *C.K. Li et al., Science (2010) 48

49 Yield Summary The High-Energy-Density Physics (HEDP) division at MIT performs cutting-edge research programs on laser-generated plasmas Y n E+10 Inertial Fusion Ignition R [g/cm 2 ] Kinetic Mix [MeV] - E i / Z i Stopping Power T e = 0.6 kev T e = 4.1 kev E /A [ MeV] i Burn Histories 1E+12 1E+11 1E+10 1E+09 1E+08 Clean Kinetic Effects Data Kinetic regime D 3 He DD-n Hydro regime Initial Density (mg/cm 3 ) HED Radiography D 3 He-p CD CD D 3 He-p DD-n 0 D 3 He 3 He Time 49

50 Density (cm -3 ) Multi-ion physics Strong gradients in pressure, electric potential or temperature can cause separation of the ion species Preliminary multi-ion-fluid vs single-ion-fluid simulation: Multi-ion fluid: Single-fluid DT shock DT i 1 = ρd Separation of species*: e Φ α + k P ln P + k E T + k T ln T Radius (µm) All main-line codes assume single-fluid. These effects will impact DT as well as D 3 He. Simulation by C. Bellei, LLNL *P. Amendt, et al. PRL 109, (2012)

51 D 3 He-proton Yield Kinetic mix Hydrodynamic instabilities cannot explain the observed yield 100 μm t = shock bang CD 4.0E E E E+10 Measured Yield 50 3 He 2.0E E E E+09 Max instability growth μm 0.0E Penetration Fraction Instabilities do not develop prior to shock bang. Instability-driven mix can only produce < 10% of observed yield. 2D-DRACO simulation by J. Delettrez, LLE; fall-line mix simulation by P. Amendt, LLNL 51

52 Kinetic mix Burn profiles for ion diffusive mix model are predicted to be observably different from D 3 He-filled implosions 2 x Simulated Burn Profiles Burn Profiles CD[5.1μm] DD 3 He D 3 He D 3 He-p and DD-p Proton Core Imaging System (PCIS) Yield / mm D 3 He-p DD-p and DD-n DD-n CEA Small Neutron Imaging System (SNIS) Radius (mm) Nuclear burn images were obtained on Nov 21 st 2013 using the MIT-developed Proton Core Imaging System (PCIS) 52

53 Multi-ion physics The reduction is comparable in magnitude for all fuel densities DD-neutron Yield / 1D-simulation Normalized to f D = mg/cc 1.5 mg/cc 0.4 mg/cc Deuterium Fraction expected scaling H. Rinderknecht, Invited Talk, APS 2013 and PhD Thesis HYADES simulations by Alex Zylstra. Points artificially spread out in f D