Return To: Session EX/W & TH/7 - Current Drive and
Prev Page: (EX/W-5) Electron Cyclotron Current Drive and Suprathermal Electron
Next Page: (TH/7-1Ra) Theory and Observation of Compressional Alfvén Eigenmodes

(EX/W-6) Property of Alfvén Eigenmode in JT-60U Reversed Shear and Weak Shear Discharges

M. Takechi¹⁾, A. Fukuyama²⁾, K. Shinohara¹⁾, M. Ishikawa³⁾, Y. Kusama¹⁾, S. Takeji¹⁾, T. Fujita¹⁾, T. Oikawa¹⁾, T. Suzuki¹⁾, N. Oyama¹⁾, T. Ozeki¹⁾, A. Morioka¹⁾, C.Z. Cheng⁴⁾, N.N. Gorelenkov⁴⁾, G.J. Kramer⁴⁾, R. Nazikian⁴⁾, JT-60 Team^1)
 
1) Japan Atomic Energy Research Institute, Naka-machi, Japan
²⁾ Department of Nuclear Engineering, Kyoto University, Japan.
³⁾ Plasma Research Center, University of Tsukuba, Japan.
⁴⁾ Princeton Plasma Physics Laboratory, Princeton, USA

Abstract.  This paper reports results of Alfvén eigenmode (AE) experiments in the JT-60U reversed shear (RS) and weak shear (WS) plasmas. The observation of rapid frequency chirping modes in low- $\beta_{h}^{}$ RS discharges with Negative-ion-based NBI (NNBI) or ICRH can be explained by considering the properties of reversed-shear-induced AE (RSAE) near q_min and their coupling to toroidal AEs (TAEs). We verify the existence of RSAEs and their coupling to TAEs for the first time from magnetic fluctuations and measured q-profile in JT-60U plasmas. Significant drop of the neutron emission rate and increase in fast neutral fluxes have been observed during the presence of bursting modes with large amplitude (ALE: Abrupt Large-amplitude Event) in high- $\beta_{h}^{}$ WS plasmas. The recently installed diagnostic of a neutron emission profile measurement reveals the transport of energetic ions associated with bursting modes.

Read the full paper in PDF format.