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- Brunsell, P., et al.
(författare)
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Extrap L-1 Experimental Stability
- 1990
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Ingår i: XVII European Conference on Controlled Fusion and Plasma Heating, Amsterdam, Netherlands, June 25-29, 1990. ; , s. 610-
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Konferensbidrag (refereegranskat)
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| 5. |
- Franz, P., et al.
(författare)
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Compact soft x-ray multichord camera : Design and initial operation
- 2003
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 74:3 II, s. 2152-2156
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Tidskriftsartikel (refereegranskat)abstract
- The design and initial operation of a compact soft x-ray (SXR) multichord camera was studied. The line integrity emissivity was measured along up to 20 lines of sight using an array of miniaturized silicon photodiodes. The application of the diagnostic to a gas-fed magnetoplasma dynamic thruster (MPDT) with an external magnetic field was also discussed.
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| 6. |
- Brunsell, Per, et al.
(författare)
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Feedback Stabilization of Multiple Resistive Wall Modes
- 2004
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 93:22, s. 225001-
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Tidskriftsartikel (refereegranskat)abstract
- Active feedback stabilization of multiple independent resistive wall modes is experimentally demonstrated in a reversed-field pinch plasma. A reproducible simultaneous suppression of several nonresonant resistive wall modes is achieved. Coupling of different modes due to the limited number of the feedback coils is observed in agreement with theory. The feedback stabilization of nonresonant RWMs also has an effect on tearing modes that are resonant in the central plasma, leading to a significant prolongation of the discharge pulse.
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| 10. |
- Brunsell, Per, et al.
(författare)
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Active control of multiple resistive wall modes
- 2005
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Ingår i: Plasma Physics and Controlled Fusion. - 0741-3335 .- 1361-6587. ; 47:12 B, s. B25-B36
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Tidskriftsartikel (refereegranskat)abstract
- A two-dimensional array of saddle coils at M-c poloidal and N-c toroidal positions is used on the EXTRAP T2R reversed-field pinch (Brunsell P R et al 2001 Plasma Phys. Control. Fusion 43 1457) to study active control of resistive wall modes (RWMs). Spontaneous growth of several RWMs with poloidal mode number m = 1 and different toroidal mode number n is observed experimentally, in agreement with linear MHD modelling. The measured plasma response to a controlled coil field and the plasma response computed using the linear circular cylinder MHD model are in quantitive agreement. Feedback control introduces a linear coupling of modes with toroidal mode numbers n, n' that fulfil the condition vertical bar n - n'vertical bar = N-c. Pairs of coupled unstable RWMs are present in feedback experiments with an array of Mc x Nc = 4 x 16 coils. Using intelligent shell feedback, the coupled modes are generally not controlled even though the field is suppressed at the active coils. A better suppression of coupled modes may be achieved in the case of rotating modes by using the mode control feedback scheme with individually set complex gains. In feedback with a larger array of Mc x Nc = 4 x 32 coils, the coupling effect largely disappears, and with this array, the main internal RWMs n = -11, -10, +5, +6 are all simultaneously suppressed throughout the discharge (7-8 wall times). With feedback there is a two-fold extension of the pulse length, compared to discharges without feedback.
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