K. Ichiguchi et al 2003 Nucl. Fusion 43 1101 doi:10.1088/0029-5515/43/10/011
K. Ichiguchi1, N. Nakajima1, M. Wakatani2, B.A. Carreras3 and V.E. Lynch3
Show affiliationsFor the large helical device (LHD), the nonlinear evolution of equilibria that are linearly unstable to ideal interchange modes is studied using the reduced MHD equations. At sufficiently low beta, each individual mode saturates without affecting directly the evolution of the other modes. They only couple through the modification of the averaged pressure profile. The change of the averaged pressure profile is limited to the local flattening near the resonant surfaces. At higher beta values and for the same initial pressure profile, a bursting phenomenon in the kinetic energy is observed. This bursting activity is caused by the overlap of multiple modes, which results in a global reduction of the pressure. However, increasing beta and using a pressure profile obtained from the nonlinear evolution at the lower beta suppress this bursting behaviour. This result indicates that the pressure profile can be self-organized so that the LHD plasma could reach a high beta regime through a stable path.
52.55.Hc Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices
52.65.Kj Magnetohydrodynamic and fluid equation
Issue 10 (October 2003)
Received 9 November 2002, accepted for publication 21 August 2003
Published 12 September 2003
K. Ichiguchi et al 2003 Nucl. Fusion 43 1101
George X Ding et al 2006 Phys. Med. Biol. 51 2549
Xin He Meng and Peng Wang 2003 Class. Quantum Grav. 20 4949
John C West 1951 J. Sci. Instrum. 28 336
William A Hiscock 1997 Class. Quantum Grav. 14 L183
Behram Kursunoglu 1952 Proc. Phys. Soc. A 65 81
R Haydock et al 1975 J. Phys. C: Solid State Phys. 8 2591
T Sugimoto et al 2006 J. Phys.: Conf. Ser. 49 43
L. Garcia et al 2003 Nucl. Fusion 43 553
P. A. Maia Neto and H. M. Nussenzveig 2000 Europhys. Lett. 50 702