Experimental validation of rotating detonation for rocket propulsion.

Space travel requires high-powered, efficient rocket propulsion systems for controllable launch vehicles and safe planetary entry. Interplanetary travel will rely on energy-dense propellants to produce thrust via combustion as the heat generation process to convert chemical to thermal energy. In propulsion devices, combustion can occur through deflagration or detonation, each having vastly different characteristics.

Automated image processing method to quantify rotating detonation wave behavior.

An image processing technique is developed to automatically determine both average and instantaneous detonation wave properties within a rotating detonation rocket engine (RDRE) using high-speed imaging. This method entails segmenting the imaged RDRE annulus into 200 azimuthal bins and tracking integrated pixel intensity in each bin. By combining individual pixel intensity temporal histories across the azimuthal bins, this provides what is termed a detonation surface that visualizes the propagation of the individual detonation fronts azimuthally around the annulus.

Time-synchronized continuous wave laser-induced fluorescence on an oscillatory xenon discharge.

A novel approach to time-synchronizing laser-induced fluorescence measurements to an oscillating current in a 60 Hz xenon discharge lamp using a continuous wave laser is presented. A sample-hold circuit is implemented to separate out signals at different phases along a current cycle, and is followed by a lock-in amplifier to pull out the resulting time-synchronized fluorescence trace from the large background signal. The time evolution of lower state population is derived from the changes in intensity of the fluorescence excitation line shape resulting from laser-induced fluorescence measurements of the 6s(')[1/2](1)(0)-6p(')[3/2](2) xenon atomic transition at λ = 834.

Kr II laser-induced fluorescence for measuring plasma acceleration.

We present the application of laser-induced fluorescence of singly ionized krypton as a diagnostic technique for quantifying the electrostatic acceleration within the discharge of a laboratory cross-field plasma accelerator also known as a Hall effect thruster, which has heritage as spacecraft propulsion. The 728.98 nm Kr II transition from the metastable 5d(4)D(7/2) to the 5p(4)P(5/2)(∘) state was used for the measurement of laser-induced fluorescence within the plasma discharge.

Anomalous electron mobility in a coaxial Hall discharge plasma.

A comprehensive analysis of measurements supporting the presence of anomalous cross-field electron mobility in Hall plasma accelerators is presented. Nonintrusive laser-induced fluorescence measurements of neutral xenon and ionized xenon velocities, and various electrostatic probe diagnostic measurements are used to locally determine the effective electron Hall parameter inside the accelerator channel. These values are then compared to the classical (collision-driven) Hall parameters expected for a quiescent magnetized plasma.