Method for Detection of Separatrix Surface Using Differential Double Probe

Amemiya, Hiroshi; Uehara, K.

doi:10.1143/jjap.45.247

Cited by 4 publications

(5 citation statements)

References 15 publications

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“…As for the plasma position, it had been demonstrated that the calculated results agree well with the visible camera and soft x-ray array within an accuracy of the measurement, ∼3 cm [7]. To investigate the separatrix position more precisely, a new method was developed to measure the separatrix position using the 2-step electrostatic probes as follows [15,16]. Two sets of double probes with different pin lengths (difference : 5 mm) are inserted in the plasma.…”

Section: Equilibrium Codementioning

confidence: 96%

Compatibility of reduced activation ferritic steel wall with high performance plasma on JFT-2M

et al. 2006

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In JFT-2M, the applicability of reduced activation ferritic steel to a fusion demonstration reactor has been demonstrated mainly concerning the ferromagnetic effect on plasma production, control, stability and confinement. The compatibility of the close ferritic wall with high-normalized beta plasmas has been investigated mainly because the demonstration reactor will utilize the wall stabilization effect. Due to improvements in the operation scenario and the modification of the guard limiter configuration, the region showing good compatibility was extended to the closer wall position (the wall position was normalized to the plasma minor radius; r wall /a ∼ 1.25) and the higher normalized beta (β N ∼ 3.5), compared with the previous works with the relatively far wall position and stronger magnetic field (Tsuzuki K. et al 2003 Nucl. Fusion. 43 1288. A reduction in the growth rate of the instability was also observed in the close wall case, which presumably corresponds to the wall stabilization effect, similar to a resistive wall without ferromagnetism.

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Section: Equilibrium Codementioning

confidence: 96%

Compatibility of reduced activation ferritic steel wall with high performance plasma on JFT-2M

et al. 2006

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“…We perform the direct observation of magnetic surfaces using the differential double probe (DDP), which is the two double probe system with long and short probe tips to detect the separatrix position as shown in Fig. 4(f) [13]. We can detect this by observing the current increment of the DDP through the differential amplifier when the top of the DDP crosses the separatrix when plasma was jogged from the core plasma region to the scrape-off layer (SOL) [14].…”

Section: Electrostatic Probe For Measuring the Ion Temperature And Mamentioning

confidence: 99%

Electrostatic Probes for Studying Transport Properties in Tokamak Plasmas

Uehara

Sadamoto

Amemiya

et al. 2010

Contrib. Plasma Phys.

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Electrostatic probes for measuring the boundary plasma in tokamaks are reviewed and presented. Transport properties in JFT-2, the ion temperature and the magnetic surface in JFT-2M and floating potential fluctuations during the strong additional heating in JT-60 are measured by several types of electrostatic probe the abovementioned purposes. The Langmuir probe including the double probe is applied to measure the spatial profile of boundary plasma in JFT-2. The ion sensitive probe, the rotating cylindrical double probe, the asymmetric double probe and the differential double probe are applied to measure the ion temperature and magnetic surface in JFT-2M. The reciprocating Langmuir probe applied to JFT-2M observes the potential and density fluctuations and a new type probe is proposed for the quick diagnostic of core hot plasmas as a development of this probe. The fluctuation observed in JT-60 is identified to be the ion cyclotron instability of the hot plasma caused by the strong anisotropy of the ion distribution function.

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“…Several probe methods have been developed to measure the ion temperature in fusion plasmas. [1][2][3][4][5] In the edges of these plasmas, the ion temperature T i has been found to exceed the electron temperature T e in tokamaks such as DITE, 6) TEXTOR, 7) and JFT-2M. 8) In the plasmas with T i > T e , the effect of the presheath is small so the ions reach the probe with almost the thermal velocity.…”

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confidence: 99%

Probe method for measuring the diffusion coefficient in edge plasma

Amemiya¹,

Uehara²,

Ohshima

et al. 2016

Jpn. J. Appl. Phys.

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A probe method to measure the diffusion coefficient and the ion temperature in the edge plasma is proposed. The probe is constructed as an asymmetric double probe, where one electrode is sensitive to the direction of magnetic field while the other is insensitive to it. The ratio of ion saturation currents to two electrodes is used to determine the diffusion coefficient from which the ion temperature is estimated. The saturation currents are calculated by taking the anisotropic diffusion to the probe into account. The present probe method is applicable in the edge plasma even with such a complicated magnetic field as that in helical devices.

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Method for Detection of Separatrix Surface Using Differential Double Probe

Cited by 4 publications

References 15 publications

Compatibility of reduced activation ferritic steel wall with high performance plasma on JFT-2M

Compatibility of reduced activation ferritic steel wall with high performance plasma on JFT-2M

Electrostatic Probes for Studying Transport Properties in Tokamak Plasmas

Probe method for measuring the diffusion coefficient in edge plasma

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