H T Powell

Publications (19)17.53 Total impact

• Conference Proceeding: Progress toward an integrated 100 TW laser-100 MeV electron linac experiment

  G.R. Hays, T. Cowan, J.K. Crane, G.P. Le Sage, M.D. Perry, H.T. Powell, M. Roth, K.B. Wharton, V.P. Yanovsky, T. Ditmire
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  ABSTRACT: Summary form only given. Advances in the chirped-pulse amplification (CPA) technique on solid state lasers have made it possible to achieve very high peak powers (>10 TW) at high repetition rates (>1 Hz). These high peak power ultrafast lasers systems are of great interest to laser-plasma interaction research and ultrafast X-ray generation. We are developing a Ti:sapphire based CPA laser system which is located near a high current 100 MeV RF linear accelerator. We are working to couple the laser to the accelerator in order to perform laser pulse interactions with a high current relativistic electron bunches. This requires that the laser be synchronized to the linear accelerator to a subpicosecond accuracy
  Lasers and Electro-Optics, 2000. (CLEO 2000). Conference on; 02/2000
• Conference Proceeding: The Mercury laser: a diode-pumped, gas-cooled Yb:S-FAP solid-statelaser

  C. Bibeau, R.J. Beach, A. Bayramian, J.C. Chanteloup, C.A. Ebbers, M.A. Emanuel, V.K. Kanz, C.D. Orth, J.E. Rothenberg, K.I. Schaffers, J.A. Skidmore, L.K. Smith, S.B. Sutton, L.E. Zapata, S.A. Payne, H.T. Powell
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  ABSTRACT: Gas-cooled, diode-pumped, Yb:crystal lasers are envisioned to be the next-generation inertial confinement fusion (ICF) solid state laser system producing high energy per pulse at modest rep-rates. Innovative solutions for building ICF lasers with high repetition rate and efficiency include: trading the flashlamps for large, low-cost laser diode arrays; using Yb:crystals for greater energy storage and thermal conductivity than Nd:glass; and employing near-sonic helium for cooling of the laser slabs
  Lasers and Electro-Optics, 2000. (CLEO 2000). Conference on; 02/2000
• Article: Petawatt laser pulses.

  M D Perry, D Pennington, B C Stuart, G Tietbohl, J A Britten, C Brown, S Herman, B Golick, M Kartz, J Miller, H T Powell, M Vergino, V Yanovsky
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  ABSTRACT: We have developed a hybrid Ti:sapphire-Nd:glass laser system that produces more than 1500 TW (1.5 PW) of peak power. The system produces 660 J of power in a compressed 440+/-20 fs pulse by use of 94-cm master diffraction gratings. Focusing to an irradiance of >7x10(20) W/cm (2) is achieved by use of a Cassegrainian focusing system employing a plasma mirror.
  Optics Letters 03/1999; 24(3):160-2. · 3.40 Impact Factor
• Conference Proceeding: Ultrafast X-ray generation and applications using laser-linacinteractions

  T Ditmire, T E Cowan, G. LeSage, M Allen, G. Hays, K. B. Wharton, M D Perry, H T Powell, J.B. Rosenzweig
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  ABSTRACT: At LLNL we have been working to integrate an intense short-pulse laser with a low-emittance relativistic electron beam utilizing a 100 MeV S-band linac. This project uses a 100 TW, 35 fs laser, which is currently under development
  Lasers and Electro-Optics Society 1999 12th Annual Meeting. LEOS '99. IEEE; 02/1999
• Conference Proceeding: Diode-pumped solid-state laser drivers for inertial fusion energy

  C Bibeau, C D Marshall, S A Payne, H T Powell
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  ABSTRACT: This paper reviews work on flashlamp-pumped solid state lasers and discusses diode-pumped solid state lasers, the Mercury laser in particular. It also discusses ICF lasers beyond Mercury.
  12/1998
• Article: Diode-Pumped Solid-State Lasers for Inertial Fusion Energy

  S. A. Payne, C. Bibeau, R. J. Beach, A. Bayramian, J. C. Chanteloup, C. A. Ebbers, M. A. Emanuel, H. Nakana, C. D. Orth, J. E. Rothenberg, K. I. Schaffers, L. G. Seppala, J. A. Skidmore, S. B. Sutton, L. E. Zapata, H. T. Powell
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  ABSTRACT: We have begun building the Mercury laser system as the first in a series of new generation diode-pumped solid-state lasers for inertial fusion research. Mercury will integrate three key technologies: diodes, crystals, and gas cooling, within a unique laser architecture that is scalable to kilojoule and megajoule energy levels for fusion energy applications. The primary near-term performance goals include 10% electrical efficiencies at 10 Hz and 100J with a 2–10 ns pulse length at 1.047 m wavelength. When completed, Mercury will allow rep-rated target experiments with multiple chambers for high energy density physics research.
  Journal of Fusion Energy 08/1998; 17(3):213-217. · 0.52 Impact Factor
• Conference Proceeding: Recent advances and challenges for diode-pumped solid-state lasers as an inertial fusion energy driver candidate

  S.A. Payne, R.J. Beach, C. Bibeau, C.A. Ebbers, M.A. Emanual, E.C. Honea, W.F. Krupke, C.D. Marshall, C.D. Orth, H.T. Powell, K.I. Schaffers, J.A. Skidmore, S.B. Sutton
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  ABSTRACT: We discuss how solid-state laser technology can serve in the interests of fusion energy beyond the goals of the National Ignition Facility (NIF), which is now being constructed to ignite a deuterium-tritium target to fusion conditions in the laboratory for the first time. We think that advanced solid-state laser technology can offer the repetition-rate and efficiency needed to drive a fusion power plant, in contrast to the single-shot character of NIF. As discussed below, we propose that a gas-cooled, diode-pumped Yb:S-FAP laser can provide new paradigm for fusion laser technology leading into the next century
  Fusion Engineering, 1997. 17th IEEE/NPSS Symposium; 11/1997
• Conference Proceeding: The Beamlet laser system as a prototype for the National IgnitionFacility (NIF)

  J.A. Caird, J M Auerbach, W.C. Behrendt, E.S. Bliss, C. Barker, J.H. Campbell, R.P. Hackel, P.G. Hartley, M A Henesian, A.F. Hint, [......], H T Powell, J T Salmon, I C Smith, D R Speck, C.E. Thompson, B M Van Wonterghem, P J Wegner, C C Widmayer, S.E. Winters, R A Zacharias
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  ABSTRACT: Summary form only given. The National Ignition Facility is designed to ignite inertial-confinement fusion (ICF) targets using 1.8 MJ of ultraviolet (351 nm) laser light generated by frequency tripling the output of 192 neodymium glass laser beams. The Beamlet laser system is a full scale scientific prototype of one of the 192 NIF beamlines. Because the estimated cost of the NIF facility is substantial ($1.1 billion) it is imperative that the performance be cost optimized. This implies operation as close as possible to power and energy extraction limits imposed by fundamental physical constraints. Control of beam quality in the NIF and the Beamlet prototype is enhanced through the use of a deformable mirror. Beamlet employs a sophisticated suite of laser diagnostic systems to measure beam quality
  Lasers and Electro-Optics Society Annual Meeting, 1996. LEOS 96., IEEE; 12/1996
• Source

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  Article: Designing fully continuous phase screens for tailoring focal-plane irradiance profiles.

  S N Dixit, M D Feit, M D Perry, H T Powell
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  ABSTRACT: An iterative algorithm for constructing fully continuous phase screens for tailoring far-field intensity profiles is presented. The algorithm is robust, stable, and, if run properly, maintains the continuous nature of the phase throughout the iterative process. The iterative procedure is applied to generate continuous phase screens to produce a 12th-power super-Gaussian far-field intensity profile.
  Optics Letters 11/1996; 21(21):1715-7. · 3.40 Impact Factor
• Conference Proceeding: The petawatt laser and its application to inertial confinement fusion

  M.D. Perry, B.C. Stuart, G. Tietbohl, J. Miller, J.A. Britten, R. Boyd, M. Everett, S. Herman, H. Nguyen, H.T. Powell, B.W. Shore
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  ABSTRACT: Summary form only given. A project to develop a 1000 TW (petawatt) class laser began in 1992 in order to provide the capability to examine the fast ignitor concept for inertial confinement fusion (ICF). The laser was designed to produce 1 kilojoule pulses with a duration less than 500 fsec and be focusable to a high irradiance. Near-diffraction-limited beams require large-scale pulse compression and sophisticated adaptive optics. Metallic gratings are capable of compressing near 1 kT pulses.
  Lasers and Electro-Optics, 1996. CLEO '96., Summaries of papers presented at the Conference on; 07/1996
• Article: 1.047-μm Yb:Sr5(PO4)3F energy storage optical amplifier

  C.D. Marshall, S.A. Payne, L.K. Smith, H.T. Powell, W.F. Krupke, B.H.T. Chai
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  ABSTRACT: The pumping and gain properties of Yb³⁺-doped Sr₅(PO₄)₃F (Yb:S-FAP) are reported. Using a tunable, free running 900-nm Cr:LiSAF oscillator as a pump source for a Yb:S-FAP rod, the saturation fluence for pumping was measured to be 2.2 J/cm² based on either the spatial, temporal, or energy transmission properties of the Yb:S-FAP rod. The emission peak of Yb:S-FAP (1047.5 nm in air) is shown to overlap with that of Nd:YLiF₄ (Nd:YLF) to within 0.1 nm, rendering Yb:S-FAP suitable as an effective power amplifier for Nd:YLF oscillators. The small signal gain, under varying pumping conditions, was measured with a cw Nd:YLF probe laser. These measurements implied emission cross sections of 6.0×10^-20 and 1.5×10^-20 cm ² for π and σ polarized light. Respectively, which fall within the error limits of the previously reported values of 7.3×10^-20 and 1.4×10^-20 cm² for π and σ polarized light, obtained from purely spectroscopic techniques. The effects of radiation trapping on the emission lifetime have been quantified and have been shown to lead to emission lifetimes as long as 1.7 ms, for large optically dense crystals. This is substantially larger than the measured intrinsic lifetime of 1.10 ms. Yb:S-FAP crystal boules up to 25×25×175 mm in size, which were grown for the above experiments and were found to have acceptable loss characteristics (<~1%/cm) and adequately large laser damage thresholds at 1064 nm (~20 J/cm² at 3 ns). Overall, diode-pumped Yb:S-FAP amplifiers are anticipated to offer a viable means of amplifying 1.047-μm light, and may be particularly well suited to applications sensitive to overall laser efficiencies, such as inertial confinement fusion energy applications
  IEEE Journal of Selected Topics in Quantum Electronics 05/1995; · 3.78 Impact Factor
• Conference Proceeding: Precision operation of the Nova laser for fusion experiments

  J.A. Caird, R.B. Ehrlich, G.L. Hermes, O.L. Landen, C.W. Laumann, R.A. Lerche, J.L. Miller, J.E. Murray, N.D. Nielsen, H.T. Powell, M.C. Rushford, R.L. Saunders, C.E. Thompson, P.J. VanArsdall, C.S. Vann, T.L. Weiland
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  ABSTRACT: The operation of a Neodymium glass laser of a special design for fusion experiments is improved by a better pulse synchronization, the gain stabilization, and the laser diagnostics. We used sensor upgrading and antifriction coating of focusing lenses. The pointing accuracy of the Nova laser meets now our goal for precision operation. (AIP) [copyright] 1994 [ital American] [ital Institute] [ital of] [ital Physics]
  10/1994
• Article: Kinoform phase plates for focal plane irradiance profile control.

  S N Dixit, J K Lawson, K R Manes, H T Powell, K A Nugent
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  ABSTRACT: A versatile, rapidly convergent, iterative algorithm is presented for the construction of kinoform phase plates for tailoring the far-field intensity distribution of laser beams. The method consists of repeated Fourier transforming between the near-field and the far-field planes with constraints imposed in each plane. For application to inertial confinement fusion, the converged far-field pattern contains more than 95% of the incident energy inside a desired region and is relatively insensitive to beam aberrations.
  Optics Letters 03/1994; 19(6):417-9. · 3.40 Impact Factor
• Conference Proceeding: Laser driven hydrodynamic instability experiments on Nova

  S G Glendinning, S V Weber, S Dixit, M A Henesian, J D Kilkenny, H T Powell, R J Wallace, J P Knauer, C.P. Verdon
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  ABSTRACT: Summary form only given, as follows. A series of experiments on hydrodynamic (Rayleigh-Taylor) instabilities seeded by drive modulations in planar foils has been performed on the Nova laser at Lawrence Livermore National Laboratory. A drive laser beam smoothed by a random phase plate and by spectral dispersion with variable bandwidth was used. The laser far-field image was measured both time integrated and time resolved. The samples (flat polyethylene foils 20 μm thick and 700 μm in diameter) are driven with ~1 × 10¹⁴ W/cm² of 0.53 μm laser light for 3 ns. The targets are radiographed during acceleration using a multiple-frame gated X-ray pinhole camera (gate time ~100 ps). The X-ray backlighter target is uranium and is illuminated by a second laser beam. The time-resolved measurement of the laser far-field agrees quantitatively with modeling. Systematic behavior of the measured modulations in optical depth has been observed which agrees qualitatively with anticipated behavior
  Plasma Science, 1993. IEEE Conference Record - Abstracts., 1993 IEEE International Conference on; 07/1993
• Article: The Nova Upgrade Facility

  W.H. Lowdermilk, E.M. Campbell, J.H. Campbell, J.T. Hunt, J.R. Murray, H.T. Powell, R.L. Smith, E. Storm, M.T. Tobin, J.B. Trenholme
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  ABSTRACT: The Nova Upgrade Facility is being designed to achieve inertial confinement fusion (ICF) ignition and gain. A baseline design of the laser and experimental facilities has been completed, and a development plan, which includes a fully integrated laser demonstration, has been formulated. With adequate funding, the activities in this plan could be completed by late 1993. Construction of the Nova Upgrade beginning at that time would make possible the achievement of ICF ignition before the end of the decade.
  Laser and Particle Beams 05/1993; 11(02):307 - 316. · 1.62 Impact Factor
• Article: Random phase plates for beam smoothing on the Nova laser.

  S N Dixit, I M Thomas, B W Woods, A J Morgan, M A Henesian, P J Wegner, H T Powell
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  ABSTRACT: We discuss the design and fabrication of 80-cm-diameter random phase plates for target-plane beam smoothing on the Nova laser. Random phase plates have been used in a variety of inertial confinement fusion target experiments, such as studying direct-drive hydrodynamic stability and producing spatially smooth x-ray backlighting sources. These phase plates were produced by using a novel sol-gel dip-coating technique developed by us. The sol-gel phase plates have a high optical damage threshold at the second- and third-harmonic wavelengths of the Nd:glass laser and have excellent optical performance.
  Applied Optics 05/1993; 32(14):2543-54. · 1.41 Impact Factor
• Conference Proceeding: High power Nd:glass lasers as drivers for inertial confinement fusion

  H.T. Powell, J.H. Campbell, J.T. Hunt, W.H. Lowdermilk, J.R. Murray, D.R. Speck
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  ABSTRACT: We review the design and performance of the 100-kJ Nova laser used for inertial confinement fusion research. In particular, we describe a major upgrade to the Nova system which is in progress. We also discuss briefly the design of a potential 10-MJ, 1000 TW laser, which we have named Athena. 33 refs., 10 figs., 2 tabs.
  09/1988
• Conference Proceeding: Optical damage in epoxy polymers by millisecond light pulses

  C.R. Wolfe, J.H. Campbell, R.E. Lyon, J.H. Pitts, H.T. Powell
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  ABSTRACT: We have studied optical damage in epoxy-based polymers used to attach absorbing cladding onto the edge of laser disks of the Nova laser. Damage was produced by exposing the polymers to a 20-4- Jcm/sup 2/ fluence of broad band Xe-flashlamp light having a pulselength of approximately 0.5 ms. This simulates the pump environment of Nd:glass laser amplifiers. The predominant damage mechanisms appear to be pyrolysis, associated with absorbing inclusions and photolysis, associated with intrinsic absorption of the polmer. The amount of damage can be minimized by: (1) careful filtering of the polymer to reduce the presence of foreign material, (2) minimizing the near uv absorption of the polymer and (3) reducing the uv emission of the flashlamps. 27 refs., 9 figs.
  10/1987
• Conference Proceeding: Laser properties of Yb³⁺-doped Sr₅(PO₄)₃F crystals

  C.D. Marshall, S.A. Payne, L.K. Smith, K.I. Schaffers, R. Beach, M. Emanuel, H.T. Powell, W.F. Krupke, B.H.T. Chai
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  ABSTRACT: We believe that Yb³⁺-doped Sr₅(PO₄)₃F (Yb:S-FAP) is particularly well adapted for low to medium power laser applications that are sensitive to overall efficiencies. Yb:S-FAP has a relatively low pump saturation intensity of 2.0 kW/cm² which is well suited to diode pumping since the ground state can be readily bleached
  Lasers and Electro-Optics Society Annual Meeting, 1994. LEOS '94 Conference Proceedings. IEEE;