Stopping of energetic sulfur and bromine ions in dense hydrogen plasma

The concepts of communicative space, media sphere and public sphere are sometimes used like synonyms one of the other. However, according to us, they are three different concepts: public sphere and media sphere are two distinct spaces symbolic systems which, both, are anchored in communicative spac

INVESTIGATION OF THE TRANSMISSION AND STOPPING OF LIGHT IONS PASSING THROUGH A PLASMA TARGET

Transmission and energy losses of 2 MeV/u Carbon and Sulphur beams passing through a plasma target, have been extensively investigated. A hydrogen plasma ignited by an electrical discharge was coupled to the Orsay Tandem beam accelerator. Fluctuations in beam transmission have been observed and attributed to a magnetic focusing effect generated during the plasma evolution. Energy loss measurements were performed on the basis of time of flight techniques and indicate an enhanced stopping power of the plasma relative to its cold matter equivalent

EFFECT OF THE ION MOTION AT LOW ELECTRON DENSITIES ON THE PROFILES OF THE LINES 4471 Å AND 4922 Å OF HeI

No abstract availabl

Determination of the parameters of a plasma JET generated by a capillary discharge

A pulsed capillary discharge has been the subject of various experimental and theoretical studies. A jet of copperhydrogen plasma with a cylindrical symmetry has been developed as a light source for spectroscopic measurements. The electron density of the plasma was obtained by using the Hβ spectral line of the hydrogen component plasma. The electron temperature was determined by means of the Boltzmann method applied to the copper profiles emitted by the plasma jet. The copper and hydrogen lines were broadened principally by the Stark effect. The electron density of the plasma was found to be about 2×1017 cm–3 and the electron temperature about 20000K

PLASMA DIAGNOSTICS IN THE HEAVY ION BEAM-DENSE PLASMA INTERACTION EXPERIMENT AT ORSAY

On décrit la source plasma utilisée lors d'expériences d'interaction entre un faisceau d'ions lourds (C4+ ou S7+) à une énergie de 2 Mev par nucléon et un plasma. Le but était de mesurer la perte d'énergie des ions dans le plasma. Les méthodes de diagnostic du plasma par spectroscopie d'émission, par interférométrie laser et par absorption laser à deux longueurs d'ondes sont présentées ainsi que les résultats.We describe the plasma source used for interaction experiments between heavy ion beams (C4+ S7+) at energies of 2 Mev per nucleon and a plasma. The purpose of these experiments was to measure the ion energy loss in the plasma. The plasma diagnostics methods by emission spectroscopy, by laser interferometry and two-wavelength laser absorption are presented as well as the results

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Abstract A pulsed capillary discharge has been the subject of various experimental and theoretical studies. A jet of copperhydrogen plasma with a cylindrical symmetry has been developed as a light source for spectroscopic measurements. The electron density of the plasma was obtained by using the H β spectral line of the hydrogen component plasma. The electron temperature was determined by means of the Boltzmann method applied to the copper profiles emitted by the plasma jet. The copper and hydrogen lines were broadened principally by the Stark effect. The electron density of the plasma was found to be about 2×10 17 cm -3 and the electron temperature about 20000K

Energy loss of heavy ions in a plasma target

The public: definitions and perceptions The public is a difficult concept to grasp. It exhibits contradictory meanings: a collective abstract entity that is based on a “togetherness” founded on the exercise of reason; a cumulative heterogeneous phenomenon formed into an audience by certain kinds of specialised proceedings; or, another possibility, the driving force of action aimed at modifying something of the individuals that one wishes to reach. In all these cases, it is not a self-defined social collective. However, we constantly speak of the public's point of view. Can we really contemplate a situation in which the public could be thought of as a potential enunciator of a point of view? Or at least as an interlocutor in communication with the institutions of which it is the public? This article describes the division between the status of the members of the public engaged in interpersonal communications with representatives of the institution and the status of the public as a collective abstract entity engaged in a “communication” with the institution

Caractérisation du seuil d'ablation des parois dans les sources de rayonnement EUV par décharge capillaire

Les sources de rayonnement Extrême Ultraviolet (EUV) par décharge capillaire connaissent un intérêt de plus en plus considérable pour de nombreuses applications scientifiques et technologiques. Au GREMI, nous étudions le fonctionnement des sources de rayonnement EUV émettant à 13.5 nm pouvant répondre à certaines applications liées à la nouvelle génération de la lithographie. Ces sources pulsées, nommées CAPELLA, AT$\lambda$AS et PROXIMA, sont basées sur une décharge capillaire en flux de gaz. Ce type de décharge produit un plasma chaud, dense et fortement ionisé émettant dans la gamme spectrale de l'EUV. En effet, les températures électroniques peuvent atteindre des dizaines d'électronvolts et les densités électroniques sont de l'ordre de $10^{17}$ cm$^{\hbox{-}3}$. Les échanges thermiques entre le plasma ainsi créé et les parois du capillaire peuvent être suffisamment important pour que les parois du capillaire soient ablatées. Cette ablation peut être plus ou moins importante selon la densité d'énergie injectée dans le capillaire. Des mesures spectroscopiques du plasma émetteur dans les gammes spectrales de l'UV et l'EUV ont montré la présence d'un seuil d'ablation situé autour de à 350 J.cm$^{\hbox{-}3}$. Nous utilisons un modèle thermique présenté [1] pour modéliser l'évolution temporelle de la température des parois du capillaire. Le seuil peut être ainsi estimé. Les résultats expérimentaux obtenus à partir de nos mesures spectroscopiques sont comparés ensuite aux résultats numériques