The time behaviour of the thermal conductivity during L to H and H to L transitions in JET

Cordey, J.G.; Muir, D.G.; Neudatchin, S V; Parail, V.; Ali-Arshad, S.; Bartlett, D.V.; Campbell, D.J.; Costley, A.E.; Colton, A.L.; Edwards, A. W.; Porte, L.; Sips, A. C. C.; Springmann, E.; Stubberfield, P.M.; Vayakis, G.; Hellermann, M. G. von; Taroni, A.; Thomsen, K.

doi:10.1088/0741-3335/36/7a/039

Cited by 59 publications

(46 citation statements)

References 6 publications

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“…To simplify the analysis and obtain a range for the achievable values of Q ⊥ , we can assume that n e (r) is roughly constant near the edge, or at least has an average value n e , and that κ ⊥ ~ constant which is roughly consistent with present experiments (e.g. 19 ). This scaling is similar to the "INTOR" scaling since nχ ⊥ ~ κ ⊥ so that χ ⊥ ≈ n -1 .…”

Section: Impurity Radiation From the Main Plasma Edgementioning

confidence: 60%

Calculations of energy losses due to atomic processes in tokamaks with applications to the International Thermonuclear Experimental Reactor divertor

Post¹,

Abdallah²,

Clark³

et al. 1995

Physics of Plasmas

119

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Reduction of the peak heat loads on the plasma facing components is essential for the success of the next generation of high fusion power tokamaks such as the International Thermonuclear Experimental Reactor (ITER) 1 . Many present concepts for accomplishing this involve the use of atomic processes to transfer the heat from the plasma to the main chamber and divertor chamber walls and much of the experimental and theoretical physics research in the fusion program is directed toward this issue. The results of these experiments and calculations are the result of a complex interplay of many processes. In order to identify the key features of these experiments and calculations and the relative role of the primary atomic processes, simple quasianalytic models and the latest atomic physics rate coefficients and cross sections have been used to assess the relative roles of central radiation losses through bremsstrahlung, impurity radiation losses from the plasma edge, charge exchange and hydrogen radiation losses from the scrape-off layer and divertor plasma and impurity radiation losses from the divertor plasma. This anaysis indicates that bremsstrahlung from the plasma center and impurity radiation from the plasma edge and divertor plasma can each play a significant role in reducing the power to the divertor plates, and identifies many of the factors which determine the relative role of each process. For instance, for radiation losses in the divertor to be large enough to radiate the power in the divertor for high power experiments, a neutral fraction of 10 -3 to 10 -2 and an impurity recycling rate of n e τ recycle of 10 16 s m -3 will be required in the divertor.

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Section: Impurity Radiation From the Main Plasma Edgementioning

confidence: 60%

Calculations of energy losses due to atomic processes in tokamaks with applications to the International Thermonuclear Experimental Reactor divertor

Post¹,

Abdallah²,

Clark³

et al. 1995

Physics of Plasmas

119

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“…It also identifies one element of the global profile readjustment which follows the L→H transition, 39,40 namely the quenching of turbulence in the core which originated at the edge. Application of this model has helped elucidate the dynamical connection between core and edge, and the appearance of a connection zone, driven by the "spillover" of energy from the strongly turbulent edge into the quasi-marginal core.…”

Section: Discussionmentioning

confidence: 99%

On the dynamics of edge-core coupling

et al. 2005

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One of the nagging, unresolved questions in fusion theory is concerned with the extent of the edge.Gyrokinetic particle simulations of toroidal ion temperature gradient (ITG) turbulence spreading using the Gyrokinetic Toroidal Code (GTC) [Z. Lin et al., Science 281, 1835] and its related dynamical model have been extended to a system with radially varying ion temperature gradient, in order to study the inward spreading of edge turbulence toward the core plasma. Due to such spreading, the turbulence intensity in the core region is significantly enhanced over the value obtained from simulations of the core region only, and the precise boundary of the edge region is blurred. Even when the core gradient is within the Dimits shift regime (i.e., dominated by self-generated zonal flows which reduce the transport to a negligible value), a significant level of turbulence can penetrate to the core due to spreading from the edge. The scaling of the turbulent front propagation speed is closer to the prediction from a nonlinear diffusion model than from one based on linear toroidal coupling.

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“…[7,37], a fast timescale for propagation of the order of 1 ms has been reported. The speed of propagation of the order of the diamagnetic drift velocity is sufficiently fast to explain the abrupt change of transport observed in many toroidal plasmas [2][3][4][5][6][7]. The large-scaleT rad fluctuation is one of the entities capable of producing a rapid transient response.…”

Section: Transient Transportmentioning

confidence: 99%

“…ITOH 1,2) , Naoki TAMURA 3) , Satoru SAKAKIBARA 3) , Naohiro KASUYA 3) , Akihide FUJISAWA 1,2) , Shin KUBO 3) , Takashi SHIMOZUMA 3) , Takeshi IDO 3) , Seiya NISHIMURA 3) , Hiroyuki ARAKAWA 4) , Tatsuya KOBAYASHI 4) , Masatoshi YAGI 1,2) , Kenji TANAKA 3) , Yoshio NAGAYAMA 3) , Kazuo KAWAHATA 3) , Shigeru SUDO 3) , Hiroshi YAMADA 3) , Akio KOMORI 3) and LHD Experiment Group We report a detailed correlation technique to identify the long-range temperature fluctuation in the Large Helical Device. Correlation hunting has successfully realized the observation of electron temperature fluctuations, which are characterized by their correlation length comparable to the plasma minor radius, with low frequency of ∼ 1-3 kHz, ballistic radial propagation (at a speed of ∼1 km/s, of the order of diamagnetic drift velocity), spatial mode number of m/n = 1/1 (or 2/1), and amplitude of ∼2% at the maximum.…”

Section: Long Range Temperature Fluctuation In Lhdmentioning

confidence: 99%

“…In future experiments on thermonuclear fusion, such as the Internal Thermonuclear Experimental Reactor (ITER), the performance and controllability of plasmas are predicted and designed based on the basis of such a presumption. However, the fast radial propagation of temperature perturbations in toroidal plasmas, i.e., the so-called "transient transport problem", has been observed in many tokamaks and helical devices during the course of the last two decades [2][3][4][5][6][7]. The temperature perturbation, which is applied to the plasma edge region, propagates inward at a speed that is 10-50 times faster than that expected from diffusive transport models.…”

Section: Introductionmentioning

confidence: 99%

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Long Range Temperature Fluctuation in LHD

Inagaki

Tokuzawa

Itoh

et al. 2011

Plasma and Fusion Research

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We report a detailed correlation technique to identify the long-range temperature fluctuation in the Large Helical Device. Correlation hunting has successfully realized the observation of electron temperature fluctuations, which are characterized by their correlation length comparable to the plasma minor radius, with low frequency of ∼ 1-3 kHz, ballistic radial propagation (at a speed of ∼1 km/s, of the order of diamagnetic drift velocity), spatial mode number of m/n = 1/1 (or 2/1), and amplitude of ∼2% at the maximum. Bicoherence analysis confirmed their nonlinear coupling with local microscopic turbulent fluctuations. This long-range temperature fluctuation is a possible carrier of fast propagation in transport processes observed so far. We also comment on the theoretical interpretation.

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The time behaviour of the thermal conductivity during L to H and H to L transitions in JET

Cited by 59 publications

References 6 publications

Calculations of energy losses due to atomic processes in tokamaks with applications to the International Thermonuclear Experimental Reactor divertor

Calculations of energy losses due to atomic processes in tokamaks with applications to the International Thermonuclear Experimental Reactor divertor

On the dynamics of edge-core coupling

Long Range Temperature Fluctuation in LHD

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