Shafranov shift in the low aspect ratio heliotron/torsatron Compact Helical System

H. Yamada; K. Ida; H. Iguchi; S. Morita; O. Kaneko; H. Arimoto; M. Hosokawa; H. Idei; S. Kubo; K. Matsuoka; K. Nishimura; S. Okamura; Y. Takeiri; Y. Takita; C. Takahashi; K. Hanatani; H. C. Howe; S. P. Hirshman; D. K. Lee

doi:10.1088/0029-5515/32/1/I03

Shafranov shift in the low aspect ratio heliotron/torsatron Compact Helical System

H. Yamada, K. Ida, H. Iguchi, S. Morita, O. Kaneko, H. Arimoto, M. Hosokawa, H. Idei, S. Kubo, K. Matsuoka, K. Nishimura, S. Okamura, Y. Takeiri, Y. Takita, C. Takahashi, K. Hanatani, H. C. Howe, S. P. Hirshman, D. K. Lee

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Abstract

The MHD equilibrium properties of neutral beam heated plasmas have been experimentally investigated in the Compact Helical System (CHS)-a low aspect ratio (A_p ∼ 5) heliotron/torsatron. This configuration is characterized by a strong breaking of helical symmetry. The radial profiles measured by various diagnostics have shown a significant Shafranov shift due to the plasma pressure. The deviation of the magnetic axis from is vacuum position has become as large as 50% of the minor radius. When the three-dimensional equilibrium code VMEC is used to reconstruct the equilibrium from the experimental data, the result is in good agreement with the experimentally observed Shafranov shift as well as with the diamagnetic pressure in plasmas with 〈β〉 ≤ 1.2% and β₀ ≤ 3.3%. This beta values corresponds to half of the conventional equilibrium β limit defined by the Shafranov shift reaching a value of half of the minor radius. Although tangential neutral beam injection causes pressure anisotropies, p _||/p_⊥ ≤ 3, the description of the equilibrium assuming isotropic pressure is consistent with the experiment.

Original language	English
Article number	I03
Pages (from-to)	25-32
Number of pages	8
Journal	Nuclear Fusion
Volume	32
Issue number	1
DOIs	https://doi.org/10.1088/0029-5515/32/1/I03
Publication status	Published - Dec 1 1992
Externally published	Yes

All Science Journal Classification (ASJC) codes

Nuclear and High Energy Physics
Condensed Matter Physics

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10.1088/0029-5515/32/1/I03

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Yamada, H., Ida, K., Iguchi, H., Morita, S., Kaneko, O., Arimoto, H., Hosokawa, M., Idei, H., Kubo, S., Matsuoka, K., Nishimura, K., Okamura, S., Takeiri, Y., Takita, Y., Takahashi, C., Hanatani, K., Howe, H. C., Hirshman, S. P., & Lee, D. K. (1992). Shafranov shift in the low aspect ratio heliotron/torsatron Compact Helical System. Nuclear Fusion, 32(1), 25-32. [I03]. https://doi.org/10.1088/0029-5515/32/1/I03

Yamada, H, Ida, K, Iguchi, H, Morita, S, Kaneko, O, Arimoto, H, Hosokawa, M, Idei, H, Kubo, S, Matsuoka, K, Nishimura, K, Okamura, S, Takeiri, Y, Takita, Y, Takahashi, C, Hanatani, K, Howe, HC, Hirshman, SP & Lee, DK 1992, 'Shafranov shift in the low aspect ratio heliotron/torsatron Compact Helical System', Nuclear Fusion, vol. 32, no. 1, I03, pp. 25-32. https://doi.org/10.1088/0029-5515/32/1/I03

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title = "Shafranov shift in the low aspect ratio heliotron/torsatron Compact Helical System",

abstract = "The MHD equilibrium properties of neutral beam heated plasmas have been experimentally investigated in the Compact Helical System (CHS)-a low aspect ratio (Ap ∼ 5) heliotron/torsatron. This configuration is characterized by a strong breaking of helical symmetry. The radial profiles measured by various diagnostics have shown a significant Shafranov shift due to the plasma pressure. The deviation of the magnetic axis from is vacuum position has become as large as 50% of the minor radius. When the three-dimensional equilibrium code VMEC is used to reconstruct the equilibrium from the experimental data, the result is in good agreement with the experimentally observed Shafranov shift as well as with the diamagnetic pressure in plasmas with 〈β〉 ≤ 1.2% and β0 ≤ 3.3%. This beta values corresponds to half of the conventional equilibrium β limit defined by the Shafranov shift reaching a value of half of the minor radius. Although tangential neutral beam injection causes pressure anisotropies, p ||/p⊥ ≤ 3, the description of the equilibrium assuming isotropic pressure is consistent with the experiment.",

author = "H. Yamada and K. Ida and H. Iguchi and S. Morita and O. Kaneko and H. Arimoto and M. Hosokawa and H. Idei and S. Kubo and K. Matsuoka and K. Nishimura and S. Okamura and Y. Takeiri and Y. Takita and C. Takahashi and K. Hanatani and Howe, {H. C.} and Hirshman, {S. P.} and Lee, {D. K.}",

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doi = "10.1088/0029-5515/32/1/I03",

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T1 - Shafranov shift in the low aspect ratio heliotron/torsatron Compact Helical System

AU - Yamada, H.

AU - Ida, K.

AU - Iguchi, H.

AU - Morita, S.

AU - Kaneko, O.

AU - Arimoto, H.

AU - Hosokawa, M.

AU - Idei, H.

AU - Kubo, S.

AU - Matsuoka, K.

AU - Nishimura, K.

AU - Okamura, S.

AU - Takeiri, Y.

AU - Takita, Y.

AU - Takahashi, C.

AU - Hanatani, K.

AU - Howe, H. C.

AU - Hirshman, S. P.

AU - Lee, D. K.

PY - 1992/12/1

Y1 - 1992/12/1

N2 - The MHD equilibrium properties of neutral beam heated plasmas have been experimentally investigated in the Compact Helical System (CHS)-a low aspect ratio (Ap ∼ 5) heliotron/torsatron. This configuration is characterized by a strong breaking of helical symmetry. The radial profiles measured by various diagnostics have shown a significant Shafranov shift due to the plasma pressure. The deviation of the magnetic axis from is vacuum position has become as large as 50% of the minor radius. When the three-dimensional equilibrium code VMEC is used to reconstruct the equilibrium from the experimental data, the result is in good agreement with the experimentally observed Shafranov shift as well as with the diamagnetic pressure in plasmas with 〈β〉 ≤ 1.2% and β0 ≤ 3.3%. This beta values corresponds to half of the conventional equilibrium β limit defined by the Shafranov shift reaching a value of half of the minor radius. Although tangential neutral beam injection causes pressure anisotropies, p ||/p⊥ ≤ 3, the description of the equilibrium assuming isotropic pressure is consistent with the experiment.

AB - The MHD equilibrium properties of neutral beam heated plasmas have been experimentally investigated in the Compact Helical System (CHS)-a low aspect ratio (Ap ∼ 5) heliotron/torsatron. This configuration is characterized by a strong breaking of helical symmetry. The radial profiles measured by various diagnostics have shown a significant Shafranov shift due to the plasma pressure. The deviation of the magnetic axis from is vacuum position has become as large as 50% of the minor radius. When the three-dimensional equilibrium code VMEC is used to reconstruct the equilibrium from the experimental data, the result is in good agreement with the experimentally observed Shafranov shift as well as with the diamagnetic pressure in plasmas with 〈β〉 ≤ 1.2% and β0 ≤ 3.3%. This beta values corresponds to half of the conventional equilibrium β limit defined by the Shafranov shift reaching a value of half of the minor radius. Although tangential neutral beam injection causes pressure anisotropies, p ||/p⊥ ≤ 3, the description of the equilibrium assuming isotropic pressure is consistent with the experiment.

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Shafranov shift in the low aspect ratio heliotron/torsatron Compact Helical System

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