| 1. |
- Bécoulet, A., et al.
(author)
-
Science and technology research and development in support to ITER and the Broader Approach at CEA
- 2013
-
In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10
-
Journal article (peer-reviewed)abstract
- In parallel to the direct contribution to the procurement phase of ITER and Broader Approach, CEA has initiated research & development programmes, accompanied by experiments together with a significant modelling effort, aimed at ensuring robust operation, plasma performance, as well as mitigating the risks of the procurement phase. This overview reports the latest progress in both fusion science and technology including many areas, namely the mitigation of superconducting magnet quenches, disruption-generated runaway electrons, edge-localized modes (ELMs), the development of imaging surveillance, and heating and current drive systems for steady-state operation. The WEST (W Environment for Steady-state Tokamaks) project, turning Tore Supra into an actively cooled W-divertor platform open to the ITER partners and industries, is presented.
|
|
| 2. |
|
|
| 3. |
- Adam, A, et al.
(author)
-
Abstracts from Hydrocephalus 2016.
- 2017
-
In: Fluids and Barriers of the CNS. - : Springer Science and Business Media LLC. - 2045-8118. ; 14:Suppl 1
-
Journal article (peer-reviewed)
|
|
| 4. |
- Allaria, E., et al.
(author)
-
Highly coherent and stable pulses from the FERMI seeded free-electron laser in the extreme ultraviolet
- 2012
-
In: Nature Photonics. - 1749-4885. ; 6:10, s. 699-704
-
Journal article (peer-reviewed)abstract
- Free-electron lasers (FELs) are promising devices for generating light with laser-like properties in the extreme ultraviolet and X-ray spectral regions. Recently, FELs based on the self-amplified spontaneous emission (SASE) mechanism have allowed major breakthroughs in diffraction and spectroscopy applications, despite the relatively large shot-to-shot intensity and photon-energy fluctuations and the limited longitudinal coherence inherent in the SASE mechanism. Here, we report results on the initial performance of the FERMI seeded FEL, based on the high-gain harmonic generation configuration, in which an external laser is used to initiate the emission process. Emission from the FERMI FEL-1 source occurs in the form of pulses carrying energy of several tens of microjoules per pulse and tunable throughout the 65 to 20 nm wavelength range, with unprecedented shot-to-shot wavelength stability, low-intensity fluctuations, close to transform-limited bandwidth, transverse and longitudinal coherence and full control of polarization.
|
|
| 5. |
|
|
| 6. |
- Bos, Peter MJ, et al.
(author)
-
Human risk assessment of single exposure in chemical incidents : present situation and new and increasing chemical incident scenarios
- 2011
-
Reports (other academic/artistic)abstract
- The release of chemicals from their containment, either accidentally or deliberately, is one of the most relevant risk scenarios in Europe. A human health risk assessment is a prerequisite for chemical incident prevention, preparedness and response. European guidance and harmonized Acute Exposure Reference Values (AERVs) are urgently needed for effective human health risk assessment in the context of chemical incidents.At present, no broad European consensus is available on guidance for risk assessment, risk management and risk communication purposes in case of chemical incidents. A review of legislation, existing or currently under revision, suggests that harmonized European guidance is not expected to be developed in the short term. An increasing number of European countries are developing their own procedures to assess the human health risk of chemical incident scenarios. The AERVs thus produced serve different purposes and are not interchangeable. Lack of international harmonization seriously obstructs a consistent response in chemical emergencies with transboundary effects within and beyond the EU, will hamper multinational companies attempting to make consistent risk assessments worldwide and will hinder consistent and transparent assessment, and management and communication of risks by different stakeholders.Emerging chemical incident risk scenarios and risk drivers have been identified. It is recommended to monitor more frequently at an early stage for new trends in chemicals, scenarios and risks from chemical incidents. A need for a specific approach to deal with single exposure to mixtures of chemicals is identified, as well as for specific guidance to adequately protect professional first responders.
|
|
| 7. |
- Clerbaux, C., et al.
(author)
-
CO measurements from the ACE-FTS satellite instrument: data analysis and validation using ground-based, airborne and spaceborne observations
- 2008
-
In: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 8, s. 2569-2594
-
Journal article (peer-reviewed)abstract
- The Atmospheric Chemistry Experiment (ACE) mission was launched in August 2003 to sound the atmosphere by solar occultation. Carbon monoxide (CO), a good tracer of pollution plumes and atmospheric dynamics, is one of the key species provided by the primary instrument, the ACE-Fourier Transform Spectrometer (ACE-FTS). This instrument performs measurements in both the CO 1-0 and 2-0 ro-vibrational bands, from which vertically resolved CO concentration profiles are retrieved, from the mid-troposphere to the thermosphere. This paper presents an updated description of the ACE-FTS version 2.2 CO data product, along with a comprehensive validation of these profiles using available observations (February 2004 to December 2006). We have compared the CO partial columns with ground-based measurements using Fourier transform infrared spectroscopy and millimeter wave radiometry, and the volume mixing ratio profiles with airborne (both high-altitude balloon flight and airplane) observations. CO satellite observations provided by nadir-looking instruments (MOPITT and TES) as well as limb-viewing remote sensors (MIPAS, SMR and MLS) were also compared with the ACE-FTS CO products. We show that the ACE-FTS measurements provide CO profiles with small retrieval errors (better than 5% from the upper troposphere to 40 km, and better than 10% above). These observations agree well with the correlative measurements, considering the rather loose coincidence criteria in some cases. Based on the validation exercise we assess the following uncertainties to the ACE-FTS measurement data: better than 15% in the upper troposphere (8–12 km), than 30% in the lower stratosphere (12–30 km), and than 25% from 30 to 100 km.
|
|
| 8. |
- de Laat, A. T. J., et al.
(author)
-
Validation of five years (2003-2007) of SCIAMACHY CO total column measurements using ground-based spectrometer observations
- 2010
-
In: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 3:5, s. 1457-1471
-
Journal article (peer-reviewed)abstract
- This paper presents a validation study of SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) carbon monoxide (CO) total column measurements from the Iterative Maximum Likelihood Method (IMLM) algorithm using ground-based spectrometer observations from twenty surface stations for the five year time period of 2003-2007. Overall we find a good agreement between SCIAMACHY and ground-based observations for both mean values as well as seasonal variations. For high-latitude Northern Hemisphere stations absolute differences between SCIAMACHY and ground-based measurements are close to or fall within the SCIAMACHY CO 2 sigma precision of 0.2 x 10(18) molecules/cm(2) (similar to 10%) indicating that SCIAMACHY can observe CO accurately at high Northern Hemisphere latitudes. For Northern Hemisphere mid-latitude stations the validation is complicated due to the vicinity of emission sources for almost all stations, leading to higher ground-based measurements compared to SCIAMACHY CO within its typical sampling area of 8 degrees x 8 degrees. Comparisons with Northern Hemisphere mountain stations are hampered by elevation effects. After accounting for these effects, the validation provides satisfactory results. At Southern Hemisphere mid-to high latitudes SCIAMACHY is systematically lower than the ground-based measurements for 2003 and 2004, but for 2005 and later years the differences between SCIAMACHY and ground-based measurements fall within the SCIAMACHY precision. The 2003-2004 bias is consistent with previously reported results although its origin remains under investigation. No other systematic spatial or temporal biases could be identified based on the validation presented in this paper. Validation results are robust with regard to the choices of the instrument-noise error filter, sampling area, and time averaging required for the validation of SCIAMACHY CO total column measurements. Finally, our results show that the spatial coverage of the ground-based measurements available for the validation of the 2003-2007 SCIAMACHY CO columns is sub-optimal for validation purposes, and that the recent and ongoing expansion of the ground-based network by carefully selecting new locations may be very beneficial for SCIAMACHY CO and other satellite trace gas measurements validation efforts.
|
|
| 9. |
- Nassar, R., et al.
(author)
-
A global inventory of stratospheric chlorine in 2004
- 2006
-
In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 111:22
-
Journal article (peer-reviewed)abstract
- Total chlorine (CITOT) in the stratosphere has been determined using the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) measurements of HCl, ClONO2, CH3Cl, CCl4, CCl3F (CFC-11), CCl2F2 (CFC-12), CHClF2 (HCFC-22), CCl2FCClF2 (CFC-113), CH3CClF2 (HCFC-142b), COClF, and ClO supplemented by data from several other sources, including both measurements and models. Separate chlorine inventories were carried out in five latitude zones (60°-82°N, 30°-60°N, 30°S-30°N, 30°-60°S, and 60°-82°S), averaging the period of February 2004 to January 2005 inclusive, when possible, to deal with seasonal variations. The effect of diurnal variation was avoided by only using measurements taken at local sunset. Mean stratospheric ClTOT values of 3.65 ppbv were determined for both the northern and southern midlatitudes (with an estimated 1σ, accuracy of ±0.13 ppbv and a precision of ±.09 ppbv), accompanied by a slightly lower value in the tropics and slightly higher values at high latitudes. Stratospheric ClTOT profiles in all five latitude zones are nearly linear with a slight positive slope in ppbv /km. Both the observed slopes and pattern of latitudinal variation can be interpreted as evidence of the beginning of a decline in global stratospheric chlorine, which is qualitatively consistent with the mean stratospheric circulation pattern and time lag necessary for transport.
|
|
| 10. |
- Pop, Mihai, et al.
(author)
-
Single-shot transverse coherence in seeded and unseeded free-electron lasers: A comparison
- 2022
-
In: Physical Review Accelerators and Beams. - 2469-9888. ; 25:040701
-
Journal article (peer-reviewed)abstract
- The advent of x-ray free-electron lasers (FELs) drastically enhanced the capabilities of several analytical techniques, for which the degree of transverse (spatial) coherence of the source is essential. FELs can be operated in self-amplified spontaneous emission (SASE) or seeded configurations, which rely on a qualitatively different initialization of the amplification process leading to light emission. The degree of transverse coherence of SASE and seeded FELs has been characterized in the past, both experimentally and theoretically. However, a direct experimental comparison between the two regimes in similar operating conditions is missing, as well as an accurate study of the sensitivity of transverse coherence to key working parameters. In this paper, we carry out such a comparison, focusing in particular on the evolution of coherence during the light amplification process.
|
|
