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Development of a fast sweep heterodyne microwave reflectometer; Developpement d`un reflectometre micro-onde heterodyne a balayage ultra rapide

Abstract

The density profile of fusion plasmas can be investigated by the reflectometry diagnostic. The measurement principle is based on the radar techniques which calculate the phase shift of a millimeter wave propagating into the plasma and reflected at a cut-off layer. We have tried to describe the density fluctuation effects upon detected signal to understand the disturbing mechanisms which prevent, sometime, the measurement of the phase. First, we have tried to understand the mechanisms and the origin of the turbulence which is responsible for phase disturbance. We point out the role of collisionality {nu}{sup *} and plasma radiation (with the Hugill normalised parameter H) which control the instability. We also demonstrate that the phase delay of the probing wave is very sensitive to the plasma MHD phenomena and is less affected by the micro-turbulence. The second part of this work is the development and the use of a new heterodyne reflectometer. This new diagnostic uses O-mode beam polarisation and works on the 26-36 GHz frequency range. It launches simultaneously into the plasma two frequencies separated by 320 MHz and we can study them separately or with the amplitude modulation technique. It possesses a better sensitivity than the previous homodyne reflectometer  More>>
Authors:
Moreau, Ph [1] 
  1. Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee
Publication Date:
Dec 01, 1997
Product Type:
Thesis/Dissertation
Report Number:
EUR-CEA-FC-1618
Reference Number:
SCA: 700320; 700340; 700480; PA: AIX-30:003784; EDB-99:027593; SN: 99002059697
Resource Relation:
Other Information: DN: 93 refs.; TH: These; PBD: Dec 1997
Subject:
70 PLASMA PHYSICS AND FUSION; BRAGG REFLECTION; COLLISIONAL PLASMA; FREQUENCY MODULATION; HETERODYNE RECEIVERS; PHASE SHIFT; PLASMA DENSITY; PLASMA DIAGNOSTICS; PLASMA INSTABILITY; RADAR; SIGNAL CONDITIONING; SWEEP CIRCUITS; TORE SUPRA TOKAMAK; WAVE PROPAGATION
OSTI ID:
308946
Research Organizations:
Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee
Country of Origin:
France
Language:
French
Other Identifying Numbers:
Other: ON: TI99612410; TRN: FR9803330003784
Availability:
INIS; OSTI as TI99612410
Submitting Site:
FRN
Size:
202 p.
Announcement Date:

Citation Formats

Moreau, Ph. Development of a fast sweep heterodyne microwave reflectometer; Developpement d`un reflectometre micro-onde heterodyne a balayage ultra rapide. France: N. p., 1997. Web.
Moreau, Ph. Development of a fast sweep heterodyne microwave reflectometer; Developpement d`un reflectometre micro-onde heterodyne a balayage ultra rapide. France.
Moreau, Ph. 1997. "Development of a fast sweep heterodyne microwave reflectometer; Developpement d`un reflectometre micro-onde heterodyne a balayage ultra rapide." France.
@misc{etde_308946,
title = {Development of a fast sweep heterodyne microwave reflectometer; Developpement d`un reflectometre micro-onde heterodyne a balayage ultra rapide}
author = {Moreau, Ph}
abstractNote = {The density profile of fusion plasmas can be investigated by the reflectometry diagnostic. The measurement principle is based on the radar techniques which calculate the phase shift of a millimeter wave propagating into the plasma and reflected at a cut-off layer. We have tried to describe the density fluctuation effects upon detected signal to understand the disturbing mechanisms which prevent, sometime, the measurement of the phase. First, we have tried to understand the mechanisms and the origin of the turbulence which is responsible for phase disturbance. We point out the role of collisionality {nu}{sup *} and plasma radiation (with the Hugill normalised parameter H) which control the instability. We also demonstrate that the phase delay of the probing wave is very sensitive to the plasma MHD phenomena and is less affected by the micro-turbulence. The second part of this work is the development and the use of a new heterodyne reflectometer. This new diagnostic uses O-mode beam polarisation and works on the 26-36 GHz frequency range. It launches simultaneously into the plasma two frequencies separated by 320 MHz and we can study them separately or with the amplitude modulation technique. It possesses a better sensitivity than the previous homodyne reflectometer and a higher frequency agility. Its heterodyne detection allows us to separate phase and amplitude informations from the detected signal. (author) 93 refs.}
place = {France}
year = {1997}
month = {Dec}
}