Plasma Actuators in Space-Based Systems

Abstract

Plasma actuators are fully electronic devices without any moving mechanical parts. Hence they have increased reliability and lower complexity when compared to conventional actuators used for same purposes. Mobile components also contribute to increased vibrations, noise, loss of energy and they require lubrication. Non-thermal plasma actuators are highly efficient as they directly convert electrical into kinetic energy without use of any mechanical parts. Lack of mobile components in plasma actuators contribute to lower mass, meaning lower cost of spacecrafts. Another benefit related to use of these actuators is their short response time, which increases dynamical and control abilities of complete spacecraft. All the benefits just stated make this technology potentially very interesting for space-based applications. Presented thesis represents feasibility study, a first step required for application of plasma actuator on a spacecraft.

This research examined two objectives. First was to study the effect of an altitude on momentum exchange between high velocity external flow and created ionic wind. Second objective was to investigate and design DBD plasma actuator able to withstand orbital thermal loads. This study consists of literature research on two most common plasma actuators; various aspects of launch, orbit and re-entry of spacecrafts; and two analytical models. First model aims in estimating the influence of an altitude on the actuator force creation, which can be used for shock stand-off distance modification, and thus steering applications. Other model aims in estimating actuator thermal loads occurring due to spacecraft orbit in Low Earth Orbit. Results show that altitude has large effect on actuator force production. Analytical model shows an average reduction of 4.51 or 4.44 times per 10 km, depending on actuator’s orientation with respect to external flow. Difficulties relating high velocity flow fields such as molecular dissociation and very high friction heat loads are presented. Results show that DBD actuator system can produced significant perturbations between spacecraft surface and natural shockwave. Made perturbations are in form of a compression wave that interacts with natural shock wave and creates a dis-balance of forces proficient for spacecraft reentry steering. Second analytical model shows that there exist actuator materials which can withstand thermal loads due to spacecraft orbital Sun exposure. This thesis shows a promising first order results needed to qualify and apply DBD actuator on spacecraft. However much research on optimization and design are still required.