Magnetic well and instability thresholds in the TJ-II stellarator

Castellano, José María; Jiménez, Javier; Hidalgo, C.; Pedrosa, M. A.; Fraguas, Ángela; Pastor, I.; Herranz, J.; Alejaldre, C.; Team, Tj‐Ii

doi:10.1063/1.1430435

Cited by 17 publications

(25 citation statements)

References 14 publications

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“…Finally, the negative and decreasing magnetic well values towards the plasma edge suggest the presence of significant fluctuations. This behaviour is observed in devices like TJ-II, as reported by Castellano et al (2002), and, with experimentation in SCR-1, we look forward to confirming that same behaviour. On the other hand, vacuum magnetic flux surface mapping was computed using a modified oscillating rod with ZnO:Zn phosphor (Coto-Vílchez et al 2017).…”

Section: Mhd Equilibrium Calculationssupporting

confidence: 85%

Progress on the small modular stellarator SCR-1: new diagnostics and heating scenarios

et al. 2020

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This work presents updates in the diagnostics systems, magnetohydrodynamics (MHD) calculations and simulations of microwave heating scenarios of the small modular Stellarator of Costa Rica 1 (SCR-1). Similarly, the design of a flexible bolometer and magnetic diagnostics (a set of Mirnov coils, Rogowski coils and two diamagnetic loops) are introduced. Furthermore, new MHD equilibrium calculations for the plasma of the SCR-1 device were performed using the VMEC code including the poloidal cross-section of the magnetic flux surfaces at different toroidal positions, profiles of the rotational transform, magnetic well, magnetic shear and total magnetic field norm. Charged particle orbits in vacuum magnetic field were computed by the magnetic field solver BS-SOLCTRA (Vargas et al. In 27th IAEA Fusion Energy Conference (FEC 2018), 2018. IAEA). A visualization framework was implemented using Paraview (Solano-Piedra et al. In 23rd IAEA Technical Meeting on the Research Using Small Fusion Devices (23rd TM RUSFD), 2017) and compared with magnetic mapping results (Coto-Vílchez et al. In 16th Latin American Workshop on Plasma Physics (LAWPP), 2017, pp. 43–46). Additionally, simulations of microwave heating scenarios were performed by the IPF-FDMC full-wave code. These simulations calculate the conversion of the ordinary waves to extraordinary waves and allow us to identify the location where the conversion takes place. Finally, the microwave heating scenarios for the $330^{\circ }$ toroidal position are presented. The microwave heating scenarios showed that the O–X–B mode conversion is around 12–14 %. It was possible to identify the spatial zone where the conversion takes place (upper hybrid frequency).

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Section: Mhd Equilibrium Calculationssupporting

confidence: 85%

Progress on the small modular stellarator SCR-1: new diagnostics and heating scenarios

et al. 2020

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“…Figure 4a shows an image plot of particle flux density, particle flux density at 60 kHz and the total particle flux integrated over all frequency up to 200 kHz. These signals show intermittent bursts [25,26], and the averaged value and intensity of the bursts increase in L-phase. The ordinary bursts orient radially outward or poloidally in the ion diamagnetic direction, while occasional bursts occur in the opposite direction.…”

Section: Difference Of Fluctuation Characteristics Before and After Tmentioning

confidence: 99%

Turbulence and transport characteristics of a barrier in a toroidal plasma

Fujisawa

Shimizu

Nakano

et al. 2006

Plasma Phys. Control. Fusion

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Abstract. Turbulence and zonal flow at a transport barrier are studied with twin heavy ion beam probes in a toroidal helical plasma. A wavelet analysis is used to extract turbulence properties, e. g., spectra of both density and potential fluctuations, coherence and phase between them, and the dispersion relation. Particle transport estimated from the fundamental characteristics is found to clearly rise with their intermittent activities after the barrier is broken down. The time-dependent analysis reveals that intermittency of turbulence is correlated with evolution of stationary zonal flow.

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“…The first application of the PDF analysis to plasma turbulence was made in the ADITYA tokamak [32] after the study of intermittency in turbulent fluids [33,34]. To date, a number of trials to classify and compare the turbulent characteristics have been conducted by constructing the PDF of plasma turbulence [35][36][37][38][39][40][41][42][43]. The usage of the PDF method may be encouraged after the plasma transport model based on SOC [44], since the SOC model predicted the scale-invariant characteristics that could be evaluated statistically.…”

Section: Probability Density Function Analysis For Nonlinearitymentioning

confidence: 99%

A Review -Observations of Turbulence and Structure in Magnetized Plasmas

Fujisawa

2010

Plasma and Fusion Research

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Magnetized plasma is an non-equilibrium matter rich in nonlinear phenomena; its structural formations are dominated by turbulence. This article provides a brief review of experiments and observations of phenomena occurring in turbulent plasmas, with an emphasis on the methodologies for characterizing turbulence, and visualizing the invisible structure created by turbulence and the internal couplings between the elemental waves that constitute turbulence. Zonal flows, streamers, blobs, and other phenomena are investigated by using analytical methods such as Fourier transformation, wavelet analysis, probabilistic density function analysis, bicoherence, wavelet bicoherence. Finally, the contemporary view of plasma turbulence is presented with discussion of unsolved transport issues in fusion plasmas, such as transport barrier formation and nonlocal transport.

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Magnetic well and instability thresholds in the TJ-II stellarator

Cited by 17 publications

References 14 publications

Progress on the small modular stellarator SCR-1: new diagnostics and heating scenarios

Progress on the small modular stellarator SCR-1: new diagnostics and heating scenarios

Turbulence and transport characteristics of a barrier in a toroidal plasma

A Review -Observations of Turbulence and Structure in Magnetized Plasmas

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