An upgrade of the magnetic diagnostic system of the diii-d tokamak for non-axisymmetric measurements

J. D. King; E. J. Strait; R. L. Boivin; D. Taussig; M. G. Watkins; J. M. Hanson; N. C. Logan; C. Paz-Soldan; D. C. Pace; D. Shiraki; M. J. Lanctot; R. J. La Haye; L. L. Lao; D. J. Battaglia; A. C. Sontag; S. R. Haskey; J. G. Bak

doi:10.1063/1.4891817

An upgrade of the magnetic diagnostic system of the diii-d tokamak for non-axisymmetric measurements

J. D. King^*, E. J. Strait, R. L. Boivin, D. Taussig, M. G. Watkins, J. M. Hanson, N. C. Logan, C. Paz-Soldan, D. C. Pace, D. Shiraki, M. J. Lanctot, R. J. La Haye, L. L. Lao, D. J. Battaglia, A. C. Sontag, S. R. Haskey, J. G. Bak

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

71 Citations (Scopus)

Abstract

The DIII-D tokamak magnetic diagnostic system [E. J. Strait, Rev. Sci. Instrum. 77, 023502 (2006)] has been upgraded to significantly expand the measurement of the plasma response to intrinsic and applied non-axisymmetric "3D" fields. The placement and design of 101 additional sensors allow resolution of toroidal mode numbers 1 ≤ n ≤ 3, and poloidal wavelengths smaller than MARS-F, IPEC, and VMEC magnetohydrodynamic model predictions. Small 3D perturbations, relative to the equilibrium field (10^-5 < δB/B₀ < 10^-4), require sub-millimeter fabrication and installation tolerances. This high precision is achieved using electrical discharge machined components, and alignment techniques employing rotary laser levels and a coordinate measurement machine. A 16-bit data acquisition system is used in conjunction with analog signal-processing to recover non-axisymmetric perturbations. Co-located radial and poloidal field measurements allow up to 14.2 cm spatial resolution of poloidal structures (plasma poloidal circumference is ∼500 cm). The function of the new system is verified by comparing the rotating tearing mode structure, measured by 14 B_P fluctuation sensors, with that measured by the upgraded B_R saddle loop sensors after the mode locks to the vessel wall. The result is a nearly identical 2/1 helical eigenstructure in both cases.

Original language	English
Article number	083503
Journal	Review of Scientific Instruments
Volume	85
Issue number	8
DOIs	https://doi.org/10.1063/1.4891817
Publication status	Published - Aug 2014

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King, J. D., Strait, E. J., Boivin, R. L., Taussig, D., Watkins, M. G., Hanson, J. M., Logan, N. C., Paz-Soldan, C., Pace, D. C., Shiraki, D., Lanctot, M. J., La Haye, R. J., Lao, L. L., Battaglia, D. J., Sontag, A. C., Haskey, S. R., & Bak, J. G. (2014). An upgrade of the magnetic diagnostic system of the diii-d tokamak for non-axisymmetric measurements. Review of Scientific Instruments, 85(8), Article 083503. https://doi.org/10.1063/1.4891817

@article{99fb102310c441b9848188f86f7939eb,

title = "An upgrade of the magnetic diagnostic system of the diii-d tokamak for non-axisymmetric measurements",

abstract = "The DIII-D tokamak magnetic diagnostic system [E. J. Strait, Rev. Sci. Instrum. 77, 023502 (2006)] has been upgraded to significantly expand the measurement of the plasma response to intrinsic and applied non-axisymmetric {"}3D{"} fields. The placement and design of 101 additional sensors allow resolution of toroidal mode numbers 1 ≤ n ≤ 3, and poloidal wavelengths smaller than MARS-F, IPEC, and VMEC magnetohydrodynamic model predictions. Small 3D perturbations, relative to the equilibrium field (10-5 < δB/B0 < 10-4), require sub-millimeter fabrication and installation tolerances. This high precision is achieved using electrical discharge machined components, and alignment techniques employing rotary laser levels and a coordinate measurement machine. A 16-bit data acquisition system is used in conjunction with analog signal-processing to recover non-axisymmetric perturbations. Co-located radial and poloidal field measurements allow up to 14.2 cm spatial resolution of poloidal structures (plasma poloidal circumference is ∼500 cm). The function of the new system is verified by comparing the rotating tearing mode structure, measured by 14 BP fluctuation sensors, with that measured by the upgraded BR saddle loop sensors after the mode locks to the vessel wall. The result is a nearly identical 2/1 helical eigenstructure in both cases.",

author = "King, {J. D.} and Strait, {E. J.} and Boivin, {R. L.} and D. Taussig and Watkins, {M. G.} and Hanson, {J. M.} and Logan, {N. C.} and C. Paz-Soldan and Pace, {D. C.} and D. Shiraki and Lanctot, {M. J.} and {La Haye}, {R. J.} and Lao, {L. L.} and Battaglia, {D. J.} and Sontag, {A. C.} and Haskey, {S. R.} and Bak, {J. G.}",

year = "2014",

month = aug,

doi = "10.1063/1.4891817",

language = "English",

volume = "85",

journal = "Review of Scientific Instruments",

issn = "0034-6748",

publisher = "American Institute of Physics",

number = "8",

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King, JD, Strait, EJ, Boivin, RL, Taussig, D, Watkins, MG, Hanson, JM, Logan, NC, Paz-Soldan, C, Pace, DC, Shiraki, D, Lanctot, MJ, La Haye, RJ, Lao, LL, Battaglia, DJ, Sontag, AC, Haskey, SR & Bak, JG 2014, 'An upgrade of the magnetic diagnostic system of the diii-d tokamak for non-axisymmetric measurements', Review of Scientific Instruments, vol. 85, no. 8, 083503. https://doi.org/10.1063/1.4891817

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T1 - An upgrade of the magnetic diagnostic system of the diii-d tokamak for non-axisymmetric measurements

AU - King, J. D.

AU - Strait, E. J.

AU - Boivin, R. L.

AU - Taussig, D.

AU - Watkins, M. G.

AU - Hanson, J. M.

AU - Logan, N. C.

AU - Paz-Soldan, C.

AU - Pace, D. C.

AU - Shiraki, D.

AU - Lanctot, M. J.

AU - La Haye, R. J.

AU - Lao, L. L.

AU - Battaglia, D. J.

AU - Sontag, A. C.

AU - Haskey, S. R.

AU - Bak, J. G.

PY - 2014/8

Y1 - 2014/8

N2 - The DIII-D tokamak magnetic diagnostic system [E. J. Strait, Rev. Sci. Instrum. 77, 023502 (2006)] has been upgraded to significantly expand the measurement of the plasma response to intrinsic and applied non-axisymmetric "3D" fields. The placement and design of 101 additional sensors allow resolution of toroidal mode numbers 1 ≤ n ≤ 3, and poloidal wavelengths smaller than MARS-F, IPEC, and VMEC magnetohydrodynamic model predictions. Small 3D perturbations, relative to the equilibrium field (10-5 < δB/B0 < 10-4), require sub-millimeter fabrication and installation tolerances. This high precision is achieved using electrical discharge machined components, and alignment techniques employing rotary laser levels and a coordinate measurement machine. A 16-bit data acquisition system is used in conjunction with analog signal-processing to recover non-axisymmetric perturbations. Co-located radial and poloidal field measurements allow up to 14.2 cm spatial resolution of poloidal structures (plasma poloidal circumference is ∼500 cm). The function of the new system is verified by comparing the rotating tearing mode structure, measured by 14 BP fluctuation sensors, with that measured by the upgraded BR saddle loop sensors after the mode locks to the vessel wall. The result is a nearly identical 2/1 helical eigenstructure in both cases.

AB - The DIII-D tokamak magnetic diagnostic system [E. J. Strait, Rev. Sci. Instrum. 77, 023502 (2006)] has been upgraded to significantly expand the measurement of the plasma response to intrinsic and applied non-axisymmetric "3D" fields. The placement and design of 101 additional sensors allow resolution of toroidal mode numbers 1 ≤ n ≤ 3, and poloidal wavelengths smaller than MARS-F, IPEC, and VMEC magnetohydrodynamic model predictions. Small 3D perturbations, relative to the equilibrium field (10-5 < δB/B0 < 10-4), require sub-millimeter fabrication and installation tolerances. This high precision is achieved using electrical discharge machined components, and alignment techniques employing rotary laser levels and a coordinate measurement machine. A 16-bit data acquisition system is used in conjunction with analog signal-processing to recover non-axisymmetric perturbations. Co-located radial and poloidal field measurements allow up to 14.2 cm spatial resolution of poloidal structures (plasma poloidal circumference is ∼500 cm). The function of the new system is verified by comparing the rotating tearing mode structure, measured by 14 BP fluctuation sensors, with that measured by the upgraded BR saddle loop sensors after the mode locks to the vessel wall. The result is a nearly identical 2/1 helical eigenstructure in both cases.

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U2 - 10.1063/1.4891817

DO - 10.1063/1.4891817

M3 - Article

SN - 0034-6748

VL - 85

JO - Review of Scientific Instruments

JF - Review of Scientific Instruments

IS - 8

M1 - 083503

ER -

An upgrade of the magnetic diagnostic system of the diii-d tokamak for non-axisymmetric measurements

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