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Title: An upgrade of the magnetic diagnostic system of the DIII-D tokamak for non-axisymmetric measurements

Journal Article · · Review of Scientific Instruments
DOI:https://doi.org/10.1063/1.4891817· OSTI ID:1351085
 [1];  [2];  [2];  [2];  [2];  [3];  [4];  [1];  [2];  [3];  [2];  [2];  [2];  [4];  [5];  [6];  [7]
  1. Oak Ridge Institute for Science and Education, Oak Ridge, TN (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Columbia Univ., New York, NY (United States)
  4. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  6. The Australia National Univ., Canberra, ACT (Australia)
  7. National Fusion Research Center, Daejeon (South Korea)

Here, the DIII-D tokamak magnetic diagnostic system 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 (MHD) 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 31 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.

Research Organization:
General Atomics, San Diego, CA (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
FC02-04ER54698
OSTI ID:
1351085
Journal Information:
Review of Scientific Instruments, Vol. 85, Issue 8; ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 54 works
Citation information provided by
Web of Science

References (26)

Principles of Plasma Diagnostics book January 2009
Chapter 2: Magnetic Diagnostics journal February 2008
Suppression of Large Edge-Localized Modes in High-Confinement DIII-D Plasmas with a Stochastic Magnetic Boundary journal June 2004
Observation of Plasma Rotation Driven by Static Nonaxisymmetric Magnetic Fields in a Tokamak journal November 2008
Plasma rotation driven by static nonresonant magnetic fields journal May 2009
Feedback Stabilization of Multiple Resistive Wall Modes journal November 2004
Active-Feedback Control of the Magnetic Boundary for Magnetohydrodynamic Stabilization of a Fusion Plasma journal August 2006
Measurement of the Resistive-Wall-Mode Stability in a Rotating Plasma Using Active MHD Spectroscopy journal September 2004
Validation of the linear ideal magnetohydrodynamic model of three-dimensional tokamak equilibria journal March 2010
Mode locking in tokamaks journal December 1990
Measurement of the electromagnetic torque in rotating DIII-D plasmas journal March 2010
Equilibrium analysis of current profiles in tokamaks journal June 1990
A review of Alfvén eigenmode observations in toroidal plasmas journal January 1999
Control of the resistive wall mode with internal coils in the DIII–D tokamak journal November 2005
Active Stabilization of the Resistive-Wall Mode in High-Beta, Low-Rotation Plasmas journal July 2006
Stabilization of the external kink and the resistive wall mode journal October 2010
Feedback stabilization of nonaxisymmetric resistive wall modes in tokamaks. I. Electromagnetic model journal September 2000
Computation of three-dimensional tokamak and spherical torus equilibria journal May 2007
Steepest-descent moment method for three-dimensional magnetohydrodynamic equilibria journal January 1983
Magnetic diagnostic system of the DIII-D tokamak journal February 2006
Magnetic field pitch-angle measurments in the PBX-M tokamak using the motional Stark effect journal November 1989
An overview of charge-exchange spectroscopy as a plasma diagnostic journal February 1994
Multichordal charge‐exchange recombination spectroscopy on the DIII‐D tokamak journal August 1986
A multilaser system for a fast sampling Thomson scattering diagnostic journal October 1990
Measurement and modeling of three-dimensional equilibria in DIII-D journal May 2011
Anomalies in the applied magnetic fields in DIII-D and their implications for the understanding of stability experiments journal December 2003

Cited By (19)

Experimental tests of linear and nonlinear three-dimensional equilibrium models in DIII-D journal July 2015
Development of the saddle loop sensors on the J-TEXT tokamak journal October 2017
Predict-first experimental analysis using automated and integrated magnetohydrodynamic modeling journal May 2018
Modal analysis of the full poloidal structure of the plasma response to n = 2 magnetic perturbations journal July 2018
Conceptual design of extended magnetic probe set to improve 3D field detection in NSTX-U journal October 2018
Two-fluid nonlinear theory of response of tokamak plasma to resonant magnetic perturbation journal November 2018
Direct measurements of internal structures of born-locked modes and the key role in triggering tokamak disruptions journal April 2019
Equilibrium drives of the low and high field side n   =  2 plasma response and impact on global confinement journal April 2016
Effect of rotation zero-crossing on single-fluid plasma response to three-dimensional magnetic perturbations journal February 2017
Kink instabilities of the post-disruption runaway electron beam at low safety factor journal March 2019
$\mathscr{H}_2$ optimal control techniques for resistive wall mode feedback in tokamaks journal February 2018
Relationship between locked modes and thermal quenches in DIII-D journal March 2018
The phase-space dependence of fast-ion interaction with tearing modes journal July 2018
Edge localized mode suppression and plasma response using mixed toroidal harmonic resonant magnetic perturbations in DIII-D journal January 2019
Identification of multiple eigenmode growth rates in DIII-D and EAST tokamak plasmas journal January 2019
Alfvén eigenmodes and fast ion transport in negative triangularity DIII-D plasmas journal June 2019
Observation of a Multimode Plasma Response and its Relationship to Density Pumpout and Edge-Localized Mode Suppression journal March 2015
Pedestal Bifurcation and Resonant Field Penetration at the Threshold of Edge-Localized Mode Suppression in the DIII-D Tokamak journal March 2015
Two-Fluid Nonlinear Theory of Response of Tokamak Plasma to Resonant Magnetic Perturbation text January 2018

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