P. M. Bell
A5061817079- Laser-Plasma Interactions and Diagnostics
- Nuclear Physics and Applications
- Advanced X-ray Imaging Techniques
- Advanced Optical Sensing Technologies
- Advanced X-ray and CT Imaging
- Photocathodes and Microchannel Plates
- Laser-induced spectroscopy and plasma
- High-pressure geophysics and materials
- Radiation Detection and Scintillator Technologies
- Medical Imaging Techniques and Applications
- Laser-Matter Interactions and Applications
- Laser Design and Applications
- Atomic and Molecular Physics
- X-ray Spectroscopy and Fluorescence Analysis
- Electron and X-Ray Spectroscopy Techniques
- Particle Detector Development and Performance
- Advancements in Photolithography Techniques
- CCD and CMOS Imaging Sensors
- Magnetic confinement fusion research
- Digital Radiography and Breast Imaging
- Ion-surface interactions and analysis
- Photonic Crystals and Applications
- Photonic and Optical Devices
- Diamond and Carbon-based Materials Research
- Radiation Therapy and Dosimetry
Lawrence Livermore National Laboratory
2014-2024
Kentech Instruments (United Kingdom)
2017-2018
C-2 Innovations (United States)
2018
General Atomics (United States)
2014-2018
Applied Energetics (United States)
2018
Oxford Instruments (United Kingdom)
2018
Sandia National Laboratories
2008-2018
Smithsonian Astrophysical Observatory
2018
Universities Space Research Association
2018
Marshall Space Flight Center
2018
For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as proof of principle various concepts. Following Lawson criterion, an ignited plasma is one where heating power high enough overcome all physical processes that cool plasma, creating positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, state can begin "burn propagation" into surrounding cold fuel, enabling possibility energy...
On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msub><a:mrow><a:mi>G</a:mi></a:mrow><a:mrow><a:mtext>target</a:mtext></a:mrow></a:msub></a:mrow></a:math> of 1.5. This is first laboratory demonstration exceeding “scientific breakeven” (or <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"...
Two new gated x-ray imaging cameras have recently been designed, constructed, and delivered to the National Ignition Facility in Livermore, CA. These x-Ray detectors are each designed fit within an aluminum airbox with a large capacity cooling plane fitted array of environmental housekeeping sensors. instruments significantly different from earlier generations images due, part, innovative impedance matching scheme, advanced phosphor screens, pulsed circuits, precision assembly fixturing,...
We demonstrate the hohlraum radiation temperature and symmetry required for ignition-scale inertial confinement fusion capsule implosions. Cryogenic gas-filled hohlraums with 2.2 mm-diameter capsules are heated unprecedented laser energies of 1.2 MJ delivered by 192 ultraviolet beams on National Ignition Facility. Laser backscatter measurements show that these absorb 87% to 91% incident power resulting in peak temperatures ${T}_{\mathrm{RAD}}=300\text{ }\text{ }\mathrm{eV}$ a symmetric...
Ignition of imploding inertial confinement capsules requires, among other things, controlling the symmetry with high accuracy and fidelity. We have used gated x-ray imaging, 10 μm 70 ps resolution, to detect emission from imploded core at National Facility. The measurements are characterize time dependent bang implosion two orthogonal directions. These were one primary diagnostics tune parameters laser Hohlraum vary cryogenically cooled ignition scale deuterium/helium filled plastic...
As the yield on implosion shots increases it is expected that peak x-ray emission reduces to a duration with FWHM as short 20 ps for ∼7 × 1018 neutron yield. However, temporal resolution of currently used gated imagers NIF 40–100 ps. We discuss benefits higher and present performance measurements dilation imager, which utilizes pulse-dilation technology [T. J. Hilsabeck et al., Rev. Sci. Instrum. 81, 10E317 (2010)10.1063/1.3479111] achieve imaging gate times below 10 The were conducted using...
A 5 ps gated framing camera was demonstrated using the pulse-dilation of a drifting electron signal. The is achieved by accelerating photoelectron derived information pulse with time varying potential [R. D. Prosser, J. Phys. E 9, 57 (1976)]. temporal dependence causes birth dependent axial velocity dispersion that spreads as it transits drift region. expanded then imaged conventional microchannel plate based and effective gating combined instrument reduced over alone. In region, image...
Indirect drive experiments at the National Ignition Facility are designed to achieve fusion by imploding a fuel capsule with x rays from laser-driven hohlraum. Previous have been unable determine whether deficit in measured ablator implosion velocity relative simulations is due inadequate models of hohlraum or physics. ViewFactor allow for first time direct measure x-ray point view. The show 15%--25% and thus explain nearly all disagreement data. In addition, data this open geometry provide...
The DIlation X-ray Imager (DIXI) is a new, high-speed x-ray framing camera at the National Ignition Facility (NIF) sensitive to x-rays in range of ≈2-17 keV. DIXI uses pulse-dilation technique achieve temporal resolution less than 10 ps, ≈10× improvement over conventional cameras currently employed on NIF (≈100 ps resolution), and otherwise only attainable with 1D streaked imaging. utilizes voltage ramp impart velocity gradient signal-bearing electrons. response, spatial resolution,...
We have constructed two slightly different high-speed framing cameras for use on NOVA and the OMEGA Upgrade. Both units are based gating of a microchannel plate, with one detector having pore length to diameter ratio half that other. will discuss factors limiting temporal resolution each compare results modeling gate width measurements taken using short-pulse laser. also time-resolved x-ray images recorded these devices data from an older (∼90 ps resolution) detector.
X-ray backlighting is a powerful tool for diagnosing large variety of high-density phenomena. Traditional area techniques used at Nova and Omega cannot be extended efficiently to National Ignition Facility scale. New, more efficient sources are required have begun show promising results. These include backlit-pinhole point-projection technique, pinhole slit arrays, distributed polychromatic sources, picket-fence backlighters. In parallel, there been developments in improving the data...
We describe the use of gated microchannel-plate detectors as high-speed framing cameras in laser-driven inertial-confinement-fusion experiments. Using an array pinholes to image target, capable generating up 16 individual frames with ∼90 ps resolution on a single laser shot are now routine use. The have been used study development intentionally applied perturbations targets. In off-line tests new demonstrated time resolutions better than 40 ps.
We present a new diagnostic for the National Ignition Facility (NIF) [1,2]. The Streaked Polar Instrumentation Diagnosing Energetic Radiation (SPIDER) is an x-ray streak camera use on almost-igniting targets, up to ~10<sup>17</sup> neutrons per shot. It measures burn history ignition campaigns with following requirements: X-Ray Energy 8-30keV, Temporal Resolution 10ps, Absolute Timing 30ps, Neutron Yield: 10<sup>14</sup> 10<sup>17</sup>. features of design are heavily shielded instrument...
First results from the analysis of neutron image data collected on implosions cryogenically layered deuterium-tritium capsules during 2011-2012 National Ignition Campaign are reported. The span a variety experimental designs aimed at increasing stagnation pressure central hotspot and areal density surrounding fuel assembly. Images neutrons produced by deuterium–tritium fusion reactions in presented, as well images that scatter dense compared with 1D 2D model predictions, consistency checked...
Accurately assessing and optimizing the implosion performance of inertial confinement fusion capsules is a crucial step to achieving ignition on NIF. We have applied differential filtering (matched Ross filter pairs) provide broadband time-integrated absolute x-ray self-emission images imploded core cryogenic layered implosions. This diagnostic measures temperature- density-sensitive bremsstrahlung emission provides estimates hot spot mass, mix pressure.
The National Ignition Facility has been used to compress deuterium-tritium an average areal density of ~1.0±0.1 g cm(-2), which is 67% the ignition requirement. These conditions were obtained using 192 laser beams with total energy 1-1.6 MJ and peak power up 420 TW create a hohlraum drive shaped profile, peaking at soft x-ray radiation temperature 275-300 eV. This pulse delivered series shocks that compressed capsule containing cryogenic radius 25-35 μm. Neutron images implosion estimate...
The electrical resistance measurement of metallic conducting materials can be done in situ a diamond-window, high-pressure cell with four-lead arrangement designed to avoid contact and lead-wire resistances. Variants the general method include designs for long (several cm) short (less than 1 mm) length samples material, use solid fluid pressure-transmitting media.
On the National Ignition Facility (NIF), hot electrons generated in laser heated Hohlraums are inferred from &gt;20 keV bremsstrahlung emission measured with time integrated FFLEX broadband spectrometer. New high energy (&gt;200 keV) resolved channels were added to infer &gt;170 that can cause ignition capsule preheat. First electron measurements near scaled by 96–192 NIF beams presented.
On the National Ignition Facility, hohlraum-driven implosion symmetry is tuned using cross-beam energy transfer (CBET) during peak power, which controlled by applying a wavelength separation between cones of laser beams. In this Letter, we present early-time measurements instantaneous soft x-ray drive at capsule reemission spheres, show that also leads to significant CBET first shock, even though intensities are 30× smaller than peak. We demonstrate resulting early P2/P0 asymmetry can be...
The Crystal Backlighter Imager (CBI) is a quasi-monochromatic, near-normal incidence, spherically bent crystal imager developed for the National Ignition Facility (NIF), which will allow inertial confinement fusion capsule implosions to be radiographed close stagnation. This not possible using standard pinhole-based area-backlighter configuration, as self-emission from hotspot overwhelms backlighter signal in final stages of implosion. CBI mitigates broadband hot spot by extremely narrow...
A new generation of fast-gated x-ray framing cameras have been developed that are capable capturing multiple frames along a single line-of-sight with 30 ps temporal resolution. The instruments constructed by integrating pulse-dilation electron imaging burst mode hybrid-complimentary metal-oxide-semiconductor sensors. Two such developed, characterized, and fielded at the National Ignition Facility OMEGA laser. These particularly suited for advanced applications in Inertial Confinement Fusion...
A new gated x-ray framing camera has been developed at the Lawrence Livermore National Laboratory for use Nova laser facility. This diagnostic, flexible imager, designed as a modular unit that can be rapidly reconfigured to change spectral response, magnification, sensitivity, and spatial temporal resolutions of instrument. The electrical gate pulse width may varied from 200 ps 2 ns depending upon whether experimental emphasis is on resolution or sensitivity. long integration times are...
We have performed a series of experiments on the Nova Laser Facility to examine hydrodynamic behavior directly driven planar foils with initial perturbations varying wavelength. The were accelerated single, frequency doubled, smoothed and temporally shaped laser beam at 0.8\ifmmode\times\else\texttimes\fi{}${10}^{14}$ W/${\mathrm{cm}}^{2}$. are in good agreement numerical simulations using computer codes LASNEX ORCHID which show growth rates reduced about 70% classical for this nonlinear regime.