Combusted Ludwieg tubes for gasdynamic laser research

The scalings laws of the combusted Ludwieg tube and its applicability to gasdynamic lasers were considered, with emphasis on the effects of the large temperature nonuniformities. The combusted Ludwieg tube was then used to drive an array of supersonic entrance gasdynamic laser nozzles. In the first experiments, the degree of amplification of a CO2 laser signal was measured in the flow immediately downstream of the array. In the second, the stagnation pressure loss originated by the nozzles was determined by measuring the static pressure and a shock angle far downstream of the array. The former demonstrated the importance of aerodynamics in gasdynamic laser design; the latter confirmed models indicating that nozzle wakes and vibrational relaxation are the main loss mechanisms. These experiments demonstrated the usefulness of the combusted Ludwieg tube and supported the concept of all supersonic multistaging for increasing the efficiency of CO2-N2 gasdynamic lasers.