Density control by pellets in plasmas with ELM mitigation by RMPs in the ASDEX Upgrade tokamak. (27th June 2018)

• Record Type: Journal Article
• Authors: Valovič, M; Lang, P T; Kirk, A; Suttrop, W; Cavedon, M; Dunne, M; Fischer, R; Garzotti, L; Guimarais, L; Leuthold, N; Mc Carthy, P J; Meyer, H; Mlynek, A; Ploeckl, B; Poli, E; Tardini, G; Viezzer, E; Wolfrum, E
• Other Names: collab.; collab.
• Is Part Of: Plasma physics and controlled fusion. Volume 60:Number 8(2018:Aug.)
• Publication Date: 2018-06-27
• Subjects: tokamak -- pellet fuelling -- ELM control by RMPs; Plasma (Ionized gases) -- Periodicals; Controlled fusion -- Periodicals; 530.44
• DOI: 10.1088/1361-6587/aacac3
• Languages: English
• ISSNs: 0741-3335

Abstract

Abstract: This paper describes the extension of the previous experimental database on density control by pellets and ELM control by RMPs in the ASDEX Upgrade tokamak. A stationary low triangularity plasma is sustained by simultaneous pellet fuelling and RMP ELM control at ion pedestal collisionality of ν * i, ped ∼ 0.5. Refuelling of the RMP induced density pump-out requires a pellet rate of Φpel ∼ 0.073 P aux / T t, ped . The duration of refuelling of density pump-out can be minimised to about 3 energy confinement times. Pellet fuelling increases or preserves ion pedestal pressure with respect to unfuelled ELM suppressed/mitigated phase. Pellets cause transition from ELM suppression to ELMy regime: At low triangularity, the first pellet triggers a transition to an ELMy phase but subsequent ELMs are not modulated by pellets. At elevated triangularity, initial pellets trigger ELM-like events but in-between pellets ELM suppression is preserved. In later phase, as density increases the plasma transitions to an ELMy phase similar to low triangularity case.