Bulk Fluid Velocity Construction from NIF Neutron Spectral Diagnostics

Transcription

1 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 ( ) 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 November 2013

2 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., NO , this conference; M. Gatu Johnson et al., NO , this conference. **B. K. Spears et al., NO , this conference.

3 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

4 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 ( ) Spec SP (161-56) Relative angles Spec A Spec E Spec SP MRS Spec A Spec E Spec SP MRS Multiple LOS allow for the construction of a resultant velocity. E22444

5 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

6 The projected velocities of ntof spectral detectors agree with measured velocities projected (km/s) Spec A Spec E Spec SP measured (km/s) measured (km/s) measured (km/s) Spec E determines the velocity x component; Spec SP determines the velocity z component. E22447

7 MRS-projected velocities show larger variations with respect to measured velocities Projected velocity (km/s) MRS Measured velocity (km/s) Resultant velocity is weighted toward ntof velocities. E22449

8 A three-shot series of controlled P 1 symcap experiments were performed to test ntof bulk-velocity measurements 4% x-ray P 1 N Round control N % x-ray P 1 N % +4% Nominal DT Nominal +4% 4% E22450

9 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 () E D2 (km/s) South pole DT scope traces DT (km/s) Time (ns) elocity from DT (km/s) Measurement error <25 km/s Nominal N P 1 down N elocity from D 2 (km/s) P 1 up N Agreement of the D 2 and DT velocities suggests that the diagnostic interpretation is correct.

10 elocity measurements from the new ntof s show the presence of sizeable Mode-1 perturbations (km/s) N DT shots since high-precision ntof upgrade DT symcaps DT layers N N N Mode-1 drive N N N Mode-1 ice N N N N N E22452

11 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., NO , this conference; M. Gatu Johnson et al., NO , this conference. **B. K. Spears et al., NO , this conference.

12 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 = d = ) d ) + d ) + d ) x y z x x y y z z j = cos { = tan 1 z 1 x y dj = 1 dz) + d ) ) z 1 d{ = 2 2 ) d ) + d ) + x y z x y y x E22446