Showing papers on "Arcjet rocket published in 2017"

Characterization of a Large-Scale Arcjet Facility Using Tunable Diode Laser Absorption Spectroscopy

Abstract: A laser-based sensor was developed and deployed for in situ monitoring of the gas temperature in the plenum after the arc heater and before the expansion nozzle in the 60 MW interaction heating fac...

Numerical Simulation of Nonequilibrium Species Diffusion in a Low-Power Nitrogen–Hydrogen Arcjet Thruster

Abstract: Species distributions in a low-power arcjet thruster are investigated using a two-dimensional thermal and chemical nonequilibrium numerical model that incorporates the self-consistent effective binary diffusion coefficient approximation treatment of diffusion. Plasma flows in arcjet thruster with different input mole ratios of nitrogen to hydrogen are modelled. It is found that species separation due to nonequilibrium chemical kinetic processes occurs mainly in the regions where the dissociation and ionization of nitrogen and hydrogen species take place. The enrichment of nitrogen molecules at the fringes of the arc and hydrogen molecules near the anode wall of the thruster occurs mainly because the recombination processes of these two gases occur in different temperature ranges. In the expansion portion of the thruster nozzle, the gas residence times are of the same order as some chemical kinetic processes. Comparison between the nitrogen and hydrogen species profiles at the constrictor and thruster exit shows that the recombination of hydrogen ions and atoms are dominant kinetic processes near the thruster centreline, while the chemical reactions of nitrogen species are almost frozen in the high speed flow. The effects of temperature and pressure gradients on the species diffusion inside the arcjet thruster are also presented, with thermal diffusion found to have a much larger influence than pressure diffusion.

Nonequilibrium modeling study on plasma flow features in a low-power nitrogen/hydrogen arcjet thruster

Abstract: Gasdynamic flow features in an electrothermal arcjet thruster with a mixture of 1:2 nitrogen/ hydrogen as the working gas have been studied by a two-temperature numerical simulation. Seven species and 17 kinetic processes are included in the chemical kinetic model used to represent dissociation, ionization, and the corresponding recombination reactions in this nitrogen/hydrogen mixture system. Based on the gas flow characteristics inside the arcjet nozzle, a new method is introduced to define the edge of the cold boundary layer, which is more convenient to analyze the evolution and development of plasma flow in an arcjet thruster. The results show that the arcjet thruster performance is determined largely by the exchange of energy and momentum between the low-density, high-temperature arc region and the high-density, coolflow region near the nozzle wall. A significant thermal nonequilibrium is found in the cold boundary layer in the expansion portion of the nozzle. The important chemical kinetic processes determining the distribution of hydrogen and nitrogen species in different flow regions are presented. It has been shown that the reaction rate of hydrogen species ionization impacted by electrons is much higher than that of nitrogen species ionization in the center of the constrictor of the arcjet thruster. This indicates that hydrogen species is very important in the conversion of applied electric energy into thermal energy in the constrictor region of the arcjet thruster.

Arcjet Tests and Thermal Response Analysis for Dual-Layer Woven Carbon Phenolic

Abstract: A new dual-layer carbon phenolic manufactured from a three-dimensional woven substrate was tested in three arcjet facilities over a range of environments up to heat flux of approximately 6 kW/cm2

Measurement of Ion Mach Number of Arcjet Plasmas by a Directional Langmuir Probe Under High-Gas Pressure

Abstract: Spatial profile of an ion Mach number for arcjet He and Ar plasmas are measured by using a directional Langmuir probe. The Ar arcjet has bright–dark emission structures, implying that expansion–compression waves are formed, whereas no structure is observed for the He discharge. It is found that for He plasma, the Mach number monotonically decreases along the jet axis, while in the Ar jet the prominent peaks appear. The peak positions are almost the same with the bright emission regions, indicating that there is a strong correlation between the plasma emission structure and the Mach number.

Towards the Development of Low Power Arcjet for Use with Green Propellant

Abstract: Conventional arcjet propellants are hydrazine and ammonia. Both are toxic and environmentally unfriendly, requiring the use of complicated handling logistics and increased cost. If successfully demonstrated in arcjets, the use of green propellants would alleviate these issues. This paper details improvements made to the design of a low-power arcjet to be used in testing. Diagnostic tools to be used to assess thruster performance were also developed. These include emission spectroscopy for the detection of thruster insulator erosion and a two-cord heterodyne laser interferometer to measure electron number densities and estimate the exit velocity of the propellant.

Low Power Arcjet Application for End of Life Satellite Servicing

Abstract: In this paper the results of a low-power arcjet study for satellites beginning-of-life and end-of life servicing by de-orbit is presented. Two distinct use cases were analysed while considering the common propellants hydrazine and ammonia, as well as the green alternative ADN based propellants. The first case allows for a stand-alone arcjet system, while the second case is hybridized with the main propulsion system. Both cases come with their individual challenges, which are high number of ignitions, long-time operation time and the necessity to cope with tank pressure blow down. Low power arcjets from the Institute of Space Systems at the University of Stuttgart serve as design reference. A number of various feeding system approaches are explored, a trade-off for minimal mass is made and an estimation on the technological readiness is given.