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Title: KSTAR Equilibrium Operating Space and Projected Stabilization at High Normalized Beta

Abstract

Along with an expanded evaluation of the equilibrium operating space of the Korea Superconducting Tokamak Advanced Research, KSTAR, experimental equilibria of the most recent plasma discharges were reconstructed using the EFIT code. In near-circular plasmas created in 2009, equilibria reached a stored energy of 54 kJ with a maximum plasma current of 0.34 MA. Highly shaped plasmas with near double-null configuration in 2010 achieved H-mode with clear edge localized mode (ELM) activity, and transiently reached a stored energy of up to 257 kJ, elongation of 1.96 and normalized beta of 1.3. The plasma current reached 0.7 MA. Projecting active and passive stabilization of global MHD instabilities for operation above the ideal no-wall beta limit using the designed control hardware was also considered. Kinetic modification of the ideal MHD n = 1 stability criterion was computed by the MISK code on KSTAR theoretical equilibria with a plasma current of 2 MA, internal inductance of 0.7 and normalized beta of 4.0 with simple density, temperature and rotation profiles. The steep edge pressure gradient of this equilibrium resulted in the need for significant plasma toroidal rotation to allow thermal particle kinetic resonances to stabilize the resistive wall mode (RWM). The impact of variousmore » materials and electrical connections of the passive stabilizing plates on RWM growth rates was analysed, and copper plates reduced the RWM passive growth rate by a factor of 15 compared with stainless steel plates at a normalized beta of 4.4. Computations of active RWM control using the VALEN code showed that the n = 1 mode can be stabilized at normalized beta near the ideal wall limit via control fields produced by the midplane in-vessel control coils (IVCCs) with as low as 0.83kW control power using ideal control system assumptions. The ELM mitigation potential of the IVCC, examined by evaluating the vacuum island overlap created by resonant magnetic perturbations, was analysed using the TRIP3D code. Using a combination of all IVCCs with dominant n = 2 field and upper/lower coils in an even parity configuration, a Chirikov parameter near unity at normalized poloidal flux 0.83, an empirically determined condition for ELM mitigation in DIII-D, was generated in theoretical high-beta equilibria. Chirikov profile optimization was addressed in terms of coil parity and safety factor profile.« less

Authors:
 [1];  [1];  [1];  [1];  [2];  [2];  [3];  [3];  [2];  [4];  [2];  [2];  [2];  [5];  [2];  [2];  [2];  [2];  [2];  [2] more »;  [2];  [6];  [1];  [3];  [3] « less
  1. Columbia University
  2. National Fusion Research Institute, Daejon, South Korea
  3. General Atomics, San Diego
  4. ORNL
  5. Lawrence Livermore National Laboratory (LLNL)
  6. Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1037097
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 51; Journal Issue: 5
Country of Publication:
United States
Language:
English

Citation Formats

Park, Y S, Sabbagh, S A, Berkery, J W, Bialek, J, Jeon, Y M, Hahn, S H, Eidietis, N W, Evans, T E, Yoon, S W, Ahn, Joonwook, Kim, J, Yang, H L, You, K I, Soukhanovskii, V A, Bae, Y S, Chung, J I, Kwon, M, Oh, Y K, Kim, W C, Kim, J Y, Lee, S G, Park, H, Reimerdes, H, Leuer, J A, and Walker, M L. KSTAR Equilibrium Operating Space and Projected Stabilization at High Normalized Beta. United States: N. p., 2011. Web. doi:10.1088/0029-5515/51/5/053001.
Park, Y S, Sabbagh, S A, Berkery, J W, Bialek, J, Jeon, Y M, Hahn, S H, Eidietis, N W, Evans, T E, Yoon, S W, Ahn, Joonwook, Kim, J, Yang, H L, You, K I, Soukhanovskii, V A, Bae, Y S, Chung, J I, Kwon, M, Oh, Y K, Kim, W C, Kim, J Y, Lee, S G, Park, H, Reimerdes, H, Leuer, J A, & Walker, M L. KSTAR Equilibrium Operating Space and Projected Stabilization at High Normalized Beta. United States. doi:10.1088/0029-5515/51/5/053001.
Park, Y S, Sabbagh, S A, Berkery, J W, Bialek, J, Jeon, Y M, Hahn, S H, Eidietis, N W, Evans, T E, Yoon, S W, Ahn, Joonwook, Kim, J, Yang, H L, You, K I, Soukhanovskii, V A, Bae, Y S, Chung, J I, Kwon, M, Oh, Y K, Kim, W C, Kim, J Y, Lee, S G, Park, H, Reimerdes, H, Leuer, J A, and Walker, M L. Sat . "KSTAR Equilibrium Operating Space and Projected Stabilization at High Normalized Beta". United States. doi:10.1088/0029-5515/51/5/053001.
@article{osti_1037097,
title = {KSTAR Equilibrium Operating Space and Projected Stabilization at High Normalized Beta},
author = {Park, Y S and Sabbagh, S A and Berkery, J W and Bialek, J and Jeon, Y M and Hahn, S H and Eidietis, N W and Evans, T E and Yoon, S W and Ahn, Joonwook and Kim, J and Yang, H L and You, K I and Soukhanovskii, V A and Bae, Y S and Chung, J I and Kwon, M and Oh, Y K and Kim, W C and Kim, J Y and Lee, S G and Park, H and Reimerdes, H and Leuer, J A and Walker, M L},
abstractNote = {Along with an expanded evaluation of the equilibrium operating space of the Korea Superconducting Tokamak Advanced Research, KSTAR, experimental equilibria of the most recent plasma discharges were reconstructed using the EFIT code. In near-circular plasmas created in 2009, equilibria reached a stored energy of 54 kJ with a maximum plasma current of 0.34 MA. Highly shaped plasmas with near double-null configuration in 2010 achieved H-mode with clear edge localized mode (ELM) activity, and transiently reached a stored energy of up to 257 kJ, elongation of 1.96 and normalized beta of 1.3. The plasma current reached 0.7 MA. Projecting active and passive stabilization of global MHD instabilities for operation above the ideal no-wall beta limit using the designed control hardware was also considered. Kinetic modification of the ideal MHD n = 1 stability criterion was computed by the MISK code on KSTAR theoretical equilibria with a plasma current of 2 MA, internal inductance of 0.7 and normalized beta of 4.0 with simple density, temperature and rotation profiles. The steep edge pressure gradient of this equilibrium resulted in the need for significant plasma toroidal rotation to allow thermal particle kinetic resonances to stabilize the resistive wall mode (RWM). The impact of various materials and electrical connections of the passive stabilizing plates on RWM growth rates was analysed, and copper plates reduced the RWM passive growth rate by a factor of 15 compared with stainless steel plates at a normalized beta of 4.4. Computations of active RWM control using the VALEN code showed that the n = 1 mode can be stabilized at normalized beta near the ideal wall limit via control fields produced by the midplane in-vessel control coils (IVCCs) with as low as 0.83kW control power using ideal control system assumptions. The ELM mitigation potential of the IVCC, examined by evaluating the vacuum island overlap created by resonant magnetic perturbations, was analysed using the TRIP3D code. Using a combination of all IVCCs with dominant n = 2 field and upper/lower coils in an even parity configuration, a Chirikov parameter near unity at normalized poloidal flux 0.83, an empirically determined condition for ELM mitigation in DIII-D, was generated in theoretical high-beta equilibria. Chirikov profile optimization was addressed in terms of coil parity and safety factor profile.},
doi = {10.1088/0029-5515/51/5/053001},
journal = {Nuclear Fusion},
number = 5,
volume = 51,
place = {United States},
year = {2011},
month = {1}
}