Electron Density Profile Measurement in Heliotron J with a Microwave AM Reflectometer

Mukai, K.; Nagasaki, K.; Zhuravlev, V. A.; Fukuda, T.; Mizuuchi, T.; Minami, Takashi; Okada, H.; Kobayashi, S.; Yamamoto, Satoshi; Hanatani, K.; Konoshima, S.; Ohshima, S.; Takeuchi, Masaki; Nishi, Daiki; Minami, Kazuaki; Lee, H.Y.; Takabatake, Y.; Kishi, S.; Yashiro, Hiroaki; Sano, F.

doi:10.1002/ctpp.200900023

Cited by 3 publications

(2 citation statements)

References 8 publications

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“…It clearly shows the stabilization comparing with the solution in Eq. (5). Errors in (U TÑ ) i are not propagated with the factors 1/ w i , but only with the factors w i /(w i 2 + mγ ) into the solution.…”

Section: A Svd-gcv Methodsmentioning

confidence: 99%

A novel electron density reconstruction method for asymmetrical toroidal plasmas

Shi

Ohshima

Tanaka

et al. 2014

Review of Scientific Instruments

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A novel reconstruction method is developed for acquiring the electron density profile from multi-channel interferometric measurements of strongly asymmetrical toroidal plasmas. It is based on a regularization technique, and a generalized cross-validation function is used to optimize the regularization parameter with the aid of singular value decomposition. The feasibility of method could be testified by simulated measurements based on a magnetic configuration of the flexible helical-axis heliotron device, Heliotron J, which has an asymmetrical poloidal cross section. And the successful reconstruction makes possible to construct a multi-channel Far-infrared laser interferometry on this device. The advantages of this method are demonstrated by comparison with a conventional method. The factors which may affect the accuracy of the results are investigated, and an error analysis is carried out. Based on the obtained results, the proposed method is highly promising for accurately reconstructing the electron density in the asymmetrical toroidal plasma.

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Section: A Svd-gcv Methodsmentioning

confidence: 99%

A novel electron density reconstruction method for asymmetrical toroidal plasmas

Shi

Ohshima

Tanaka

et al. 2014

Review of Scientific Instruments

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“…The density is saturated at 1.4 × 10 19 m −3 and starts to decrease at about 15 ms after SMBI. The density profile for these two discharges is measured with a microwave reflectmeter [13] at #15.5 section. In the open shutter case, the density profile, which is rather flat before SMBI, rapidly changes to a peaked one after SMBI, while the profile change is slow and mild in the closed shutter case [14] .…”

Section: Effects Of Smbi Fuelingmentioning

confidence: 99%

Recent Progress in Plasma Control Studies on the Improvement of Plasma Performance in Heliotron J

Mizuuchi

Nagasaki

Okada

et al. 2011

Plasma Sci. Technol.

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This paper reviews recent progress on plasma control studies to improve plasma performance in Heliotron J. The SMBI fueling is successfully applied to Heliotron J plasma. A supersonic H 2 -beam is effective to increase fueling efficiency and make a peaked density profile.Local fueling with a short pulse by SMBI can increase the core plasma density avoiding the degradation due to the edge cooling. Second harmonic ECCD experiments have been performed by injecting a focused Gaussian beam with a parallel refractive index of -0.05  N ||  0.6. The experimental results show that the electron cyclotron (EC) driven current is determined not only by N || but also by local magnetic field (B) structure where the EC power is deposited. The detailed analysis of the observed N || and B dependences is in progress with a ray-tracing simulation using TRAVIS code. Fast ion velocity distribution has been investigated using fast protons generated by ICRF minority heating. In the standard configuration in Heliotron J, CX-NPA measurements show the higher effective temperature of fast minority protons in the on-axis resonance case than that in the HFS (high field side) off-axis resonance case. However, the increase of the bulk ion temperature in the HFS resonance case is larger than that in the on-axis resonance.

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Electron Density Profile Behavior during SMBI Measured with AM Reflectometer in Heliotron J Plasma

Mukai

Nagasaki

Mizuuchi

et al. 2011

Plasma and Fusion Research

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The electron density profile was measured using a microwave amplitude modulation (AM) reflectometer in Heliotron J plasmas, where plasma performance was improved using supersonic molecular beam injection (SMBI) as a fueling method. Immediately after the SMBI pulse, for the case in which the supersonic molecular beam penetrates deeply, the density profile rapidly peaks, and the electron density increases in both core and edge regions. Afterward, while the line-averaged electron density is monotonically increasing, the density profile becomes more peaked. In this phase, the edge electron density measured by a Langmuir probe decreases and the peaking factor of the SX profiles measured by an absolute extreme ultraviolet array increases. These trends are consistent with the electron density trend determined by the AM reflectometer. SMBI affects particle confinement and transport, thus possibly increasing plasma stored energy.

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Electron Density Profile Measurement in Heliotron J with a Microwave AM Reflectometer

Cited by 3 publications

References 8 publications

A novel electron density reconstruction method for asymmetrical toroidal plasmas

A novel electron density reconstruction method for asymmetrical toroidal plasmas

Recent Progress in Plasma Control Studies on the Improvement of Plasma Performance in Heliotron J

Electron Density Profile Behavior during SMBI Measured with AM Reflectometer in Heliotron J Plasma

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