Resistive wall stabilized operation in rotating high beta NSTX plasmas

S. A. Sabbagh; A. C. Sontag; J. M. Bialek; D. A. Gates; A. H. Glasser; J. E. Menard; W. Zhu; M. G. Bell; R. E. Bell; A. Bondeson; C. E. Bush; J. D. Callen; M. S. Chu; C. C. Hegna; S. M. Kaye; L. L. Lao; B. P. LeBlanc; Y. Q. Liu; R. Maingi; D. Mueller; K. C. Shaing; D. Stutman; K. Tritz; C. Zhang

doi:10.1088/0029-5515/46/5/014

Resistive wall stabilized operation in rotating high beta NSTX plasmas

S. A. Sabbagh, A. C. Sontag, J. M. Bialek, D. A. Gates, A. H. Glasser, J. E. Menard, W. Zhu, M. G. Bell, R. E. Bell, A. Bondeson, C. E. Bush, J. D. Callen, M. S. Chu, C. C. Hegna, S. M. Kaye, L. L. Lao, B. P. LeBlanc, Y. Q. Liu, R. Maingi, D. MuellerK. C. Shaing, D. Stutman, K. Tritz, C. Zhang

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150 Citations (Scopus)

Abstract

The National Spherical Torus Experiment (NSTX) has demonstrated the advantages of low aspect ratio geometry in accessing high toroidal and normalized plasma beta, and β_N ≡ 10 ⁸〈β_t〉 aB₀/I_p. Experiments have reached β_t = 39% and β_N = 7.2 through boundary and profile optimization. High β_N plasmas can exceed the ideal no-wall stability limit, β_Nno-wall, for periods much greater than the wall eddy current decay time. Resistive wall mode (RWM) physics is studied to understand mode stabilization in these plasmas. The toroidal mode spectrum of unstable RWMs has been measured with mode number n up to 3. The critical rotation frequency of Bondeson-Chu, Ω_crit = ω_A/(4q²), describes well the RWM stability of NSTX plasmas when applied over the entire rotation profile and in conjunction with the ideal stability criterion. Rotation damping and global rotation collapse observed in plasmas exceeding β_Nno-wall differs from the damping observed during tearing mode activity and can be described qualitatively by drag due to neoclassical toroidal viscosity in the helically perturbed field of an ideal displacement. Resonant field amplification of an applied n = 1 field perturbation has been measured and increases with increasing β_N. Equilibria are reconstructed including measured ion and electron pressure, toroidal rotation and flux isotherm constraint in plasmas with core rotation ω/ω_A up to 0.48. Peak pressure shifts of 18% of the minor radius from the magnetic axis have been reconstructed.

Original language	English
Pages (from-to)	635-644
Number of pages	10
Journal	Nuclear Fusion
Volume	46
Issue number	5
DOIs	https://doi.org/10.1088/0029-5515/46/5/014
Publication status	Published - 2006 May 1

All Science Journal Classification (ASJC) codes

Nuclear and High Energy Physics
Condensed Matter Physics

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10.1088/0029-5515/46/5/014

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Sabbagh, S. A., Sontag, A. C., Bialek, J. M., Gates, D. A., Glasser, A. H., Menard, J. E., Zhu, W., Bell, M. G., Bell, R. E., Bondeson, A., Bush, C. E., Callen, J. D., Chu, M. S., Hegna, C. C., Kaye, S. M., Lao, L. L., LeBlanc, B. P., Liu, Y. Q., Maingi, R., ... Zhang, C. (2006). Resistive wall stabilized operation in rotating high beta NSTX plasmas. Nuclear Fusion, 46(5), 635-644. https://doi.org/10.1088/0029-5515/46/5/014

@article{0f295694436c43d5ad71e855130790bd,

title = "Resistive wall stabilized operation in rotating high beta NSTX plasmas",

abstract = "The National Spherical Torus Experiment (NSTX) has demonstrated the advantages of low aspect ratio geometry in accessing high toroidal and normalized plasma beta, and βN ≡ 10 8〈βt〉 aB0/Ip. Experiments have reached βt = 39% and βN = 7.2 through boundary and profile optimization. High βN plasmas can exceed the ideal no-wall stability limit, βNno-wall, for periods much greater than the wall eddy current decay time. Resistive wall mode (RWM) physics is studied to understand mode stabilization in these plasmas. The toroidal mode spectrum of unstable RWMs has been measured with mode number n up to 3. The critical rotation frequency of Bondeson-Chu, Ωcrit = ωA/(4q2), describes well the RWM stability of NSTX plasmas when applied over the entire rotation profile and in conjunction with the ideal stability criterion. Rotation damping and global rotation collapse observed in plasmas exceeding βNno-wall differs from the damping observed during tearing mode activity and can be described qualitatively by drag due to neoclassical toroidal viscosity in the helically perturbed field of an ideal displacement. Resonant field amplification of an applied n = 1 field perturbation has been measured and increases with increasing βN. Equilibria are reconstructed including measured ion and electron pressure, toroidal rotation and flux isotherm constraint in plasmas with core rotation ω/ωA up to 0.48. Peak pressure shifts of 18% of the minor radius from the magnetic axis have been reconstructed.",

author = "Sabbagh, {S. A.} and Sontag, {A. C.} and Bialek, {J. M.} and Gates, {D. A.} and Glasser, {A. H.} and Menard, {J. E.} and W. Zhu and Bell, {M. G.} and Bell, {R. E.} and A. Bondeson and Bush, {C. E.} and Callen, {J. D.} and Chu, {M. S.} and Hegna, {C. C.} and Kaye, {S. M.} and Lao, {L. L.} and LeBlanc, {B. P.} and Liu, {Y. Q.} and R. Maingi and D. Mueller and Shaing, {K. C.} and D. Stutman and K. Tritz and C. Zhang",

year = "2006",

month = may,

day = "1",

doi = "10.1088/0029-5515/46/5/014",

language = "English",

volume = "46",

pages = "635--644",

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Sabbagh, SA, Sontag, AC, Bialek, JM, Gates, DA, Glasser, AH, Menard, JE, Zhu, W, Bell, MG, Bell, RE, Bondeson, A, Bush, CE, Callen, JD, Chu, MS, Hegna, CC, Kaye, SM, Lao, LL, LeBlanc, BP, Liu, YQ, Maingi, R, Mueller, D, Shaing, KC, Stutman, D, Tritz, K & Zhang, C 2006, 'Resistive wall stabilized operation in rotating high beta NSTX plasmas', Nuclear Fusion, vol. 46, no. 5, pp. 635-644. https://doi.org/10.1088/0029-5515/46/5/014

TY - JOUR

T1 - Resistive wall stabilized operation in rotating high beta NSTX plasmas

AU - Sabbagh, S. A.

AU - Sontag, A. C.

AU - Bialek, J. M.

AU - Gates, D. A.

AU - Glasser, A. H.

AU - Menard, J. E.

AU - Zhu, W.

AU - Bell, M. G.

AU - Bell, R. E.

AU - Bondeson, A.

AU - Bush, C. E.

AU - Callen, J. D.

AU - Chu, M. S.

AU - Hegna, C. C.

AU - Kaye, S. M.

AU - Lao, L. L.

AU - LeBlanc, B. P.

AU - Liu, Y. Q.

AU - Maingi, R.

AU - Mueller, D.

AU - Shaing, K. C.

AU - Stutman, D.

AU - Tritz, K.

AU - Zhang, C.

PY - 2006/5/1

Y1 - 2006/5/1

N2 - The National Spherical Torus Experiment (NSTX) has demonstrated the advantages of low aspect ratio geometry in accessing high toroidal and normalized plasma beta, and βN ≡ 10 8〈βt〉 aB0/Ip. Experiments have reached βt = 39% and βN = 7.2 through boundary and profile optimization. High βN plasmas can exceed the ideal no-wall stability limit, βNno-wall, for periods much greater than the wall eddy current decay time. Resistive wall mode (RWM) physics is studied to understand mode stabilization in these plasmas. The toroidal mode spectrum of unstable RWMs has been measured with mode number n up to 3. The critical rotation frequency of Bondeson-Chu, Ωcrit = ωA/(4q2), describes well the RWM stability of NSTX plasmas when applied over the entire rotation profile and in conjunction with the ideal stability criterion. Rotation damping and global rotation collapse observed in plasmas exceeding βNno-wall differs from the damping observed during tearing mode activity and can be described qualitatively by drag due to neoclassical toroidal viscosity in the helically perturbed field of an ideal displacement. Resonant field amplification of an applied n = 1 field perturbation has been measured and increases with increasing βN. Equilibria are reconstructed including measured ion and electron pressure, toroidal rotation and flux isotherm constraint in plasmas with core rotation ω/ωA up to 0.48. Peak pressure shifts of 18% of the minor radius from the magnetic axis have been reconstructed.

AB - The National Spherical Torus Experiment (NSTX) has demonstrated the advantages of low aspect ratio geometry in accessing high toroidal and normalized plasma beta, and βN ≡ 10 8〈βt〉 aB0/Ip. Experiments have reached βt = 39% and βN = 7.2 through boundary and profile optimization. High βN plasmas can exceed the ideal no-wall stability limit, βNno-wall, for periods much greater than the wall eddy current decay time. Resistive wall mode (RWM) physics is studied to understand mode stabilization in these plasmas. The toroidal mode spectrum of unstable RWMs has been measured with mode number n up to 3. The critical rotation frequency of Bondeson-Chu, Ωcrit = ωA/(4q2), describes well the RWM stability of NSTX plasmas when applied over the entire rotation profile and in conjunction with the ideal stability criterion. Rotation damping and global rotation collapse observed in plasmas exceeding βNno-wall differs from the damping observed during tearing mode activity and can be described qualitatively by drag due to neoclassical toroidal viscosity in the helically perturbed field of an ideal displacement. Resonant field amplification of an applied n = 1 field perturbation has been measured and increases with increasing βN. Equilibria are reconstructed including measured ion and electron pressure, toroidal rotation and flux isotherm constraint in plasmas with core rotation ω/ωA up to 0.48. Peak pressure shifts of 18% of the minor radius from the magnetic axis have been reconstructed.

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U2 - 10.1088/0029-5515/46/5/014

DO - 10.1088/0029-5515/46/5/014

M3 - Article

AN - SCOPUS:33646352223

SN - 0029-5515

VL - 46

SP - 635

EP - 644

JO - Nuclear Fusion

JF - Nuclear Fusion

IS - 5

ER -

Resistive wall stabilized operation in rotating high beta NSTX plasmas

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