The Tore Supra Data Acquisition System was completely redesigned in 1996, for plasma control and long pulse operation. It is now based on the Rtworks package which provides all the software basic ...modules to build a distributed on-line system, from data acquisition level up to run control and data display. In the same time, the real-time plasma control system has been improved with several control units upgraded with VME hardware and PowerPC processors interconnected through a fast shared memory network.
The graphical user interface (GUI) for the supervision of Tore Supra is intended to supervise the start-up and the shut-down of the installation, to control general state (state of all diagnostics, ...state of the system and network) and to follow the pulse sequence. Implementation of a new multi-platform, modular GUI for Tore Supra is in progress. This provides not only a simpler, more structured view for the non-specialist user, but also is open-ended and adaptable to a wide variety of uses. The actual implementation of a GUI is a question of user-ergonomics. Hence, a user-directed study in 2000 produced a specification for the interface. The information is treated with a hierarchical order. At the top level, only the global state of the supervised elements appears, i.e. the general state of every diagnostics, the pulse sequence, the safety systems. If a problem occurs, the operator has access to the lower level detailed state of the concerned element, simply with a double-click. An event log also helps the operator to analyse the chronology of the alarms arising during the pulse. Although the GUI is mainly used in the control room on X terminals under Unix, it should also be accessible via a portable PC for the purpose of maintenance, or directly from any office to see how the physics program is progressing. The choice of Java, multi-platform object programming language was thus adopted with access via any web browser. The modularity of the GUI is made possible by a distributed architecture (remote method invocation) between the graphic client and different servers: one for the diagnostics and the sequence, one for the system and the network and one for the configuration database. All the components interact with each other in a very simple and standard way. This distributed architecture allows the progressive set up of the new interface. The first step, being produced for mid-2001 is the GUI for the supervision of diagnostics. This prototype will help us to validate all the concepts. The second step in mid-2002 will be the complete GUI to supervise and execute pulse sequences and maintenance operations.
The quasi-elastic scattering of 1 GeV protons permits the three-dimensional reconstruction of the density distribution in extended bodies. Fast multiwire proportional chambers are used to localize ...the position of every incoming and outgoing charged particle and to determine the coordinates at the interaction vertex. This article describes tests on a human head fixed on formalin. The comparison with computed tomography scans and anatomical sections is encouraging. Slices with a volume element of 5.5 mm3 illustrate the sensitivity of the method. The results also demonstrate the ability of the method to select the density distribution of hydrogen by making use of the kinematic relations specific to elastic scattering. Trials of this method in living humans are being planned.
Progress in Nuclear Scattering Radiography Charpak, G.; Guillerminet, B.; Leopold, M. ...
IEEE transactions on nuclear science,
01/1979, Letnik:
26, Številka:
1
Journal Article
Recenzirano
using conventional techniques of high energy physics, density distributions inside thick bodies can be mapped reconstructing the interaction vertex of charged particles in the GeV region. As compared ...to X-ray computer assisted tomography, nuclear scattering radiography offers the advantages of being fully three-dimensional and of reducing the overall radiation dose for a comparable image quality; furthermore, a subset of the data that corresponds to elastic interactions allows to measure the hydrogen density distribution in the object which is a unique feature of this method. Preliminary results obtained on a preserved human head are here presented.
The combination of r.f. waves in the lower hybrid (LH) and ion cyclotron frequency ranges offers a versatile and efficient way of heating tokamak plasmas while controlling their properties and ...magnetohydrodynamic stability through the control of the current density profile. Experimental and theoretical studies on the applications of such plasma waves have been carried out on Tore Supra during recent years and are reported here.
The LH system coupled up to 6.5 MW during 2 s at 3.7 GHz through two multijunction launchers. In the longest plasma shot, the total injected LH energy reaches a record value of 170 MJ during a 62 s LH pulse, at a power level of 2.8 MW, corresponding to an average power density of 17 MW m
−2. The ion cyclotron resonant frequency (ICRF) system (35–80 MHz) is composed of three resonant double-loop antennae. Up to 4 MW have been coupled with a single antenna, allowing a record power density through the Faraday screen of 16 MW m
−2 to be reached. 30 s steady-state r.f. pulses have been obtained with up to 54 MJ delivered to the plasma. One of the major observations has been the transition to the so-called “stationary lower hybrid enhanced performance (LHEP) regime” (
I
P = 0.8 MA;
n
e0 = 2.8 × 10
19m
−3;
P
LH = 3.2 MW) in which the (flat)_central current density (
q
0 ∼2) and (peaked) electron temperature profiles (
T
e0 ∼ 6–8 keV) are fully decoupled. This regime exhibits a significant improvement of the global confinement (40%) owing to the increase in
l
i, i.e. in the magnetic shear in the outer half of the discharge, supplemented by a large reduction in the electron thermal diffusivity in the central zone where the magnetic shear vanishes because of the slight off-axis character of the LH power and current deposition.
Transp analyses show that LHEP plasmas provide access to the second ballooning stability regime. At higher current and density (
I
p = 1.5 MA;
n
e0 = 6 × 10
3m
−3), ICRH stabilization of sawteeth (4 MW) combined with lower hybrid current drive (LHCD) current profile modifications has allowed to extend the stabilized phase for up to 1 s with 3.4 MW of LH power, the duration of sawtooth-free periods increasing with increasing LH power. The dynamical properties of fast electrons during LHCD have been investigated recently on Tore Supra through power modulation experiments. It is shown that slowing down always predominates and, from the long-time evolution of the hard X-ray emission, the radial diffusion rate of the fast electrons is estimated to be 0.1–0.3 m
2s
−1.
Theoretical developments have focused on the modelling of LHCD and also on fast wave current drive (FWCD) and fast wave heating. The effect of intrinsic stochasticity on the propagation of LH waves is discussed and a fully developed statistical theory of stochastic wave diffusion and multipass absorption, with applications to Tore Supra through a wave diffusion-Fokker-Planck (WDFP) numerical code, is briefly presented. This model provides a simple explanation for the temperature dependence of the LHCD efficiency in small tokamaks. The ion cyclotron resonant heating (ICRH) full-wave code
Alcyon has been upgraded to compute the power and current deposition profiles from direct electron absorption of the fast wave (electron Landau damping-transit time magnetic pumping). The code has been used to study FWCD in Tore Supra, the Joint European Torus and the International Thermonuclear Experimental Reactor.
Finally a new concept of an efficiently cooled reflector antenna for LHCD applications in a steady-state reactor is briefly described.
Abstract
Indigenous Peoples and local communities with nature-dependent livelihoods are disproportionately affected by climate change impacts, but their experience, knowledge and needs receive ...inadequate attention in climate research and policy. Here, we discuss three key findings of a collaborative research consortium arising from the
Local Indicators of Climate Change Impacts
project. First, reports of environmental change by Indigenous Peoples and local communities provide holistic, relational, placed-based, culturally-grounded and multi-causal understandings of change, largely focused on processes and elements that are relevant to local livelihoods and cultures. These reports demonstrate that the impacts of climate change intersect with and exacerbate historical effects of socioeconomic and political marginalization. Second, drawing on rich bodies of inter-generational knowledge, Indigenous Peoples and local communities have developed context-specific responses to environmental change grounded in local resources and strategies that often absorb the impacts of multiple drivers of change. Indigenous Peoples and local communities adjust in diverse ways to impacts on their livelihoods, but the adoption of responses often comes at a significant cost due to economic, political, and socio-cultural barriers operating at societal, community, household, and individual levels. Finally, divergent understandings of change challenge generalizations in research examining the human dimensions of climate change. Evidence from Indigenous and local knowledge systems is context-dependent and not always aligned with scientific evidence. Exploring divergent understandings of the concept of change derived from different knowledge systems can yield new insights which may help prioritize research and policy actions to address local needs and priorities.
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