Flexible heliac configuration

Harris, J. H.; Cantrell, J. L.; Hender, T. C.; Carreras, B. A.; Morris, Rob

doi:10.2172/5800899

Cited by 3 publications

(3 citation statements)

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“…We discuss our results by comparing them with the analyses based on the stellarator expansion. It is not, however, easy to check absolute values such as the beta limit, since usually the pressure profiles depend on the individual study [14].…”

Section: Discussionmentioning

confidence: 99%

Stability calculations for the m = 1/n = 1 mode in heliotron configurations using the three-dimensional MHD equilibrium and stability (BETA) code

et al. 1986

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Stability against the m = 1/n =1 internal mode is investigated in a Heliotron E model configuration for both currentless and flux conserving torus (FCT) equilibria. The beta limit in the first stability region is β̄ ≤ 2%, where β̄ denotes the average beta. This is consistent with the maximum beta value obtained in Heliotron E. For β̄ ⩾ 5%, a second stability region appears. It is found that the stability is sensitive to additional vertical magnetic fields. When the magnetic axis is shifted inward, the stability degrades, whereas, when it is shifted outward, the instability disappears for the above-given range of beta values. – The stability is also examined in another heliotron configuration which has a rotational transform larger than unity for all flux surfaces. Its first stability beta limit is larger than that for Heliotron E. For this configuration, an unstable free boundary mode with m = 1/n = 1 is found. A comparison of these results with analyses based on the stellarator expansion method is given.

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Section: Discussionmentioning

confidence: 99%

Stability calculations for the m = 1/n = 1 mode in heliotron configurations using the three-dimensional MHD equilibrium and stability (BETA) code

et al. 1986

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“…H-1NF is a medium sized heliac [18] with major radius ∼1 m and average plasma minor radius ∼0.2 m. The coil system of H-1NF allows the configuration to be varied across a broad range, 0.6 < ι < 2.0. This allows avoidance of major rational surfaces and islands in the main confinement volume [19]. The variation is achieved by selectively controlling the ratio of currents in some of the coils with respect to the central ring conductor.…”

Section: Methodsmentioning

confidence: 99%

Determination of error field sources by accurate mapping of the magnetic geometry of the H-1 heliac

Kumar¹,

Blackwell²,

Harris³

2009

Nucl. Fusion

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High precision mapping of the vacuum flux surfaces of the H-1NF heliac is carried out using electron-beam multiwire tomography for various magnetic configurations and field strengths. The extreme accuracy of this technique has been exploited to understand the nature of error fields and to determine the best-fit empirical values for the H-1NF coil parameters, by point-by-point matching experimental surface data with computer modelling results. This has helped in developing a highly accurate computer model for H-1NF magnetic configurations.

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“…The TJ-II is a four period flexible heliac type stellarator [13], [14] optimally suited for the study the influence of rotational transform profiles on MHD and confinement. Twisting of the magnetic axis around a central coil system is the main mechanism to achieve the rotational transform in TJ-II, achieving record values as high as 2.4 in short pulses.…”

Section: Introductionmentioning

confidence: 99%

Magnetic configuration sweep control in heliac type stellarators

Romero

Pacios²,

Peña³

et al. 2014

Nucl. Fusion

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A novel magnetic configuration sweep control system for the TJ-II Heliac device is described. The system is prepared to establish a reference for plasma, torus or vessel current while the coil configuration currents are swept during a single plasma discharge. It can also be run in a special simulation mode, which does not require powering the TJ-II device, intended for commissioning and experiment preparation purposes. Preliminary tests with the system have shown its ability to perform rotational transform scans while establishing a waveform for torus current independently, despite variable plasma conditions. This opens up new experimental possibilities to study the influence of rotational transform and shear independently.

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Flexible heliac configuration

Cited by 3 publications

References 0 publications

Stability calculations for the m = 1/n = 1 mode in heliotron configurations using the three-dimensional MHD equilibrium and stability (BETA) code

Stability calculations for the m = 1/n = 1 mode in heliotron configurations using the three-dimensional MHD equilibrium and stability (BETA) code

Determination of error field sources by accurate mapping of the magnetic geometry of the H-1 heliac

Magnetic configuration sweep control in heliac type stellarators

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