Suppression of resistive wall instabilities with distributed, independently controlled, active feedback coils

Cates, C.; Shilov, M.; Mauel, M. E.; Navratil, G.A.; Maurer, D.A.; Mukherjee, S.; Nadle, D.; Bialek, J.; Boozer, Allen H.

doi:10.1063/1.874223

Cited by 62 publications

(64 citation statements)

References 38 publications

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“…The RWM manifests itself as an n = 1 radial fieldB R coming through the wall. The slowing down of the mode growth makes stabilization tractable by feedback control with an external (to the vacuum vessel) coil which opposes the change iñ B R at the wall, i.e., acts to make the wall behave as a perfect conductor [7,8]. Experiments in the tokamaks HBTX at Columbia University and DIII-D at General Figure 6: Amplitudes of the poloidal harmonics of the perturbed magnetic field δB ψ of a stabilized resistive wall mode.…”

Section: Evaluation Of Resistive Wall Mode Control Coil Requirements mentioning

confidence: 99%

Physics basis for the advanced tokamak fusion power plant, ARIES-AT

Jardin

Kessel

Mau

et al. 2006

Fusion Engineering and Design

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The advanced tokamak is considered as the basis for a fusion power plant. The ARIES-AT design has an aspect ratio of A ≡ R/a = 4.0, an elongation and triangularity of κ = 2.17, δ = 0.84 (evaluated at the separatrix surface), a toroidal beta of β = 9.2% (normalized to the vacuum toroidal field on at the plasma center), which corresponds to a normalized beta of β N ≡ 100 × β/(I P (M A)/a(m)B(T )) = 5.4. These beta values are chosen to be 10% below the ideal MHD stability limit. The bootstrap-current fraction is f BS ≡ I BS /I P = 0.91. This leads to a design with total plasma current I P = 12.8M A, and toroidal field of 11.1T (at the coil edge) and 5.8T (at the plasma center). The major and minor radii are 5.2 and 1.3 m. The effects of H-mode edge gradients and the stability of this configuration to non-ideal modes is analyzed. The current drive system consists of ICRF/FW for on-axis current drive and a Lower Hybrid system for off-axis. Transport projections are presented using the GLF23 model. The approach to power and particle exhaust using both plasma core and scrape-off-layer radiation is presented.

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Section: Evaluation Of Resistive Wall Mode Control Coil Requirements mentioning

confidence: 99%

Physics basis for the advanced tokamak fusion power plant, ARIES-AT

Jardin

Kessel

Mau

et al. 2006

Fusion Engineering and Design

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“…In analogy to the control of the vertical instability in elongated tokamaks, feedback control using externally applied magnetic fields has been demonstrated in HBT-EP [1] and DIII-D [2,3]. Secondly, toroidal plasma rotation can stabilize the RWM due to an interaction between the quasi-static magnetic perturbation and the rapid plasma flow [4].…”

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confidence: 99%

Measurement of the Resistive-Wall-Mode Stability in a Rotating Plasma Using Active MHD Spectroscopy

et al. 2004

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“…The HBT-EP experiment studies the physics and control of beta-limiting MHD instabilities such as the resistive wall mode (RWM) [12][13][14] . The RWM is an ideal external kink mode whose growth rate has been slowed to a magnetic diffusion time set by the presence of a nearby conducting wall.…”

Section: Hbt-ep Device and Magneticsmentioning

confidence: 99%

“…This is compared with modeling of the artificial plasma experiment using the finite-element electromagnetic code VALEN 18 , in order to characterize the electromagnetic properties of the conducting wall in HBT-EP. VALEN contains a detailed 3-dimensional model of the close-fitting conducting wall in HBT-EP, and is used to simulate a variety of RWM feedback experiments carried out on the device 12,19,20 .…”

Section: Valen Modelingmentioning

confidence: 99%

In situ “artificial plasma” calibration of tokamak magnetic sensors

Shiraki

Levesque

Bialek

et al. 2013

Review of Scientific Instruments

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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 are 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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Suppression of resistive wall instabilities with distributed, independently controlled, active feedback coils

Cited by 62 publications

References 38 publications

Physics basis for the advanced tokamak fusion power plant, ARIES-AT

Physics basis for the advanced tokamak fusion power plant, ARIES-AT

Measurement of the Resistive-Wall-Mode Stability in a Rotating Plasma Using Active MHD Spectroscopy

In situ “artificial plasma” calibration of tokamak magnetic sensors

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