Showing papers on "Arcjet rocket published in 2018"

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 ...

Numerical Study of Plasma–Electrode Interaction During Arc Discharge in a DC Plasma Torch

Abstract: Energy transfer within an arc is of crucial importance in numerous applications, such as thermal spraying and electric propulsion (arcjet and magnetoplasmadynamic thruster). Its control will frequently determine the viability of a process or a device. However, a lot of numerical works done to model arc discharge using finite volume or finite element method consider the arc core only, while the near-electrode layers are ignored and replaced by a presumed boundary condition. This greatly limits the reliability of the simulation model. The goal of this paper is to make the bulk plasma coupled with electrode regions, where the special space charge layer (sheath) on cathode is taken into account. This is achieved by a simplified 1-D sheath model developed in this paper, which is then applied on a nontransferred dc plasma torch to study the thermodynamic and electromagnetic interaction between plasma and electrodes. The simulated results in electrode and plasma regions are presented, the predicted temporal evolution of electric potential with sheath model is in good agreement with the experimental measurements.

Overview of thermal arcjet thruster development

Abstract: Purpose This paper aims to provide an overview of current and historical arcjet development. The reviewed arcjets are considered with respect to both design and thruster relevant parameters. Correspondingly, the paper enables the identification of adequate design criteria and of the probable thruster parameters. Design/methodology/approach The approach consists of a database for thruster relevant parameters in conjunction with relevant operational requirements (such as type of propellant) and specific design criteria (such as e.g. propellant injection systems). Findings The synopsis of both operational parameter and respectively assigned design allows for the derivation of development approaches for arcjets under given high level requirements such as power regime. Research limitations/implications The paper is a general review. However, its strength is in the synthesis of the arcjet classification, the functional evidence of design criteria and the application scenario. Practical implications Not only basic but also specific design criteria are analyzed and evaluated leading to a recommendation feature of the paper with respect to the overall design of adequate arcjets. Social implications Within the scope of the Clean Space initiative, new applications and scenarios from the operation of arcjets arise enabling EOL phases of spacecraft that fulfill respective levels of debris mitigation and, in addition, the requirements concerning the adequately adapted re-entry of spacecrafts that are at end of life. Originality/value The paper is a general review. However, its strength is in the synthesis of the arcjet classification, the functional evidence of design criteria and the application scenario.

Characteristics of an under-expanded supersonic flow in arcjet plasmas

Abstract: A compact apparatus to produce arcjet plasma was fabricated to investigate supersonic flow dynamics. Periodic bright–dark emission structures were formed in the arcjets, depending on the plasma source and ambient gas pressures in the vacuum chamber. A directional Langmuir probe (DLP) and emission spectroscopy were employed to characterize plasma parameters such as the Mach number of plasma flows and clarify the mechanism for the generation of the emission pattern. In particular, in order to investigate the influence of the Mach number on probe size, we used two DLPs of different probe size. The results indicated that the arcjets could be classified into shock-free expansion and under-expansion, and the behavior of plasma flow could be described by compressible fluid dynamics. Comparison of the Langmuir probe results with emission and laser absorption spectroscopy showed that the small diameter probe was reliable to determine the Mach number, even for the supersonic jet.

Thermal Response Analysis of Porous Carbon-based Non-Ablative Heatshield in an Arcjet Flow Condition

Abstract: A computational method capable of calculating radiative heat transfer in a porous carbon-based material is developed in this study. In the method, a radiative conductivity value is statistically evaluated using a three-dimensional model of the material constructed using X-ray computed tomography images. The method is applied for thermal response analysis of a non-ablative heat shield called the Non-Ablative Lightweight Thermal protection system (NALT), which is heated in an arcjet flow. The arcjet heating environment is calculated in a coupled manner between nonequilibrium arcjet flow computation and NALT thermal response analysis. The results shows that the computational method developed satisfactorily reproduces the surface and in-depth temperature data measured.

Arcjet plasma temperature estimation in thruster device

Abstract: Дано описание применения методов кинетической теории газов для оценки параметров плазмы дугового разряда электротермического микродвигателя корректирующих двигательных установок. Известное утверждение об адиабатическом характере процесса сжатия за счет роста температуры газа имеет первостепенное значение для установления больцмановского распределения возбужденных атомов по энергетическим уровням. На примере применения аргона в качестве рабочего тела предложен подход к определению газовой температуры электродугового микродвигателя. Результаты исследования могут быть использованы при конструировании летательных аппаратов.

IRAS: Low-cost Constellation Satellite Design, Electric Propulsion and Concurrent Engineering

Abstract: The Integrated Research Platform for affordable Satellites (IRAS) is a joint research project by DLR, Fraunhofer, IRS and industry partners aimed at developing cost-reducing technologies for satellites. This paper describes the various contributions of the IRS to IRAS, such as development of a reference satellite constellation for implementation and demonstration of new technologies. The digital concurrent engineering platform as an IRAS subproject is being described with regards to the envisioned aim and future application for unifying engineering tools from multiply stakeholders. It allows to create an efficient design toolchain to reduce development time and costs. The evolutionary system design converger is a contribution on the level of electric propulsion systems to the platform. It is given as a subsystem example of the capabilities of the digital concurrent engineering platform. Additional examples of analysis and outputs are given for the IRAS use case. Grid ion thrusters with xenon are likely to be able to provide an electric propulsion system with the lowest total system mass, while an ammonia based arcjet system will allow for the fastest regeneration of the constellation at a reasonable mass fraction. Additive manufacturing with its significant potential for space hardware cost reduction, while maintaining or increasing system performances due to function integration, is explained. An arcjet nozzle with integrated regenerative cooling channels has been identified as promising component. It is being manufactured from tungsten powder through selective laser melting.

The Effects of Swirl on Low Power Arcjet Thruster Flowfield and Heat Transfer Characteristics

Abstract: A steady, three-dimensional numerical model is developed for the low power arcjet thrusters. Numerical investigation was carried out to determine the effects of swirl on the flowfield and heat transfer characteristics inside the arcjet nozzle. Two different three-dimensional arcjet nozzle configurations with axial injectors and radial injectors are used in this numerical study in order to reveal the effects of swirl on the flowfield and heat transfer characteristics inside the arcjet nozzle. Comparisons of the flowfield and heat transfer characteristics in the two different three-dimensional configurations, i.e., with axial injectors and radial injectors respectively, are performed to reveal the effects of the swirl flow. The distributions of pressure, temperature, axial velocity and tangential velocity in the two different three-dimensional configurations are presented. The modeling results show that there exist evident three-dimensional effects of the flowfield in both the configuration with axial injectors and the nozzle with radial injectors. The swirl in the configuration with axial injectors is dissipated with small magnitude while it is inerratic for the case with radial injectors. The tangential velocity magnitude in the nozzle with radial injectors is big enough to persist downstream and is enhanced at the constrictor entrance. It is found that the swirl flow has evident influences on the flowfield, heat transfer characteristics inside the arcjet nozzle and little effect on electric field and thrust of the thruster when the arcjet thruster operated under the operation condition used in the study.

Multicomponent Arcjet plasma Parameters

Abstract: To determine the plasma arc parameters of an arcjet thruster, the kinetic theory of gases is used. We can find a well-known statement about the adiabatic character of the compression process due to the growth of the gas temperature in a change in its spectral composition and in the Doppler effect. The use of tungsten in the nozzle design details explains the appearance of atoms of this element in the plasma volume. The emission spectra of tungsten allow us to indirectly judge the temperature of the arc discharge and its character. Absorption of the long-wavelength wing of the line contour at λ = 465.987 nm substantiates our conclusion about the consumption of the anode material in the process of operating the arcjet. The Doppler shift of the emission lines of argon allows us to determine the rate of the gas jet escape. The results of the study can be useful in the design of aircraft.

Visualization of a Periodic Structure in Arcjet Plasma by Laser Absorption Spectroscopy

Abstract: We performed spatially-resolved laser absorption spectroscopy of argon arcjet plasma with characteristic optical emission structures. We observed a periodic change of temperatures corresponding to the emission intensities alone the jet axis.