Effect of the m=2, n=1 magnetic island rotation on the intrinsic plasma flow of TCABR density limit plasmas

• Type: Article in International Conference Proceedings Book
• Date: 2015

Authors

F. Salzedas (Author) FEUP; G. Ronchi (Author) Other; J.H.F. Severo (Author) Other; R.M.O. Galvão (Author) Other; E.K. Sanada (Author) Other

Conference proceedings International

Title: 22nd IAEA Technical Meeting on Research Using Small Fusion Devices

22nd IAEA Technical Meeting on Research Using Small Fusion Devices

Prague, 12 a 14 de outubro, 2015

Scientific classification

FOS: Natural sciences > Physical sciences

CORDIS: Physical sciences > Physics > Applied physics > Experimental physics

Associated Projects

USP/UP/2013 - Estudo do Efeito da Rotação da Coluna de Plasma na Instabilidade Disruptiva em Tokamaks

Other information

Abstract (EN): Magnetic islands are known to degrade confinement of energy and particles in tokamak plasmas. They are also present in the precursor of density limit disruptions being observed until the onset of the energy quench of the disruption. So it is very important to have complete knowledge on the physics of magnetic islands. In the past decades considerable experimental and theoretical work brought significant advances on the understanding of the dynamics of magnetic islands. Nonetheless some important questions are still open. One of them is how the island moves relative to the background plasma, which has implications on the island stability and its influence on radial transport of energy and particles. Theoretical models routinely assume a no-slip island through the plasma with the plasma inside the magnetic island moving together with the island. A series of experiments has been carried on at TCABR to investigate this question, from which resulted experimental evidence that the island may be slipping through the plasma. Plasma flow was measured with Doppler spectroscopy of the impurity lines of C VI in ohmic discharges with 60 kA =< I p =< 80 kA, B T = 1.06 T, a=0.18 m, R 0 =0.61 m that end with density limit disruption with a m=2, n=1 magnetic island in its precursor. It was observed that while the island is small the toroidal island velocity, vϕ21, is more than ten times higher than the toroidal ion velocity, vϕi, at the island radial position, with both velocities in the counter current direction. As the island poloidal magnetic field amplitude increased, vϕ21 decreases due to island-wall interaction while vϕi show a small increase that becomes more pronounced as the dBθ/dt amplitude increases. Afterwards the ions toroidal acceleration becomes negative like the island acceleration and the ions slow down with a similar acceleration as the island’s acceleration. The disruption was observed when the island toroidal velocity was about two to three times higher than the ions toroidal velocity and both the island and the ions had negative acceleration. The island velocity was inferred from Mirnov coils signals.

Language: English

Type (Professor's evaluation): Scientific

Notes: Apresentação oral - Oral comunication http://old.ipp.cas.cz/Tokamak/conf/RUSFD/