Kelly, R. M.O'Byrne, S.2026-07-032026-07-0397807354483390094-243XORCID:/0009-0007-2076-6766/work/219175472https://hdl.handle.net/1885/733812343In this report we investigate the suitability of different gases for TDLAS of low density hypersonic nozzle-exit flows, but tunnel results are not be presented yet. Oxygen (for an Earth atmosphere), carbon dioxide (for a Martian atmosphere) and seeded rubidium are the considered candidates for TDLAS measurements. We demonstrate the design of a simple, minimum-path-length TDLAS system that can be used to measure the temperature and velocity of a hypersonic nozzle flow. This system is tested in laboratory air, and the absorption signals are then scaled using an in-house code to predict absorption in rarefied flows in the shock tunnel, comparing between different candidate optical configurations. A design for TDLAS measurements inside a hypersonic facility is discussed, along with the challenges associated with hypersonic ground test facilities.This work was funded by the Defence Science and Technology Group under DST Research agreement MyIP:9442 Hypersonic Aerosciences and Advanced Diagnostics, and the authors acknowledge this support.enPublisher Copyright: © 2024 AIP Publishing LLC.2024-02-0810.1063/5.019190085185771039