Laser-Based Diagnostics for Arc Heated Flows

Arc jet facilities are crucial tools in the development of thermal protection materials for vehicles re-entering Earth’s atmosphere. To ensure that the arc jet tests provide the desired conditions, the state of the test gas in the arc jet facility must be accurately known. Existing instrumentation relies on probes which perturb the flow and which cannot distinguish between the multiple species comprising the flow. Physical Sciences Inc. proposes to develop and deliver a laser-induced fluorescence system to provide non-intrusive, real-time measurements of several key properties of the flow, including number densities and spatial profiles of atomic oxygen and nitric oxide, flow velocities, and translational temperatures. During Phase I, the feasibility of this approach was proven by calculating the number densities of the target species in one of the arc jet facilities at AEDC, measuring the level of background emission in that facility, and using this information to estimate the signal to noise levels to be expected in a Phase II program. As a result of the measurement program to be carried out in Phase II, the facility operators will be able to provide more accurate testing services to their customers in the US Air Force and in the aerospace industry.