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2010
Several diagnostic systems in magnetically confined fusion plasmas provide line-integrated measurements along chords, including bolometry, visible light, soft-Xray ~SXR!, or neutron diagnostics. The task of retrieval of spatial distribution of the plasma emissivity from the line-integrated measurements constitutes an important part of fusion data a…
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2008
The last flux surface can be used to identify the plasma configuration of discharges. For automated recognition of JET configurations, a learning system based on support vector machines has been developed. Each configuration is described by 12 geometrical parameters. A multiclass system has been developed by means of the one-versus-the-rest approac…
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2008
We present the main design options and implementation of an X -mode reflectometer developed and successfully installed at JET using an innovative approach. It aims to prove the viability of measuring density profiles with high spatial and temporal resolution using broadband reflectometry operating in long and complex transmission lines. It probes t…
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2008
The measurement of the fuel mixture remains a very difficult task in thermonuclear plasmas, where the hydrogen isotopes are fully stripped and do not emit line radiation. On the other hand, direct determination of the ion species mix will be essential in the reactor to keep the mixture close to 50/50 and maximize the fusion output. In this paper, t…
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2008
Advance tokamak scenarios are gaining more and more importance in operating tokamaks. These scenarios pose challenging control problems, since they require the simultaneous achievement of ambitious plasma parameters. The inherent coupling among the various variables calls for an integrated approach for the design of the controllers. This paper desc…
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2008
An analytical Bayesian inversion of the JET interferometry line integrated densities into density profiles and associated uncertainty information, is demonstrated. These are used, with a detailed model of plasma polarimetry, to predict the rotation and ellipticity for the JET polarimeter. This includes the lateral channels, for over 45,000 time poi…
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2005
In this paper the mechanical design of the new active MHD antennas for JET is described and the structural/mechanical analysis for the antennas is presented. These new antennas replace the existing n = 1 or 2 saddle coils with a set of eight smaller antennas designed to excite Toroidal Alfvén Eigenmodes (TAE's) with high toroidal mode number (n ~ …
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2004
On the Joint European Torus ( JET ) , a key source of calibrated electron temperature T e profiles is from the measurements of the full electron cyclotron emission ( ECE ) spectrum made by a Fourier transform spectrometer ( FTS ) . It is absolutely calibrated by using a calibration source inside the vacuum vessel. High spatial and temporal resoluti…
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2004
A microwave interferometry technique is applied for the first time for detecting a discrete spectrum of Alfvén cascade (AC) eigenmodes excited with fast ions in reversed magnetic shear plasmas of the Joint European Torus. The interferometry measurements of plasma density perturbations associated with ACs show an unprecedented frequency and time re…
Showing 31 - 39 of 39 UKAEA Paper Results