1,721,209 research outputs found
L’ESPERIENZA DI UTILIZZO DELLA SPETTROMETRIA DI MASSA NELLE CAMERE DA VUOTO DEGLI ESPERIMENTI DI FUSIONE TERMONUCLEARE CONTROLLATA
No full textTECNICHE DI CONDIZIONAMENTO DELLA PRIMA PARETE NEGLI ESPERIMENTI DI FUSIONE TERMONUCLEARE CONTROLLATA
No full textA vented pump limiter for the reversed field pinch RFX
No full textThe reversed field pinch (RFP) plasma performance, as in the Tokamak, is strongly correlated with the edge neutral particle control. The drawbacks of the conventional magnetic divertors and throat limiters on the RFP plasma have slackened the application of an active particle control system in existing devices. An advanced solution, based on the idea of the `vented pump limiter' experimented on Tore Supra, has been conceived for RFX. This type of pump limiter is very attractive for a RFP. In this paper, the design of a `vented limiter' prototype for RFX is presented. Up to six modules of this limiter can be installed at the equatorial plane of RFX, allowing a particle exhaust efficiency comparable with a divertor or a throat limiter working in a Tokamak. Finally, the optimization of this concept for the next step RFP device is presented
Three-dimensional analysis and magnetic shield design for an electromagnetic valve by an FE code
No full textPROGRESS ON THE HEATING AND CURRENT DRIVE SYSTEMS FOR ITER
No full textThe electron cyclotron (EC), ion cyclotron (IC), heating-neutral beam (H-NB) and, although not in the day 1 baseline, lower hybrid (LH) systems intended for ITER have been reviewed in 2007/2008 in light of progress of physics and technology in the field. Although the overall specifications are unchanged, notable changes have been approved. Firstly, it has been emphasized that the H&CD systems are vital for the ITER programme. Consequently, the full 73 MW should be commissioned and available on a routine basis before the D/T phase. Secondly, significant changes have been approved at system level, most notably: the possibility to operate the heating beams at full power during the hydrogen phase requiring new shine through protection; the possibility to operate IC with 2 antennas with increased robustness (no moving parts); the possible increase to 2 MW of key components of the EC transmission systems in order to provide an easier upgrading of the EC power as may be required by the project; the addition of a building dedicated to the RF power sources and to a testing facility for acceptance of diagnostics and heating port plugs. Thirdly, the need of a plan for developing, in time for the active phase, a CD system such as LH suitable for very long pulse operation of ITER was recognised. The review describes these changes and their rationale. © 2009 Elsevier B.V. All rights reserved
Behaviour of a DC zero-flux current sensor: magnetic field analysis and comparison with experimental results
No full textThe magnetic section of the finite-element ANSYS code, in particular its optimization feature, has been used to predict the behavior of a zero-flux current sensor, briefly described, which is intended to be used in a fusion experiment to measure pulsed currents up to 50 kA, over a bandwidth from DC to 10 kHz. The computed results fit well with those coming from experimental tests performed on a prototype
Thermal fluxes due to plasma-wall interactions: Experimental measurements and numerical analyses
No full textThe experimental results obtained from thermonuclear fusion devices highlight an uneven thermal flux distribution on the first wall, due to enhanced localized plasma-wall interactions. A numerical model to evaluate these thermal fluxes was implemented taking into account both the axisymmetric and the localized energy contributions. This paper illustrates the model, its approximations and the required input data to be taken from experimental measurements. The results of the thermal nonlinear dynamic analyses carried out for the RFX first wall and vacuum vessel are presented and compared with the vessel temperature measurements acquired during the experimental sessions. The simulations of the thermal responses show that more than 40% of the total plasma energy is concentrated in the region where the plasma-wall interaction is enhanced by the presence of locked modes
3D nonlinear magnetostatic analysis of a double-walled cylindrical shield
No full textThe performance of a double-walled cylindrical shield for magnetostatic field has been optimized using a 3-D numerical code. The shielding factor of the double-walled screen has been evaluated by varying the geometrical parameters. The optimization of the screen and the design criteria are reported. The influence on the shielding factor of the presence of a hole perpendicular to the cylindrical shield has been evaluated by calculating the field penetration into the internal region of the screen. Finally, the FEM (finite-element method) results have been tested by means of measurements performed on a shield prototype. The comparison between the numerical and experimental data shows good agreement, especially in the region where the finite-element model has been refined with more element
A finite element analysis of an electromagnetic flow control valve
No full textThe behavior of an electromagnetic control valve under a perturbative magnetic field is evaluated. The electromagnetic valve is numerically modeled by means of a nonlinear 2D field-element code. The electromagnetic force produced on the valve's plug is obtained using the Maxwell stress tensor approach, under both normal and perturbed conditions. The numerical results are compared with those of experimental tests, which have been carried out under the same conditions as the numerical analysis
Magnetostatic shielding design for electronic apparatus in fusion experiments
No full textIn controlled nuclear fusion research with magnetic confinement, experimental devices must produce high electromagnetic fields that can reach some tesla in the plasma zone. Therefore, a high stray magnetic field, slowly varying as a function of time, is present around the machines. For this reason, the numerous electronic apparatus and plasma diagnostics need an effective magnetostatic shield for their correct working condition.
Many examples of magnetic shields for different apparatus have been analysed: video, various electronic instruments and plasma diagnostics. After a brief description of electromagnetic problems arising in the fusion plants, the paper provides two examples of applications: the shield for a standard rack instrument and the shield for a small photo-multiplier head. The shielding effect has been evaluated considering non-linear materials for the shields. Moreover the magnetic field distortion in the space, due to the presence of the ferromagnetic material, has been evaluated in order to estimate the effect of the shields on the plasma magnetic confinement
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