Performance Evaluation of a Novel Inductive Atmosphere-Breathing EP System

Challenging space mission scenarios include those in low altitude orbits, where the atmosphere creates significant drag to the S/C and forces their orbit to an early decay. An atmosphere-breathing electric propulsion system (ABEP) ingests the residual atmosphere through an intake and uses it as propellant for an electric thruster that compensates the drag. Theoretically applicable to any planet with atmosphere, the system might allow to orbit for an unlimited period without carrying propellant on-board. IRS has several decades of heritage on the development of inductively heated plasma generators (IPG). Such devices are electrodeless, therefore issues of potential electrode erosion are eliminated. This paper deals with the complete refurbishment of a facility that was previously used for RIT testing, for the use of IPG6-S, a small scale IPG with an input power up to 3.5 kW. This facility allows more reliable test conditions. First operational and performance tests of IPG6-S have been performed. IPG6-S serves as test bed for the development of an inductive plasma thruster (IPT) for ABEP application. A newly designed water-cooled de Laval nozzle has been built and applied to IPG6-S. The nozzle is modular, it has the possibility of having various configurations so to assess its performance in terms of plasma acceleration and thrust production. Within this paper plasma plume energy has been measured by means of a cavity calorimeter and correlated to current, power, and pressure in the injector head.Peer ReviewedPostprint (published version

Influence of Specific Energy Inhomogeneity on the CO2 Splitting Performance in a High-Power Plasma Jet

Plasma-based CO2 conversion is a promising pathway towards greenhouse gas recycling. In the corresponding research field, various types of plasma reactors are applied for carbon dioxide dissociation. So far, spatial inhomogeneities of the specific energy (SEI) distribution in plasma generators, e.g., induced by non-uniform heating or an inhomogeneous mass distribution, are not the focus of the investigations. In this work, the spatial inhomogeneity of mass-specific enthalpy in the plasma jet of the inductive plasma generator IPG4 at the Institute of Space Systems (IRS) is examined. For this, the mean mass-specific enthalpy as well as the radial distribution of the local enthalpy are measured using plasma probes. Moreover, the influence of the determined specific enthalpy inhomogeneity on the CO2 splitting performance is quantified. It is shown that an inhomogeneous radial distribution of the specific energy can significantly lower the carbon dioxide conversion, compared to a homogeneous case. With regards to IPG4, the performance reduction is 16 %.Comment: 30 pages, 12 figure

Mars and Venus entry simulation capabilities of IRS plasma wind tunnel PWK3

An assessment is made for the inductively driven plasma wind tunnel PWK3 with the goal to derive relevant mass specific enthalpies for typical Mars and Venus atmospheric entry missions. For this purpose an integral method has been used which links the plasma power to the radial distribution of total pressure and fully catalytic heat flux in the plasma jet on basis of a relation from Marvin and Pope. Rebuilding the enthalpies with this relation allows for the derivation of a gas specific proportionality factor. This factor enables the derivation of the mass specific enthalpies at the centre line and the radial profiles for the respective condition are not necessarily required any more. Correspondingly a review of reference CO2 plasma conditions obtained in past investigations at IRS leads to the identification of an operational envelope in terms of the mass specific enthalpies which are from an energy consideration the prerequisite for the creation of similarities with respect to the real atmospheric entry maneuvers. The analysis shows that PWK3 is capable to cover the full range of mass specific enthalpies that are required for typical Mars and Venus atmospheric entry scenarios

DEVELOPMENT OF A DEPLOYABLE DECELERATOR CONCEPT FOR SMALL MARS LANDERS

Small exploration spacecraft and landers have proven to be scientifically useful and capable with missions such as Philae or Hayabusa 2. For the exploration of planetary bodies with atmospheres, novel and efficient entry, descent and landing (EDL) technologies are being explored. One of these concepts is the rigid deployable decelerator, which would be an alternative to existing EDL systems if proven to be feasible. For a Mars micro lander mission with an entry mass of 25 kg and a ballistic coefficient of 3:5 kg=m2, a concept for a deployable decelerator was developed. First, a flow-field analysis of different possible geometries of the deployed structure with Ansys Fluent was performed. From this, the pressure and temperature distribution and qualitatively the heat flux density along the profile wall of each geometry were determined. Subsequently, for a conical geometry, a design for a deployment mechanism was developed based on the umbrella concept, where a deployable structure spans a flexible thermally resistant cloth. The mechanism developed is a combination of folding parallelised struts, similar to an umbrella, and telescopic rods. Focusing on the strut structure and based on the results of the flow field analysis, with Ansys it was then investigated whether the design can in principle withstand the mechanical loads generated by the maximum dynamic pressure and how the temperature behind the deployed cloth is distributed under the maximum thermal load

Relation between Crystal Structure and Transition Temperature of Superconducting Metals and Alloys

Using the Roeser–Huber equation, which was originally developed for high temperature superconductors (HTSc) (H. Roeser et al., Acta Astronautica 62 (2008) 733), we present a calculation of the superconducting transition temperatures, Tc, of some elements with fcc unit cells (Pb, Al), some elements with bcc unit cells (Nb, V), Sn with a tetragonal unit cell and several simple metallic alloys (NbN, NbTi, the A15 compounds and MgB2). All calculations used only the crystallographic information and available data of the electronic configuration of the constituents. The model itself is based on viewing superconductivity as a resonance effect, and the superconducting charge carriers moving through the crystal interact with a typical crystal distance, x. It is found that all calculated Tc-data fall within a narrow error margin on a straight line when plotting (2x) 2 vs. 1/Tc like in the case for HTSc. Furthermore, we discuss the problems when obtaining data for Tc from the literature or from experiments, which are needed for comparison with the calculated data. The Tc-data presented here agree reasonably well with the literature data

Experimental investigation of MHD impact on argon plasma flows by variation of magnetic flux density

The interaction between a probe body and argon plasma flow is investigated to examine to what extent the probe head temperature and the bow shock distance can be influenced by applying a strong magnetic field. The experiments are performed using a strong permanent magnet installed inside a probe body with a spherical, coated probe head. Former investigations showed strong influence on the bow shock geometry but also on the inflow plasma jet. Several boundary conditions have been varied to evaluate their influence toward the experiment. For an uncoated probe head the measured MHD impact was found to be of the same order of magnitude as for the coated case. Electrical isolation of the probe toward the vacuum chamber yielded only slight influence. The variation of the field strength was realized by changing the amount of magnet segments installed. Pictures were analyzed to minute the MHD interaction for each test case. It was found that the bow shock distance increased and the temperature of the probe head decreased while increasing the magnetic field density. This analysis precedes a thorough characterization of the plasma condition

Simultaneous in Situ Measurements of Small-Scale Structures in Neutral, Plasma, and Atomic Oxygen Densities During the WADIS Sounding Rocket Project

In this paper we present an overview of measurements conducted during the WADIS-2 rocket campaign. We investigate the effect of small-scale processes like gravity waves and turbulence on the distribution of atomic oxygen and other species in the mesosphere–lower thermosphere (MLT) region. Our analysis suggests that density fluctuations of atomic oxygen are coupled to fluctuations of other constituents, i.e., plasma and neutrals. Our measurements show that all measured quantities, including winds, densities, and temperatures, reveal signatures of both waves and turbulence. We show observations of gravity wave saturation and breakdown together with simultaneous measurements of generated turbulence. Atomic oxygen inside turbulence layers shows two different spectral behaviors, which might imply a change in its diffusion properties