Resistive wall modes in the EXTRAP T2R reversed-field pinch

Brunsell, Per R.; Malmberg, Jenny-Ann; Yadikin, D.; Cecconello, M.

doi:10.1063/1.1604775

Cited by 36 publications

(42 citation statements)

References 21 publications

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“…The n = 5 in the reference case appears lower than the others only because the shot is so short that the mode cannot even grow. The dashed line in the figure corresponds to a case (#16369) in which only the most unstable internally non-resonant RWMs n = −11, −10, −9, −8 [11] are controlled. The same gain was used for these modes while it was kept at zero for all the others.…”

Section: Wise Shellmentioning

confidence: 99%

Comparison of strategies and regulator design for active control of MHD modes

Cavinato

Gregoratto

Marchiori

et al. 2005

Fusion Engineering and Design

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Section: Wise Shellmentioning

confidence: 99%

Comparison of strategies and regulator design for active control of MHD modes

Cavinato

Gregoratto

Marchiori

et al. 2005

Fusion Engineering and Design

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“…Generally, there is a quantitative agreement between experimental and linear MHD growth rates for the dominant modes. 20 The experimentally measured growth rates of the main RWMs are compared with linear MHD calculations in Fig. 8.…”

Section: Tearing and Resistive Wall Modes In T2rmentioning

confidence: 99%

Feedback stabilization of resistive wall modes in a reversed-field pinch

et al. 2005

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An array of saddle coils having Nc=16 equally spaced positions along the toroidal direction has been installed for feedback control of resistive wall modes (RWMs) on the EXTRAP T2R reversed-field pinch [P. R. Brunsell, H. Bergsaker, M. Cecconello et al., Plasma Phys. Controlled Fusion 43, 1457 (2001)]. Using feedback, multiple nonresonant RWMs are simultaneously suppressed for three to four wall times. Feedback stabilization of RWMs results in a significant prolongation of the discharge duration. This is linked to a better sustainment of the plasma and tearing mode toroidal rotation with feedback. Due to the limited number of coils in the toroidal direction, pairs of modes with toroidal mode numbers n,n′ that fulfill the condition ∣n−n′∣=Nc are coupled by the feedback action from the discrete coil array. With only one unstable mode in a pair of coupled modes, the suppression of the unstable mode is successful. If two modes are unstable in a coupled pair, two possibilities exist: partial suppression of both modes or, alternatively, complete stabilization of one target mode while the other is left unstable.

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“…Non-rigid, multimode behavior has been theoretically predicted [7] in tokamaks, and initial experimental evidence on NSTX [5] and HBT-EP [8] has been reported, as well as previous detailed study of these issues for RFP devices [9,10] . Plasma response effects will be crucial to understanding these multimode MHD physics issues.…”

Section: Introductionmentioning

confidence: 99%

The high beta tokamak-extended pulse magnetohydrodynamic mode control research program

Maurer¹,

Bialek²,

Byrne³

et al. 2011

Plasma Phys. Control. Fusion

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Abstract. The High Beta Tokamak-Extended Pulse (HBT-EP) magnetohydrodynamic (MHD) mode control research program is studying ITER relevant internal modular feedback control coil configurations and their impact on kink mode rigidity, advanced digital control algorithms, and the effects of plasma rotation and three dimensional magnetic fields on MHD mode stability. A new segmented adjustable conducting wall has been installed on HBT-EP made up of 20 independent, movable, wall shell segments instrumented with 3 distinct sets of 40 saddle coils totaling 120 in-vessel modular feedback control coils. Each internal coil set has been designed with varying toroidal angular coil coverage of 5 • , 10 • , and 15 • , spanning the toroidal angle range of an ITER port plug based internal coil to test Resistive Wall Mode (RWM) interaction and multimode MHD plasma response to such highly localized control fields. In addition, we have implemented 336 new poloidal and radial magnetic sensors to quantify the applied three dimensional fields of our control coils along with the observed plasma response. This paper describes the design and implementation of the new control shell incorporating these control and sensor coils on HBT-EP, and the research program plan on the upgraded HBT-EP to understand how best to optimize the use of modular feedback coils to control instability growth near the ideal wall stabilization limit, answer critical questions about the role of plasma rotation in active control of the RWM and the Ferritic Resistive Wall Mode (FRWM), and to improve the performance of MHD control systems used in fusion experiments and future burning plasma systems.

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Resistive wall modes in the EXTRAP T2R reversed-field pinch

Cited by 36 publications

References 21 publications

Comparison of strategies and regulator design for active control of MHD modes

Comparison of strategies and regulator design for active control of MHD modes

Feedback stabilization of resistive wall modes in a reversed-field pinch

The high beta tokamak-extended pulse magnetohydrodynamic mode control research program

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