D. Thorn, A. MacPhee, J. Ayers, J. Galbraith, C. Hardy, N. Izumi, D. Bradley, L. Pickworth, B. Bachmann, B. Kozioziemski, O. Landen, D. Clark, M. Schneider, K. Hill, M. Bitter, S. Nagel, P. Bell, S. Person, H. Khater, C. Smith, J. Kilkenny
In inertial confinement fusion (ICF) experiments on the National Ignition Facility (NIF), measurements of average ion temperature using DT neutron time of flight broadening and of DD neutrons do not show the same apparent temperature. Some of this may be due to time and space dependent temperature profiles in the imploding capsule which are not taken into account in the analysis. As such, we are attempting to measure the electron temperature by recording the free-free electron-ion scattering-spectrum from the tail of the Maxwellian temperature distribution. This will be accomplished with the new NIF Continuum Spectrometer (ConSpec) which spans the x-ray range of 20 keV to 30
keV (where any opacity corrections from the remaining mass of the ablator shell are negligible) and will be sensitive to temperatures between ∼ 3 keV and 6 keV. The optical design of the ConSpec is designed to be adaptable to an x-ray streak camera to record time resolved free-free electron continuum spectra for direct measurement of the dT/dt evolution across the burn width of a DT plasma. The spectrometer is a conically bent Bragg crystal in a focusing geometry that allows for the dispersion plane to be perpendicular to the spectrometer axis. Additionally, to address the spatial temperature dependence, both time integrated and time resolved pinhole and penumbral imaging will be
provided along the same polar angle. The optical and mechanical design of the instrument is presented along with estimates for the dispersion, solid angle, photometric sensitivity, and performance.
B. Bachmann, H. Abu-Shawareb, N. Alexander, J. Ayers, C. Bailey, P. Bell, L. Benedetti, D. Bradley, G. Collins, L. Divol, T. Döppner, S. Felker, J. Field, A. Forsman, J. Galbraith, C. Hardy, T. Hilsabeck, N. Izumi, C. Jarrot, J. Kilkenny, S. Kramer, O. Landen, T. Ma, A. MacPhee, N. Masters, S. Nagel, A. Pak, P. Patel, L. Pickworth, J. Ralph, C. Reed, J. Rygg, D. Thorn
X-ray penumbral imaging has been successfully fielded on a variety of inertial confinement fusion (ICF) capsule
implosion experiments on the National Ignition Facility (NIF). We have demonstrated sub-5 μm resolution imaging of
stagnated plasma cores (hot spots) at x-ray energies from 6 to 30 keV. These measurements are crucial for improving
our understanding of the hot deuterium-tritium fuel assembly, which can be affected by various mechanisms, including
complex 3-D perturbations caused by the support tent, fill tube or capsule surface roughness. Here we present the
progress on several approaches to improve x-ray penumbral imaging experiments on the NIF. We will discuss
experimental setups that include penumbral imaging from multiple lines-of-sight, target mounted penumbral apertures
and variably filtered penumbral images. Such setups will improve the signal-to-noise ratio and the spatial imaging
resolution, with the goal of enabling spatially resolved measurements of the hot spot electron temperature and material
mix in ICF implosions.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.