Measurements of Air Plasma/Ablator Interactions in an Inductively Coupled Plasma Torch

MacDonald, Megan E.; Jacobs, Carolyn; Laux, Christophe O.; Zander, Fabian; Morgan, Richard G.

doi:10.2514/1.t4402

Cited by 41 publications

(46 citation statements)

References 37 publications

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“…The results were very similar; in most cases, the TCRP and pyrometer results were within 2% of each other. Some of these results have been previously reported by MacDonald et al [23]. Figure 10 shows an example result from one of these tests.…”

Section: B Plasma Torch Testingsupporting

confidence: 64%

Surface Temperature Measurements in Hypersonic Testing Using Digital Single-Lens Reflex Cameras

Zander

2016

Journal of Thermophysics and Heat Transfer

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A newly adapted temperature measurement technique is presented for measuring aerospace relevant high surface temperatures. A comparatively cheap, available digital single-lens reflex camera is used as the imaging system for a two-color ratio pyrometry technique. This provides a highly spatially resolved imaging system that uses the blue, green, and red pixels for the ratio pyrometry measurements. At the Centre for Hypersonics at the University of Queensland, a Canon EOS 400D camera was spectrally calibrated using a tungsten filament lamp and a monochromator. With the knowledge of the spectral response of the pixels, emission ratio calculations determining the temperature can be undertaken for images of any surface, which fulfills the requirement of radiating as a gray body. For this particular camera, the measurable temperature limits were determined to be between approximately 1500 and 3000 K. Two tests cases are presented demonstrating the use of this technique: first, a heated carbon-carbon sample tested in the X2 expansion tube, and second, a material sample in a plasma torch. In both cases, the temperature measurements were validated using an alternative method of measurement, and the two-color ratio pyrometry measured temperatures were found to be within 5% of the alternative measurement. This technique provides a highly spatially resolved, yet comparatively cheap method of temperature measurement for hightemperature surfaces such as those encountered in the aerospace field. It is anticipated that this technique can help provide more detailed information of the surface state during future aerospace testing. Nomenclature c = speed of light, m · s −1 h = Plank constant, 6.626 × 10 −34 m 2 · kg · s −1 k = Boltzmann constant, 1.381 × 10 −23 m 2 · kg · s −2 · K −1 L B = black-body radiance, W · m −2 · sr −1 · m −1 L G = gray-body radiance, W · m −2 · sr −1 · m −1 T = temperature, K ∈ = emissivity, -λ = wavelength, m

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Section: B Plasma Torch Testingsupporting

confidence: 64%

Surface Temperature Measurements in Hypersonic Testing Using Digital Single-Lens Reflex Cameras

Zander

2016

Journal of Thermophysics and Heat Transfer

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“…Conversely, in an oxidation reaction controlled environment, oxygen diffuses faster through a boundary layer than it is consumed at the surface and ablation increases with surface temperature. Recession rates of the CBCF material in high-enthalpy environments are also reported by MacDonald et al (56 µm/sec) 22 Three low-resolution spectrometers were used for observation of the gas-phase. Advantage of this instrument is a fast scanning of a wide spectral range (200 -1,000 nm) that allows for detection of multiple molecules and atoms, present in ablation analysis.…”

Section: Representative Resultsmentioning

confidence: 75%

“…These can be detected with this setup. Several research groups are recently applying emission spectroscopy to analyze the reactive boundary layer forming around ablative heat shield materials 19,22,43,44 . MacDonald et al 22 preformed ablation tests in an inductively coupled plasma.…”

Section: Discussionmentioning

confidence: 99%

“…Several research groups are recently applying emission spectroscopy to analyze the reactive boundary layer forming around ablative heat shield materials 19,22,43,44 . MacDonald et al 22 preformed ablation tests in an inductively coupled plasma. The setup consisted of a similar low-resolution spectrometer with a spectral resolution of 1.16 nm, which is lower than the resolution provided by the spectrometer used for our setup.…”

Section: Discussionmentioning

confidence: 99%

“…The facilities in use for material characterization are most commonly arc-heated [17][18][19][20] or induction coupled 21,22 torches, which provide high gas enthalpies with air as test gas, ideal for the simulation of atmospheric reentry. The subsonic 1.2MW Inductively Coupled Plasma (ICP) torch of the Plasmatron facility at the von Karman Institute (VKI) is able to reproduce the aerothermodynamic environment of atmospheric entry in the stagnation point boundary layer of a test object for a wide range of pressures and heat fluxes [23][24][25] .…”

Section: Introductionmentioning

confidence: 99%

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Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

Helber

Chazot

Hubin

et al. 2016

JoVE

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Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution for future high-speed reentry missions. But despite the advancements made since Apollo, heat flux prediction remains an imperfect science and engineers resort to safety factors to determine the TPS thickness. This goes at the expense of embarked payload, hampering, for example, sample return missions.Ground testing in plasma wind-tunnels is currently the only affordable possibility for both material qualification and validation of material response codes. The subsonic 1.2MW Inductively Coupled Plasmatron facility at the von Karman Institute for Fluid Dynamics is able to reproduce a wide range of reentry environments. This protocol describes a procedure for the study of the gas/surface interaction on ablative materials in high enthalpy flows and presents sample results of a non-pyrolyzing, ablating carbon fiber precursor. With this publication, the authors envisage the definition of a standard procedure, facilitating comparison with other laboratories and contributing to ongoing efforts to improve heat shield reliability and reduce design uncertainties.The described core techniques are non-intrusive methods to track the material recession with a high-speed camera along with the chemistry in the reactive boundary layer, probed by emission spectroscopy. Although optical emission spectroscopy is limited to line-of-sight measurements and is further constrained to electronically excited atoms and molecules, its simplicity and broad applicability still make it the technique of choice for analysis of the reactive boundary layer. Recession of the ablating sample further requires that the distance of the measurement location with respect to the surface is known at all times during the experiment. Calibration of the optical system of the applied three spectrometers allowed quantitative comparison. At the fiber scale, results from a post-test microscopy analysis are presented.

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Design of New Carbon-Phenolic Ablators: Manufacturing, Plasma Wind Tunnel Tests and Finite Element Model Rebuilding

et al. 2021

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Ablative materials represent a widespread solution for shielding space vehicles from overheating during a reentry phase in atmosphere where the high heating fluxes and the consequent high temperatures cannot be compatible with the vehicle structure and with the safety of the payload and/or the crew. In this work, two different kinds of carbon-phenolic ablators with a density of 0.3 g/cm3 were manufactured and their mechanical and thermal properties were experimentally evaluated. The thermal protection performances of the developed ablators were assessed in a hypersonic plasma wind tunnel facility, setting representative enthalpy and heat flux conditions (6 and 13 MW/m2), consistent with atmospheric reentry missions from high energy orbits. Data of the experimental tests were compared with the results obtained by a finite element model built up for these materials with the commercial software SAMCEF Amaryllis. All results enlighten the good performances of the ablators under severe heat flux conditions and outline their operating limits.

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Measurements of Air Plasma/Ablator Interactions in an Inductively Coupled Plasma Torch

Cited by 41 publications

References 37 publications

Surface Temperature Measurements in Hypersonic Testing Using Digital Single-Lens Reflex Cameras

Surface Temperature Measurements in Hypersonic Testing Using Digital Single-Lens Reflex Cameras

Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

Design of New Carbon-Phenolic Ablators: Manufacturing, Plasma Wind Tunnel Tests and Finite Element Model Rebuilding

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