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Jarrott LC, Bachmann B, Ma T, Benedetti LR, Field FE, Hartouni EP, Hatarik R, Izumi N, Khan SF, Landen OL, Nagel SR, Nora R, Pak A, Peterson JL, Schneider MB, Springer PT, Patel PK. Thermal Temperature Measurements of Inertial Fusion Implosions. PHYSICAL REVIEW LETTERS 2018; 121:085001. [PMID: 30192614 DOI: 10.1103/physrevlett.121.085001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 05/14/2018] [Indexed: 06/08/2023]
Abstract
Accurate measurement of the thermal temperature in inertially confined fusion plasmas is essential for characterizing ignition performance and validating the basic physics understanding of the stagnation conditions. We present experimental results from cryogenic deuterium-tritium implosions on the National Ignition Facility using a differential filter spectrometer designed to measure the thermal electron temperature from x-ray continuum emission from the stagnated plasma. Furthermore, electron temperature measurements, used in conjunction with the Doppler-broadened DT neutron spectra, allow one to infer the partition of energy in the hot spot between internal energy and unconverted kinetic energy.
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Le Pape S, Berzak Hopkins LF, Divol L, Pak A, Dewald EL, Bhandarkar S, Bennedetti LR, Bunn T, Biener J, Crippen J, Casey D, Edgell D, Fittinghoff DN, Gatu-Johnson M, Goyon C, Haan S, Hatarik R, Havre M, Ho DDM, Izumi N, Jaquez J, Khan SF, Kyrala GA, Ma T, Mackinnon AJ, MacPhee AG, MacGowan BJ, Meezan NB, Milovich J, Millot M, Michel P, Nagel SR, Nikroo A, Patel P, Ralph J, Ross JS, Rice NG, Strozzi D, Stadermann M, Volegov P, Yeamans C, Weber C, Wild C, Callahan D, Hurricane OA. Fusion Energy Output Greater than the Kinetic Energy of an Imploding Shell at the National Ignition Facility. PHYSICAL REVIEW LETTERS 2018; 120:245003. [PMID: 29956968 DOI: 10.1103/physrevlett.120.245003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 05/04/2018] [Indexed: 06/08/2023]
Abstract
A series of cryogenic, layered deuterium-tritium (DT) implosions have produced, for the first time, fusion energy output twice the peak kinetic energy of the imploding shell. These experiments at the National Ignition Facility utilized high density carbon ablators with a three-shock laser pulse (1.5 MJ in 7.5 ns) to irradiate low gas-filled (0.3 mg/cc of helium) bare depleted uranium hohlraums, resulting in a peak hohlraum radiative temperature ∼290 eV. The imploding shell, composed of the nonablated high density carbon and the DT cryogenic layer, is, thus, driven to velocity on the order of 380 km/s resulting in a peak kinetic energy of ∼21 kJ, which once stagnated produced a total DT neutron yield of 1.9×10^{16} (shot N170827) corresponding to an output fusion energy of 54 kJ. Time dependent low mode asymmetries that limited further progress of implosions have now been controlled, leading to an increased compression of the hot spot. It resulted in hot spot areal density (ρr∼0.3 g/cm^{2}) and stagnation pressure (∼360 Gbar) never before achieved in a laboratory experiment.
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Ghorbani M, Saei-Dehkordi S, Mohebbi A, Pak A. Corrigendum to “Evaluation of Some Chemical Quality Characteristics of Honey Produced in Iran” [Journal of Food Quality and Hazards Control 4 (2017) 113-118]. JOURNAL OF FOOD QUALITY AND HAZARDS CONTROL 2018. [DOI: 10.29252/jfqhc.5.1.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
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29
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Pogozhikh M, Golovko T, Pak A, Dyakov A. Study of regularities of distributing powdered dietetic additives in coarse dispersed foodstuffs. FOOD SCIENCE AND TECHNOLOGY 2017. [DOI: 10.15673/fst.v11i4.733] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An important intervention in the composition of food products is enrichment of food with micronutrients. In this regard, the authors investigated how the additive with the corresponding trace element will be distributed in the food product, and in this case, in minced meat, in order to meet the human needs for microelements.Micronutrient deficiencies have a significant impact on the nutritional status and health of the population in well developed and developing countries. These deficiencies cause a delay in the growth of children, various diseases, mortality, brain damage, reduced cognitive capacity and the ability of people of all ages. The global scale of micronutrient deficiencies in dietary intakes, in particular the lack of trace elements, has led to the development of powdered dietary supplements containing essential elements that enrich the coarse-type food products to increase their nutritional value. The dietary supplement should provide the daily requirement of trace elements in the human body; therefore, it should be added to the product in a normalized amount and evenly distributed in the product.Two nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) analysis were performed to determine the distribution of the additive in food products. The analysis was carried out in two stages respectively: study of molecules mobility by measuring the spin-spin relaxation time (Т2) and spin-lattice relaxation (Т1) on a pulsed NMR spectrometer; establishment of a connection between the exponent of the amplitude of the sample A0 and its mass. Based on the data obtained, as a result of the measurement, a curve is constructed for the dependence of the amplitude of the echo signal from the value (time interval between the probing pulses). The spin label used in this work is one of the first variants of a paramagnetic probe-an easily accessible transition metal ion Mn2+. According to the constructed graphs and tomograms from the results of the studies, it is possible to study the characteristics of this dietary supplement and the expediency of its use.
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Benedetti LR, Izumi N, Khan SF, Kyrala GA, Landen OL, Ma T, Nagel SR, Pak A. Simplified model of pinhole imaging for quantifying systematic errors in image shape. APPLIED OPTICS 2017; 56:8719-8731. [PMID: 29091687 DOI: 10.1364/ao.56.008719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 09/28/2017] [Indexed: 06/07/2023]
Abstract
We examine systematic errors in x-ray imaging by pinhole optics for quantifying uncertainties in the measurement of convergence and asymmetry in inertial confinement fusion implosions. We present a quantitative model for the total resolution of a pinhole optic with an imaging detector that more effectively describes the effect of diffraction than models that treat geometry and diffraction as independent. This model can be used to predict loss of shape detail due to imaging across the transition from geometric to diffractive optics. We find that fractional error in observable shapes is proportional to the total resolution element we present and inversely proportional to the length scale of the asymmetry being observed. We have experimentally validated our results by imaging a single object with differently sized pinholes and with different magnifications.
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Karl K, Borkon A, Aggarwal S, Allen K, Davis R, Pak A, Thompson E, Wang J, Kao A, Magalski A, Lawhorn S, Khumari T, Austin B. Strategies to Reduce Tricuspid Regurgitation After Heart Transplant. J Heart Lung Transplant 2017. [DOI: 10.1016/j.healun.2017.01.408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Magalski A, Beauchamp S, Borkon A, Kao A, Aggarwal S, Pak A, Wang J, Allen K. Challenges of Heart Transplant in Patients with L-Transposition of the Great Vessels. J Heart Lung Transplant 2017. [DOI: 10.1016/j.healun.2017.01.727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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33
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Beauchamp S, Borkon A, Karl K, Aggarwal S, Kao A, Magalski A, Allen K, Austin B, Khumari T, Lawhorn S, Long N, Wang J, Davis R, Thompson E, Pak A. Cocaine Use Does Not Contribute to Accelerated CAD as Determined by Angiography or IVUS. J Heart Lung Transplant 2017. [DOI: 10.1016/j.healun.2017.01.1462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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34
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Albert F, Lemos N, Shaw JL, Pollock BB, Goyon C, Schumaker W, Saunders AM, Marsh KA, Pak A, Ralph JE, Martins JL, Amorim LD, Falcone RW, Glenzer SH, Moody JD, Joshi C. Observation of Betatron X-Ray Radiation in a Self-Modulated Laser Wakefield Accelerator Driven with Picosecond Laser Pulses. PHYSICAL REVIEW LETTERS 2017; 118:134801. [PMID: 28409970 DOI: 10.1103/physrevlett.118.134801] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Indexed: 06/07/2023]
Abstract
We investigate a new regime for betatron x-ray emission that utilizes kilojoule-class picosecond lasers to drive wakes in plasmas. When such laser pulses with intensities of ∼5×10^{18} W/cm^{2} are focused into plasmas with electron densities of ∼1×10^{19} cm^{-3}, they undergo self-modulation and channeling, which accelerates electrons up to 200 MeV energies and causes those electrons to emit x rays. The measured x-ray spectra are fit with a synchrotron spectrum with a critical energy of 10-20 keV, and 2D particle-in-cell simulations were used to model the acceleration and radiation of the electrons in our experimental conditions.
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Jarrott LC, Benedetti LR, Chen H, Izumi N, Khan SF, Ma T, Nagel SR, Landen OL, Pak A, Patel PK, Schneider M, Scott HA. Hotspot electron temperature from x-ray continuum measurements on the NIF. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11E534. [PMID: 27910566 DOI: 10.1063/1.4961074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report on measurements of the electron temperature in the hotspot of inertially confined, layered, spherical implosions on the National Ignition Facility using a differential filtering diagnostic. Measurements of the DT and DD ion temperatures using neutron time-of-flight detectors are complicated by the contribution of hot spot motion to the peak width, which produce an apparent temperature higher than the thermal temperature. The electron temperature is not sensitive to this non-thermal velocity and is thus a valuable input to interpreting the stagnated hot spot conditions. Here we show that the current differential filtering diagnostic provides insufficient temperature resolution for the hot spot temperatures of interest. We then propose a new differential filter configuration utilizing larger pinhole size to increase spectral fluence, as well as thicker filtration. This new configuration will improve measurement uncertainty by more than a factor of three, allowing for a more accurate hotspot temperature.
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Nagel SR, Benedetti LR, Bradley DK, Hilsabeck TJ, Izumi N, Khan S, Kyrala GA, Ma T, Pak A. Comparison of implosion core metrics: A 10 ps dilation X-ray imager vs a 100 ps gated microchannel plate. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11E311. [PMID: 27910406 DOI: 10.1063/1.4959917] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The dilation x-ray imager (DIXI) [T. J. Hilsabeck et al., Rev. Sci. Instrum. 81, 10E317 (2010); S. R. Nagel et al., ibid. 83, 10E116 (2012); S. R. Nagel et al., ibid. 85, 11E504 (2014)] is a high-speed x-ray framing camera that uses the pulse-dilation technique to achieve a temporal resolution of less than 10 ps. This is a 10 × improvement over conventional framing cameras currently employed on the National Ignition Facility (NIF) (100 ps resolution), and otherwise only achievable with 1D streaked imaging. A side effect of the dramatically reduced gate width is the comparatively lower detected signal level. Therefore we implement a Poisson noise reduction with non-local principal component analysis method [J. Salmon et al., J. Math. Imaging Vision 48, 279294 (2014)] to improve the robustness of the DIXI data analysis. Here we present results on ignition-relevant experiments at the NIF using DIXI. In particular we focus on establishing that/when DIXI gives reliable shape metrics (P0, P2, and P4 Legendre modes, and their temporal evolution/swings).
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Khan SF, Izumi N, Glenn S, Tommasini R, Benedetti LR, Ma T, Pak A, Kyrala GA, Springer P, Bradley DK, Town RPJ. Automated analysis of hot spot X-ray images at the National Ignition Facility. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11E334. [PMID: 27910429 DOI: 10.1063/1.4962184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
At the National Ignition Facility, the symmetry of the hot spot of imploding capsules is diagnosed by imaging the emitted x-rays using gated cameras and image plates. The symmetry of an implosion is an important factor in the yield generated from the resulting fusion process. The x-ray images are analyzed by decomposing the image intensity contours into Fourier and Legendre modes. This paper focuses on the additional protocols for the time-integrated shape analysis from image plates. For implosions with temperatures above ∼4 keV, the hard x-ray background can be utilized to infer the temperature of the hot spot.
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Ma T, Chen H, Patel PK, Schneider MB, Barrios MA, Casey DT, Chung HK, Hammel BA, Berzak Hopkins LF, Jarrott LC, Khan SF, Lahmann B, Nora R, Rosenberg MJ, Pak A, Regan SP, Scott HA, Sio H, Spears BK, Weber CR. Development of a krypton-doped gas symmetry capsule platform for x-ray spectroscopy of implosion cores on the NIF. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11E327. [PMID: 27910341 DOI: 10.1063/1.4960753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The electron temperature at stagnation of an ICF implosion can be measured from the emission spectrum of high-energy x-rays that pass through the cold material surrounding the hot stagnating core. Here we describe a platform developed on the National Ignition Facility where trace levels of a mid-Z dopant (krypton) are added to the fuel gas of a symcap (symmetry surrogate) implosion to allow for the use of x-ray spectroscopy of the krypton line emission.
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Gauthier M, Kim JB, Curry CB, Aurand B, Gamboa EJ, Göde S, Goyon C, Hazi A, Kerr S, Pak A, Propp A, Ramakrishna B, Ruby J, Willi O, Williams GJ, Rödel C, Glenzer SH. High-intensity laser-accelerated ion beam produced from cryogenic micro-jet target. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11D827. [PMID: 27910336 DOI: 10.1063/1.4961270] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report on the successful operation of a newly developed cryogenic jet target at high intensity laser-irradiation. Using the frequency-doubled Titan short pulse laser system at Jupiter Laser Facility, Lawrence Livermore National Laboratory, we demonstrate the generation of a pure proton beam a with maximum energy of 2 MeV. Furthermore, we record a quasi-monoenergetic peak at 1.1 MeV in the proton spectrum emitted in the laser forward direction suggesting an alternative acceleration mechanism. Using a solid-density mixed hydrogen-deuterium target, we are also able to produce pure proton-deuteron ion beams. With its high purity, limited size, near-critical density, and high-repetition rate capability, this target is promising for future applications.
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Eder D, Spears B, Casey D, Pak A, Ma T, Izumi N, Pollock B, Weber C, Kritcher A, Jones O, Milovich J, Town R, Robey H, Hinkel D, Callahan D, Hatchett S, Knauer J, Yeamans C, Bleuel D, Nagel S, Hatarik R, Khan S, Sayre D, Caggiano J, Grim G, Eckart M, Fittinghoff D, Merrill F, Bradley D. Simulations of symcap and layered NIF experiments with top/bottom laser asymmetry to impose P1 drive on capsules. ACTA ACUST UNITED AC 2016. [DOI: 10.1088/1742-6596/717/1/012014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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41
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Davis P, Döppner T, Rygg JR, Fortmann C, Divol L, Pak A, Fletcher L, Becker A, Holst B, Sperling P, Redmer R, Desjarlais MP, Celliers P, Collins GW, Landen OL, Falcone RW, Glenzer SH. X-ray scattering measurements of dissociation-induced metallization of dynamically compressed deuterium. Nat Commun 2016; 7:11189. [PMID: 27079420 PMCID: PMC4835540 DOI: 10.1038/ncomms11189] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 03/01/2016] [Indexed: 11/22/2022] Open
Abstract
Hydrogen, the simplest element in the universe, has a surprisingly complex phase diagram. Because of applications to planetary science, inertial confinement fusion and fundamental physics, its high-pressure properties have been the subject of intense study over the past two decades. While sophisticated static experiments have probed hydrogen's structure at ever higher pressures, studies examining the higher-temperature regime using dynamic compression have mostly been limited to optical measurement techniques. Here we present spectrally resolved x-ray scattering measurements from plasmons in dynamically compressed deuterium. Combined with Compton scattering, and velocity interferometry to determine shock pressure and mass density, this allows us to extract ionization state as a function of compression. The onset of ionization occurs close in pressure to where density functional theory-molecular dynamics (DFT-MD) simulations show molecular dissociation, suggesting hydrogen transitions from a molecular and insulating fluid to a conducting state without passing through an intermediate atomic phase.
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Borkon M, Aggarwal S, Dryton G, Kao A, Allen K, Davis R, Pak A, Thompson E, Magalski A, Austin B, Khumari T, Lawhorne S, Gosch K. Tricuspid Annuloplasty Definitely Improves Patient Outcomes in the First Year After Heart Transplantation. J Heart Lung Transplant 2016. [DOI: 10.1016/j.healun.2016.01.571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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43
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Dewald EL, Tommasini R, Mackinnon A, MacPhee A, Meezan N, Olson R, Hicks D, LePape S, Izumi N, Fournier K, Barrios MA, Ross S, Pak A, Döppner T, Kalantar D, Opachich K, Rygg R, Bradley D, Bell P, Hamza A, Dzenitis B, Landen OL, MacGowan B, LaFortune K, Widmayer C, Van Wonterghem B, Kilkenny J, Edwards MJ, Atherton J, Moses EI. Capsule Ablator Inflight Performance Measurements Via Streaked Radiography Of ICF Implosions On The NIF*. ACTA ACUST UNITED AC 2016. [DOI: 10.1088/1742-6596/688/1/012014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Dewald EL, Hartemann F, Michel P, Milovich J, Hohenberger M, Pak A, Landen OL, Divol L, Robey HF, Hurricane OA, Döppner T, Albert F, Bachmann B, Meezan NB, MacKinnon AJ, Callahan D, Edwards MJ. Generation and Beaming of Early Hot Electrons onto the Capsule in Laser-Driven Ignition Hohlraums. PHYSICAL REVIEW LETTERS 2016; 116:075003. [PMID: 26943541 DOI: 10.1103/physrevlett.116.075003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Indexed: 06/05/2023]
Abstract
In hohlraums for inertial confinement fusion (ICF) implosions on the National Ignition Facility, suprathermal hot electrons, generated by laser plasma instabilities early in the laser pulse ("picket") while blowing down the laser entrance hole (LEH) windows, can preheat the capsule fuel. Hard x-ray imaging of a Bi capsule surrogate and of the hohlraum emissions, in conjunction with the measurement of time-resolved bremsstrahlung spectra, allows us to uncover for the first time the directionality of these hot electrons and infer the capsule preheat. Data and Monte Carlo calculations indicate that for most experiments the hot electrons are emitted nearly isotropically from the LEH. However, we have found cases where a significant fraction of the generated electrons are emitted in a collimated beam directly towards the capsule poles, where their local energy deposition is up to 10× higher than the average preheat value and acceptable levels for ICF implosions. The observed "beaming" is consistent with a recently unveiled multibeam stimulated Raman scattering model [P. Michel et al., Phys. Rev. Lett. 115, 055003 (2015)], where laser beams in a cone drive a common plasma wave on axis. Finally, we demonstrate that we can control the amount of generated hot electrons by changing the laser pulse shape and hohlraum plasma.
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Casey DT, Milovich JL, Smalyuk VA, Clark DS, Robey HF, Pak A, MacPhee AG, Baker KL, Weber CR, Ma T, Park HS, Döppner T, Callahan DA, Haan SW, Patel PK, Peterson JL, Hoover D, Nikroo A, Yeamans CB, Merrill FE, Volegov PL, Fittinghoff DN, Grim GP, Edwards MJ, Landen OL, Lafortune KN, MacGowan BJ, Widmayer CC, Sayre DB, Hatarik R, Bond EJ, Nagel SR, Benedetti LR, Izumi N, Khan S, Bachmann B, Spears BK, Cerjan CJ, Gatu Johnson M, Frenje JA. Improved Performance of High Areal Density Indirect Drive Implosions at the National Ignition Facility using a Four-Shock Adiabat Shaped Drive. PHYSICAL REVIEW LETTERS 2015; 115:105001. [PMID: 26382681 DOI: 10.1103/physrevlett.115.105001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Indexed: 06/05/2023]
Abstract
Hydrodynamic instabilities can cause capsule defects and other perturbations to grow and degrade implosion performance in ignition experiments at the National Ignition Facility (NIF). Here, we show the first experimental demonstration that a strong unsupported first shock in indirect drive implosions at the NIF reduces ablation front instability growth leading to a 3 to 10 times higher yield with fuel ρR>1 g/cm(2). This work shows the importance of ablation front instability growth during the National Ignition Campaign and may provide a path to improved performance at the high compression necessary for ignition.
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Döppner T, Callahan DA, Hurricane OA, Hinkel DE, Ma T, Park HS, Berzak Hopkins LF, Casey DT, Celliers P, Dewald EL, Dittrich TR, Haan SW, Kritcher AL, MacPhee A, Le Pape S, Pak A, Patel PK, Springer PT, Salmonson JD, Tommasini R, Benedetti LR, Bond E, Bradley DK, Caggiano J, Church J, Dixit S, Edgell D, Edwards MJ, Fittinghoff DN, Frenje J, Gatu Johnson M, Grim G, Hatarik R, Havre M, Herrmann H, Izumi N, Khan SF, Kline JL, Knauer J, Kyrala GA, Landen OL, Merrill FE, Moody J, Moore AS, Nikroo A, Ralph JE, Remington BA, Robey HF, Sayre D, Schneider M, Streckert H, Town R, Turnbull D, Volegov PL, Wan A, Widmann K, Wilde CH, Yeamans C. Demonstration of High Performance in Layered Deuterium-Tritium Capsule Implosions in Uranium Hohlraums at the National Ignition Facility. PHYSICAL REVIEW LETTERS 2015; 115:055001. [PMID: 26274424 DOI: 10.1103/physrevlett.115.055001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Indexed: 06/04/2023]
Abstract
We report on the first layered deuterium-tritium (DT) capsule implosions indirectly driven by a "high-foot" laser pulse that were fielded in depleted uranium hohlraums at the National Ignition Facility. Recently, high-foot implosions have demonstrated improved resistance to ablation-front Rayleigh-Taylor instability induced mixing of ablator material into the DT hot spot [Hurricane et al., Nature (London) 506, 343 (2014)]. Uranium hohlraums provide a higher albedo and thus an increased drive equivalent to an additional 25 TW laser power at the peak of the drive compared to standard gold hohlraums leading to higher implosion velocity. Additionally, we observe an improved hot-spot shape closer to round which indicates enhanced drive from the waist. In contrast to findings in the National Ignition Campaign, now all of our highest performing experiments have been done in uranium hohlraums and achieved total yields approaching 10^{16} neutrons where more than 50% of the yield was due to additional heating of alpha particles stopping in the DT fuel.
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Pollock BB, Tsung FS, Albert F, Shaw JL, Clayton CE, Davidson A, Lemos N, Marsh KA, Pak A, Ralph JE, Mori WB, Joshi C. Formation of Ultrarelativistic Electron Rings from a Laser-Wakefield Accelerator. PHYSICAL REVIEW LETTERS 2015; 115:055004. [PMID: 26274427 DOI: 10.1103/physrevlett.115.055004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Indexed: 06/04/2023]
Abstract
Ultrarelativistic-energy electron ring structures have been observed from laser-wakefield acceleration experiments in the blowout regime. These electron rings had 170-280 MeV energies with 5%-25% energy spread and ∼10 pC of charge and were observed over a range of plasma densities and compositions. Three-dimensional particle-in-cell simulations show that laser intensity enhancement in the wake leads to sheath splitting and the formation of a hollow toroidal pocket in the electron density around the wake behind the first wake period. If the laser propagates over a distance greater than the ideal dephasing length, some of the dephasing electrons in the second period can become trapped within the pocket and form an ultrarelativistic electron ring that propagates in free space over a meter-scale distance upon exiting the plasma. Such a structure acts as a relativistic potential well, which has applications for accelerating positively charged particles such as positrons.
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Naji DI, Pak A, Lawless J, Main ML. Rapid progression of Staphylococcus lugdunensis mechanical prosthetic valve endocarditis. Echo Res Pract 2015; 2:I11-I12. [PMID: 26693342 PMCID: PMC4676448 DOI: 10.1530/erp-15-0017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 06/04/2015] [Indexed: 11/10/2022] Open
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Berzak Hopkins LF, Meezan NB, Le Pape S, Divol L, Mackinnon AJ, Ho DD, Hohenberger M, Jones OS, Kyrala G, Milovich JL, Pak A, Ralph JE, Ross JS, Benedetti LR, Biener J, Bionta R, Bond E, Bradley D, Caggiano J, Callahan D, Cerjan C, Church J, Clark D, Döppner T, Dylla-Spears R, Eckart M, Edgell D, Field J, Fittinghoff DN, Gatu Johnson M, Grim G, Guler N, Haan S, Hamza A, Hartouni EP, Hatarik R, Herrmann HW, Hinkel D, Hoover D, Huang H, Izumi N, Khan S, Kozioziemski B, Kroll J, Ma T, MacPhee A, McNaney J, Merrill F, Moody J, Nikroo A, Patel P, Robey HF, Rygg JR, Sater J, Sayre D, Schneider M, Sepke S, Stadermann M, Stoeffl W, Thomas C, Town RPJ, Volegov PL, Wild C, Wilde C, Woerner E, Yeamans C, Yoxall B, Kilkenny J, Landen OL, Hsing W, Edwards MJ. First high-convergence cryogenic implosion in a near-vacuum hohlraum. PHYSICAL REVIEW LETTERS 2015; 114:175001. [PMID: 25978240 DOI: 10.1103/physrevlett.114.175001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Indexed: 06/04/2023]
Abstract
Recent experiments on the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] demonstrate that utilizing a near-vacuum hohlraum (low pressure gas-filled) is a viable option for high convergence cryogenic deuterium-tritium (DT) layered capsule implosions. This is made possible by using a dense ablator (high-density carbon), which shortens the drive duration needed to achieve high convergence: a measured 40% higher hohlraum efficiency than typical gas-filled hohlraums, which requires less laser energy going into the hohlraum, and an observed better symmetry control than anticipated by standard hydrodynamics simulations. The first series of near-vacuum hohlraum experiments culminated in a 6.8 ns, 1.2 MJ laser pulse driving a 2-shock, high adiabat (α∼3.5) cryogenic DT layered high density carbon capsule. This resulted in one of the best performances so far on the NIF relative to laser energy, with a measured primary neutron yield of 1.8×10(15) neutrons, with 20% calculated alpha heating at convergence ∼27×.
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Ma T, Hurricane OA, Callahan DA, Barrios MA, Casey DT, Dewald EL, Dittrich TR, Döppner T, Haan SW, Hinkel DE, Berzak Hopkins LF, Le Pape S, MacPhee AG, Pak A, Park HS, Patel PK, Remington BA, Robey HF, Salmonson JD, Springer PT, Tommasini R, Benedetti LR, Bionta R, Bond E, Bradley DK, Caggiano J, Celliers P, Cerjan CJ, Church JA, Dixit S, Dylla-Spears R, Edgell D, Edwards MJ, Field J, Fittinghoff DN, Frenje JA, Gatu Johnson M, Grim G, Guler N, Hatarik R, Herrmann HW, Hsing WW, Izumi N, Jones OS, Khan SF, Kilkenny JD, Knauer J, Kohut T, Kozioziemski B, Kritcher A, Kyrala G, Landen OL, MacGowan BJ, Mackinnon AJ, Meezan NB, Merrill FE, Moody JD, Nagel SR, Nikroo A, Parham T, Ralph JE, Rosen MD, Rygg JR, Sater J, Sayre D, Schneider MB, Shaughnessy D, Spears BK, Town RPJ, Volegov PL, Wan A, Widmann K, Wilde CH, Yeamans C. Thin shell, high velocity inertial confinement fusion implosions on the national ignition facility. PHYSICAL REVIEW LETTERS 2015; 114:145004. [PMID: 25910132 DOI: 10.1103/physrevlett.114.145004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Indexed: 06/04/2023]
Abstract
Experiments have recently been conducted at the National Ignition Facility utilizing inertial confinement fusion capsule ablators that are 175 and 165 μm in thickness, 10% and 15% thinner, respectively, than the nominal thickness capsule used throughout the high foot and most of the National Ignition Campaign. These three-shock, high-adiabat, high-foot implosions have demonstrated good performance, with higher velocity and better symmetry control at lower laser powers and energies than their nominal thickness ablator counterparts. Little to no hydrodynamic mix into the DT hot spot has been observed despite the higher velocities and reduced depth for possible instability feedthrough. Early results have shown good repeatability, with up to 1/2 the neutron yield coming from α-particle self-heating.
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