High-Energy, Short-Pulse Fiber Injection Lasers at Lawrence Livermore National Laboratory

AbstractLaser-plasma accelerators (LPAs) driven by picosecond-scale, kilojoule-class lasers can generate particle beams and x-ray sources that could be utilized in experiments driven by multi-kilojoule, high-energy-density science (HEDS) drivers such as the OMEGA laser at the Laboratory for Laser Energetics (LLE) or the National Ignition Facility at Lawrence Livermore National Laboratory. This paper reports on the development of the first LPA driven by a short-pulse, kilojoule-class laser (OMEGA EP) connected to a multi-kilojoule HEDS driver (OMEGA). In experiments, electron beams were produced with electron energies greater than 200 MeV, divergences as low as 32 mrad, charge greater than 700 nC, and conversion efficiencies from laser energy to electron energy up to 11%. The electron beam charge scales with both the normalized vector potential and plasma density. These electron beams show promise as a method to generate MeV-class radiography sources and improved-flux broadband x-ray sources at HEDS drivers.

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The implementation and data analysis of an interferometer for intense short pulse laser experiments

High Power Laser Science and Engineering ◽

10.1017/hpl.2016.21 ◽

2016 ◽

Vol 4 ◽

Cited By ~ 6

Author(s):

Jaebum Park ◽

Hector A. Baldis ◽

Hui Chen

Keyword(s):

Data Analysis ◽

Short Pulse ◽

Lawrence Livermore National Laboratory ◽

National Laboratory ◽

Optical Probe ◽

Fringe Analysis ◽

Energetic Electrons ◽

Short Pulse Laser ◽

Laser Facility ◽

Laser Experiments

We present an interferometry setup and the detailed fringe analysis method for intense short pulse (SP) laser experiments. The interferometry scheme was refined through multiple campaigns to investigate the effects of pre-plasmas on energetic electrons at the Jupiter Laser Facility at Lawrence Livermore National Laboratory. The interferometer used a frequency doubled ( $\unicode[STIX]{x1D706}=0.527~\unicode[STIX]{x03BC}\text{m}$ ) 0.5 ps long optical probe beam to measure the pre-plasma density, an invaluable parameter to better understand how varying pre-plasma conditions affect the characteristics of the energetic electrons. The hardware of the diagnostic, data analysis and example data are presented. The diagnostic setup and the analysis procedure can be employed for any other SP laser experiments and interferograms, respectively.

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The importance of EBIT data for Z-pinch plasma diagnostics

Canadian Journal of Physics ◽

10.1139/p07-170 ◽

2008 ◽

Vol 86 (1) ◽

pp. 267-276 ◽

Cited By ~ 26

Author(s):

A S Safronova ◽

V L Kantsyrev ◽

P Neill ◽

U I Safronova ◽

D A Fedin ◽

...

Keyword(s):

Electron Beam ◽

Lawrence Livermore National Laboratory ◽

National Laboratory ◽

Theoretical Models ◽

High Energy ◽

High Energy Density ◽

Strong Electron ◽

Model Calculations ◽

X Ray ◽

Z Pinch

The results from the last six years of X-ray spectroscopy and spectropolarimetry of high-energy density Z-pinch plasmas complemented by experiments with the electron beam ion trap (EBIT) at the Lawrence Livermore National Laboratory (LLNL) are presented. The two topics discussed are the development of M-shell X-ray W spectroscopic diagnostics and K-shell Ti spectropolarimetry of Z-pinch plasmas. The main focus is on radiation from a specific load configuration called an “X-pinch”. In this work the study of X-pinches with tungsten wires combined with wires from other, lower Z materials is reported. Utilizing data produced with the LLNL EBIT at different energies of the electron beam the theoretical prediction of line positions and intensity of M-shell W spectra were tested and calibrated. Polarization-sensitive X-pinch experiments at the University of Nevada, Reno (UNR) provide experimental evidence for the existence of strong electron beams in Ti and Mo X-pinch plasmas and motivate the development of X-ray spectropolarimetry of Z-pinch plasmas. This diagnostic is based on the measurement of spectra recorded simultaneously by two spectrometers with different sensitivity to the linear polarization of the observed lines and compared with theoretical models of polarization-dependent spectra. Polarization-dependent K-shell spectra from Ti X-pinches are presented and compared with model calculations and with spectra generated by a quasi-Maxwellian electron beam at the LLNL EBIT-II electron beam ion trap.PACS Nos.: 32.30.Rj, 52.58.Lq, 52.70.La

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Rayleigh–Taylor instabilities in high-energy density settings on the National Ignition Facility

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1717236115 ◽

2018 ◽

Vol 116 (37) ◽

pp. 18233-18238 ◽

Cited By ~ 17

Author(s):

Bruce A. Remington ◽

Hye-Sook Park ◽

Daniel T. Casey ◽

Robert M. Cavallo ◽

Daniel S. Clark ◽

...

Keyword(s):

Energy Density ◽

Inertial Confinement Fusion ◽

Spatial Scales ◽

Lawrence Livermore National Laboratory ◽

National Laboratory ◽

High Energy ◽

High Energy Density ◽

Material Strength ◽

National Ignition Facility ◽

Rt Instability

The Rayleigh–Taylor (RT) instability occurs at an interface between two fluids of differing density during an acceleration. These instabilities can occur in very diverse settings, from inertial confinement fusion (ICF) implosions over spatial scales of∼10−3−10−1cm (10–1,000 μm) to supernova explosions at spatial scales of∼1012cm and larger. We describe experiments and techniques for reducing (“stabilizing”) RT growth in high-energy density (HED) settings on the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. Three unique regimes of stabilization are described: (i) at an ablation front, (ii) behind a radiative shock, and (iii) due to material strength. For comparison, we also show results from nonstabilized “classical” RT instability evolution in HED regimes on the NIF. Examples from experiments on the NIF in each regime are given. These phenomena also occur in several astrophysical scenarios and planetary science [Drake R (2005)Plasma Phys Controlled Fusion47:B419–B440; Dahl TW, Stevenson DJ (2010)Earth Planet Sci Lett295:177–186].

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K-shell spectroscopy of Au plasma generated with a short-pulse laser1This article is part of a Special Issue on the 10th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas.

Canadian Journal of Physics ◽

10.1139/p11-034 ◽

2011 ◽

Vol 89 (5) ◽

pp. 647-651 ◽

Cited By ~ 4

Author(s):

C. Zulick ◽

F. Dollar ◽

H. Chen ◽

K. Falk ◽

G. Gregori ◽

...

Keyword(s):

Short Pulse ◽

Lawrence Livermore National Laboratory ◽

National Laboratory ◽

Laser System ◽

Oscillator Strengths ◽

X Rays ◽

Plasma Diagnostic ◽

International Colloquium ◽

X Ray ◽

Population Distributions

The production of X-rays from electron transitions into K-shell vacancies (Kα,β) emission) is a well-known process in atomic physics and has been extensively studied as a plasma diagnostic in low- and mid-Z materials. However, X-ray spectra from near neutral high-Z ions are very complex, and their interpretation requires the use of state-of-the-art atomic calculations. In this experiment, the Titan laser system at Lawrence Livermore National Laboratory was used to deliver an approximately 350 J laser pulse, with a 10 ps duration and a wavelength of 1054 nm, to a gold (Au) target. A transparent bent quartz crystal spectrometer with a hard X-ray energy window, ranging from 17 to 102 keV, was used to measure the emission spectrum. Kα1,α2 and Kβ1,γ1 transitions were observed over a range of target sizes. Additionally, a series of shots were conducted with a pre-ionizing long pulse (3 ns, 1–10 J, 527 nm) on the backside of the target. FLYCHK, an atomic non-LTE code, designed to provide ionization and population distributions, was used to model the experiment. Kα/Kβ ratios were found to be in good agreement with the predicted value for room temperature Au targets.

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Laser-driven ion accelerators: Spectral control, monoenergetic ions and new acceleration mechanisms

Laser and Particle Beams ◽

10.1017/s0263034607070012 ◽

2007 ◽

Vol 25 (1) ◽

pp. 3-8 ◽

Cited By ~ 71

Author(s):

K. FLIPPO ◽

B.M. HEGELICH ◽

B.J. ALBRIGHT ◽

L. YIN ◽

D.C. GAUTIER ◽

...

Keyword(s):

Short Pulse ◽

National Laboratory ◽

Tumor Therapy ◽

Target Surface ◽

Heavy Ion ◽

High Energy ◽

Ion Beams ◽

Acceleration Process ◽

Monitoring And Control ◽

Light Ions

Los Alamos National Laboratory short pulse experiments have shown using various target cleaning techniques such that heavy ion beams of different charge states can be produced. Furthermore, by controlling the thickness of light ions on the rear of the target, monoenergetic ion pulses can be generated. The spectral shape of the accelerated particles can be controlled to yield a range of distributions, from Maxwellian to ones possessing a monoenergetic peak at high energy. The key lies in understanding and utilizing target surface chemistry. Careful monitoring and control of the surface properties and induction of reactions at different temperatures allows well defined source layers to be formed, which in turn lead to the desired energy spectra in the acceleration process. Theoretical considerations provide understanding of the process of monoenergetic ion production. In addition, numerical modeling has identified a new acceleration mechanism, the laser break-out afterburner that could potentially boost particle energies by up to two orders of magnitude for the same laser parameters. This mechanism may enable application of laser-accelerated ion beams to venues such as compact accelerators, tumor therapy, and ion fast ignition.

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High energy laser facilities at Lawrence Livermore National Laboratory

10.1063/1.33264 ◽

1982 ◽

Author(s):

N. C. Holmes

Keyword(s):

Lawrence Livermore National Laboratory ◽

National Laboratory ◽

High Energy ◽

Energy Laser ◽

High Energy Laser

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Time of flight measurements of ion energies produced by 140 fS laser pulses at the Lawrence Livermore National Laboratory ultra short-pulse laser

10.1063/1.46876 ◽

1994 ◽

Cited By ~ 1

Author(s):

G. Guethlein ◽

D. Price ◽

J. Swenson ◽

M. Glinsky ◽

R. Shepherd ◽

...

Keyword(s):

Short Pulse ◽

Lawrence Livermore National Laboratory ◽

National Laboratory ◽

Laser Pulses ◽

Short Pulse Laser ◽

Ion Energies ◽

Fs Laser ◽

Ultra Short Pulse ◽

Flight Measurements ◽

Ultra Short Pulse Laser

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Characterization of short-pulse laser-produced plasmas at the Lawrence Livermore National Laboratory ultrashort-pulse laser

10.1117/12.147569 ◽

1993 ◽

Author(s):

Ronnie L. Shepherd ◽

Dwight F. Price ◽

William E. White ◽

Albert L. Osterheld ◽

Rosemary S. Walling ◽

...

Keyword(s):

Pulse Laser ◽

Ultrashort Pulse ◽

Short Pulse ◽

Lawrence Livermore National Laboratory ◽

National Laboratory ◽

Ultrashort Pulse Laser ◽

Short Pulse Laser

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Damage Mechanisms in Optical Materials For High-Power, Short-Wavelength Laser Systems

MRS Bulletin ◽

10.1557/s088376940005483x ◽

1986 ◽

Vol 11 (3) ◽

pp. 46-47

Author(s):

Richard F. Haglund

Keyword(s):

High Power ◽

Short Wavelength ◽

Optical Materials ◽

Short Pulse ◽

National Laboratory ◽

Average Power ◽

High Energy ◽

Excimer Lasers ◽

Large Space ◽

Active Volume

Damage to optical materials under intense photon irradiation has always been a major problem in the design and operation of high-energy and high-average-power lasers. In short-wavelength lasers, operating at visible and ultraviolet wavelengths, the problem appears to be especially acute; presently attainable damage thresholds seriously compromise the engineering design of laser windows and mirrors, pulsed power trains and oscillator-amplifier systems architecture. Given the present interest in ultraviolet excimer lasers and in short-pulse, high-power free-electron lasers operating at visible and shorter wavelengths, the “optical damage problem” poses a scientific and technological challenge of significantdimensions. The solution of this problem even has significant implications outside the realm of lasers, for example, in large space-borne systems (such as the Hubble Telescope) exposed to intense ultraviolet radiation.The dimensions of the problem are illustrated by the Large-Aperture krypton-fluoride laser amplifier Module (LAM) shown schematically in Figure 1. This device, now operating at the Los Alamos National Laboratory, is typical of current and planned large excimer lasers for fusion applications. The LAM has an active volume of some 2 m3, and optical surfaces (resonator mirror and windows) exceeding 1 m2 in size; the fabrication of these optical elements was the most expensive and time-consuming single item in the construction of the laser. During laser operation, a population inversion in an Ar-Kr-F2 mix ture is created through electron-beam excitation of the laser gas by two 400 kA beams of 650 keV electrons from a cold cathode discharge. The electron trajectories in the gas are constrained by a 4 kG magnetic field transverse to the optical axis produced by a pair of large Helmholtzcoils.

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