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Israel G. Cabane M. Brun J-F. Niemann H. Way S. Riedler W. Steller M. Raulin F. Coscia D. 《Space Science Reviews》2002,104(1-4):433-468
ACP's main objective is the chemical analysis of the aerosols in Titan's atmosphere. For this purpose, it will sample the
aerosols during descent and prepare the collected matter (by evaporation, pyrolysis and gas products transfer) for analysis
by the Huygens Gas Chromatograph Mass Spectrometer (GCMS). A sampling system is required for sampling the aerosols in the
135'32 km and 22'17 km altitude regions of Titan's atmosphere. A pump unit is used to force the gas flow through a filter.
In its sampling position, the filter front face extends a few mm beyond the inlet tube. The oven is a pyrolysis furnace where
a heating element can heat the filter and hence the sampled aerosols to 250 °C or 600 °C. The oven contains the filter, which
has a thimble-like shape (height 28 mm). For transferring effluent gas and pyrolysis products to GCMS, the carrier gas is
a labeled nitrogen 15N2, to avoid unwanted secondary reactions with Titan's atmospheric nitrogen.
Aeraulic tests under cold temperature conditions were conducted by using a cold gas test system developed by ONERA. The objective
of the test was to demonstrate the functional ability of the instrument during the descent of the probe and to understand
its thermal behavior, that is to test the performance of all its components, pump unit and mechanisms.
In order to validate ACP's scientific performance, pyrolysis tests were conducted at LISA on solid phase material synthesized
from experimental simulation. The chromatogram obtained by GCMS analysis shows many organic compounds. Some GC peaks appear
clearly from the total mass spectra, with specific ions well identified thanks to the very high sensitivity of the mass spectrometer.
The program selected for calibrating the flight model is directly linked to the GCMS calibration plan. In order not to pollute
the two flight models with products of solid samples such as tholins, we excluded any direct pyrolysis tests through the ACP
oven during the first phase of the calibration. Post probe descent simulation of flight results are planned, using the much
representative GCMS and ACP spare models.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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We discuss the current theoretical understanding of the large scale flows observed in the solar convection zone, namely the differential rotation and meridional circulation. Based on multi-D numerical simulations we describe which physical processes are at the origin of these large scale flows, how they are maintained and what sets their unique profiles. We also discuss how dynamo generated magnetic field may influence such a delicate dynamical balance and lead to a temporal modulation of the amplitude and profiles of the solar large scale flows. 相似文献
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Lasek Andrzej Brun Edmond Antoine 《IEEE transactions on aerospace and electronic systems》1967,(3):460-464
An attempt to employ a magnetically driven shock tube as a tool for aerodynamic studies of high velocity and high enthalpy flows is described. Examples of results are given. 相似文献
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An experimental study of the spatio-temporal evolution of the transition in a shock-tube wall boundary-layer has been carried out with thin film heat transfer gauges placed all along the tube. The results show that the transition appears, for small initial pressures, under the form of turbulent spots which are periodically created: these spots grow and are transported roughly at a velocity slightly smaller than the inviscid flow, regressing towards the contact surface. For higher initial pressures, a continuous transitional front is created which moves at about the same velocity as the shock-wave. These results seem to explain previous and often contradictory interpretations based on quasi-punctual measurements but the fact remains that the characterization criteria of the transition in unsteady boundary layers are still to be studied. 相似文献
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