High-repetition-rate krypton tagging velocimetry in Mach-6 hypersonic flows
Abstract
A 100 kHz krypton (Kr) tagging velocimetry (KTV) technique was demonstrated in a Mach-6 Ludwieg tube using a burst-mode laser-pumped optical parametric oscillator system. The single-beam KTV scheme at 212 nm produced an insufficient signal in this large hypersonic wind tunnel because of its low Kr seeding ( ≤ 5 % ), low static pressure ( ∼ 2.5 t o r r ), and long working distance ( ∼ 1 m ). To overcome these issues, a new scheme using two excitation beams was developed to enhance KTV performance. A 355 nm laser beam was combined with the 212 nm beam to promote efficient two-photon Kr excitation at 212 nm, and increase the probability of 2 + 1 resonant-enhanced multiphoton ionization by adding a 355 nm beam. A signal enhancement of approximately six times was obtained. Using this two-excitation beam approach, strong long-lasting KTV was successfully demonstrated at a 100 kHz repetition rate in a Mach-6 flow.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 14, 2022
- Source ID
- 10.1364/ao.449263
Entities
People
- Matthew Borg
- Naibo Jiang
- Paul Hsu
- S. Alexander Schumaker
- Stephen W. Grib
- Sukesh Roy
Organizations
- Air Force Research Laboratory
- National Aeronautics and Space Administration