Pressure, by definition, characterizes the conditions within an isobaric implosion core at peak compression [Gus'kov et al., Nucl. Fusion 16, 957 (1976); Betti et al., Phys. Plasmas 8, 5257 (2001)] and is a key parameter in quantifying its near-ignition performance [Lawson, Proc. Phys. Soc. London, B 70, 6 (1957); Betti et al., Phys. Plasmas 17, 058102 (2010); Goncharov et al., Phys. Plasmas 21, 056315 (2014); and Glenzer et al., Phys. Plasmas 19, 056318 (2012)]. At high spectral energy, where the x-ray emission from an imploded hydrogen core is optically thin, the emissivity profile can be inferred from the spatially resolved core emission. This emissivity, which can be modeled accurately under hot-core conditions, is dependent almost entirely on the pressure when measured within a restricted spectral range matched to the temperature range anticipated for the emitting volume. In this way, the hot core pressure at the time of peak emission can be inferred from the measured free-free emissivity profile. The pressure and temperature dependences of the x-ray emissivity and the neutron-production rate explain a simple scaling of the total filtered x-ray emission as a constant power of the total neutron yield for implosions of targets of similar design over a broad range of shell implosion isentropes. This scaling behavior has been seen in implosion simulations and is confirmed by measurements of high-isentrope implosions [Sangster et al., Phys. Plasmas 20, 056317 (2013)] on the OMEGA laser system [Boehly et al., Opt. Commun. 133, 495 (1997)]. Attributing the excess emission from less-stable, low-isentrope implosions, above the level expected from this neutron-yield scaling, to the higher emissivity of shell carbon mixed into the implosion's central hot spot, the hot-spot “fuel–shell” mix mass can be inferred.
Skip Nav Destination
,
,
,
,
,
,
,
Article navigation
February 2015
Research Article|
February 12 2015
X-ray continuum as a measure of pressure and fuel–shell mix in compressed isobaric hydrogen implosion cores
R. Epstein
;
R. Epstein
1Laboratory for Laser Energetics,
University of Rochester
, Rochester, New York 14623, USA
Search for other works by this author on:
V. N. Goncharov;
V. N. Goncharov
1Laboratory for Laser Energetics,
University of Rochester
, Rochester, New York 14623, USA
Search for other works by this author on:
F. J. Marshall;
F. J. Marshall
1Laboratory for Laser Energetics,
University of Rochester
, Rochester, New York 14623, USA
Search for other works by this author on:
R. Betti;
R. Betti
2Fusion Science Center and Laboratory for Laser Energetics,
University of Rochester
, Rochester, New York 14623, USA
Search for other works by this author on:
R. Nora;
R. Nora
2Fusion Science Center and Laboratory for Laser Energetics,
University of Rochester
, Rochester, New York 14623, USA
Search for other works by this author on:
A. R. Christopherson;
A. R. Christopherson
2Fusion Science Center and Laboratory for Laser Energetics,
University of Rochester
, Rochester, New York 14623, USA
Search for other works by this author on:
I. E. Golovkin;
I. E. Golovkin
3
Prism Computational Sciences
, Madison, Wisconsin 53711, USA
Search for other works by this author on:
J. J. MacFarlane
J. J. MacFarlane
3
Prism Computational Sciences
, Madison, Wisconsin 53711, USA
Search for other works by this author on:
R. Epstein
1
V. N. Goncharov
1
F. J. Marshall
1
R. Betti
2
R. Nora
2
A. R. Christopherson
2
I. E. Golovkin
3
J. J. MacFarlane
3
1Laboratory for Laser Energetics,
University of Rochester
, Rochester, New York 14623, USA
2Fusion Science Center and Laboratory for Laser Energetics,
University of Rochester
, Rochester, New York 14623, USA
3
Prism Computational Sciences
, Madison, Wisconsin 53711, USA
Phys. Plasmas 22, 022707 (2015)
Article history
Received:
August 06 2014
Accepted:
January 22 2015
Citation
R. Epstein, V. N. Goncharov, F. J. Marshall, R. Betti, R. Nora, A. R. Christopherson, I. E. Golovkin, J. J. MacFarlane; X-ray continuum as a measure of pressure and fuel–shell mix in compressed isobaric hydrogen implosion cores. Phys. Plasmas 1 February 2015; 22 (2): 022707. https://doi.org/10.1063/1.4907667
Download citation file:
Pay-Per-View Access
$40.00
Sign In
You could not be signed in. Please check your credentials and make sure you have an active account and try again.
Citing articles via
Progress toward fusion energy breakeven and gain as measured against the Lawson criterion
Samuel E. Wurzel, Scott C. Hsu
A review of plasma acceleration and detachment mechanisms in propulsive magnetic nozzles
Kunlong Wu, Zhiyuan Chen, et al.
Key advancements toward eliminating the “drive deficit” in ICF hohlraum simulations
Hui Chen, D. T. Woods, et al.
Related Content
The effects of microstructure on propagation of laser-driven radiative heat waves in under-dense high-Z plasma
Phys. Plasmas (March 2018)
Gamma Reaction History ablator areal density constraints upon correlated diagnostic modeling of National Ignition Facility implosion experiments
Phys. Plasmas (March 2015)
Cryogenic-target performance and implosion physics studies on OMEGA
Phys. Plasmas (February 2009)
Performance of direct-drive cryogenic targets on OMEGA
Phys. Plasmas (April 2008)
The effect of turbulent kinetic energy on inferred ion temperature from neutron spectra
Phys. Plasmas (July 2014)