In situ "artificial plasma" calibration of tokamak magnetic sensors

D. Shiraki; J. P. Levesque; J. Bialek; P. J. Byrne; B. A. Debono; M. E. Mauel; D. A. Maurer; G. A. Navratil; T. S. Pedersen; N. Rath

doi:10.1063/1.4808366

In situ "artificial plasma" calibration of tokamak magnetic sensors

D. Shiraki, J. P. Levesque, J. Bialek, P. J. Byrne, B. A. Debono, M. E. Mauel, D. A. Maurer, G. A. Navratil, T. S. Pedersen, N. Rath

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

8 Scopus citations

Abstract

A unique in situ calibration technique has been used to spatially calibrate and characterize the extensive new magnetic diagnostic set and close-fitting conducting wall of the High Beta Tokamak-Extended Pulse (HBT-EP) experiment. A new set of 216 Mirnov coils has recently been installed inside the vacuum chamber of the device for high-resolution measurements of magnetohydrodynamic phenomena including the effects of eddy currents in the nearby conducting wall. The spatial positions of these sensors are calibrated by energizing several large in situ calibration coils in turn, and using measurements of the magnetic fields produced by the various coils to solve for each sensor's position. Since the calibration coils are built near the nominal location of the plasma current centroid, the technique is referred to as an "artificial plasma" calibration. The fitting procedure for the sensor positions is described, and results of the spatial calibration are compared with those based on metrology. The time response of the sensors is compared with the evolution of the artificial plasma current to deduce the eddy current contribution to each signal. This is compared with simulations using the VALEN electromagnetic code, and the modeled copper thickness profiles of the HBT-EP conducting wall are adjusted to better match experimental measurements of the eddy current decay. Finally, the multiple coils of the artificial plasma system are also used to directly calibrate a non-uniformly wound Fourier Rogowski coil on HBT-EP.

Original language	English
Article number	063502
Journal	Review of Scientific Instruments
Volume	84
Issue number	6
DOIs	https://doi.org/10.1063/1.4808366
State	Published - Jun 2013
Externally published	Yes

Funding

The authors would like to thank Steve Raftopoulos of Princeton Plasma Physics Laboratory for his metrology work. The authors also thank Nick Rivera and Jim Andrello for their technical assistance with the project. This work was supported by U.S. Department of Energy Grant DE-FG02-86ER53222.

Funders	Funder number
U.S. Department of Energy	DE-FG02-86ER53222

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This output contributes to the following UN Sustainable Development Goals (SDGs)

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title = "In situ {"}artificial plasma{"} calibration of tokamak magnetic sensors",

abstract = "A unique in situ calibration technique has been used to spatially calibrate and characterize the extensive new magnetic diagnostic set and close-fitting conducting wall of the High Beta Tokamak-Extended Pulse (HBT-EP) experiment. A new set of 216 Mirnov coils has recently been installed inside the vacuum chamber of the device for high-resolution measurements of magnetohydrodynamic phenomena including the effects of eddy currents in the nearby conducting wall. The spatial positions of these sensors are calibrated by energizing several large in situ calibration coils in turn, and using measurements of the magnetic fields produced by the various coils to solve for each sensor's position. Since the calibration coils are built near the nominal location of the plasma current centroid, the technique is referred to as an {"}artificial plasma{"} calibration. The fitting procedure for the sensor positions is described, and results of the spatial calibration are compared with those based on metrology. The time response of the sensors is compared with the evolution of the artificial plasma current to deduce the eddy current contribution to each signal. This is compared with simulations using the VALEN electromagnetic code, and the modeled copper thickness profiles of the HBT-EP conducting wall are adjusted to better match experimental measurements of the eddy current decay. Finally, the multiple coils of the artificial plasma system are also used to directly calibrate a non-uniformly wound Fourier Rogowski coil on HBT-EP.",

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AU - Debono, B. A.

AU - Mauel, M. E.

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AU - Navratil, G. A.

AU - Pedersen, T. S.

AU - Rath, N.

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In situ "artificial plasma" calibration of tokamak magnetic sensors

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