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Title: High-{rho}R Implosions for Fast-Ignition Fuel Assembly

Abstract

Thick, 40 {mu}m plastic shells filled with 25-35 atm of D{sub 2} or D{sup 3}He were imploded on a low-adiabat ({alpha}{approx_equal}1.3) and with a low-implosion velocity ({approx}2x10{sup 7} cm/s) on the OMEGA laser to generate massive cores of compressed plasma with high areal densities optimal for fast ignition. The targets are driven by 20-kJ relaxation adiabat-shaping laser pulses to keep the inner portion of the shell nearly Fermi degenerate. The measured kinetic energy downshift of proton spectra is in good agreement with the theoretical predictions yielding burn-averaged areal densities of 0.130{+-}0.017 g/cm{sup 2} and peak {rho}R during the burn of about 0.24{+-}0.018 g/cm{sup 2}, the largest {rho}R measured on OMEGA to date. The same implosions with empty plastic shells are expected to reach 1.3 g/cm{sup 2} across the core (i.e., 2{rho}R) enough to stop fast electrons with energies up to 4.5 MeV typical of fast ignition scenarios.

Authors:
; ;  [1];  [2]; ; ; ; ; ; ;  [1];  [3]; ; ; ;  [4]
  1. Fusion Science Center and Laboratory for Laser Energetics, University of Rochester, New York 14623 (United States)
  2. (United States)
  3. NRCN, Negev and Ben Gurion University of the Negev, Beer-Sheva 84015 (Israel)
  4. MIT Plasma Science and Fusion Center and Fusion Science Center, Cambridge Massachusetts, 02139 (United States)
Publication Date:
OSTI Identifier:
20861603
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 98; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevLett.98.025004; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DEUTERIUM; ELECTRONS; FUEL ASSEMBLIES; HELIUM 3; IGNITION; IMPLOSIONS; KINETIC ENERGY; LASERS; MEV RANGE 01-10; PLASMA; PROTON SPECTRA; PULSES; RELAXATION; VELOCITY

Citation Formats

Zhou, C. D., Betti, R., Meyerhofer, D. D., Dept. of Mechanical Eng. and Physics and Astronomy, University of Rochester, Rochester, New York 14627, Theobald, W., Radha, P. B., Smalyuk, V. A., Glebov, V. Yu., Stoeckl, C., Anderson, K. S., Sangster, T. C., Shvarts, D., Li, C. K., Petrasso, R. D., Frenje, J. A., and Seguin, F. H. High-{rho}R Implosions for Fast-Ignition Fuel Assembly. United States: N. p., 2007. Web. doi:10.1103/PHYSREVLETT.98.025004.
Zhou, C. D., Betti, R., Meyerhofer, D. D., Dept. of Mechanical Eng. and Physics and Astronomy, University of Rochester, Rochester, New York 14627, Theobald, W., Radha, P. B., Smalyuk, V. A., Glebov, V. Yu., Stoeckl, C., Anderson, K. S., Sangster, T. C., Shvarts, D., Li, C. K., Petrasso, R. D., Frenje, J. A., & Seguin, F. H. High-{rho}R Implosions for Fast-Ignition Fuel Assembly. United States. doi:10.1103/PHYSREVLETT.98.025004.
Zhou, C. D., Betti, R., Meyerhofer, D. D., Dept. of Mechanical Eng. and Physics and Astronomy, University of Rochester, Rochester, New York 14627, Theobald, W., Radha, P. B., Smalyuk, V. A., Glebov, V. Yu., Stoeckl, C., Anderson, K. S., Sangster, T. C., Shvarts, D., Li, C. K., Petrasso, R. D., Frenje, J. A., and Seguin, F. H. Fri . "High-{rho}R Implosions for Fast-Ignition Fuel Assembly". United States. doi:10.1103/PHYSREVLETT.98.025004.
@article{osti_20861603,
title = {High-{rho}R Implosions for Fast-Ignition Fuel Assembly},
author = {Zhou, C. D. and Betti, R. and Meyerhofer, D. D. and Dept. of Mechanical Eng. and Physics and Astronomy, University of Rochester, Rochester, New York 14627 and Theobald, W. and Radha, P. B. and Smalyuk, V. A. and Glebov, V. Yu. and Stoeckl, C. and Anderson, K. S. and Sangster, T. C. and Shvarts, D. and Li, C. K. and Petrasso, R. D. and Frenje, J. A. and Seguin, F. H.},
abstractNote = {Thick, 40 {mu}m plastic shells filled with 25-35 atm of D{sub 2} or D{sup 3}He were imploded on a low-adiabat ({alpha}{approx_equal}1.3) and with a low-implosion velocity ({approx}2x10{sup 7} cm/s) on the OMEGA laser to generate massive cores of compressed plasma with high areal densities optimal for fast ignition. The targets are driven by 20-kJ relaxation adiabat-shaping laser pulses to keep the inner portion of the shell nearly Fermi degenerate. The measured kinetic energy downshift of proton spectra is in good agreement with the theoretical predictions yielding burn-averaged areal densities of 0.130{+-}0.017 g/cm{sup 2} and peak {rho}R during the burn of about 0.24{+-}0.018 g/cm{sup 2}, the largest {rho}R measured on OMEGA to date. The same implosions with empty plastic shells are expected to reach 1.3 g/cm{sup 2} across the core (i.e., 2{rho}R) enough to stop fast electrons with energies up to 4.5 MeV typical of fast ignition scenarios.},
doi = {10.1103/PHYSREVLETT.98.025004},
journal = {Physical Review Letters},
number = 2,
volume = 98,
place = {United States},
year = {Fri Jan 12 00:00:00 EST 2007},
month = {Fri Jan 12 00:00:00 EST 2007}
}
  • Scaling relations to optimize implosion parameters for fast-ignition inertial confinement fusion are derived and used to design high-gain fast-ignition targets. A method to assemble thermonuclear fuel at high densities, high {rho}R, and with a small-size hot spot is presented. Massive cryogenic shells can be imploded with a low implosion velocity V{sub I} on a low adiabat {alpha} using the relaxation-pulse technique. While the low V{sub I} yields a small hot spot, the low {alpha} leads to large peak values of the density and areal density. It is shown that a 750 kJ laser can assemble fuel with V{sub I}{approx_equal}1.7x10{sup 7}more » cm/s, {alpha}{approx_equal}0.7, {rho}{approx_equal}400 g/cc, {rho}R{approx_equal}3 g/cm{sup 2}, and a hot-spot volume of less than 10% of the compressed core. If fully ignited, this fuel assembly can produce high gains of interest to inertial fusion energy applications.« less
  • Thick, 40-um plastic shells filled with 25 to 35 atm of D2 or D3He were imploded on a low-adiabat (a ~~ 1.3) and with a low-implosion velocity (~2 x 10^7 cm/s) on the OMEGA laser to generate massive cores of compressed plasma with high areal densities optimal for fast ignition.
  • Determining fuel areal density ({rho}R) in moderate-{rho}R (100-200 mg/cm{sup 2}) cryogenic deuterium-tritium (DT) implosions is challenging as it requires new spectrometry techniques and analysis methods to be developed. In this paper, we describe a new method for analyzing the spectrum of knock-on deuterons (KO-Ds), elastically scattered by primary DT neutrons, from which a fuel {rho}R can be inferred for values up to {approx}200 mg/cm{sup 2}. This new analysis method, which uses Monte Carlo modeling of a cryogenic DT implosion, improves significantly the previous analysis method in two fundamental ways. First, it is not affected by significant spatial-yield variations, which degrademore » the diagnosis of the fuel {rho}R (spatial yield variations of about {+-}20% are typically observed), and second, it does not break down when the fuel {rho}R exceeds {approx}70 mg/cm{sup 2}.« less
  • Scaling relations to optimize implosion parameters for fast-ignition inertial confinement fusion are derived and used to design high-gain fast-ignition targets. A method to assemble thermonuclear fuel at high densities, high pR, and with a small-size hot spot is presented.
  • The first observation of ignition-relevant areal-density deuterium from implosions of capsules with cryogenic fuel layers at ignition-relevant adiabats is reported. The experiments were performed on the 60-beam, 30-kJUV OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. Neutron-averaged areal densities of 202+-7 mg/cm^2 and 182+-7 mg/cm^2 (corresponding to estimated peak fuel densities in excess of 100 g/cm^3) were inferred using an 18-kJ direct-drive pulse designed to put the converging fuel on an adiabat of 2.5. These areal densities are in good agreement with the predictions of hydrodynamic simulations indicating that the fuel adiabat can be accuratelymore » controlled under ignition-relevant conditions.« less