T.E. Cowan Director, Nevada Terawatt Facility Department of Physics University of Nevada, Reno January 27, rd Meeting of the Fusion Science Center for Extreme States of Matter and Fast Ignition Physics LLE, Rochester, January 26-27, 2006 Capabilities of the new UNR Multi-Terawatt laser and Z-pinch facility

Executive Summary Laser development at the Nevada Terawatt Facility (NTF) as progressed to the point where we can offer substantial laser time for FSC experiments TW coupled to 2 TW Z-pinch active (since 12/05) TW into stand-alone chamber available in March ‘ TW assembly in April 2006, commissioning in June ‘ TW “Leopard” available for science winter 2006 (stand alone & Z-pinch) (includes additional 100 J, 1 ns beam) -- 2 nd 100 TW beam available mid 2007 (sooner, depending on FSC interest) NTF Magnetized HEDP program could be interesting for advanced FI concepts -- Magnetized isochoric heating (with OFES) -- Probing of compressed, or hot matter -- Advanced cone target designs -- Enhanced laser absorption & heating in -- Z-pinch x-ray backlighter for laser-produced WDM ( R. Sheppard-LLNL, P. Audebert-LULI ) New concepts for FSC experiments -- Wire array precursor plasma column as hot (100 eV) plasma target for electron transport (F. Beg) -- Laser-Z-pinch FI (Y. Sentoku) Background work: - SPL probing of current and mass flow in wire-array Z-pinches - Dopant spectroscopy in wire-array implosions ( B. Jones, SNL )

ICF and Fast Ignition fuel assemblies can be driven by Z-pinch devices

The Nevada Terawatt Facility (NTF) combines unique resources for High Energy Density research 2 TW Zebra is most powerful pulsed-power or x-ray machine at any US university. Similar to Magpie (Imperial College). Higher energy and high impedence vs. planned COBRA (Cornell). 2 TW (2 MV, 1 MA, 80 ns, 160 kJ) “Zebra” pulsed-power z-pinch generator 100 TW high-intensity short-pulse laser “Leopard” coupled to Zebra generator (staged laser development: presently ~10 TW “Tomcat” SPL) World-class Particle-in-Cell simulation team with 96 node Linux cluster Extensive plasma spectroscopy and atomic physics capabilities -- theory, experiment, and modeling – within the Physics Department

Magnetized High Energy Density laser-plasmas - enhanced laser-heating of strongly magnetized matter - astrophysics-relevant laboratory plasmas Implosion and Radiation Dynamics of wire-array Z-pinch Plasmas - short-pulse optical probing of current & mass flow - hard x-ray backlighting - proton radiography of magnetic fields Advanced laser-particle acceleration - enhanced particle & radiation generation - injection into pulsed accelerator Materials dynamics & ultra-fast probing of magnetically compressed matter Combination of a high-intensity laser coupled to a high power z-pinch creates new scientific opportunities UNR/NTF allows to test concepts, and stage experiments, for large scale HED facilities

Hard x-ray backlighting with kJ’s on Z-Beamlet SPL backlighting of Z-pinch implosions at NTF will allow hard x-ray, proton deflection and optical probing...with J’s at NTF (see B.Y. Cho talk) Proton deflectometry of magnetic turbulence... (see J. Fuchs talk)

High intensity laser irradiation of magnetized solid may exhibit electron confinement and transient heating Laser  ce >> ei r Larmour << mfp Magnetized if: r Larmour ~ r laser Enhanced heating if: At 1 MG, W/cm 2, 100 TW Leopard + Zebra: ~ 30 keV per atom in 10  m thick Al foil (kT ~ 2 keV) (PIC simulation: Y. Sentoku)

Enhanced Target Heating by the External B-Field (2D PIC) E L ⊥ B ext E L || B ext t= 480 fs

B=3MG Hot electrons are confined by the external magnetic field for few ps Electron energy density  n e /n 0 I= W/cm 2 (a=0.5) Electron energy spectrum (B=3MG) Cold electrons are heated to 2keV! (Y. Sentoku, A. Kemp, M. Bakeman et al.)

Z=6 n i = /cm 3 n e =Zn i T i (0) = 0 T h (0)= 30keV T c (0)= 1keV/Z I= W/cm 2 Pulse length = 700fs Target = 10  m n h = /cm 3 Collisions, electron diffusion by scattering, and radiative energy loss have now been included in simulation. Ion temperatures of several 100 eV, at solid density (Z=6) for up to a few ps, may be possible with the “Tomcat”-Zebra coupling. (Experiments at UNR begun December 2005.) (Y. Sentoku, A. Kemp, M. Bakeman et al.)

B ~ 30 MG Future possibilities for laser interaction with dense and/or magnetized matter -- transport, “hot” stopping jxB compression of solid-D 2 -filled cylindrical liner: I = 0.9 MA, B ~ 30MG (at 120  m). 5-fold in radius (600  m  m) 25x solid density 35-Mbar Fermi-degenerate electron pressure (p ~ 0.05n e 5/3 h 2 /m) Laser Fast Particles Laser Fast Particles J J Anode Cathode

Operation:“short pulse”“long pulse” Marx charged to85 kV 85 kV Stored energy 150 kJ150 kJ Load current0.9 – 1 MA0.5 – 0.6 MA Current rise time90 ns200 ns Marx capacitor bankPulse forming line Intermediate storage LoadVacuum chamber The z-pinch (Zebra) is a flexible pulsed-power generator, with an accessible load region for integration with lasers short pulse long pulse

Short-pulse oscillator Grating Stretcher Ti:S regenerative amplifier Optical parametric chirped-pulse amplifiers (OPCPA) Nd:glass rod amplifiers Target Chamber GLX-200 uses SESAM technology to produce 3 nJ / 200 fs / 6.6-nm FWHM pulses All-reflective Offner- triplet produces 0.5 nJ / 1 ns pulses A 2-stage OPCPA produces > 20 mJ at 5 Hz, sufficient to generate plasma and to facilitate alignment of the stretcher, compressor, and plasma diagnostics Nd:glass disk amplifiers A Ti:sapphire regen allows for earlier activation and enhances system reliability as a back-up to the OPCPA Both silicate and phosphate glasses are used to achieve needed bandwidth and disk amps allow B not to grow excessively 21 cm x 42 cm gold gratings are used in a two-pass roof-mirror configuration An off-axis parabola with a 30-cm focal length focuses 9-cm- diameter beams onto targets Grating Compressor Long-pulse beamline “Leopard” is based on proven LULI 100 TW laser design, allowing concentration on laser-Z coupling & applications

Light from the ~10 TW “Tomcat” system has been compressed and transported to Zebra

On the floor….

Lens focusing will provide up to 5 x W/cm 2 1 st compressed & focused light to Zebra, 10/12/05. P. Wiewior & team.

Zebra load: 6.35mm diameter steel rod Magnetic field = 35 Tesla (100,000x Earth’s field) laser First Zebra+Tomcat shots at the NT 2 F E laser ≈ 5 J Δt ≈ 5 ps 0.15 x 0.3 mm focal spot I ≈ 2x10 15 W/cm 2 laser shadow imaging reproducible results: 2 similar shots with B=0 2 similar shots at current peak expansion velocity v ≈ km/s suggesting T ≈ 10 eV for Fe 10+ (prepulse-produced plasma) expansion in magnetic field slower shows instability 1 mm TW laser

Terawatt power is enabled by energy pulse compression to nanoseconds (Z-pinch) and picoseconds (Laser) Z-Pinch 200,000 Joules 100 nanoseconds ~few millimeters 2 Terawatt <kilovolt particles Movie courtesy of J. Chittendon 100 TW Laser 35 Joules nanoseconds ~few micrometers 100 Terawatt >megavolt particles pulse energy pulse duration size power particle energy “Ocean’s Eleven” meets “Star Wars” 1 MA X-ray emission Implosion

N ~ 10^19 cm^ eV R ~ 2 mm L ~ 2 cm I ~ 100 kA B ~ 100kG Wire-array z-pinch precursor plasma would make an interesting hot plasma target (100 eV) for electron transport

Laser (optical) backlighting allows to resolve plasma evolution during wire-array implosions on Zebra Plasma streaming from wires to produce precursor plasma on array axis V. V. Ivanov, V. I. Sotnikov, T. E. Cowan, P. J. Laca, A. L. Astanovitskiy, B. Le Galloudec – UNR G. S. Sarkisov - Ktech Corp. B. Jones, C. A. Coverdale, C. Deeney, T.A. Mehlhorn – SNL B.V. Oliver - ATK-MRC J.N. Leboeuf - UCLA

2, 2d 2-frame shadowgraphy or schlieren diagnostics 1, 1d 3 2-frame shadowgraphy or schlieren diagnostics or Mach-Zehnder interferometer Faraday channel, shadowgraphy, shearing interferometer, and schlieren diagnostic 34 ns d(4) 2d(5) Long pulse train 150ps 22.5º 8 CCD cameras: bit 0.5x0.5K - 1x1K Faraday rotation diagnostics was developed on Zebra facility and synchronized to current pulse (+/- 5 ns) 9 ns Short pulse train Streak camera Filtered PCDs CCD 3f CCD 3s CCD 3i CCD 3sch CCD 1s CCD 1ds Screen Box

Direct evidence of current flow in precursor plasma column Al 16 x 15 µm wire array Faraday channel Shadowgram Precursor Magnetic bubble Faraday effect 1 Al 8 x 15 µm wire array B av = MG I = MA * α 0 = 5° # 514 α 0 = -5° # 494 Faraday channel Shadowgram Interferogram * -V. Ivanov et al., “Investigation of Magnetic Fields in 1-MA Wire Arrays and X-pinches”, submitted to IEEE TPS

Current t, ns X-ray a b c I, MA a 2 mm 1mm b c Large-scale structures (in addition to small scale) arise in the nonlinear stage Al 16 x 15 µm wire arrays Bubbles arise in the chain of cells Imprints from wires d Convective cells? #498 #501

Al 4 x 20 µm wire arrays The Faraday effect shows trapped magnetic fields in the streams Al 8 x 15 µm wire arrays Axis Faraday effect in the streams Faraday channel Shadowgram Single wire 1st observation of magnetic flux trapped in streams #547 #515

Executive Summary Laser development at the Nevada Terawatt Facility (NTF) as progressed to the point where we can offer substantial laser time for FSC experiments TW coupled to 2 TW Z-pinch active (since 12/05) TW into stand-alone chamber available in March ‘ TW assembly in April 2006, commissioning in June ‘ TW “Leopard” available for science winter 2006 (stand alone & Z-pinch) (includes additional 100 J, 1 ns beam) -- 2 nd 100 TW beam available mid 2007 (sooner, depending on FSC interest) NTF Magnetized HEDP program could be interesting for advanced FI concepts -- Magnetized isochoric heating (with OFES) -- Probing of compressed, or hot matter -- Advanced cone target designs -- Enhanced laser absorption & heating in -- Z-pinch x-ray backlighter for laser-produced WDM ( R. Sheppard-LLNL, P. Audebert-LULI ) New concepts for FSC experiments -- Wire array precursor plasma column as hot (100 eV) plasma target for electron transport (F. Beg) -- Laser-Z-pinch FI (Y. Sentoku) Background work: - SPL probing of current and mass flow in wire-array Z-pinches - Dopant spectroscopy in wire-array implosions ( B. Jones, SNL )