DIII-D Diagnostic Systems

Boivin, R. L.; Luxon, J.L.; Austin, M. E.; Brooks, N.H.; Burrell, K.H.; Doyle, E. J.; Fenstermacher, M.E.; Gray, D.S.; Groth, M.; Hsieh, C. L.; Jayakumar, R. J.; McKee, G. R.; Lasnier, C.J.; Leonard, A.W.; Moyer, R. A.; Rhodes, T. L.; Rost, J. C.; Rudakov, D.L.; Schaffer, M. J.; Strait, E.J.; Thomas, D.M.; Vanzeeland, M.; Watkins, J.G.; West, W.P.; Wong, Chi-Wing

doi:10.13182/fst05-a1043

Cited by 11 publications

(3 citation statements)

References 112 publications

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“…To complement the BES measurements, several other diagnostics were used (Ref. 37 and references therein). The electron temperature was measured using a 40 channel electron cyclotron emission radiometer located at a toroidal angle of 81 • .…”

Section: Methodsmentioning

confidence: 99%

Two-dimensional plasma density evolution local to the inversion layer during sawtooth crash events using Beam Emission Spectroscopy

Bose¹,

Fox²,

Liu³

et al. 2022

Preprint

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We present methods for analyzing Beam Emission Spectroscopy (BES) data to obtain the plasma density evolution associated with rapid sawtooth crash events at the DIII-D tokamak. BES allows coverage over a 2-D spatial plane, inherently local measurements, with fast time responses, and therefore provides a valuable new channel for data during sawtooth events. A method is developed to remove sawtooth-induced edge-light pulses contained in the BES data. The edge light pulses appear to be from the D α emission produced by edge recycling during sawtooth events, and are large enough that traditional spectroscopic filtering and data analysis techniques are insufficient to deduce physically meaningful quantities. A cross-calibration of 64 BES channels is performed using a novel method to ensure accurate measurements. For the large-amplitude density oscillations observed, we discuss and use the non-linear relationship between BES signal δI/I 0 and plasma density variation δn e /n e0 . 2-D BES images cover a 8 cm × 20 cm region around the sawtooth inversion layer and show large-amplitude density oscillations, with additional significant spatial variations across the inversion layer, which grows and peaks near the time of the temperature crash. The edge light removal technique and method of converting large-amplitude δI/I 0 to δn e /n e0 presented here may help analyze other impulsive MHD phenomena in tokamaks.

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Section: Methodsmentioning

confidence: 99%

Two-dimensional plasma density evolution local to the inversion layer during sawtooth crash events using Beam Emission Spectroscopy

Bose¹,

Fox²,

Liu³

et al. 2022

Preprint

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“…Thus, every modern magnetic fusion device must be very well armed with diagnostics, such as the array on DIII-D [3]. This array is shown schematically in fig.…”

Section: Introductionmentioning

confidence: 99%

“…Most other devices have similar comprehensive armaments of diagnostics, exemplified in this series of Special Issues of FS&T. Papers on the overall attributes of the diagnostic complements have already appeared for DIII-D [3], FTU [4], TEXTOR [5,6], JT-60 [7], JFT-2M [8] and Alcator C-Mod [9]. They provide a valuable compendium of the application of instruments and of observed data for real situations.…”

Section: Introductionmentioning

confidence: 99%

Plasma Measurements: An Overview of Requirements and Status

Young¹

2008

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This paper introduces this special issue on plasma diagnostics for magnetic fusion devices. Its primary purpose is to relate the measurements of plasma parameters to the physics challenges to be faced on operating and planned devices, and also to identify the diagnostic techniques that are used to make these measurements. The specific physics involved in the application of the techniques will be addressed in subsequent chapters.This chapter is biased toward measurements for tokamaks because of their proximity to the burning plasma frontier, and to set the scene for the development work associated with ITER. Hence, there is some emphasis on measurements for alpha-physics studies and the needs for plasma measurements as input to actuators to control the plasma, both for optimizing the device performance and for protection of the surrounding material.The very different approach to the engineering of diagnostics for a burning plasma is considered, emphasizing the needs for new calibration ideas, reliability and hardness against, and compatibility with, radiation. New ideas take a long time to be converted into "work-horse" sophisticated diagnostics so that investment in new developments is essential for ITER, particularly for the measurement of alpha-particles

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A multichannel, frequency-modulated, tunable Doppler backscattering and reflectometry system

Hillesheim

Peebles

Rhodes

et al. 2009

Review of Scientific Instruments

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A novel multichannel Doppler backscattering system has been designed and tested for application on the DIII-D [J. L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] and National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 (2000)] fusion plasma devices. Doppler backscattering measures localized intermediate wavenumber (k(perpendicular)rho(i) approximately 1-4,k(perpendicular) approximately 2-15 cm(-1)) density fluctuations and the propagation velocity of turbulent structures. Microwave radiation is launched at a frequency that approaches a cutoff layer in the plasma and at an angle that is oblique to the cutoff layer. Bragg backscattering occurs near the cutoff layer for fluctuations with k(perpendicular) approximately -2k(i), where k(i) is the incident probe wave vector at the scattering location. The turbulence propagation velocity can be determined from the Doppler shift in the return signal together with knowledge of the scattering wavenumber. Ray tracing simulations are used to determine k(perpendicular) and the scattering location. Frequency modulation of a voltage-controlled solid state microwave source followed by frequency multiplication is used to create an array of finely spaced (Delta f=350 MHz) frequencies spanning 1.4 GHz. The center of the array bandwidth is tunable within the range of approximately 53-78 GHz. This article details the system design, laboratory tests, and presents initial data from DIII-D plasmas.

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DIII-D Diagnostic Systems

Cited by 11 publications

References 112 publications

Two-dimensional plasma density evolution local to the inversion layer during sawtooth crash events using Beam Emission Spectroscopy

Two-dimensional plasma density evolution local to the inversion layer during sawtooth crash events using Beam Emission Spectroscopy

Plasma Measurements: An Overview of Requirements and Status

A multichannel, frequency-modulated, tunable Doppler backscattering and reflectometry system

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