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Diagnosing fuel and asymmetries in cryogenic deuterium-tritium implosions using charged-particle spectrometry at OMEGA
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Image of FIG. 1.
FIG. 1.

: The MRS and the CPSs (CPS1 and CPS2) on the OMEGA chamber. The line of sight for each diagnostic is illustrated in terms of the polar angle and azimuthal angle . These spectrometers are used to simultaneously measure the spectra of elastically scattered deuterons, so-called KO-Ds, from which fuel and asymmetries in cryogenic DT implosions can be directly inferred. The MRS can operate in either charged-particle or down-scattered neutron mode; the latter mode allows for measurements of the down-scattered neutron spectrum from which of the fuel can be inferred as well.

Image of FIG. 2.
FIG. 2.

The birth spectrum of KO-Ds elastically scattered by primary 14.1 MeV neutrons. Due to kinematics, the KO-D high-energy end point is at 12.5 MeV.

Image of FIG. 3.
FIG. 3.

(a) Density and (b) temperature profiles used in the modeling of a cryogenic DT implosion with a of . The black line represents the average, while the gray lines indicate the envelopes (represented by the standard deviation) in which the density and temperature profiles were varied. The variations were made to still meet the measured burn averaged ion temperature of , position of the high-density region of . Resulting birth profiles of the primary neutrons and KO-Ds are shown in (c) and (d). In addition, the modeling was constrained by isobaric conditions at bang time, burn duration, DT-fuel composition, and steady state during burn.

Image of FIG. 4.
FIG. 4.

KO-D spectra for different fuel s. The error bars shown in each spectrum represent the effect of varying density and temperature profiles. As illustrated, the shape of the KO-D spectrum depends strongly on , while density and temperature profile effects play minor roles as indicated by the error bars. The KO-D spectra are normalized to unity.

Image of FIG. 5.
FIG. 5.

Examples of measured KO-D spectra for four different low-adiabat cryogenic DT implosions. Simulated fits [gray lines (red online)] to the measured spectra are also shown. From the fits, a fuel of , , , and was determined for shot 43 070, 43 945, 49 035, and 48 734, respectively. The errors of the inferred values are due to mainly modeling uncertainties as discussed in Sec. II and statistical uncertainties in the experimental data. See text for more detailed information about these implosions.

Image of FIG. 6.
FIG. 6.

(a) Observed average as a function of 1D predicted for implosions with a capsule offset of less than to the target-chamber center. (b) Observed as a function of capsule offset. These data sets are for low-adiabat DT [dark gray data points (blue online)] and [light gray data points (red online)] implosions driven at various intensities. Similar performance relative to 1D and similar as a function of capsule offset is observed for both DT and implosions, indicating that the analysis of the KO-D spectrum is accurate.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Diagnosing fuel ρR and ρR asymmetries in cryogenic deuterium-tritium implosions using charged-particle spectrometry at OMEGA