<i>Vacuum Physics and Technology</i>

The existing literature data shows that conventional aluminium alloys may not be suitable for use in stellar-radiation environments as their hardening phases are prone to dissolve upon exposure to energetic irradiation, resulting in alloy softening which may reduce the lifetime of such materials impairing future human-based space missions. The innovative methodology of crossover alloying is herein used to synthesize an aluminium alloy with a radiation resistant hardening phase. This alloy-a crossover of 5xxx and 7xxx series Al-alloys-is subjected to extreme heavy ion irradiations in situ within a TEM up to a dose of 1 dpa and major experimental observations are made: the Mg 32 (Zn,Al) 49 hardening precipitates (denoted as T-phase) for this alloy system surprisingly survive the extreme irradiation conditions, no cavities are found to nucleate and displacement damage is observed to develop in the form of black-spots. This discovery indicates that a high phase fraction of hardening precipitates is a crucial parameter for achieving superior radiation tolerance. Based on such observations, this current work sets new guidelines for the design of metallic alloys for space exploration.

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“…In summary, the following list of requirements must be observed in selecting space materials [5][6][7][8][9][10][11][12][13][14][15][16][17] :…”

Section: Introductionmentioning

confidence: 99%

Prototypic Lightweight Alloy Design for Stellar‐Radiation Environments

et al. 2020

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“…The central funnel is extended by a duct of 10 cm length (PTFE) preventing contaminated air from the proximity of the instrument to stream through the measurement zone. PTFE is chosen because of its low porosity and its low outgassing rate under reduced pressure (Weissler and Carlson, 1980). In addition, it is hydrophobic and generally non-adhesive, thus preventing the deposition of hydrometeors or condensate at the inlet.…”

Section: Integrationmentioning

confidence: 99%

Compact and Lightweight Mid-IR Laser Spectrometer for Balloon-borne Water Vapor Measurements in the UTLS

Gräf¹,

Scheidegger²,

Kupferschmid³

et al. 2020

Preprint

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Abstract. We describe the development, characterization and first field deployments of a quantum cascade laser direct absorption spectrometer (QCLAS) for water vapor measurements in the upper troposphere and lower stratosphere. The instrument is sufficiently small (30×23×11 cm3) and lightweight (3.9 kg) to be carried by meteorological balloons and used for frequent soundings in the upper troposphere and lower stratosphere (UTLS). The spectrometer is a fully independent system, operating autonomously for the duration of a balloon flight. To achieve the required robustness, while satisfying stringent mass limitations, the concepts for optics and electronics have been fundamentally reconsidered compared to laboratory-based spectrometers. A significant enhancement of the mechanical and optical stability is achieved by integrating a segmented circular multipass cell. The H2O mixing ratio is retrieved by calibration-free evaluation of the spectral data, i.e., only relying on SI-traceable measurements and absorption line parameters. An open-path design reduces the risk of contamination, allows fast response and thus high vertical resolution. Laboratory-based characterization experiments show an agreement within 2 % to reference measurements and a precision of 0.1 % under conditions comparable to the UTLS. The instrument successfully performed two balloon-borne test flights up to 28 km altitude. In the troposphere, the retrieved spectroscopic data was in excellent agreement with the parallel measurements by a frost point hygrometer (CFH). At higher altitude, the quality of the spectral data remained unchanged, but outgassed water vapor within the instrument enclosure was reducing the accuracy of the retrieved water vapor data. Despite this limitation, these test flights demonstrated the successful deployment of a laser spectrometer in the UTLS aboard a low-volume meteorological balloon, with the perspective of future highly resolved, accurate and cost-efficient soundings.

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“…In fact, molecular free passes A without collision at the mentioned pressure range (or corresponding densities 10 13 -10 15 cm-3 ) are much more than diagram diameters d, but can be about the tube length £ (we assumed neutral collision cross section a -10-16 cm-2 , [9]). …”

Section: ' "'mentioning

confidence: 99%

“…First, the ,... 10 em long by ,... 1 em diameter connecting tube is a section of bellows which acts like a series of diaphragms rather than a smooth-wa 11 ed pipe. Second, the pressure region is intermediate between laminar and molecular flow so that the conductance, L, and hence the pressure drop, t.P = Q.L, where Q is the gas throughput, is dependent on pressure as given by the Knudsen fo.rmul a [9]:…”

Section: The Experimental Arrangement On the Nbstfmentioning

confidence: 99%