Recent Heliotron E Physics Study Activities and Engineering Developments

Obiki, T.; Wakatani, Masahiro; Sato, Motoyasu; Sudo, S.; Sano, F.; Mutoh, T.; Itoh, K.; Kondo, K.; Nakasuga, M.; Hanatani, K.; Zushi, H.; Mizuuchi, T.; Kaneko, Hiroshi; Okada, H.; Takeiri, Y.; Nakamura, Yuji; Besshou, S.; Ijiri, Y.; Iima, M.; Senju, T.; Yaguchi, K.; Baba, Teruhiko; Kobayashi, S.; Matsuo, Keiji; Muraoka, Katsunori; Tsukishima, Takashige; Nakajima, Masamitsu

doi:10.13182/fst90-a29174

Cited by 34 publications

(8 citation statements)

References 23 publications

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“…The Heliotron E experiment [37] has been in operation since 1980. Throat baffle plates were installed in one fifth of the torus in a recent modification [38]. The divertor plasma parameters were unchanged by the baffles, but the neutral densities in the baffled and non-baffled sections were different under some plasma conditions; this was consistent with theoretical predictions.…”

Section: Heliotron Esupporting

confidence: 68%

Stellarators

et al. 1990

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Section: Heliotron Esupporting

confidence: 68%

Stellarators

et al. 1990

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“…Heliotron E [17] is an l = 2/m = 19 heliotron/torsatron device. The major radius of the torus is R 0 = 2.2 m and the average plasma minor radius is ā ≈ 0.2 m. The inner radius of the rounded parts of the vacuum chamber is 0.41 m, so the 'X point' structure of the boundary magnetic field is well inside the vacuum chamber.…”

Section: Experimental Conditionsmentioning

confidence: 99%

Main divertor flows in Heliotron E: their distribution and dependence on NBI and ECH

Chechkin

Voitsenya

Mizuuchi³

et al. 2000

Nucl. Fusion

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In the l = 2/m = 19 Heliotron E heliotron/torsatron device, with a currentless plasma heated by NBI and ECH, the poloidal distributions were measured of diverted plasma flows near the vacuum chamber wall in eight sections of one helical field pitch. A vertical asymmetry of these distributions was observed, contrary to what had been expected from the helical symmetry of the `ideal' (unperturbed) vacuum divertor magnetic configuration. Under NBI conditions, the density normalized divertor plasma flow Jd/n̄e was a rising function of the density normalized absorbed power Pabs/n̄e. This is considered to be a consequence of the power degradation of confinement. With second harmonic ECH, where the main part of the launched power was absorbed in the central region, a similar power dependence as for the NBI was observed. With fundamental ECH, where a considerable fraction of the microwave power was absorbed at the periphery, Jd/n̄e for some areas of the divertor trace distinctly exceeded those obtained under NBI-only conditions with the same Pabs/n̄e. On the other hand, two different time responses (fast and slow) of Jd were observed for the perpendicular NBI and fundamental ECH cases in some particular positions. The slow response is considered to be caused by a diffusion-like outflow of the bulk plasma to the divertor. The fast outflow of particles to the divertor might be caused by a loss of locally trapped high energy electrons and ions.

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“…Vol.31, No. 12 (1991) (2) The electron pressure profiles of ECH plasmas with the optimum configuration (a* = 0.05 and /3* = -0.192, magnetic axis shift 20 mm inward) have been measured in detail. The electron pressure in this configuration is clearly higher than that for the standard configuration.…”

Section: Optimum Configuration With a Limitermentioning

confidence: 99%

“…Recently, active control of the magnetic field configuration of Heliotron E [1] has been intensively studied for optimization of confinement and investigation of transport [2,3]. For helical systems, similar studies are carried out in ATF [4] and CHS [5].…”

Section: Introductionmentioning

confidence: 99%

Optimum confinement of ECH plasmas in Heliotron E

et al. 1991

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The optimum confinement of plasmas produced by electron cyclotron heating (ECH) in Heliotron E and some other significant transport characteristics of ECH plasmas have been studied experimentally by changing the magnetic field configuration. It is found that the plasma confinement can be improved by minor changes of the magnetic field configuration. The main results are as follows: (1) Plasmas with a minor radius reduced (by means of a limiter) to two thirds of the value in the original (non-limited) configuration have optimum confinement properties when the magnetic axis is shifted inward by 20 mm. (2) The electron pressure in an optimized plasma configuration (confirmed by neutral beam injection) is higher than that in a standard ECH plasma. (3) The insertion of a carbon limiter causes the plasma line density to increase, with no significant degradation of the core temperature or density. (4) Magnetic field perturbations hardly affect the temperature and density profiles, unless the magnetic axis is shifted outward by a large (50 mm) distance. (5) Transport analysis indicates that significant improvement in the confinement properties can be achieved by slightly manipulating the magnetic field configuration.

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Recent Heliotron E Physics Study Activities and Engineering Developments

Cited by 34 publications

References 23 publications

Stellarators

Stellarators

Main divertor flows in Heliotron E: their distribution and dependence on NBI and ECH

Optimum confinement of ECH plasmas in Heliotron E

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