Plasma TEC

Princeton, NJ, United States

Plasma TEC

Princeton, NJ, United States

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Ragona R.,Ghent University | Ragona R.,Plasma TEC | Messiaen A.,Plasma TEC
Fusion Engineering and Design | Year: 2017

The main advantages of ICRH&CD are its ability to achieve power deposition in the center of the plasma column without any density limit along with direct heating of plasma ions. The challenge is then to couple large amount of power through the plasma boundary, where an evanescence layer has to be crossed, without exceeding the voltage standoff at the antenna. A solution presently considered is the reduction of the power density by means of antennas distributed all along the wall of the machine. In we have shown that a suitable launcher can be constituted by sections of Traveling Wave Antenna (TWA) mounted in resonant ring systems. They are launching a traveling wave in one direction along the structure that leaks its energy to the plasma and is refueled periodically by generators. Each section is constituted by a series of equidistant mutually coupled grounded straps aligned in the poloidal direction which radiates its power to the plasma proportionally to the total strap number divided by their inter-strap distance. Due to the large number of radiating elements, the launched power spectrum is very selective. A detailed discussion on the multi-section antenna is made in view of its test on a mock-up. We study the influence, in ring shaped structures, of its geometrical parameters on its response along with the influence of the periodicity of sections and feedings. This extends the work done in The aim is to prepare for a proof-of-concept system to be tested in an operating tokamak machine. © 2017 The Author(s).


Pegourie B.,French Atomic Energy Commission | Panayotis S.,French Atomic Energy Commission | Languille P.,Aix - Marseille University | Martin C.,Aix - Marseille University | And 52 more authors.
Journal of Nuclear Materials | Year: 2013

This paper presents an analysis of the carbon-deuterium circulation and the resulting balance in Tore Supra over the period 2002-2007. Carbon balance combines the estimation of carbon gross erosion from spectroscopy, net erosion and deposition using confocal microscopy, lock-in thermography and SEM, and a measure of the amount of deposits collected in the vacuum chamber. Fuel retention is determined from post-mortem (PM) analyses and gas balance (GB) measurements. Special attention was paid to the deuterium outgassed during the nights and weekends of the experimental campaign (vessel under vacuum, Plasma Facing Components at 120 °C) and during vents (vessel at atmospheric pressure, PFCs at room temperature). It is shown that this outgassing is the main process reconciling the PM and GB estimations of fuel retention, closing the coupled carbon-deuterium balance. In particular, it explains why the deuterium concentration in deposits decreases with increasing depth. © 2013 Elsevier B.V. All rights reserved.


Douai D.,French Atomic Energy Commission | Kogut D.,French Atomic Energy Commission | Lyssoivan A.,Plasma TEC | Brezinsek S.,Jülich Research Center | And 17 more authors.
Journal of Nuclear Materials | Year: 2015

Abstract The isotopic exchange efficiencies of JET Ion Cyclotron Wall Conditioning (ICWC) discharges produced at ITER half and full field conditions are compared for JET carbon (C) and ITER like wall (ILW). Besides an improved isotope exchange rate on the ILW providing cleaner plasma faster, the main advantage compared to C-wall is a reduction of the ratio of retained discharge gas to removed fuel. Complementing experimental data with discharge modeling shows that long pulses with high (∼240 kW coupled) ICRF power maximizes the wall isotope removal per ICWC pulse. In the pressure range 1-7.5 × 10-3 Pa, this removal reduces with increasing discharge pressure. As most of the wall-released isotopes are evacuated by vacuum pumps in the post discharge phase, duty cycle optimization studies for ICWC on JET-ILW need further consideration. The accessible reservoir by H2-ICWC at ITER half field conditions on the JET-ILW preloaded by D2 tokamak operation is estimated to be 7.3 × 1022 hydrogenic atoms, and may be exchanged within 400 s of cumulated ICWC discharge time. © 2015 EURATOM.


Ongena J.,Laboratory for Plasma Physics Brusells | Messiaen A.,Laboratory for Plasma Physics Brusells | Van Eester D.,Laboratory for Plasma Physics Brusells | Schweer B.,Laboratory for Plasma Physics Brusells | And 23 more authors.
Physics of Plasmas | Year: 2014

The current status of the mechanical and electromagnetic design for the ICRF antenna system for W7-X is presented. Two antenna plugins are discussed: one consisting of a pair of straps with pre-matching to cover the first frequency band, 25-38 MHz, and a second one consisting of two short strap triplets to cover a frequency band around 76 MHz. This paper focusses on the two strap antenna for the lower frequency band. Power coupling of the antenna to a reference plasma profile is studied with the help of the codes TOPICA and Microwave Studio that deliver the scattering matrix needed for the optimization of the geometric parameters of the straps and antenna box. Radiation power spectra for different phasings of the two straps are obtained using the code ANTITER II and different heating scenario are discussed. The potential for heating, fast particle generation, and current drive is discussed. The problem of RF coupling through the plasma edge and of edge power deposition is summarized. Important elements of the complete ion cyclotron resonance heating system are discussed: a resonator circuit with tap feed to limit the maximum voltage in the system, and a decoupler to counterbalance the large mutual coupling between the 2 straps. The mechanical design highlights the challenges encountered with this antenna: adaptation to a large variety of plasma configurations, the limited space within the port to accommodate the necessary matching components and the watercooling needed for long pulse operation. © 2014 EURATOM.


Ongena J.,Laboratory for Plasma Physics Brusells | Messiaen A.,Laboratory for Plasma Physics Brusells | Dumortier P.,Laboratory for Plasma Physics Brusells | Durodie F.,Laboratory for Plasma Physics Brusells | And 22 more authors.
AIP Conference Proceedings | Year: 2014

The current status of the mechanical and electromagnetic design for the ICRF antenna system for W7-X is presented. Two antenna plugins are discussed: one consisting of a pair of straps with pre-matching to cover the first frequency band 25-38 MHz and a second one consisting of two short strap triplets to cover a frequency band around 76 MHz. This paper focusses on the two strap antenna for the lower frequency band. Power coupling of the antenna to a reference plasma profile is studied with the help of the codes TOPICA and Microwave Studio, that deliver the scattering matrix needed for the optimization of the geometric parameters of the straps and antenna box. Radiation power spectra for different phasings of the two straps are obtained using the code ANTITER II and different heating scenarii are discussed. The potential for heating, fast particle generation and current drive is discussed. The problem of RF coupling through the plasma edge and of edge power deposition is summarized. The system contains a prematching capacitor to limit the maximum voltage in the system, and the large mutual coupling between the 2 straps is counterbalanced by the use of a decoupler. The mechanical design highlights the challenges encountered with this antenna: adaptation to a large variety of plasma configurations, the limited space within the port to accommodate the necessary matching components and the watercooling needed for long pulse operation. © 2014 AIP Publishing LLC.


Telesca G.,Ghent University | Zagorski R.,EURATOM | Brezinsek S.,Plasma TEC | Fundamenski W.,EURATOM | And 6 more authors.
Plasma Physics and Controlled Fusion | Year: 2011

The code COREDIV, self-consistent with respect to both the interaction of plasma core-edge and main plasma impurities, is used to simulate nitrogen-seeded discharges in JET. The model is fully described and numerical results are compared with experimental data pertaining to two series of discharges differing in input power, confinement, the level of power radiated and the puffing rate of the main gas. Impurity sources, their transport and densities are considered as functions of the edge and core parameters and consistency of their radiated power is discussed. Special emphasis is given to analysis of the fluxes of carbon and recycled deuterium. © 2011 IOP Publishing Ltd.

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