Experimental study of radial electric field and electrostatic potential fluctuation in the Large Helical Device

Ido, T.; Shimizu, A.; Nishiura, M.; Nagaoka, K.; Yokoyama, M.; Ida, K.; Yoshinuma, M.; Toi, K.; Itoh, K.; Nakano, H.; Nakamura, S.; Watanabe, F.; Satake, S.; Yoshimura, Y.; Osakabe, M.; Tanaka, K.; Tokuzawa, T.; Takeiri, Y.; Tsumori, K.; Ikeda, K.; Kubo, S.; Shimozuma, Τ.; Igami, H.; Takahashi, H.; Tamura, N.

doi:10.1088/0741-3335/52/12/124025

Cited by 28 publications

(43 citation statements)

References 36 publications

(43 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Phase contrast imaging measures fluctuations as line integrated signals and has been successfully employed for studying RSAE in sawtoothing plasmas in C-mod [88]. HIBPs are a unique fluctuation diagnostic and have also been applied to studies of EP driven fluctuations in stellarator/helical devices [89,90].…”

Section: 24mentioning

confidence: 99%

Energetic particle physics in fusion research in preparation for burning plasma experiments

2014

View full text Add to dashboard Cite

The area of energetic particle (EP) physics in fusion research has been actively and extensively researched in recent decades. The progress achieved in advancing and understanding EP physics has been substantial since the last comprehensive review on this topic by Heidbrink and Sadler (1994 Nucl. Fusion 34 535). That review coincided with the start of deuterium-tritium (DT) experiments on the Tokamak Fusion Test Reactor (TFTR) and full scale fusion alphas physics studies. Fusion research in recent years has been influenced by EP physics in many ways including the limitations imposed by the 'sea' of Alfvén eigenmodes (AEs), in particular by the toroidicity-induced AE (TAE) modes and reversed shear AEs (RSAEs). In the present paper we attempt a broad review of the progress that has been made in EP physics in tokamaks and spherical tori since the first DT experiments on TFTR and JET (Joint European Torus), including stellarator/helical devices. Introductory discussions on the basic ingredients of EP physics, i.e., particle orbits in STs, fundamental diagnostic techniques of EPs and instabilities, wave particle resonances and others, are given to help understanding of the advanced topics of EP physics. At the end we cover important and interesting physics issues related to the burning plasma experiments such as ITER (International Thermonuclear Experimental Reactor).

show abstract

Section: 24mentioning

confidence: 99%

Energetic particle physics in fusion research in preparation for burning plasma experiments

2014

View full text Add to dashboard Cite

show abstract

“…The Heavy Ion Beam Probe (HIBP) is a unique diagnostic to study directly the electric potential and turbulence characteristics in toroidal plasmas from the core to the edge [2,3]. The HIBP was used in the T-10 circular tokamak [4], in TJ-II, a four-period flexible heliac with helical plasma axis [5] and in the stellarators CHS [6] and LHD [7] to study the potential with high spatial (< 1 cm) and temporal (1 µs) resolution in plasmas with comparable parameters, but in different magnetic configurations. Comparison for Ohmic (OH) and Electron Cyclotron Resonance Heating (ECRH) plasmas in the two machines, T-10 and TJ-II reveals similar tendencies of the potential profiles [8,9].…”

Section: Introductionmentioning

confidence: 99%

Plasma Potential in Toroidal Devices: T-10, TJ-II, CHS and LHD

Melnikov

Hidalgo²,

Ido

et al. 2012

Plasma and Fusion Research

View full text Add to dashboard Cite

Direct measurements of the electric potential ϕ, using the Heavy Ion Beam Probing, have been undertaken in the T-10 tokamak, and in the helical devices with various magnetic topology: TJ-II, CHS and LHD. L-mode plasmas were considered. Despite the large differences in machine sizes, heating methods and the topology of the magnetic field, the observed ϕ shows the striking similarities: (i) Similar magnitudes of E r ; (ii) For low densities, n e < 0.5 × 10 19 m −3 , ϕ is positive, and an increase in n e is associated with the decrease of positive ϕ and formation of a negative E r ; (iii) For higher densities, n e > (0.5-1) × 10 19 m −3 , both ϕ and E r tends to be negative despite the use of different heating methods: Ohmic and ECR heating in T-10, ECRH and/or NBI in TJ-II, CHS and LHD; (iv) Application of ECRH, causing a rise in T e , results in more positive values for ϕ and E r . The analysis show that the main features of the ϕ dependences on the n e and T e agree with neoclassical predictions on the four devices within experimental and simulation precisions.

show abstract

“…While in plasmas of smaller temperature, positive radial electric fields have been measured in the edge region and connected to changes in impurity transport [13], impurity hole plasmas display a negative electric field in the core [14]; in spite of this experimental observation, transport analyses need an outward pinch in order to describe the time evolution of the impurity concentration.…”

mentioning

confidence: 99%

Moderation of neoclassical impurity accumulation in high temperature plasmas of helical devices

Velasco¹,

Calvo²,

Satake³

et al. 2016

Nucl. Fusion

View full text Add to dashboard Cite

Achieving impurity and helium ash control is a crucial issue in the path towards fusion-grade magnetic confinement devices, and this is particularly the case of helical reactors, whose low-collisionality ion-root operation scenarios usually display a negative radial electric field which is expected to cause inwards impurity pinch. In this work we discuss, based on experimental measurements and standard predictions of neoclassical theory, how plasmas of very low ion collisionality, similar to those observed in the impurity hole of the Large Helical Device [1-3], can be an exception to this general rule, and how a negative radial electric field can coexist with an outward impurity flux. This interpretation is supported by comparison with documented discharges available in the International Stellarator-Heliotron Profile Database, and it can be extrapolated to show that achievement of high ion temperature in the core of helical devices is not fundamentally incompatible with low core impurity content.

show abstract

Experimental study of radial electric field and electrostatic potential fluctuation in the Large Helical Device

Cited by 28 publications

References 36 publications

Energetic particle physics in fusion research in preparation for burning plasma experiments

Energetic particle physics in fusion research in preparation for burning plasma experiments

Plasma Potential in Toroidal Devices: T-10, TJ-II, CHS and LHD

Moderation of neoclassical impurity accumulation in high temperature plasmas of helical devices

Contact Info

Product

Resources

About