M. Talvard | Université Paris Saclay (original) (raw)

Papers by M. Talvard

Communication presentee a IAEA technical committee meeting on the avoidance and control of tokama... more Communication presentee a IAEA technical committee meeting on the avoidance and control of tokamak distuptions, Culham (UK), 10-12 Sept. 1991Available at INIST (FR), Document Supply Service, under shelf-number : RM 1490 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Available at INIST (FR), Document Supply Service, under shelf-number : RM 1277 / INIST-CNRS - Ins... more Available at INIST (FR), Document Supply Service, under shelf-number : RM 1277 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX

We present the latest results obtained with the wide-field submillimeter camera ArTeMiS that is o... more We present the latest results obtained with the wide-field submillimeter camera ArTeMiS that is operating on APEX since July 2013. This camera is presently equipped with 1870 pixels at 350 μm and 800 pixels at 450 μm simultaneously. ArTéMiS is a PI-camera open to the ESO and Swedish community. It has already taken a part in the 2016-2017 scientific results of APEX. So far, it offers the best performance in terms of mapping speed at 350 and 450 μm in the southern hemisphere. Major improvements of the APEX telescope have been achieved at the end of 2017, requiring a complete removal of the instruments in the C-Cabin. In the meantime, the ArTeMiS camera has been kept safe at the ALMA Operations Support Facility (OSF) building. We took advantage of this re-installation to improve a bit more the optical coupling of detectors. We present here the present status of the camera. Since APEX operation is now guaranteed until the end of 2022, our prospects are to install in time new detectors presently developed at CEA/Léti in the frame of R&D developments made for the future SPICA space mission. Those detectors, which have new polarization capabilities, are also presented.

Research in Nondestructive Evaluation, 2000

Molecular oxygen can act as a collisional quencher of the singlet excited state of chlorophyll a.... more Molecular oxygen can act as a collisional quencher of the singlet excited state of chlorophyll a. This effect is well described for chlorophyll a in various solvents but not for chlorophyll a in the antenna complexes of photosynthetic organisms. We studied the chlorophyll fluorescence decay of Chlorella vulgaris cells under different oxygen concentrations but did not find any evidence for quenching by oxygen.

Aims. Expanding HII regions and propagating shocks are common in the environment of young high-ma... more Aims. Expanding HII regions and propagating shocks are common in the environment of young high-mass star-forming complexes. They can compress a pre-existing molecular cloud and trigger the formation of dense cores. We investigate whether these phenomena can explain the formation of high-mass protostars within an infrared dark cloud located at the position of G327.3-0.6 in the Galactic plane, in between two large infrared bubbles and two HII regions. Methods. The region of G327.3-0.6 was imaged at 450µm with the CEA P-ArTéMiS bolometer array on the Atacama Pathfinder EXperiment telescope in Chile. APEX/LABOCA and APEX-2A, and Spitzer/IRAC and MIPS archives data were used in this study. Results. Ten massive cores were detected in the P-ArTéMiS image, embedded within the infrared dark cloud seen in absorption at both 8 and 24µm. Their luminosities and masses indicate that they form high-mass stars. The kinematical study of the region suggests that the infrared bubbles expand toward the...

which has been recently named MESSINE (Model for Electromagnetic Simplified Simulation In Nondest... more which has been recently named MESSINE (Model for Electromagnetic Simplified Simulation In Nondestructive Evaluation), to predict eddy current signal. The proposed model first discretizes the eddy current distribution into current loops. A parametric

Fusion Science and Technology, 2009

ABSTRACT None. Consists of a list of team members and affiliations.

Note: Proc. 18th EPS Conference on Controlled Fusion and Plasma Physics, Berlin, F.R.G., June 199... more Note: Proc. 18th EPS Conference on Controlled Fusion and Plasma Physics, Berlin, F.R.G., June 1991, Vol. 15C, Part -201, A51(1991) Reference CRPP-CONF-1991-033 Record created on 2008-05-13, modified on 2017-05-12

High dynamic range dust continuum map of the NGC 6334 star-forming complex at 350 microns obtaine... more High dynamic range dust continuum map of the NGC 6334 star-forming complex at 350 microns obtained by combining high-resolution ground-based observations taken with the ArTeMiS camera on the APEX telescope and Herschel Space Observatory data from the HOBYS key project (Motte et al., 2010AA Russeil et al. 2013A&A...554A..42R). The effective angular resolution is ~ 8" (HPBW). (2 data files).

Astronomy & Astrophysics

Context. The Orion molecular cloud is the closest region of high-mass star formation. It is an id... more Context. The Orion molecular cloud is the closest region of high-mass star formation. It is an ideal target for investigating the detailed structure of massive star-forming filaments at high resolution and the relevance of the filament paradigm for the earliest stages of intermediate- to high-mass star formation. Aims. Within the Orion A molecular cloud, the integral-shaped filament (ISF) is a prominent, degree-long structure of dense gas and dust with clear signs of recent and ongoing high-mass star formation. Our aim is to characterise the structure of this massive filament at moderately high angular resolution (8′′ or ~0.016 pc) in order to measure the intrinsic width of the main filament, down to scales well below 0.1 pc, which has been identified as the characteristic width of filaments. Methods. We used the ArTéMiS bolometer camera at APEX to map a ~0.6 × 0.2 deg2 region covering OMC-1, OMC-2, and OMC-3 at 350 and 450 μm. We combined these data with Herschel-SPIRE maps to reco...

Fusion Science and Technology

In view of high-power, long pulse steady-state operation, Tore Supra has incorporated in its desi... more In view of high-power, long pulse steady-state operation, Tore Supra has incorporated in its design the active control of heat and particles in a realistic environment. A new inner-wall technology was developed in 1994 and is to be tested in 1995-1996 with a totally rebuilt 40-deg toroidal sector. A carbon-fiber-reinforced carbon-metal compound is based on the newest brazing technology and regorous quality control. Components such as the toroidal pump limiter and the guard limiters of plasma-heating antennas are being developed in the same way. For structures where brazing is difficult, boron carbide-coated components have been developed and installed in Tore Supra. For lower heat fluxes, a bolted concept has been designed and tested. The influence of inner-first-wall misalignment in Tore Supra on the power exhaust limitation of brazed components has been studied. Results from the technological development for the different power exhaust systems and the associated experimental knowl...

Plasma Physics and Controlled Fusion, 1991

ABSTRACT Recent Lower Hybrid Current Drive (LHCD) experiments in TORE SUPRA and JET are reported.... more ABSTRACT Recent Lower Hybrid Current Drive (LHCD) experiments in TORE SUPRA and JET are reported. Large multijunction launchers have allowed the coupling of 5 MW to the plasma for several seconds with a maximum of 3.8 kw/cm2. Measurements of the scattering matrices of the antennae show good agreement with theory. The current drive efficiency in TORE SUPRA is about 0.2 x 10(20) Am-2/W with LH power alone and reaches 0.4 x 10(20) Am-2/W in JET thanks to a high volume-averaged electron temperature (1.9 keV) and also to a synergy between Lower Hybrid and Fast Magnetosonic Waves. At N(e)BAR = 1.5 x 10(19) m-3 in TORE SUPRA, sawteeth are suppressed and m = 1 MHD oscillations the frequency of which clearly depends on the amount of LH power are observed on soft x-rays, and also on non-thermal ECE. In JET ICRH produced sawtooth-free periods are extended by the application of LHCD (2.9 s. with 4 MW ICRH) and current profile broadening has been clearly observed consistent with off-axis fast electron populations. LH power modulation experiments performed in TORE SUPRA at N(e)BAR = 4 x 10(19) m-3 show a delayed central electron heating despite the off-axis creation of suprathermal electrons, thus ruling out the possibility of a direct heating through central wave absorption. A possible explanation in terms of anomlous fast electron transport and classical slowing down would yield a diffusion coefficient of the order of 10 m2/s for the fast electrons. Other interpretations such as an anomalous heat pinch or a central confinement enhancement cannot be excluded. Finally, successful pellet fuelling of a partially LH driven plasma was obtained in TORE SUPRA, 28 successive pellets allowing the density to rise to N(e)BAR = 4 x 10(19) m-3. This could be achieved by switching the LH power off for 90 ms before each pellet injection, i.e. without modifying significantly the current density profile.