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thumb|Tir d'un projectile par un obusier M198. Un projectile (du latin projectus : jeté en avant) est un corps lancé ou projeté pour atteindre une cible. Dans le domaine de la balistique, il s'agit plus particulièrement d'un corps projeté par une arme. Un projectile peut provenir d'une arme de jet (flèche) ou d'une arme à feu (balle/calibre inférieur à 20 mm, obus/calibre supérieur à 20 mm…), ou bien être lancé à main nue comme une pierre, un pavé, une dague, un marteau ou une lance. Notes et références Catégorie:Munition

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Concepts associés (29)

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Séances de cours associées (15)

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Enhanced critical current densities in (Bi, Pb)(2)Sr2Ca2Cu3O10 silver-sheathed tapes by splayed columnar defects after 600 MeV proton irradiation

Splayed columnar defects are efficient pinning centers for magnetic vortices in High-T-c Superconductors. Irradiation with 000 MeV protons as primary projectiles generates heavy fission fragments in (Bi, Pb)(2)Sr2Ca2Cu3O10 via a p-Bi nuclear reaction. The high-Z secondary projectiles are sufficiently energetic to create randomly oriented columnar defects with important effects on the magnetic and transport critical current densities of (Bi, Pb)(2)Sr2Ca2Cu3O10 Ag-sheathed tapes. These effects are discussed on the basis of the splayed defect topology.

1997

Chargement

Population modelling of the He II energy levels in tokamak plasmas: I. Collisional excitation model

Otto Asunta, Patrick Blanchard, Yann Camenen, Stefano Coda, Basil Duval, Ambrogio Fasoli, Jonathan Marc Philippe Faustin, Davide Galassi, Javier García Hernández, Jonathan Graves, Jan Horacek, Samuel Lanthaler, Yves Martin, Mikhail Maslov, Federico Nespoli, Hamish William Patten, Alessandro Pau, Antonio José Pereira de Figueiredo, David Pfefferlé, Richard Pitts, Olivier Sauter, Cristian Sommariva, Duccio Testa, Nicola Vianello, Henri Weisen, Dalziel Joseph Wilson, Marco Wischmeier, Liang Yao, Yao Zhou

Helium is widely used as a fuel or minority gas in laboratory fusion experiments, and will be present as ash in DT thermonuclear plasmas. It is therefore essential to have a good understanding of its atomic physics. To this end He II population modelling has been undertaken for the spectroscopic levels arising from shells with principal quantum number n = 1-5. This paper focuses on a collisional excitation model; ionisation and recombination will be considered in a subsequent article. Heavy particle collisional excitation rate coefficients have been generated to supplement the currently-available atomic data for He II, and are presented for proton, deuteron, triton and alpha-particle projectiles. The widely-used criterion for levels within an n shell being populated in proportion to their statistical weights is reassessed with the most recent atomic data, and found not to apply to the He II levels at tokamak densities (10(18)-10(21) m(-3)). Consequences of this and other likely sources of errors are quantified, as is the effect of differing electron and ion temperatures. Line intensity ratios, including the so-called 'branching ratios' and the fine-structure beta(1), beta(2), beta(3), and gamma ratios, are discussed, the latter with regard to their possible use as diagnostics.

2019

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Hypervelocity impact testing on stochastic and structured open porosity cast Al-Si cellular structures for space applications

Andreas Mortensen

A hypervelocity (6.7–7.0 km/s) impact testing campaign was conducted using Ø 2 mm, 95% Al projectiles onto A357 aluminium alloy stochastic foams with 4–5 mm typical pore dimensions, or alternatively diamond cubic periodic structures of cast AlSi12 with a 6 mm lattice parameter, in order to assess their performance as shielding material against orbital impacts. Either 0.15 mm Al foil or multi-layer insulation (MLI) was used as a front bumper material. It was found that the periodic structures failed to retain the impact debris for any incident angle of impact between 0° and 12°, at least in part due to ricochets and/or spalled material finding its way through open straight channels within the periodic structure. A porous material architecture traversed by no open, straight path is thus required for proper impact protection. Stochastic foams satisfy this criterion and indeed were found to stop the debris. Depending on bumper configuration, stochastic foams gave comparable performance to that of simple Whipple shield designs at 1.3–1.9 ×  the areal weight. We suggest that a finer pore structure with respect to the projectile diameter should yield a higher impact absorption per areal weight. As an auxiliary result, it was found that MLI as a front bumper was less efficient in fragmenting the projectile compared to Al foil of similar areal weight. In conclusion, open porosity stochastic foams are a promising material as sandwich panel cores for space applications, as they may reduce the need for a dedicated shield, so long as the small debris produced by the impact can be isolated from the satellite systems.

2018

Chargement

Fusée (astronautique)

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Balle (projectile)

Une balle est un projectile d'arme à feu d'un calibre inférieur à , de type pistolet, carabine, fusil, pistolet mitrailleur, fusil mitrailleur… (au-delà, on parlera d'obus). Le mot « balle » dési

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La poudre noire, parfois dénommée poudre à canon ou poudre à fusil, est le plus ancien explosif chimique connu. De couleur noire, elle est constituée d'un mélange déflagrant de soufre, de nitrate de

PHYS-101(en): General physics : mechanics (English)

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ME-628: High Strain Rate Mechanics of Materials

This course offers fundamentals concepts of material behavior under dynamic loads such as impact and shock. lt will cover experimental methods and analytical modeling approaches to describe the dynamic deformation behavior of metals, ceramics and polymeric materials.

PHYS-101(g): General physics : mechanics

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