MHD equilibrium in Tokamaks with reversed current density

Taborda, David Ciro

doi:10.11606/d.43.2012.tde-11032013-131439

Cited by 1 publication

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References 28 publications

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“…According to equation 1-6, Optical Emissivity ( ) changes due to: Real emissivity from each radiation process is not measurable directly, although some assumptions can be done according to the diagnostic spectral characteristics. Moreover, the radial dependence of emissivity parameters, such as density, temperature and impurities concentration can be modeled from plasma emissivity equations [5,6,15,23].…”

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confidence: 99%

Emissivity Profiles at TCABR Tokamak

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The determination of plasma equilibrium profiles is necessary to evaluate the properties of the confinement and to investigate perturbation effects. Optical diagnostics can be used to determine some of these profiles. However, these diagnostics measure all emitted radiation at a solid angle that illuminate each diagnostic channel through a slit. Therefore, the real measured quantity is the emissivity integrated along the line-of-sight and some unfolding procedure, like Abel's inversion, is commonly used to recover the emissivity profile. In TCABR tokamak, at the Physics Institute of the University of São Paulo, a 24-channel bolometer and a 20-channel soft X-ray optical diagnostics are used to measure the plasma emissivity in wavelength range from 1.0 to 1000 nm, depending on the used filters. In this work, a numerical simulation is used to compute the signal measured by the diagnostics for a given emissivity profile, allowing direct comparison with the experimental data and avoiding the use of the Abel's inversion directly and the numerical difficulties associated with unfolding procedures. By considering TCABR tokamak geometry, spatial coordinates can be related to the normalized linear coordinates of the plasma by imposing a plasma emissivity model that depends on some free parameters, allowing the emissivity resulting in each point can be calculated. Thus, the luminosity of each channel is calculated by the integral of the emissivity modeled in each lineof-sight (Radon Transformation). Emissivity model free parameters are determined by fitting calculated luminosity to measured one. We considered three types of emissivity profiles: a parabolic model in law of power, a Gaussian model and a model based on Bessel functions. We observed that the parabolic profile fits well the bolometer data, while the Gaussian profile is adequate to describe the data obtained with the soft X-ray detector.

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Section: -6mentioning

confidence: 99%

Emissivity Profiles at TCABR Tokamak

Oliveira¹

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MHD equilibrium in Tokamaks with reversed current density

Cited by 1 publication

References 28 publications

Emissivity Profiles at TCABR Tokamak

Emissivity Profiles at TCABR Tokamak

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