Reaction of turbulence at the edge and in the center of the plasma column to pulsed impurity injection caused by the sputtering of the wall coating in L-2M stellarator

Batanov, G. M.; Berezhetskiǐ, M. S.; Borzosekov, V. D.; Vasilkov, D. G.; Vafin, I. Yu.; Grebenshchikov, S. E.; Grishina, I. A.; Колик, Л. В.; Konchekov, E. M.; Larionova, N. F.; Летунов, А. А.; Logvinenko, V. P.; Malakhov, D. V.; Meshcheryakov, A. I.; Petrov, A. E.; Sarksian, K. A.; Скворцова, Н. Н.; Степахин, В. Д.; Kharchev, N. K.; Kharchevskii, A. A.; Khol'nov, Yu.V.; Shchepetov, S. V.

doi:10.1134/s1063780x17080049

Cited by 10 publications

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“…Transition processes of two types are routinely observed in the L-2M plasma: the first type is caused by an abrupt change in the ECRH power, while the second happens spontaneously during heating at a constant power [21][22][23]. In the present study, we statistically analyze only transition processes caused by an abrupt increase in the ECRH power.…”

Section: Experimental Set-up and Data Analysis Techniquementioning

confidence: 99%

“…This leads to a high energy flux onto the vacuum vessel wall with the following sputtering of the wall coating and pulsed impurity injection into the plasma. This pulsed impurity injection was delayed by 1 ms relative to the switching-on of the secondary gyrotron and resulted, among other things, in a decrease in the electron temperature T e [21].…”

Section: Experimental Set-up and Data Analysis Techniquementioning

confidence: 99%

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Evolution of statistical properties of microturbulence during transient process under electron cyclotron resonance heating of the L-2M stellarator plasma

Batanov

Borzosekov

Gorshenin

et al. 2019

Plasma Phys. Control. Fusion

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The formalism of compound Cox processes was used for statistical analysis of turbulent density fluctuations of plasma during a transient process at electron cyclotron resonance heating of L-2M stellarator plasmas. Short-wavelength (k=20-30 cm −1 ) density fluctuations in the central region of the plasma column were measured by the collective backscattering technique. The transient process was caused by sputtering of wall coating and subsequent pulsed impurity injection into the plasma after a step-like increase of the heating power. The evolution of the following parameters was studied: probability density function (PDF) and dynamic and diffusive components of variance of density fluctuations increments. It was found that density fluctuations increments increase simultaneously with average electron density increase and electron temperature decrease during the transient process. It was shown that the PDF of fluctuation increments is characterized by the existence of heavy tails and it can be represented as a composition of four normal laws. Deviation from normal law that happens in the form of random bursts was observed. Duration and frequency of the bursts increases with the level of fluctuation increments and this increase is accompanied by the increase of both components of the variance.

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Section: Experimental Set-up and Data Analysis Techniquementioning

confidence: 99%

Section: Experimental Set-up and Data Analysis Techniquementioning

confidence: 99%