The polarization of an e.m. wave propagating in a plasma with magnetic shear. The measurement of poloidal magnetic field in a Tokamak

Marco, F. De; Segrè, S. E.

doi:10.1088/0032-1028/14/3/002

Cited by 54 publications

(56 citation statements)

References 2 publications

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“…This principle was proposed by Marco and Segre as potential diagnostic of magnetic field for fusion plasmas in 1972. 6 The first laser polarimeter for fusion plasma was implemented in TEXTOR tokamak 7 and several different techniques for the measurement have been developed. 2,8 Three-wave polarimetry was first proposed by Dodel and Kunz in 1978 9 and has been successfully applied on tokamaks and the reversed-field pinch.…”

Section: J-text Polarismentioning

confidence: 99%

First results from the J-TEXT high-resolution three-wave polarimeter-interferometer

Chen

Zhuang

Wang

et al. 2012

Review of Scientific Instruments

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A laser-based far-infrared polarimeter-interferometer system utilizing the three-wave technique has been implemented on the J-TEXT tokamak. The polarimeter determines the Faraday effect by measuring the phase difference between two collinear, counter-rotating, circularly polarized laser beams. The first results of the polarimeter-interferometer designed for J-TEXT have been obtained in the most recent J-TEXT experimental campaign. Simultaneous polarimetric and interferometric measurement is achieved, with phase resolution up to 0.1°, at bandwidth of 50 kHz. The temporal resolution, which is dependent on the laser's frequency offset, is ∼1 μs. Continual spatial measurement covering 45 cm (80% of the plasma cross-section) is realized by utilizing 1D parabolic beam expansion optics. Three initial test chords are installed and future plans call for expansion up to 30 chords with 1.5 cm chord spacing, providing high spatial resolution for measurement of electron density and current density profiles. Reliability of both polarimetric and interferometric measurement is confirmed by comparison with computation and data from a hydrocyanic acid (HCN) interferometer. With the high temporal and phase resolution, perturbations associated with the sawtooth cycle and MHD activity have been observed.

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Section: J-text Polarismentioning

confidence: 99%

First results from the J-TEXT high-resolution three-wave polarimeter-interferometer

Chen

Zhuang

Wang

et al. 2012

Review of Scientific Instruments

View full text Add to dashboard Cite

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“…Sensitive terahertz detectors of the type shown here, besides other applications, can be of particular interest for the control of current density profiles which is important for tokamak operation. [4][5][6][7][8] We also note that the CPGE and LPGE are also observed at valence-toconduction band transitions, [9][10][11] at direct intersubband transitions, 1 and in wide band GaN semiconductor heterojunctions. 12 Thus, the applicability of the CPGE/LPGE detection scheme may well be extended into the visible, the near-infrared, and in the midinfrared spectral ranges.…”

mentioning

confidence: 87%

Subnanosecond ellipticity detector for laser radiation

Ganichev

Kiermaier

Weber

et al. 2007

Applied Physics Letters

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NbTiN superconducting nanowire detectors for visible and telecom wavelengths single photon counting on Si3N4 photonic circuits Appl. Phys. Lett. 102, 051101 (2013) Superconducting single-photon counting system for optical experiments requiring time-resolution in the picosecond range Rev. Sci. Instrum. 83, 123103 (2012) Enhanced performance of resonant sub-terahertz detection in a plasmonic cavity Appl. Phys. Lett. 100, 083506 (2012) Plasmonic detector/spectrometer of subterahertz radiation based on two-dimensional electron system with embedded defect Appl. Phys. Lett. 100, 082102 (2012) Ultra-low-noise MoCu transition edge sensors for space applications

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“…The principle of polarimetry as a plasma diagnostic was first proposed in 1972. 2 The intrinsic a) Invited paper, published as part of the Proceedings of the 20th Topical Conference on High-Temperature Plasma Diagnostics, Atlanta, Georgia, USA, June 2014. b) Author to whom correspondence should be addressed. Electronic mail: ge-zhuang@hust.edu.cn similarity between polarimetry and interferometry makes them possible to be combined for multi-field measurement.…”

Section: Introductionmentioning

confidence: 99%

High resolution polarimeter-interferometer system for fast equilibrium dynamics and MHD instability studies on Joint-TEXT tokamak (invited)

Chen

Zhuang

et al. 2014

Review of Scientific Instruments

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A high-performance Faraday-effect polarimeter-interferometer system has been developed for the J-TEXT tokamak. This system has time response up to 1 μs, phase resolution < 0.1° and minimum spatial resolution ∼15 mm. High resolution permits investigation of fast equilibrium dynamics as well as magnetic and density perturbations associated with intrinsic Magneto-Hydro-Dynamic (MHD) instabilities and external coil-induced Resonant Magnetic Perturbations (RMP). The 3-wave technique, in which the line-integrated Faraday angle and electron density are measured simultaneously by three laser beams with specific polarizations and frequency offsets, is used. In order to achieve optimum resolution, three frequency-stabilized HCOOH lasers (694 GHz, >35 mW per cavity) and sensitive Planar Schottky Diode mixers are used, providing stable intermediate-frequency signals (0.5-3 MHz) with S/N > 50. The collinear R- and L-wave probe beams, which propagate through the plasma poloidal cross section (a = 0.25-0.27 m) vertically, are expanded using parabolic mirrors to cover the entire plasma column. Sources of systematic errors, e.g., stemming from mechanical vibration, beam non-collinearity, and beam polarization distortion are individually examined and minimized to ensure measurement accuracy. Simultaneous density and Faraday measurements have been successfully achieved for 14 chords. Based on measurements, temporal evolution of safety factor profile, current density profile, and electron density profile are resolved. Core magnetic and density perturbations associated with MHD tearing instabilities are clearly detected. Effects of non-axisymmetric 3D RMP in ohmically heated plasmas are directly observed by polarimetry for the first time.

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The polarization of an e.m. wave propagating in a plasma with magnetic shear. The measurement of poloidal magnetic field in a Tokamak

Cited by 54 publications

References 2 publications

First results from the J-TEXT high-resolution three-wave polarimeter-interferometer

First results from the J-TEXT high-resolution three-wave polarimeter-interferometer

Subnanosecond ellipticity detector for laser radiation

High resolution polarimeter-interferometer system for fast equilibrium dynamics and MHD instability studies on Joint-TEXT tokamak (invited)

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