The European 2MW, 170GHz coaxial cavity gyrotron for ITER Hogge, J.-P.; Albajar, F.; Alberti, S. ...
2007 Joint 32nd International Conference on Infrared and Millimeter Waves and the 15th International Conference on Terahertz Electronics,
2007-Sep.
Conference Proceeding
Odprti dostop
In the reference ECH design, ITER requires a total of 20 MW/CW power at 170 GHz using gyrotrons with a unit power of 1 MW. A higher power per unit (2 MW/gyrotron) would result in a strong reduction ...of the cost of the whole ECRH system, and would also relax the room constraints on the launcher antenna design. The high power capability of coaxial cavity gyrotrons has been demonstrated with short pulse experiments at FZK. A collaborative effort between European research associations CRPP-EPFL, FZK and Thales Electron Devices (TED) has been launched by the European Fusion Development Agreement (EFDA) in 2003, aiming at the development of an industrial 170 GHz/2 MW/CW coaxial cavity gyrotron. The first prototype, although designed to be CW compatible is expected to reach 2 MW/ls and has been delivered by end of 2006. It will be tested in Lausanne, where a specially dedicated test facility has been built. The test facility has been designed to be flexible enough, allowing the possible commissioning of tubes with different characteristics, as well the tests of the launcher antenna at full performances. Initial experiments are planned for the end of the third quarter 2007.
The morphological changes found in kidneys of patients undergoing chronic Cyclosporine A (CSA) treatment could, despite of numerous attempts, not yet be reproduced in reliable experimental models. ...The purpose of the present investigation was to systematically scan the in vivo fixed kidneys in CSA treated Wistar rats at the light and electron microscopic level. The study revealed changes in the proximal tubules, i.e., inclusion bodies, vacuolization, microcalcifications and regeneration. Some glomeruli displayed a thickening of the parietal sheet of Bowman's capsule. At the electron microscopic level, individual necroses of myocytes in the tunica media of afferent arterioles were observed. Thus, at the ultrastructural level, the kidneys of CSA treated normotensive Wistar rats do reveal morphological changes similar to those occurring in man.
abridged We present a detailed comparison of fundamental dark matter halo properties retrieved by a substantial number of different halo finders. These codes span a wide range of techniques including ...friends-of-friends (FOF), spherical-overdensity (SO) and phase-space based algorithms. We further introduce a robust (and publicly available) suite of test scenarios that allows halo finder developers to compare the performance of their codes against those presented here. This set includes mock haloes containing various levels and distributions of substructure at a range of resolutions as well as a cosmological simulation of the large-scale structure of the universe. All the halo finding codes tested could successfully recover the spatial location of our mock haloes. They further returned lists of particles (potentially) belonging to the object that led to coinciding values for the maximum of the circular velocity profile and the radius where it is reached. All the finders based in configuration space struggled to recover substructure that was located close to the centre of the host halo and the radial dependence of the mass recovered varies from finder to finder. Those finders based in phase space could resolve central substructure although they found difficulties in accurately recovering its properties. Via a resolution study we found that most of the finders could not reliably recover substructure containing fewer than 30-40 particles. However, also here the phase space finders excelled by resolving substructure down to 10-20 particles. By comparing the halo finders using a high resolution cosmological volume we found that they agree remarkably well on fundamental properties of astrophysical significance (e.g. mass, position, velocity, and peak of the rotation curve).
The general control of tokamak plasmas has evolved considerably over the past few years with an increase in the plasma pulse length, an increase in the control of additional heating and fueling, and ...an increase in the degree to which the shape of the plasma can be varied. The Tokamak Configuration Variable (TCV) is specifically designed to explore the operational benefits of plasma shaping over a wide variety of plasma shapes. Consequently, considerable attention has been given to the control of the poloidal field coil currents that impose the desired shape. All aspects of the control of TCV plasmas, from the diagnostic measurements to the power supplies, via particular control algorithms and overall supervision are discussed.
"Some half dozen persons have written technically on combinatory logic, and most of these, including ourselves, have published something erroneous. Since some of our fellow sinners are among the most ...careful and competent logicians on the contemporary scene, we regard this as evidence that the subject is refractory. Thus fullness of exposition is necessory for accurary; and excessive condensation would be false economy here, even more than it is ordinarily."
A collaborative effort between European research Associations and Thales Electron Devices (TED) has been launched by the European Fusion Development Agreement (EFDA) in 2003, aiming at the ...development of an industrial 170 GHz/2 MW/CW coaxial cavity gyrotron. The first prototype is expected to reach 2 MW/1s and is presently being tested in Lausanne at a dedicated test facility. The test facility has been designed to be flexible: allowing the possible commissioning of tubes with different characteristics, as well the tests of a version of the ITER upper launcher antenna at full performances. The test facility has been commissioned during the first test phases on the gyrotron which include: high voltage stand-off, coaxial insert alignment and cathode conditioning without depressed collector power supply at a slightly reduced electron beam power of 85 kV/78 A/2 ms. The short pulse (<5 ms) operation of the gyrotron has demonstrated stable single mode operation in the designed TE -34,19 mode at RF power levels in excess of 1.4 MW, at below nominal electron beam parameters (79 kV/75 A). Further RF optimization in view of reaching the nominal beam parameters of 90 kV/75 A is presently underway and the status of the short pulse (<100 ms) experimental results will be reported.
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