Status and Prospects in Stellarator Research  at Ipp Kipt

Moiseenko, V.Е.; Kovtun, Yu. V.; Garkusha, I.E.

doi:10.46813/2021-131-003

Cited by 3 publications

(3 citation statements)

References 11 publications

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“…Moreover, plasma production is possible with RF heating below the ion cyclotron frequency. This method is mainly used in small stellarators [7]. In the mid-sized helical device compact helical system (CHS) the plasma production was performed by a Nagoya type-III antenna [8].…”

Section: Introductionmentioning

confidence: 99%

First experiments on plasma production using field-aligned ICRF fast wave antennas in the large helical device

et al. 2021

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The results of the first experimental series to produce a plasma using the ion cyclotron range of frequency (ICRF) in the large helical device (LHD) within the minority scenario developed at Uragan-2M (U-2M) are presented. The motivation of this study is to provide plasma creation in conditions when an electron cyclotron resonance heating start-up is not possible, and in this way widen the operational frame of helical machines. The major constraint of the experiments is the low RF power to reduce the possibility of arcing. No dangerous voltage increase at the radio-frequency (RF) system elements and no arcing has been detected. As a result, a low plasma density is obtained and the antenna-plasma coupling is not optimal. However, such plasmas are sufficient to be used as targets for further neutral beam injection (NBI) heating. This will open possibilities to explore new regimes of operation at LHD and Wendelstein 7-X (W7-X) stellarator. The successful RF plasma production in LHD in this experimental series stimulates the planning of further studies of ICRF plasma production aimed at increasing plasma density and temperature within the ICRF minority scenario as well as investigating the plasma prolongation by NBI heating.

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Section: Introductionmentioning

confidence: 99%

First experiments on plasma production using field-aligned ICRF fast wave antennas in the large helical device

et al. 2021

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“…In helium plasma at k || ≈ 1 m −1 and B t = 2.75 T, depending on the magnitude of the magnetic field in front of the FAIT antenna (≈2.2-2.6 T), the critical density ranges is (1.9-2.3)× 10 16 m −3 . For other modes with higher k ∥ critical density scales as N ec, FW ∝ |k || | 2 . This means that more modes penetrate to plasma when the plasma density is higher.…”

Section: Icrf Plasma Productionmentioning

confidence: 99%

“…Plasma production is practiced at the ion cyclotron range of frequencies (ICRF) in pure gases (He, H 2 , D 2 and others) [2,3]. It was tried at Large Helical Device (LHD) [4].…”

Section: Introductionmentioning

confidence: 99%

ICRF plasma production at hydrogen minority regime in LHD

Kovtun,

Kasahara,

Moiseenko

et al. 2023

Nucl. Fusion

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his study aim is to develop further an ion cyclotron range of frequencies (ICRF) method of plasma production in stellarators based on the minority heating. The previous studies demonstrate production of low density plasma (9.5×1017 m−3) at low power of up to 0.2 MW. The higher ICRF heating power experiments become possible after introducing a programmable ICRF power ramp up at the front of the ICRF pulse. With this trick, all the shots went with the antenna voltage within the safe range. Increase of the ICRF power predictably results in increase of the density of produced plasma. Without pre-ionization the plasma density achieved was 6×1018 m-3 which is 6 times higher than in previous experiments. However, the electron temperature was not high, the light impurities were hot fully stripped, and there were no recombination peaks after termination of the ICRF pulse. Plasma density is too low to provide good conditions for efficient plasma heating. For the reference, the ICRF heating of high density cold plasma prepared by electron cyclotron resonance heating (ECRH) is performed. Both electrons and ions were heated to high temperatures, and this plasma state is sustained. The antenna-plasma coupling was much better which result in larger heating power with the lower antenna voltage.

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