Bulletin of the American Physical Society
21st Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 64, Number 8
Sunday–Friday, June 16–21, 2019; Portland, Oregon
Session J3: AETD: Velocimetry 1 |
Hide Abstracts |
Chair: Mike Bowden, LANL Room: Pavilion East |
Tuesday, June 18, 2019 11:00AM - 11:30AM |
J3.00001: Characterizing Performance of Broadband Laser Ranging Invited Speaker: Michelle Rhodes Broadband Laser Ranging (BLR) has been developed as a surface position diagnostic for non-planar shock experiments that is complementary and compatible with Photonic Doppler Velocimetry (PDV). BLR uses very short broadband laser pulses to make relative time-of-flight measurements to a moving surface and a fixed reference surface. Recording an amplified dispersive Fourier transform of the reflected pulses enables very accurate relative position measurements at a high repetition rate. Several experiments have been conducted aiming to understand the capabilities of this new diagnostic tool. The accuracy and precision of the instrument will be explored along with some interesting and unexpected systematic effects from hardware physics. [Preview Abstract] |
Tuesday, June 18, 2019 11:30AM - 11:45AM |
J3.00002: High Resolution Broadband Laser Ranging Andrea Albert Broadband Laser Ranging (BLR) is an optical diagnostic that measures the position along the line of sight of surfaces and particle clouds moving at speeds of a few kilometers per second at a repetition rate of 20 ns. BLR is a spectral interferometer that uses dispersive Fourier transforms to translate the beat frequency between a reference leg and a signal leg into a surface distance. Current generations of BLR measure position with a resolution of 20 microns and use mod-locked 1550 nm fiber lasers with a 20 nm bandwidth. Better position and time resolution is expected from using a broader bandwidth. We present results from a series of tests performed using a new BLR system with a 90 nm bandwidth. LA-UR-19-21392 [Preview Abstract] |
Tuesday, June 18, 2019 11:45AM - 12:00PM |
J3.00003: ABSTRACT WITHDRAWN |
Tuesday, June 18, 2019 12:00PM - 12:15PM |
J3.00004: Simultaneous Green and Infrared PDV Matthew Briggs, Andrea Albert, Patrick Younk We have developed a fiber PDV system that operates at 532nm, i.e., Green PDV. The fringe constant, or {\#} fringes/change in position, is three times higher than in traditional PDV, which is implemented with 1550 nm lasers. Because of that, we expect approximately three times better velocity resolution in the new system. By using a bare fiber probe, we are able to test it side-by-side with the traditional 1550 nm infrared PDV. We will present our design and results. Our results show that indeed we find about three times the velocity resolution with this new system compared to the 1550 nm PDV. The shorter wavelength also allows tighter focusing, which we took advantage of to probe some of the details of Asay foil measurements. We report on these results as well. LA-UR-19-21661 [Preview Abstract] |
Tuesday, June 18, 2019 12:15PM - 12:30PM |
J3.00005: Dark-fringe velocimeter for measuring fast transient features in shock wave profiles with 1 m/s precision and 50 ps time resolution B. La Lone, E. Miller, E. Larson, J. Wesolowski We have developed a velocimetry system that is capable of recording \textasciitilde 1 m/s velocity changes on the 50 ps timescale for shock wave compression experiments. This is an order of magnitude improvement in the velocity-time resolution product over existing techniques. Similar to a VISAR, Doppler-shifted laser light from a moving target is directed into a Michelson interferometer with an unbalanced path length of 50 ps. To achieve excellent velocity sensitivity while also retaining high time resolution, the initial phase of the interferometer is actively balanced to be destructively interfering. In this manner, small changes in velocity result in relatively large changes in the interferometer output levels. Destructive interfering of the cavity is achieved by tuning the laser current and temperature with a custom feedback circuit. The system was tested on elastic precursor measurements of iron and steel targets and showed promising results. A path forward for improving the diagnostic is provided. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700