Fast scanning heterodyne receiver for the measurement of the time evolution of the electron temperature profile on TFTR

Taylor, G.; Efthimion, P. C.; McCarthy, Michael; Arunasalam, V.; Bitzer, R.; Bryer, J.; Cutler, R.; Fredd, E.; Goldman,; Kaufman, D.

doi:10.2172/6948327

Cited by 3 publications

(5 citation statements)

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“…The ion temperatures were measured by the TFTR Group with charge exchange recombination spectroscopy ͑CHERS͒; 26,27 the electron density profiles were obtained with the multi-channel infrared interferometer ͑MIRI͒ diagnostic; 28,29 and the electron temperatures were measured with electron cyclotron emission ͑ECE͒. 30 Fractional error bars for ECE electron temperature data typically range from 5% to 10%; here, we assume fractional error bars of 7.5%. For the MIRI electron density data, an uncertainty of 0.2ϫ10 19 m Ϫ3 is assumed for all density points.…”

Section: A Data For Discharges Consideredmentioning

confidence: 99%

Sensitivity of predictive tokamak plasma transport simulations

et al. 1997

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The sensitivity of our time-dependent simulations of low confinement (L-mode) discharges to variations in initial profiles and time-dependent boundary conditions has been explored. These time-dependent tokamak plasma simulations were performed using a theory-based Multi-mode transport model that includes ion temperature gradient (ITG) and trapped electron modes (TEM), kinetic and resistive ballooning modes and neoclassical modes. The density and temperature profiles predicted in our simulations of L-mode discharges are found to be robust, even with significant variations in the initial or boundary conditions. Although transport associated with a single mode can be strongly affected by local changes in plasma parameters resulting from changes in the boundary conditions, the total transport remains largely unchanged because of compensation by other transport modes. The sensitivity of the predicted temperature and density profiles to a variation in the Multi-mode model is also examined. When the Dominguez-Waltz theory of transport driven by ITG and TEM modes is replaced in the Multi-mode model by the Weiland description, we find that the predictions of the Weiland model more closely match the experimental data.

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Section: A Data For Discharges Consideredmentioning

confidence: 99%

Sensitivity of predictive tokamak plasma transport simulations

et al. 1997

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“…the noise temperature reported is about 50 000 K for the 75-110 GHz receiver (Taylor et al 1984). It varies across the band by a factor of more than two.…”

Section: Types Of Ece Heterodyne Radiometersmentioning

confidence: 89%

“…At PLT the frequency range 60-90 GHz was scanned every 10 ms with a DSB receiver with a centre IF of 375 MHz and a bandwidth of 250 MHz (Efthimion et al 1979). To cover a wider spectral range, three separate scanning receivers for the bands 75-110, 110-170 and 170-220 GHz are installed at TFTR (Taylor et al 1984). The receivers are DSB receivers with centre frequencies of 375, 1500 and 3950 MHz, respectively.…”

Section: Types Of Ece Heterodyne Radiometersmentioning

confidence: 99%

Heterodyne methods in millimetre wave plasma diagnostics with applications to ECE, interferometry and reflectometry

Hartfuss

Geist

Hirsch

1997

Plasma Phys. Control. Fusion

186

173

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Basic principles of heterodyne techniques are introduced and the various components of a heterodyne system are summarized. Special applications in ECE, interferometry and reflectometry are discussed after introducing the diagnostic principles. Realized systems as described in the literature are briefly outlined. Ordering principles are radiometer types in the case of ECE, mixing scheme and generation and stabilization of local oscillator and intermediate frequency signals in the case of interferometry and reflectometry. Special techniques and their impact on the performance of the diagnostic instruments are discussed. Contents Introduction 1694 Components of the heterodyne receiver 1695 2.1 Heterodyne detection scheme 1696 2.1.1 Mixers 1697 2.1.2 Local oscillators 1705 2.1.3 IF chain 1706 2.2 Sensitivity 1707 2.3 Antennas and waveguides 1709 Radiometry of electron cyclotron emission 1711 3.1 Principles of ECE diagnostics 1711 3.1.1 Frequency and intensity of the emission 1711 3.

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“…with room temperature and liquid nitrogen cooled blackbody sources. Details of the receivers have been discussed elsewhere [9]. The transmission system between TFTR and the receivers was designed to operate between 75 GHz and 5 210 GHz.…”

Section: Experimental Arrangementmentioning

confidence: 99%

“…Since the mas-.netic field varies approximately inversely with the major radius in a tokamak, the emission frequency is localized in position. Fast frequency scanning heterodyne receivers [7,9]…”

Section: Introductionmentioning

confidence: 99%

Evolution of the electron temperature profile of ohmically heated plasmas in TFTR

Taylor

Efthimion

Arunasalam

et al. 1985

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Biackbody electron cyclotron emission was used to ascertain and study the evolution and behavior of the electron temperature profile in ohmicaliy heated plasmas in the Tokamak Fusion Test Reactor (TFTR). The emission was measured with absolutely calibrated millimeter wavelength radiometers. The temperature profile normal izect to the central temperature and minor radius is observed to Broaden substantially with decreasing llmlter safety factor q a , and Ls insensitive to the plasma minor radius. Sawtooth activity was seen in the core of most TFTR discharges and appeared to Be associated with a flattening of the electron temperature profile within the plasma core where q < l. Two types or sawtooth behavior were identified in large TFTR plasmas {minor radius, a ;> 0.8 m) : a typically 35-to msec period "normal" sawtooth, and a "compound" sawtooth with 70-80 msec period. The compound sawtooth was characterized by what appeared to be a partial reconnection, which occurs 3way from the plasma core, in addition to a full reconnection. A muit ir >ie linear regression analysis of the central electron temperature [T Co)] with toroidal field (B T), major radius (R), minor radius (a), plasma current (I) and V niSTRlBUTIOH Of HIE KCDMEOT IS IMO effective Ion charge (Z eff > results In a scaling of the form, T e fo) a B T 0 ' 78 R* °-3 1 a 1 " 1 Z eff 0, ^1 D. where the major radial dependence was obtained by comparison with eariier PLT data. This temperature scaling is consistent with the TFTR confinement scaling of Efthiraion et al. {!].

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Fast scanning heterodyne receiver for the measurement of the time evolution of the electron temperature profile on TFTR

Cited by 3 publications

References 0 publications

Sensitivity of predictive tokamak plasma transport simulations

Sensitivity of predictive tokamak plasma transport simulations

Heterodyne methods in millimetre wave plasma diagnostics with applications to ECE, interferometry and reflectometry

Evolution of the electron temperature profile of ohmically heated plasmas in TFTR

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