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  • Magneto-Inertial Fusion& Magnetized HED Physics

    Bruno S. Bauer, UNR& Magneto-Inertial Fusion Community

    Workshop on Scientific Opportunitiesin High Energy Density Plasma Physics

    Washington, DCAugust 25-27, 2008

  • The mainline path to fusion energy is basedon the established fact that magnetic fieldssignificantly improve the insulation ofthermonuclear fuel from its surroundings.Can the same insulation improve theperformance of inertially confined systems?A body of theoretical literature suggeststhat it can. Magnetized high energy densityphysics experiments are now helping to testand develop this idea, while significantlyadvancing a vital fundamental frontier ofHED science.

    Abstract

    BSB 8/24/08

  • Magneto-Inertial Fusion (MIF)& Magnetized HED Physics

    1. Can magnetic field benefit inertial fusion?

    2. Does MIF research advance fundamental HED science? Is it important to other fields? Are the ingredients for significant progress available?

    BSB 8/24/08

  • Fermi recognized intense pulsed Bcould reduce thermal conduction

    Enrico Fermi, "Super Lecture No. 5--Thermal Conduction as Affectedby a Magnetic Field," Los Alamos Report 344, Sept. 17, 1945.

    "A possible method of cutting down the conduction to the walls wouldbe the application of a strong magnetic field, H. This tends to makethe electrons go in circles between collisions, so impedes theirmobility. Actually, it makes them go in spirals, and does not reducethe conductivity parallel to H but only to the other two dimensions,so one would probably want to design the container elongated in thedirection of H, or even toroidal... with the lines of force never leavingthe deuterium... rather large fields will be required... thus a field inexcess of 20,000 gausses would help reduce conduction loss. Whileit would not be possible to produce such fields in a large volume in asteady state,the technical problem of making the field is much aidedby the fact that the time during which the field is needed is muchshorter than the usual relaxation time of magnetic fields, so it needbe applied only instantaneously."

  • FSC

    A strong magnetic field can relax the conditions for hot-spot ignition

    Bhsrhs

    Bhs~ 10 MG: Bhs~100 MG:

    4104 0.2|| for cee1.2

    4102 0.01|| for cee12

    r=270 m r/rhs > 5 r=27 m -particles trapped: r/rhs 0.5, c0.1

    *P. W. McKenty, et al., Phys. Plasmas 8, 2315 (2001)

    Considering NIF 1.5 MJ, direct-drive point design* hs 30g/cc, Ths 7keV (before ignition), rhs 50m.

    Tens of MG magnetic field is needed for effective reduction of thehot-spot thermal losses through magnetic insulation.

    Effective confinement of the alpha particles (relaxation of the hot-spot R requirement), requires Bhs~100 MG.

    O.V. Gotchev, N.W. Jang, J.P. Knauer, M.D. Barbero, D.D. Meyerhofer & R. Betti, UR-LLER.D. Petrasso & C.K. Li, MIT Plasma Science and Fusion Center BSB 8/24/08

  • FSC

    A laser-driven implosion of magnetized cylindrical plasma examines magnetic insulation in ICF

    Current driven in coilInitial B ~ 0.1 MG

    Implode with40 OMEGA beams 1-ns 14-kJ pulse

    Preliminary results B ~ 60 MG10 more neutrons than with B=0

    CH shell target20-m thick

    8-atm D2 fill gas

    RES, BSB 8/24/08

  • FSC

    Magnetic fields are measured via deflection of the D3He backlighter protons traversing the target area

    Cylindrical implosion target860 m diam.,1.5 mm long

    Target stalkBacklighter target stalk

    MIFEDS coil4 mm diam. 1200 m wide

    Cylindrical implosion target860 m diam. and 1.5 mm long

    Target stalk Backlighter target stalk

    MIFEDS coil4 mm diam. 1200 m wide

    Proton maps at T0+2.9 ns(shot 51069)

    Data analysis combined with GEANT4 particle transport code simulations suggest B up to about 60 MG has been observed

    RES 8/24/08

  • FSC

    Modeling shows magnetic field gives higher T-- still to be confirmed experimentally

    Stagnation phase

    LILAC MHD simulations show shock heating ionizes and preheats plasma; then adiabatic compression gives keV ion temperature

    Plasma ~ 50% on axis; about ~ 12 at 10 m RES , BSB 8/24/08

  • One concept for MIF

    RES, BSB 4/22/07

    E.g., Al can driven by I > 1 MA, B ~ 100 T

  • Magneto-inertial fusion:Dense fuel + magnetic insulation

    Particle EnergyConfinement Confinement

    ICF Inertial InertialMIF Inertial MagneticMFE Magnetic Magnetic

    DT fuel:100 gm/cm3e- thermalconduction:E ~ 10 ps

    j x B = p10-9 gm/cm3E ~ 1 s

    Eg, 0.1 gm/cm3E ~ 100 ns

    RES, BSB 4/22/07

  • Cylindrical compact-torus plasma

    Initial FRC~ 20-30 kG~ 200 eV~ 1017 cm-3

    Cylindrical liner implosion

    LANL-AFRL liner-on-plasma compression seeks to examine MIF physics in fusion regime

    Final FRC~ 1019 cm-3~ 2-4 MG~ 1-5 keV

    Shiva Star: 16MA, 9MJ

  • FRX-L: The Field Reversed Configuration (FRC) Plasma Injector for MTF

  • Field Reversed Configurationhigh- self-organized plasma

    ~ 1

    compact torus like spheromak

    Can translate into liner

    The LANL FRC has parameters orders of magnitude different than previous FRCs.How will FRC behave under compression? How will liner interact with FRC?

  • Large current compresses liner=> large kinetic energy (MJ) => Mbar pressure

    107 amps< 10 s

    B ~ 100 tesla (40,000 atm)

    Liner = thin-walled aluminumcylinder the size of a beer can

    RES, BSB 8/24/08

  • AFRL radiographs of liner implosiondemonstrate good liner performance

    Stationary 6-mm probe jacket

    Elastic-plastic deformed 7-mm thick liner at 12:1 radial compression

    Flash x-rayradiographs

    Side-on viewof liner moving4 mm/s

    Initial 1-mm thickAluminum liner

    RES, BSB 4/22/07

    Courtesy of J. Degnan, AFRL

  • Glide planes interfere with FRC injection

  • AFRL success with shaped linerRadiograph plus simulation Radiograph alone

    Glide planes eliminated

    Enhanced magnetic mirror centers FRC

  • U N C L A S S I F I E D

    Operated by the Los Alamos National Security, LLC for the DOE/NNSA

    The liner-FRC compression experiment will enable the study of many MIF physics issues

    Can multi-keV temperatures be obtained by compression of a magnetically confined plasma to megabar pressures using a solid metal liner?

    What limits liner compression and dwell time? How do nearby boundaries (walls) driven by intense magnetic and radiation fields turn into plasmas? How are hydrodynamic instabilities at boundaries changed in the presence of a thermonuclear (fusing) plasma? How can we minimize impurity influx?

    Do we have the right material conductivity and transport models (for both walls and plasma)? What effects do velocity shear, initial density profile, finite Larmor radius, and other conditions have on particle and energy transport at MHEDLP conditions?

    Visit http://fusionenergy.lanl.gov/mhedlp-wp.pdf for community white paper on Magnetized HEDLP (April 20, 2007) for many more questions!

    http://fusionenergy.lanl.gov/mhedlp-wp.pdf

  • The liner-FRC compression experiment will enable the study of many MIF physics issues

    Idealized imploded liner

    Idealized compressed FRC(interferogram)

    Rayleigh-Taylor growth;Wall plasma interactions

    High-, collisional MHD;rotational instability

    Impurities; energy losses;fusion reaction rate

  • MIF could have advantagesLow bigger, cheaper targets High To reduced radial convergence (e.g., 10)Low v less power, intensity more & cheaper energy possibleLow v, Bo adiabatic compression no pulse shaping, no shocksBig targets, low v massive pushers long dwell, burn timesB rB, not r, for alpha deposition

  • MIF could be profitableCost-effective capacitor bank driverEfficiently heated G~10 hot spotOverall fusion gain could reach G~50 with edge fueling (by cool fuel at wall or jets)Non-cryogenic, macroscopic, simple targetDriver stand off via recyclable transmission lines or plasma jets10 GJ output ~ $50 of heat per shot

  • Recycled tin flibe-insulatedtransmission lines

    Flibe primarycoolant at 550 oC(Tmelt = 459 oC)

    Tin Tmelt = 232 oC inserted short time

    Studied by P. Peterson, UC Berkeley

    MoltenFlibe

    SolidFlibe

    Steel

    FusionBurst

    Tin

    IM-1 01-0659 (4/01)

    Structural insulator

    MIF might use Flibe working fluid

    Note no line of sight needed; electricity goes around corners

  • Miniature plasma jets from capillary discharges merge to form a plasma ring (Witherspoon, 2007)

    Imploding plasma liners can be an inexpensive path to forming cm & s-scale HED plasmas

    Forming a plasma liner with an array of dense plasma jets using pulsed power technology: Plasma gun development at HyperV:

    Many potential applicationsFundamental studies of HEDLP, including laser-plasma interactions* and diagnostic development

    Laboratory astrophysics and materials science* studies

    Experimental validation of rad-hydro simulations

    High flux pulsed neutron sources & ultimately MIF

    For MIF only

  • Significant development of high-Mach-number Plasma Jets by HyperV Technologies

    x

    y

    0 0.05 0.1 0.150

    0.1

    0.2

    0.3

    0.4

    ro2.3E-042.1E-041.8E-041.6E-041.4E-041.1E-049.1E-056.9E-054.6E-052.3E-050.0E+00

    t = 7.20013E-06

    Density

    ro_max=2.29E-004

    DW, YCFT, BSB 8/24/08

  • Plasma liners could be advantageous

    Standoff delivery of imploding momentumInexpensive liner fabricationRepetitive operationFast compressionPos