Uwe Bauder

Electrostatic Probe and Camera Measurements for Modeling the iMPD SIMP-LEX

In order to further investigate and characterize the instationary magnetoplasmadynamic thruster SIMP-LEX, measurement as well as modeling approaches were taken. Triple probe and time of ight probe measurements were conducted for a bank energy of 80J, varying the distance between the electrodes as well as the position of the probes along the axes. From these measurements, electron temperature, electron density and velocity of the plasma plume could be determined as a function of time. They showed to be in reasonably good agreement with data found in literature. Additionall, the position, form and velocity of the plasma plume was observed by means of a high speed camera in 100ns steps after thruster ignition. From these pictures it is possible to clearly discern three phases of one plasma pulse. It was also possible to determine a mean velocity of the rst plasma wave. To understand the thruster further and to be able to predict thruster characteristics, a model of the thruster was established bytaking a simple slug model approach. This model was extended to better represent the physical phenomena within the thruster. The data obtained from the measurements mentioned above were used to verify and correct this model.

Current Numerical and Experimental Investigations of the Hybrid DC-RF Thruster TIHTUS

Electric space propulsion delivers high exhaust velocities usually in combination with relatively low thrust levels. Raising the thrust level at a constant high exhaust velocity, fuel consumption for a specific mission is reduced and payload mass is increased. Also, an increase in mission flexibility and a reduction of duration can be achieved. Promising thrusters are hybrid concepts like TIHTUS. This thruster combines an arcjet and an ICP in series. The proof of concept already shows promising results. After a description of the thruster system actual experimental and theoretical optimizations of the standalone ICP are summarized. For a decrease of wall thickness from 2.3 mm to 1.25 mm the thermal plasma power is increased by 40 % and the thinner quartz tube can resist higher heat loads, too. These results show the potential for large improvements of the overall thruster parameters and motivate a research program for further optimization of the already promising TIHTUS engine. In this program, theoretical and experimental investigation will be accompanied by numerical simulations for a detailed understanding of the relevant processes and the identification of the prospects of success for further optimization. The current status of development of the numerical tool is also described.

Development of a Two Phase Solver Accounting for Solid Particles in Continuum Gas Flows

The Euler-Lagrangian approach is used for the simulation of solid particles in hypersonic entry flows. For flow field simulation, the program SINA (Sequential Iterative Nonequilibrium Algorithm) developed at the Institut fur Raumfahrtsysteme is used. The model for the effect of the carrier gas on a particle includes drag force only. Other parameters like lift Magnus force or damping torque are not taken into account so far. The reverse effect of the particle phase on the gaseous phase is currently neglected. Parametric analysis is done regarding the impact of variation in the physical input conditions like position, velocity, size and material of the particle. Convective heat fluxes onto the surface of the particle and its radiative cooling are discussed. The variation of particle temperature under different conditions is presented. The influence of various input conditions on the trajectory is explained. A semi empirical model for the particle wall interaction is also discussed and the influence of the wall on the particle trajectory with different particle conditions is presented.

Two-Phase Flow Solver for Hypersonic Entry Flows in a Dusty Martian Atmosphere

The occurrence of global dust storms on Mars is one of the most spectacular meteorological events in the solar system. The following question arises: What influence might dust particles have on the heat flux onto a heat shield of a planetary probe entering the Martian atmosphere? For the numerical simulation of such an entry, the sequential iterative nonequilibrium algorithm program previously developed at the Institut fur Raumfahrtsysteme is used. A five-species model (CO2, O2, CO, O, and C) is implemented in the code. The Euler–Lagrangian approach is used for the modeling and simulation of the solid dust particles in the hypersonic entry flow. An adequate model for the drag force computation is implemented. The heat transfer model of the particles consists of convective heating and radiation cooling. With these models, heat fluxes onto the heat shield of the Mars sample return orbiter spacecraft due to impingement of particles are computed and compared with the convective heat fluxes from the continuum ...

Improvement and Extension of the Loosely Coupled Navier- Stokes Code SINA to Different Gases

The Finite-Volume Navier-Stokes code SINA was originally developed for the numerical simulation of re-entry problems and plasma wind tunnels. Therefore, the chemistry was fixed to Parks model for N 2O2. In order to expand the operation purpose to hydro gen driven electric plasma sources or Martian atmosphere entry simulation for example, the chemistry part of the loosely coupled scheme is rebuilt more flexible using external files for the definition of the reaction scheme. A reaction schem e for hydrogen is implemented and the results are shown. The chemistry is solved using a Newton-method with numerical derivation and an Euler timestep for stability.