Publication

Fast polarizers installation for ECRH and ECE in TCV

Timothy Goodman, Federico Alberto Alfredo Felici, Laurie Porte
2010
Conference Papers

Abstract

We report on the installation of fast polarizers for ECRH injection and ECE diagnostics, in the TCV tokamak. The main goal is to change the polarization during a plasma shot and react to changing conditions such as: plasma current and position, ECRH injection angles as well as ECE oblique observation angle and correlation ECE frequency. This will allow tracking of plasma variations, find optimum parameters to maximize ECRH absorption and improve the quality and consistency of ECE measurements. The polarization is varied using two fast polarizers, from General Atomics, positioned either in the evacuated transmission line for ECRH, or in a similar non-evacuated line near a real-time moveable directional antenna for ECE. A programmable driver is used to control a servo-motor and allows three operation modes during a plasma shot: fixed angle position, pre-programmed reference waveform and following of a real-time reference waveform. Preliminary tests of the motor controller achieved an 8 Hz bandwidth for a 4 +/-degrees amplitude motion and a 2.2 Hz bandwidth for a +/- 4 degrees amplitude motion. The fast polarizers are presently in the ECE system and the control hardware is being installed. (C) 2011 Elsevier B.V. All rights reserved.

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https://infoscience.epfl.ch/entities/publication/be6011f8-839e-47d4-a5c6-4dd2635f9b65

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Timothy Goodman, Federico Alberto Alfredo Felici, Laurie Porte
2010
Conference Papers

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/be6011f8-839e-47d4-a5c6-4dd2635f9b65

About this result

Related concepts (29)

Tokamak

A tokamak (ˈtoʊkəmæk; токамáк) is a device which uses a powerful magnetic field to confine plasma in the shape of a torus. The tokamak is one of several types of magnetic confinement devices being developed to produce controlled thermonuclear fusion power. , it was the leading candidate for a practical fusion reactor. Tokamaks were initially conceptualized in the 1950s by Soviet physicists Igor Tamm and Andrei Sakharov, inspired by a letter by Oleg Lavrentiev. The first working tokamak was attributed to the work of Natan Yavlinsky on the T-1 in 1958.

Neutral-beam injection

Neutral-beam injection (NBI) is one method used to heat plasma inside a fusion device consisting in a beam of high-energy neutral particles that can enter the magnetic confinement field. When these neutral particles are ionized by collision with the plasma particles, they are kept in the plasma by the confining magnetic field and can transfer most of their energy by further collisions with the plasma. By tangential injection in the torus, neutral beams also provide momentum to the plasma and current drive, one essential feature for long pulses of burning plasmas.

Polarizer

A polarizer or polariser (see spelling differences) is an optical filter that lets light waves of a specific polarization pass through while blocking light waves of other polarizations. It can filter a beam of light of undefined or mixed polarization into a beam of well-defined polarization, that is polarized light. The common types of polarizers are linear polarizers and circular polarizers. Polarizers are used in many optical techniques and instruments, and polarizing filters find applications in photography and LCD technology.

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