Due to the complicated environment of the plasma sheath, it is difficult to experimentally measure plasma characteristics in the narrow geometry where sheaths from opposite boundaries overlap. Since such geometries are often found in industrial plasma applications, accurate measurements of this type are of significant interests. In this paper, we employ micron-sized dust grains as non-perturbative probes of the plasma environment. A particle-freefall technique is then used to measure the sheath profiles produced by a rf plasma within a glass box. The results show that this technique can identify the plasma operating conditions for which the sheaths on opposite walls begin to overlap as well as the magnitude of the effect.

In space technology many concepts for magnetic fields are under discussion for the use in advanced propulsion, shielding from radiation or as aid for thermal protection system for the atmospheric entry of spacecraft. Two experiments have been conducted to investigate the feasibility of using magnetic fields to reduce the heat flux onto a thermal protection system during atmospheric entry. For this purpose a modified heat flux probe with embedded permanent magnets has been exposed to a plasma jet and the structure of the bow shock in front of the probe has been observed using an emission spectroscopy setup. The intensity ratio of ionized argon lines for the experiment with and without magnets has been determined and used to analyze the magnetic field`s impact on the flow. Complementary experiments in a low power capacitively driven plasma have been conducted using micron sized particles as probes to map electric fields in a magnetically perturbed plasma. The results from both experiments are presented and analogies are drawn from both approaches. The experiments have shown that the interactions of the magnetic field with the plasma can create strong electric fields which strongly influence the ions even though the field is too weak to magnetize the ions.

The confinement provided by a glass box is proving ideal for the formation of vertically aligned structures and a convenient method for controlling the number of dust particles comprising these dust structures as well as their sizes and shapes. In this paper, the electronic confinement of the glass box is mapped, and the particle interactions between the particle pairs inside the glass box are measured. The ion-wake field is shown to exist within the glass box, and its vertical and horizontal extents are measured.

Microgravity experiments are essential for research in space science, biology, fluid mechanics, combustion, and material sciences. One way to conduct microgravity experiments on Earth is by using drop tower facilities. These facilities combine a high quality of microgravity, adequate payload masses and have the advantage of virtually unlimited repeatability under same experimental conditions, at a low cost.In a collaboration between the Institute of Space Systems (IRS) at the University of Stuttgart and Baylor University (BU) in Waco, Texas, a new drop tower is currently under development at the Center for Astrophysics, Space Physics and Engineering Research (CASPER). The design parameters of the drop tower ask for at least 1.5 sin free fall duration while providing a quality of at least 10(-5) g. Previously, this quality has only been achieved in vacuum drop tower facilities where the capsule experiences virtually zero aerodynamic drag during its free fall. Since this design comes at high costs, a different drop tower design concept, which does not require an evacuated drop shaft, was chosen. It features a dual-capsule system in which the experiment capsule is shielded from aerodynamic forces by surrounding it with a drag shield during the drop. As no other dual-capsule drop tower has been able to achieve a quality as good as or better than 10-5 g previous work optimized the design with an aerodynamic perspective by using computational fluid dynamics (CFD) simulations to determine the ideal shape and size of the outer capsule and to specify the aerodynamically crucial dimensions for the overall system. Experiments later demonstrated that the required quality of microgravity can be met with the proposed design.The main focus of this paper is the mechanical realization of the capsule as well as the development and layout of the surrounding components, such as the release mechanism, the deceleration device and the drop shaft. Because the drop tower facility is a complex system with many interdependencies between all of the components, several engineering challenges had to be addressed. For example, initial disturbances that are caused by the release mechanism are a common issue that arises at drop tower facilities. These vibrations may decrease the quality of microgravity during the initial segment of free fall. Because this would reduce the free fall time experiencing high quality microgravity, a mechanism has been developed to provide a soft release. Challenges and proposed solutions for all components are highlighted in this paper.

In this paper a method is described that allows mapping of the forces acting on dust particles in a GEC reference cell. Monodisperse particles are dropped into the plasma environment and their trajectories are tracked using a high-speed camera system to determine local accelerations and respective forces. Collecting data from a large number of particle drops allows the identification of three-dimensional vector fields for the acting forces. The procedure is described and multiple examples in which the method has been applied are given. These examples include a simple plasma sheath, plasmas perturbed by a horizontal and vertical dipole magnet, an array of multiple magnets mimicking the fields found at a lunar swirl, and the fields inside a glass box used for particle confinement. Further applicability in other plasma environments will be discussed shortly.

 Abstract —The Inductively heated plasma generator (IPG6B) University provides valuable insight into the nature of high-enthalpy plasma flows in Helium, argon, and nitrogen. The device and its diagnostics have yet to be characterized. In order for the device to be useful for reentry simulations or for fusion reactor materials testing, a thorough map of its behavior at a wide range of pressures and gas flows were to investigated. For this reason various experiments have been performed with a cavity calorimeter in order to determine the plasma power at distinct parameters. Although there is considerable work yet to do, the results have demonstrated trends in the devices behavior which will allow optimal operating conditions to be inferred. Additionally over the course of the analysis of these experiments, a Matlab algorithm was written to isolate stable regions of data and extrapolate equilibrium values and time constants from them. This quantifies the time required for experimental measurements to reach equilibrium after experimental parameters have been

The interaction between a magnetic field and plasma close to a nonconductive surface is of interest for both science and technology. In space, crustal magnetic fields on celestial bodies without atmosphere can interact with the solar wind. In advanced technologies such as those used in fusion or spaceflight, magnetic fields can be used to either control a plasma or protect surfaces exposed to the high heat loads produced by plasma. In this paper, a method will be discussed for investigating magnetic field plasma interactions close to a nonconductive surface inside a Gaseous Electronics Conference reference cell employing dust particles as probes. To accomplish this, a magnet covered by a glass plate was exposed to a low power argon plasma. The magnetic field was strong enough to magnetize the electrons, while not directly impacting the dynamics of the ions or the dust particles used for diagnostics. In order to investigate the interaction of the plasma with the magnetic field and the nonconductive surface, micron-sized dust particles were introduced into the plasma and their trajectories were recorded with a high-speed camera. Based on the resulting particle trajectories, the accelerations of the dust particles were determined and acceleration maps over the field of view were generated which are representative of the forces acting on the particles. The results show that the magnetic field is responsible for the development of strong electric fields in the plasma, in both horizontal and vertical directions, leading to complex motion of the dust particles.

We discuss the inductively heated plasma generator (IPG) facility in application to the generation of the thermal dusty plasma formed by the positively charged dust particles and the electrons emitted by them. We develop a theoretical model for the calculation of plasma electrical conductivity under typical conditions of the IPG. We show that the electrical conductivity of dusty plasma is defined by collisions with the neutral gas molecules and by the electron number density. The latter is calculated in the approximations of an ideal and strongly coupled particle system and in the regime of weak and strong screening of the particle charge. The maximum attainable electron number density and corresponding maximum plasma electrical conductivity prove to be independent of the particle emissivity. Analysis of available experiments is performed, in particular, of our recent experiment with plasma formed by the combustion products of a propane–air mixture and the CeO2 particles injected into it. A good correlation between the theory and experimental data points to the adequacy of our approach. Our main conclusion is that a level of the electrical conductivity due to the thermal ionization of the dust particles is sufficiently high to compete with that of the potassium-doped plasmas.

The IPG6-B is an inductively heated plasma generator located at Baylor University’s Center for Astrophysics, Space Physics, and Engineering Research (CASPER) in Waco, Texas. Because the IPG6-B is relatively new, there remain many unknowns about its performance. During this project, a cavity calorimeter and a Pitot probe were used to characterize the facility by varying several operating parameters. Working gases included helium, argon, and nitrogen. The obtained data was used to calculate heat losses and Mach number of the plasma flow. Oscilloscope data of electric parameters was analyzed as well. Additionally, secondary effects, such as arcing and unstable discharges, were observed.

The interaction between plasma and a static magnetic field is investigated experimentally. A cylindrical dipole magnet was placed in horizontal orientation underneath a glass surface and placed into a Gaseous Electronics Conference Radio Frequency Reference Cell. Experiments were run with the magnet dipole axis oriented both parallel and perpendicular to the camera axis. Experiments were conducted at a pressure of 1.33 and 5.33 Pa and melamine formaldehyde particles were introduced into plasma, acting as a diagnostic tool and reacting to the forces in the plasma. The electric accelerations in both the vertical and horizontal directions are a result of the presence of the magnetic field. It was found that these vertical and horizontal forces caused confinement, resulting in complex motion and horizontal transport of the dust particles within the plasma.

An assessment of a decentralized inductively heated plasma waste treatment system for energy recovery has been done. The modular miniaturized high enthalpy plasma source IPG6 is a reference for the system and has been qualified for inert but also chemically aggressive gas compositions. An identification and review of applications were undertaken. Niches of high environmental and societal importance are considered: hospital waste (threshold countries), shipboard waste and marine litter. The wastes are reviewed deriving relevant parameter for a system analysis aiming for the derivation of energy production and efficiencies. The system analysis shows advantageous constellation due to the wastes’ energy leading to self-feeding systems.

Introduction: At the Center for Astrophysics, Space Physics and Engineering Research (CASPER) at Baylor University, Texas, a GEC reference cell has been used to conduct experiments investigating magnetic field plasma surface interactions. The results of these experiments shall be used to help understand the formation of lunar swirls which are known to be located close to regions of magnetic anomalies. Strong crustal magnetic fields can influence the lunar plasma environment by separating charges and thus creating electric fields. This in turn can alter the incoming solar wind flux and dust transport processes. Experiments have been conducted to map electric forces in a plasma close to a magnet using dust as a probe. These experiments were conducted in preparation for future experiments within flowing plasma, representing the solar wind, which will be accomplished using the inductively heated plasma generator (IPG6-B) developed in close collaboration with the Institute of Space Systems (IRS), University of Stuttgart, Germany.