Bulk Fluid elocity Construction from NIF Neutron Spectral Diagnostics ntof-4.5 DT-Lo (64-309) ntof-3.9 DSF (64-275) ntof-4.5 BT (64-253) MRS ntof-4.5 DT-Hi (64-330) Spec E (90-174) Spec A (116-316) Spec SP (161-56) J. P. Knauer University of Rochester Laboratory for Laser Energetics 55th Annual Meeting of the American Physical Society Division of Plasma Physics Denver, CO 11 15 November 2013
Summary The velocity of the neutron emission region is routinely measured by National Ignition Facility (NIF) neutron spectral diagnostics A minimum 2 method is used to determine the best fit for the resultant velocity ( x, y, z ) from the measured detector velocity components* The velocity calculation is checked by a series of perturbed drive experiments** Gas-filled targets have lower neutron-emitting fluid velocities than layered targets mass perturbation is seen in layered target experiments large velocities are measured for implosions with drive and mass perturbations E22443 *R. Hatarik et al., NO7.00010, this conference; M. Gatu Johnson et al., NO7.00014, this conference. **B. K. Spears et al., NO7.00012, this conference.
Collaborators J. A. Caggiano, R. Hatarik, J. M. McNaney, and B. K. Spears Lawrence Livermore National Laboratory M. Gatu Johnson and J. A. Frenje MIT Plasma Science Fusion Center J. D. Kilkenny General Atomics
Neutron time-of-flight (ntof) measurements are made on three nearly orthogonal lines of sight (LOS) and are complemented by the magnetic recoil spectrometer (MRS) ntof-4.5 DT-Lo (64-309) ntof-3.9 DSF (64-275) ntof-4.5 BT (64-253) MRS ntof-4.5 DT-Hi (64-330) Spec E (90-174) Spec A (116-316) Spec SP (161-56) Relative angles Spec A Spec E Spec SP MRS Spec A 138 69 42 Spec E 138 99 146 Spec SP 69 99 107 MRS 42 146 107 Multiple LOS allow for the construction of a resultant velocity. E22444
Neutron-emitting fluid velocity ( x, y, z ) is determined by fitting to the measured detector velocity projections elocities projected along the instrumental LOS are calculated with x, y, and z proj = ) x + ) y + ) z det x det y det z det meas proj det det _ x, y, z 2 = Rdet meas2 ddet 9 ic x, y, and z are calculated by minimizing 2 d x, d y, and d z are calculated from the error matrix The polar velocity vector and its associated errors are calculated from Cartesian components 2 E22445
The projected velocities of ntof spectral detectors agree with measured velocities projected (km/s) Spec A 100 50 0 50 100 100 50 0 50 100 Spec E 100 50 0 50 100 Spec SP 100 50 0 50 100 measured (km/s) measured (km/s) measured (km/s) Spec E determines the velocity x component; Spec SP determines the velocity z component. E22447
MRS-projected velocities show larger variations with respect to measured velocities Projected velocity (km/s) 100 50 0 50 MRS 100 100 50 0 50 100 Measured velocity (km/s) Resultant velocity is weighted toward ntof velocities. E22449
A three-shot series of controlled P 1 symcap experiments were performed to test ntof bulk-velocity measurements 4% x-ray P 1 N130625 Round control N130507 +4% x-ray P 1 N130814 4% +4% Nominal DT Nominal +4% 4% E22450
elocity components are measured using both D 2 and DT neutron arrival times agreeing on all three shots South pole D 2 scope traces Signal () Signal () E22451 0.20 0.15 0.10 0.05 10 8 6 4 2 0 D2 (km/s) 62 12 78 830 850 870 890 South pole DT scope traces DT (km/s) 76 1 76 358 362 366 370 Time (ns) elocity from DT (km/s) 50 0 50 Measurement error <25 km/s Nominal N130507 P 1 down N130625 50 0 50 elocity from D 2 (km/s) P 1 up N130814 Agreement of the D 2 and DT velocities suggests that the diagnostic interpretation is correct.
elocity measurements from the new ntof s show the presence of sizeable Mode-1 perturbations (km/s) 180 150 120 90 60 30 0 N130503 DT shots since high-precision ntof upgrade DT symcaps DT layers N130505 N130507 N130625 Mode-1 drive N130628 N130814 N130331 Mode-1 ice N130501 N130530 N130710 N130802 N130812 E22452
Summary/Conclusions The velocity of the neutron emission region is routinely measured by National Ignition Facility (NIF) neutron spectral diagnostics A minimum 2 method is used to determine the best fit for the resultant velocity ( x, y, z ) from the measured detector velocity components* The velocity calculation is checked by a series of perturbed drive experiments** Gas-filled targets have lower neutron-emitting fluid velocities than layered targets mass perturbation is seen in layered target experiments large velocities are measured for implosions with drive and mass perturbations E22443 *R. Hatarik et al., NO7.00010, this conference; M. Gatu Johnson et al., NO7.00014, this conference. **B. K. Spears et al., NO7.00012, this conference.
The polar velocity vector and its associated errors are calculated from Cartesian components Given Cartesian velocity components J K K L N O and their errors O P, i, and z as well as d, i, and iz can be determined x y z Jd K d K d L x y z N O O P = 2+ 2+ 2 1 d = ) d ) + d ) + d ) x y z 2 2 2 2 2 2 x x y y z z j = cos { = tan 1 z 1 x y dj = 1 dz) + d ) ) 2 2 2 2 2 2 z 1 d{ = 2 2 ) d ) + d ) + x y z 2 2 2 2 x y y x E22446