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Title: Low Fuel Convergence Path to Direct-Drive Fusion Ignition

Abstract

A new class of inertial fusion capsules is presented that combines multishell targets with laser direct drive at low intensity (2.8 × 10 14 W/cm 2) to achieve robust ignition. The targets consist of three concentric, heavy, metal shells, enclosing a volume of tens of μg of liquid deuterium-tritium fuel. Ignition is designed to occur well “upstream” from stagnation, with minimal pusher deceleration to mitigate interface Rayleigh-Taylor growth. As a result, laser intensities below thresholds for laser plasma instability and cross beam energy transfer facilitate high hydrodynamic efficiency (~10%).

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2];  [2];  [2]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE (originally DOE/LANL); USDOE
OSTI Identifier:
1410615
Report Number(s):
LA-UR-16-20796
Journal ID: ISSN 0031-9007; PRLTAO; TRN: US1800136
Grant/Contract Number:
AC52-06NA25396; FG02-051ER54810
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 116; Journal Issue: 25; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Molvig, Kim, Schmitt, Mark J., Albright, Brian James, Dodd, Evan S., Hoffman, Nelson M., McCall, Gene H., and Ramsey, Scott D. Low Fuel Convergence Path to Direct-Drive Fusion Ignition. United States: N. p., 2016. Web. doi:10.1103/PhysRevLett.116.255003.
Molvig, Kim, Schmitt, Mark J., Albright, Brian James, Dodd, Evan S., Hoffman, Nelson M., McCall, Gene H., & Ramsey, Scott D. Low Fuel Convergence Path to Direct-Drive Fusion Ignition. United States. doi:10.1103/PhysRevLett.116.255003.
Molvig, Kim, Schmitt, Mark J., Albright, Brian James, Dodd, Evan S., Hoffman, Nelson M., McCall, Gene H., and Ramsey, Scott D. 2016. "Low Fuel Convergence Path to Direct-Drive Fusion Ignition". United States. doi:10.1103/PhysRevLett.116.255003. https://www.osti.gov/servlets/purl/1410615.
@article{osti_1410615,
title = {Low Fuel Convergence Path to Direct-Drive Fusion Ignition},
author = {Molvig, Kim and Schmitt, Mark J. and Albright, Brian James and Dodd, Evan S. and Hoffman, Nelson M. and McCall, Gene H. and Ramsey, Scott D.},
abstractNote = {A new class of inertial fusion capsules is presented that combines multishell targets with laser direct drive at low intensity (2.8 × 1014 W/cm2) to achieve robust ignition. The targets consist of three concentric, heavy, metal shells, enclosing a volume of tens of μg of liquid deuterium-tritium fuel. Ignition is designed to occur well “upstream” from stagnation, with minimal pusher deceleration to mitigate interface Rayleigh-Taylor growth. As a result, laser intensities below thresholds for laser plasma instability and cross beam energy transfer facilitate high hydrodynamic efficiency (~10%).},
doi = {10.1103/PhysRevLett.116.255003},
journal = {Physical Review Letters},
number = 25,
volume = 116,
place = {United States},
year = 2016,
month = 6
}

Journal Article:
Free Publicly Available Full Text
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  • Hydrodynamic simulations of realistic high-gain fast-ignition targets are preformed, including one-dimensional simulations of the implosion and two-dimensional simulations of ignition by a collimated electron beam and burn propagation. These simulations are used to generate gain curves for fast-ignition direct-drive inertial confinement fusion.
  • Hydrodynamic simulations of realistic high-gain fast-ignition targets are performed, including one-dimensional simulations of the implosion and two-dimensional simulations of ignition by a collimated electron beam and burn propagation. These simulations are used to generate gain curves for fast-ignition direct-drive inertial confinement fusion. The minimum energy required for ignition is computed for fast-electron beams with a monoenergetic or Maxwellian distribution, generated by a constant or Gaussian laser pulse. It is found that realistic fast-ignition targets can be ignited by monoenergetic collimated electron beams with a radius of 20 {mu}m, duration of 10 ps, and energy of 15 kJ. Simulations using ponderomotivemore » temperature scaling for fast electrons and Gaussian laser pulses predict a minimum laser energy for ignition of 235 kJ (105 kJ) for the energy conversion efficiency from the laser to fast electrons 0.3 (0.5) and the wavelength of 1.054 {mu}m. Such large energies are required because ultra-intense lasers are predicted to generate very energetic (multi-MeV) electrons with stopping distance exceeding the target size. The fast-electron energy, the stopping distance and the minimum energy required for ignition can be reduced using frequency-doubled laser pulses. Simulations of idealized cone targets are also performed in order to determine a lower bound of the gain deterioration due to the cone.« less
  • Relations between stagnation and in-flight phases are derived both analytically and numerically, for hydrodynamic variables relevant to direct-drive inertial confinement fusion implosions. Scaling laws are derived for the stagnation values of the shell density and areal density and for the hot-spot pressure, temperature, and areal density. A simple formula is also derived for the thermonuclear energy gain and in-flight aspect ratio.