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Capabilities of the new UNR Multi-Terawatt laser and Z-pinch facility

Capabilities of the new UNR Multi-Terawatt laser and Z-pinch facility. T.E. Cowan Director, Nevada Terawatt Facility Department of Physics University of Nevada, Reno January 27, 2006

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Capabilities of the new UNR Multi-Terawatt laser and Z-pinch facility

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  1. Capabilities of the new UNR Multi-Terawatt laser and Z-pinch facility T.E. Cowan Director, Nevada Terawatt Facility Department of Physics University of Nevada, Reno January 27, 2006 3rd Meeting of the Fusion Science Center for Extreme States of Matter and Fast Ignition Physics LLE, Rochester, January 26-27, 2006

  2. 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 • -- 10 TW coupled to 2 TW Z-pinch active (since 12/05) • -- 10 TW into stand-alone chamber available in March ‘06 • -- 100 TW assembly in April 2006, commissioning in June ‘06 • -- 100 TW “Leopard” available for science winter 2006 (stand alone & Z-pinch) • (includes additional 100 J, 1 ns beam) • -- 2nd 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)

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

  4. The Nevada Terawatt Facility (NTF) combines unique resources for High Energy Density research • 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 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).

  5. Combination of a high-intensity laser coupled to a high power z-pinch creates new scientific opportunities • 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 UNR/NTF allows to test concepts, and stage experiments, for large scale HED facilities

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

  7. High intensity laser irradiation of magnetized solid may exhibit electron confinement and transient heating Laser Magnetized if: wce >> nei rLarmour << lmfp Enhanced heating if: rLarmour ~ rlaser (PIC simulation: Y. Sentoku) At 1 MG, 1018 W/cm2, 100 TW Leopard + Zebra: ~ 30 keV per atom in 10 mm thick Al foil (kT ~ 2 keV)

  8. Enhanced Target Heating by the External B-Field (2D PIC) EL ⊥ Bext EL || Bext t= 480 fs

  9. Electron energy spectrum (B=3MG) Hot electrons are confined by the external magnetic field for few ps (Y. Sentoku, A. Kemp, M. Bakeman et al.) I=2.5•1017 W/cm2 (a=0.5) B=3MG Cold electrons are heated to 2keV! Electron energy density •ne/n0

  10. Collisions, electron diffusion by scattering, and radiative energy loss have now been included in simulation. (Y. Sentoku, A. Kemp, M. Bakeman et al.) Z=6 ni=4•1022 1/cm3 ne=Z•ni Ti(0) = 0 Th(0)= 30keV Tc(0)= 1keV/Z I=2•1017W/cm2 Pulse length = 700fs Target = 10m nh=10•1021 1/cm3 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.)

  11. Future possibilities for laser interaction with dense and/or magnetized matter -- transport, “hot” stopping B ~ 30 MG J Fast Particles Fast Particles Laser Laser J Anode Cathode • jxB compression of solid-D2-filled cylindrical liner: • I = 0.9 MA, B ~ 30MG (at 120 mm). • 5-fold in radius (600 mm - 120 mm) • 25x solid density • 35-Mbar Fermi-degenerate electron pressure (p ~ 0.05ne5/3 h2/m)

  12. Load Vacuum chamber Marx capacitor bank Pulse forming line Intermediate storage The z-pinch (Zebra) is a flexible pulsed-power generator, with an accessible load region for integration with lasers short pulse long pulse Operation: “short pulse” “long pulse” Marx charged to 85 kV 85 kV Stored energy 150 kJ 150 kJ Load current 0.9 – 1 MA 0.5 – 0.6 MA Current rise time 90 ns 200 ns

  13. “Leopard” is based on proven LULI 100 TW laser design, allowing concentration on laser-Z coupling & applications 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 Short-pulse oscillator Grating Stretcher A Ti:sapphire regen allows for earlier activation and enhances system reliability as a back-up to the OPCPA 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 Ti:S regenerative amplifier Optical parametric chirped-pulse amplifiers (OPCPA) Nd:glass rod amplifiers 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 Nd:glass disk amplifiers Long-pulse beamline Grating Compressor An off-axis parabola with a 30-cm focal length focuses 9-cm-diameter beams onto targets Target Chamber

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

  15. On the floor….

  16. Lens focusing will provide up to 5 x 1017 W/cm2 1st compressed & focused light to Zebra, 10/12/05. P. Wiewior & team.

  17. First Zebra+Tomcat shots at the NT2F TW laser 1 mm Elaser ≈ 5 J Δt ≈ 5 ps 0.15 x 0.3 mm focal spot I ≈ 2x1015 W/cm2 laser shadow imaging reproducible results: 2 similar shots with B=0 2 similar shots at current peak expansion velocity v ≈ 10-40 km/s suggesting T ≈ 10 eV for Fe10+ (prepulse-produced plasma) expansion in magnetic field slower shows instability laser Zebra load: 6.35mm diameter steel rod Magnetic field = 35 Tesla (100,000x Earth’s field)

  18. Terawatt power is enabled by energy pulse compression to nanoseconds (Z-pinch) and picoseconds (Laser) 1 MA Implosion X-ray emission Z-Pinch 200,000 Joules 100 nanoseconds ~few millimeters 2 Terawatt <kilovolt particles Movie courtesy of J. Chittendon 100 TW Laser 35 Joules 0.00035 nanoseconds ~few micrometers 100 Terawatt >megavolt particles pulse energy pulse duration size power particle energy “Ocean’s Eleven” meets “Star Wars”

  19. Wire-array z-pinch precursor plasma would make an interesting hot plasma target (100 eV) for electron transport N ~ 10^19 cm^-3 100 eV R ~ 2 mm L ~ 2 cm I ~ 100 kA B ~ 100kG

  20. 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

  21. Faraday rotation diagnostics was developed on Zebra facility and synchronized to current pulse (+/- 5 ns) 1, 1d 3 2, 2d Long pulse train 1 2 3 1d(4) 2d(5) 150ps 22.5º 34 ns Streak camera Short pulse train Filtered PCDs 1 23 45 Faraday channel, shadowgraphy, shearing interferometer, and schlieren diagnostic 9 ns 2-frame shadowgraphy or schlieren diagnostics Screen Box CCD 1s 8 CCD cameras: 12-14 bit 0.5x0.5K - 1x1K CCD 3f CCD 1ds CCD 3s 2-frame shadowgraphy or schlieren diagnostics or Mach-Zehnder interferometer CCD 3sch CCD 3i

  22. 1 Direct evidence of current flow in precursor plasma column Precursor Magnetic bubble Al 16 x 15 µm wire array α0 = -5° #494 Faraday channel Shadowgram Bav= 0.1-0.2MG I = 0.1-0.2 MA * Faraday effect Al 8 x 15 µm wire array α0 = 5° #514 Faraday channel Shadowgram Interferogram * -V. Ivanov et al., “Investigation of Magnetic Fields in 1-MA Wire Arrays and X-pinches”, submitted to IEEE TPS

  23. b d c a 2 mm I, MA 1mm a b c Current X-ray 0 100 200 t, ns Large-scale structures (in addition to small scale) arise in the nonlinear stage Al 16 x 15 µm wire arrays Imprints from wires #498 Convective cells? #501 Bubbles arise in the chain of cells

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

  25. 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 • -- 10 TW coupled to 2 TW Z-pinch active (since 12/05) • -- 10 TW into stand-alone chamber available in March ‘06 • -- 100 TW assembly in April 2006, commissioning in June ‘06 • -- 100 TW “Leopard” available for science winter 2006 (stand alone & Z-pinch) • (includes additional 100 J, 1 ns beam) • -- 2nd 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)

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