28 September 2017 On the design of the NIF Continuum Spectrometer
Author Affiliations +
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.
Conference Presentation
© (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
D. B. Thorn, D. B. Thorn, A. MacPhee, A. MacPhee, J. Ayers, J. Ayers, J. Galbraith, J. Galbraith, C. M. Hardy, C. M. Hardy, N. Izumi, N. Izumi, D. K. Bradley, D. K. Bradley, L. A. Pickworth, L. A. Pickworth, B. Bachmann, B. Bachmann, B. Kozioziemski, B. Kozioziemski, O. Landen, O. Landen, D. Clark, D. Clark, M. B. Schneider, M. B. Schneider, K. W. Hill, K. W. Hill, M. Bitter, M. Bitter, S. Nagel, S. Nagel, P. M. Bell, P. M. Bell, S. Person, S. Person, H. Y. Khater, H. Y. Khater, C. Smith, C. Smith, J. Kilkenny, J. Kilkenny, } "On the design of the NIF Continuum Spectrometer", Proc. SPIE 10390, Target Diagnostics Physics and Engineering for Inertial Confinement Fusion VI, 1039009 (28 September 2017); doi: 10.1117/12.2275289; https://doi.org/10.1117/12.2275289


XBSS: the X-Ray Background Spectroscopic Survey
Proceedings of SPIE (October 14 1997)
X-Ray Imaging By Penumbral Reconstruction
Proceedings of SPIE (July 26 1979)
Structure and intensity of x ray radiation in a laser...
Proceedings of SPIE (December 11 2001)
X-ray spectroscopy and imaging of a plasma collision
Proceedings of SPIE (September 17 1995)

Back to Top