The first observations of Laser Induced Breakdown (LIB) in gases were made upon the days of the invention of lasers and were initially reported by Maker. In those experiments it was observed that, gases which are normally transparent to optical radiation (e.g., Air), could be transformed in high-temperature plasmas by focusing a laser beam onto a small volume. When the operating conditions...
INTRODUCTION
A broad range of high-enthalpy and plasma technology applications exhibit thermochemical nonequilibrium effects, ranging from solar physics and thermal plasmas [1], combustion and plasma-assisted ignition [2], diagnostics [3], and materials technology in general. In aerospace applications, the radiative heat flux to the heat shield of planetary entry probes [4] depends on the...
Carbon dioxide radiative prediction is an important aspect in many scientific and industrial applications. Highly accurate databases such as HITRAN \cite{GORDON20173}, HITEMP \cite{ROTHMAN20102139} or CDSD \cite{TASHKUN2003165}\cite{TASHKUN20111403} are designed to reconstruct the spectrum in a given temperature accurately. However, in the context of atmospheric entry these databases have some...
In order to represent the interactions between particles composing chemical systems of practical interest for the hypersonic community, such as N2 + N [1], CO + O and O2 + C [2], and O2 + O [3], during the last decade a variety of Potential Energy Surfaces (PESs) has been computed starting from the first principle of quantum physics. The accuracy of these potentials, together with the...
- Introduction
The reentry of space debris is a major safety concern. Since only part of the debris are destroyed in the atmosphere, it is essential to be able to characterize the size, number and impact zone of the remaining fragments. Estimating the survivability of an object and its trajectory requires an accurate knowledge of the aerothermodynamics of the shock layer surrounding it.
At...
Laser breakdown is observed when a high-intensity laser beam is focused into a small region of gas. The discharge is composed of two stages: (a) creation of the priming electrons, and (b) formation of a highly conductive and absorbing plasma. This initial phase is then followed by a post-discharge, characterized by the formation and propagation of a shock wave from the focal region. The...
Background
Upcoming missions to Mars considered by JAXA generate strong motivation in designing advanced thermal protection systems (TPSs) with low design margins, in an effort to reduce the launching costs and increase the scientific value of the mission by embedding larger payloads and to enhance the reliability and safety of the reentry systems. The sizing of the TPSs relies on...
Abstract
Radiation processes are important for the description and understanding of plasma phenomena, since the radiative heat flux on the capsule can be substantial [1]. Experimental measurements are often complicated for several reasons. An alternative is the numerical simulation. Here, the common approach is the coupling of a CFD method with a radiation solver and a radiation...
1. Introduction
Computational Fluid Dynamics (CFD) represent the most cost-effective tool to characterize re-entry flows aiming at providing an accurate prediction of engineering inputs (e.g. surface heat fluxes) for the design of TPS and the overall success of space missions. The vast majority of state-of-the-art CFD codes tackling hypersonic applications rely on...
1. Introduction
Hypersonic aerothermodynamics (ATD) involves a plethora of complex physical phenomena. The harsh environment within the post-shock region produces a significant effect on the flow where fluid properties such as specific heat, viscosity and thermal conductivity can no longer be considered constant as in traditional aerodynamics. Instead they vary with temperature,...
Status of ESTHER and the associated VUV and CO2 IR instrumentation TRP's
REVISED SHOCK LAYER RADIATION MODELING FOR AIR
Brett A. Cruden(1), Aaron M. Brandis
(1)AMA Inc, NASA Ames Research Center, Moffett Field, CA 94035, USA, E-mail:Brett.A.Cruden@nasa.gov
ABSTRACT
At the previous RHTG workshop, we reported a series of shock layer radiation measurements collected between 7-9 km/s and the corresponding disagreement to predicted radiance through the NEQAIR...
During atmospheric entry high velocity free-stream gas decelerates rapidly through a shock near the vehicle surface. This sudden compression results in very high post-shock temperatures which are sufficient to cause thermochemical changes in the gas, including dissociation and ionisation. The internal energy modes of the flow also become excited, causing electromagnetic radiation to be...
SHOCK LAYER KINETICS OF CO AND CO2-BASED ATMOSPHERES
Brett A. Cruden(1), Aaron M. Brandis
(1)AMA Inc, NASA Ames Research Center, Moffett Field, CA 94035, USA, E-mail:Brett.A.Cruden@nasa.gov
ABSTRACT
The present paper reports the analysis of shocks in pure CO at velocities from 3-9 km/s in NASA Ames’ Electric Arc Shock Tube (EAST) facility, with the intent of simplifying the analysis...
Detailed spectrally and spatially resolved radiance has been measured in the Electric Arc Shock Tube at NASA Ames Research Center for conditions relevant to Titan entry, with varying atmospheric composition, free-stream density (equivalently, altitude) and shock velocity. The test campaign measured radiation at velocities from 4.7 km/s to 8 km/s and free-stream pressures of 0.1, 0.28 and 0.47...
A compact reflectometer has been developed at Instituto de Plasmas e Fus\~{a}o Nuclear for Fusion plasma monitoring applications. This work describes the application of this diagnostic to the conditions and requirements of atmosperic entry flows, where the knowledge of the properties for the plasma surrounding the vehicle is key.
Indeed, on the next experimental fusion reactors, the number...
We use optical emission spectroscopy to measure spectrally resolved radiation from a recombining nitrogen plasma for temperatures ranging from 3200 to 7000 K. An inductively coupled plasma torch is used to create an equilibrium plasma, which is then forced to rapidly recombine by flowing through a water-cooled tube. The density of atomic nitrogen is measured and found to be overpopulated. This...
Thermodynamics has always been a fundamental and necessary discipline in support of fluid dynamics. In subsonic and (moderately) supersonic flows, the thermodynamic description of the fluid is relatively simple and can be accomplished at macroscopic, phenomenological level. Things complicate when energy densities in the flow field increase, as in aerothermodynamics. Nonequilibrium processes...
A test campaign was performed in the GHIBLI arc jet facility in the framework of the European funded LIGHT-TPS project, devoted to research and development of Ultra-High Temperature Ceramics (UHTC) coatings on Ceramic Matrix Composites (CMC) for super light-weight Thermal Protection Systems (TPS) of space re-entry vehicles.
Two UHTC coatings made of different zirconium diboride (ZrB2)...
Two-photon induced polarization spectroscopy (TIPS) is a laser diagnostic technique that relies on the simultaneous absorption of two photons, one being contributed by a strong, circularly polarized pump beam and the other by a weaker, linearly polarized probe beam. The two beams are crossed at a slight angle thus defining the measurement volume. Through consideration of the two-photon...
Future space missions, such as planned asteroid sample return missions or interplanetary missions such as return from Mars, will involve entry speeds from 13 to 15km/s. While current hyperbolic Earth re-entry conditions such as Apollo, Hayabusa, and Stardust all featured some degree of radiative heating, a 15 km/s Earth entry will cross the threshold into the region where radiative heat flux...
The atmospheric entry of spacecraft is characterized by very high entry speeds and the formation of a bow shock in front of the blunt body. The sudden deceleration of the vehicle converts the kinetic energy of the vehicle into thermal energy of the gas which gets dissipated in the form of convective and radiative heat transfer. The gas species trapped inside the shock layer undergo a very high...
The current study is aimed at developing a simulation framework that is rooted in ab-initio theory and deals with thermal, chemical, and radiative non-equilibrium during hypersonic planetary entry in a unified manner. Computing the population of individual energy states or the radiative intensity corresponding to a given frequency is unfeasible, even for the simplest flow problem, owing to the...
This work presents the STELLAR (State-To-State ELementARy Rates) database update for CO$_2$, providing a dataset suited for the modeling of vibrationally-specific excitation (V--T) and dissociation (V--D) processes in Carbon Dioxide.
The implemented datasets provide a better and more physically consistent description of the physical-chemical processes in emerging applications (such as...
Previous investigations have demonstrated how flowfield modelling can effect predicted level of radiation on a prospect future demonstrator-vehicle concept entering at hyperbolic velocity (Merrifield 2014). Thus far, sensitivities within the radiation database have only be briefly examined (Joiner 2015) by comparing PARADE and NEQAIR radiation databases. A significant difference uncovered in...
The instrumentation package COMARS+ was part of the back cover instrumentation of the ExoMars Schiaparelli lander and consisted of three COMARS sensors and one broadband radiometer. The aerothermal sensors called COMARS combine four discrete sensors measuring static pressure, total heat flux, temperature and radiative heat flux. The Schiaparelli capsule was launched on top of a Proton launcher...
ESA recently flew an entry, descent, and landing demonstrator module called Schiaparelli that entered the atmosphere of Mars on the 19th of October, 2016. The instrumentation suite included heatshield and backshell pressure transducers and thermocouples (known as AMELIA) and backshell radiation and direct heatflux-sensing sensors (known as COMARS and ICOTOM). Due to the failed landing of...
The aerothermal characterization of the instrumentation package COMARS+ of the Schiaparelli lander of the Exomars 2016 mission has been carried out in Martian flow environment of the arc heated facility L2K. The combined sensors COMARS and the broadband radiometer for radiative heat flux measurements were able to successfully measure the radiative heat flux on the back cover close to the...
In spite of the crash of Schiaparelli, the Exomars Descent Module in October 2016, following a nevertheless successful aerothermodynamic entry, data from the infrared radiometers ICOTOM embedded of the COMARS modules was sent to the orbiter before and after the blackout phase. Three pairs of radiometers were located in line on the back shield of the probe in order to monitor the infrared...
We present a reinvestigation of the Galileo 1995 Jupiter entry, where we attempt to reinvestigate the question of the excessive heating at the shoulder, which is postulated to occur due to radiative heating.
We consider two improvements to the radiative model: H2 molecular systems contributions to the plasma emission and absorption coefficients are accounted for, and a ray-tracing model...
The paper is focused on the state-to-state kinetics modeling the dissociation and ionization of hydrogen in high-enthalpy shock tubes. The model determines the rate coefficients of electron impact processes from the non-equilibrium electron energy distribution function (eedf) obtained solving the Boltzmann equation.
Entry computations for Martian atmosphere yield to significant radiative heat loads. CO2 is the main constituent of this atmosphere and a complex molecule. This molecule and its dissociative products have the ability to strongly emit and absorb radiative heat loads. In fact, previous investigations [1] revealed radiative heating to be crucial not only for the stagnation point region but also...
Sending a manned mission to Mars is often viewed as one of next steps in space exploration. Naturally, all the challenges associated with this endeavour must be well-understood in order to sustain a permanent human presence. One of these challenges is the creation of a breathable environment. In this work, it is argued that a sustainable oxygen supply in Mars can be achieved by converting...
This keynote deliver the status of the ESA activities in the newly created area of flight vehicle engineering and aerothermodynamics. The keynote show mission, programs, technologies, and techniques on the above mentioned areas and provides an overview of the Agency current and upcoming activities.
This keynote will also include a small round table about ESA upcoming research activities on...
The results of the airborne observation of ATV-1 resulted in excellent data about re-entry break-up [1]. The triangulation of the video data showed experimentally the distribution of debris on ground and the spectral data allowed some insight into the destructive entry process[1].
![ATV-1 re-entry][1]
ATV-1 during re-entry flight (photo: C. Carpenter/B. Moede, NASA Ames)
The High...
The paper and presentation will introduce the mission and the R&D activities with respect to material, plasma sciences undertaken by the Japanese space start-up 'Astro Live Experiences' (ALE) to develop safe, unparalleled and on-demand shooting stars . Various topics will be covered including, but not limited to:
- the ALE mission and benefit for society
- modeling of plasma and material...
The elemental composition In our early solar system is still one of the key questions to understand its evolution as well as our solar system objects (planets, asteroids, comet, … ) as we know them today [4,5]. Since many decades, scientists try to unravel this composition by a wide variety of experiments, i.e. by laboratory analysis of Interplanetary Dust Particles (IDPs) available from the...
We present a Computational Fluid Radiative Dynamics simulation of the Saint Valentin entry. CFD simulations have been carried out using the ESA code TINA, whereas radiative transfer simulations have been carried out using the SPARK Line-by-Line code, with an updated database capable of reproducing molecular VUV radiation of high temperature air plasmas.
A sensitivity analysis of the radiative...
- Introduction
Meteoroids largely disintegrate during their entry in the atmosphere, contributing significantly to the input of cosmic material to Earth. Yet, their atmospheric entry is not well understood. Among the daily material delivered into our planet, the Chelyabinsk event in 2013 [1] renewed awareness of potential hazards motivating the planning of deflection and mitigation...