Avoidance of disruptions at high βN in ASDEX Upgrade with off-axis ECRH

Autor: Esposito, B [ 1 ], Granucci, G [ 2 ], Maraschek, M [ 3 ], Nowak, S [ 2 ], Gude, A [ 3 ], Igochine, V [ 3 ], Lazzaro, E [ 2 ], McDermott, R [ 3 ], Poli, E [ 3 ], Stober, J [ 3 ], Suttrop, W [ 3 ], Treutterer, W [ 3 ], Zohm, H [ 3 ], Brunetti, D [ 2 ], ASDEX Upgrade Team
Rok vydání: 2011
Předmět:
Zdroj: Nuclear fusion 51 (2011): 083051. doi:10.1088/0029-5515/51/8/083051
info:cnr-pdr/source/autori:Esposito, B [ 1 ] ; Granucci, G [ 2 ] ; Maraschek, M [ 3 ] ; Nowak, S [ 2 ] ; Gude, A [ 3 ] ; Igochine, V [ 3 ] ; Lazzaro, E [ 2 ] ; McDermott, R [ 3 ] ; Poli, E [ 3 ] ; Stober, J [ 3 ] ; Suttrop, W [ 3 ] ; Treutterer, W [ 3 ] ; Zohm, H [ 3 ] ; Brunetti, D [ 2 ]; and ASDEX Upgrade Team/titolo:Avoidance of disruptions at high betaN in ASDEX Upgrade with off-axis ECRH/doi:10.1088%2F0029-5515%2F51%2F8%2F083051/rivista:Nuclear fusion/anno:2011/pagina_da:083051/pagina_a:/intervallo_pagine:083051/volume:51
ISSN: 1741-4326
0029-5515
DOI: 10.1088/0029-5515/51/8/083051
Popis: Experiments on disruption avoidance have been carried out in H-mode ASDEX Upgrade plasmas: the localized perpendicular injection of ECRH (1.5 MW ∼ 0.2P tot) onto the q = 2 resonant surface has led to the delay and/or complete avoidance of disruptions in a high βN scenario (I p = 1 MA, B t = 2.1 T, q 95 ∼ 3.6, with NBI ∼7.5 MW). In these discharges (at low q 95 and low density) neoclassical tearing modes (NTMs) are excited: the growth and locking of the m/n = 2/1 mode leads to the disruption. The scheme of the experiment is successfully applied in the same way as in previous disruption avoidance experiments in FTU and ASDEX Upgrade. As soon as the disruption precursor signal (the locked mode detector and/or the loop voltage) reaches the preset threshold, the ECRH power is triggered by real-time control. A poloidal scan in deposition location (ρdep) has been carried out by setting the poloidal launching mirrors at different angles in each discharge. The results depend on ρdep: complete disruption avoidance can be achieved when the power is injected close to or onto the 2/1 island. When ECRH is injected outside the island (either at radii inside or outside the q = 2 surface), the discharge is disrupted as in the reference case.
Databáze: OpenAIRE
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