The influence of transversal density nonuniformity on the propagation of electromagnetic surface waves along plasma slabs and columns in the presence of collisions is analysed and illustrated by numerical evaluations for phase diagrams of axially homogeneous plasmas. Moreover, the changes in dispersion and damping caused by the occurence of plasma resonances in the transversal/radial density profile are studied. In addition, complex modes and backward waves in the collisionless dispersion curves of isotropic plasmas are treated.

The resurgence in interest in aircraft electro-aerodynamic (EAD) propulsion has been sparked due to recent advancements in EAD thrusters, which generate thrust by employing a plasma generated through electrical discharge. With potentially quieter propulsion that could contribute to the generation of lift or the control of attitude, it is important to determine the feasibility of an EAD-propelled airplane. First, the main propulsive characteristics (thrust generation and power consumption) of EAD thrusters were drawn from the literature and compared with existing technologies. Second, an algorithm was developed to couple standard equations of flight with EAD propulsion performance and treat the first-order interactions. It fairly replicated the performance of the only available autonomous EAD-propelled drone. A test case based on an existing commercial UAV of 10 kg equipped with current-generation EAD thrusters anticipated a flight of less than 10 min, lower than 30 m in height, and below 8 m · s ⁻¹ in velocity. Achieving over 2 h of flight at 30 m of height at 10 m · s ⁻¹ requires the current EAD thrust to be doubled without altering the power consumption. For the same flight performance as the baseline UAV, the prediction asked for a tenfold increase in the thrust at the same power consumption.

The aim of this work is to systematically quantify and rank the effects of nine different design parameters on the fluid mechanic abilities of a dielectric barrier discharge (DBD) plasma actuator supplied with an alternating current. The ranking and quantification not only consider the parameters themselves but also their interactions with each other. In order to perform this ranking, a Design of Experiment approach is used. This allows the most significant design parameters for the thrust generation, power consumption and thrust to power consumed ratio (force efficiency) of DBD actuator performance to be determined in a systematic way. The results show that the thrust generation is driven by the voltage, distance between the electrodes, AC frequency, and geometry of the exposed electrode, in that order. A high voltage and high frequency, with a thin dielectric, a narrow inter-electrode gap, and a thin and narrow air-electrode results in an increase in the thrust generation.The thrust to power ratio of a DBD is employed as a proxy for the fluid mechanic efficiency. The analysis of the force efficiency shows that the voltage, frequency, distance between the electrodes, and geometry of the air electrode have significant effects. The higher force efficiency is obtained for a high voltage, low frequency, short inter-electrode gap, thin dielectric of low permittivity with a narrow and thin exposed electrode. Finally, two actuators are investigated to determine the best scaling laws for the power consumption as a function of voltage and frequency. In these experiments, the power consumption was a function of voltage to the power of 2.5 and frequency to the power of 1.5. This systematic study of the parameters and their interactions allows general guidelines to be obtained for the best fluid mechanic performance of a DBD, viz. its thrust generation and force efficiency.

Recent developments in electro-aerodynamics (EAD) thrusters that use plasma have demonstrated their abilities for aircraft propulsion, at least for low-velocity drones. Further improvements in the technology bring EAD propulsion closer to full-scale applications. However, certain doubts still exist concerning their behavior in different atmospheric conditions. The study focuses on the effects of altitude on the propulsive performance of a corona discharge thruster in the troposphere. A thruster is placed in a climatic chamber that can vary the temperature and pressure independently, and force and current measurements provide the thrust generation and power consumption of the thruster. First, tests under varying pressure between 500 and 1000 hPa were performed at room temperature. As expected, at constant voltage, they highlight that the power increases almost linearly when the pressure decreases. Conversely, they demonstrated that the thrust decreases with pressure at a constant current. The combined effects result in a loss of effectiveness (i.e. thrust-to-power ratio) when the pressure reduces. Yet, a plateau of maximum effectiveness is achieved between 800 and 1000 hPa. Secondly, the temperature was varied between −20 °C and +30 °C at ground pressure. No significant effect was captured concerning the current and power, and a weak decrease in thrust was measured at higher temperatures. Finally, altitudes between 0 and 6 km were simulated by combining pressure and temperature modifications. Mostly led by the pressure drop, the power decreases linearly when the altitude increases, but the thrust decreases to a plateau between 3 and 6 km. Hence, the effectiveness also decreases with altitude down to a stagnation between 3 and 6 km. The coupled decreases in drag and thrust with altitude engender a small decrease in the maximum achievable freestream velocity of the thruster down to a plateau over 3 km.