Kinematics of Nonlinearly Interacting MHD Instabilities in a Plasma

Technical Report · Sat Jul 01 04:00:00 EDT 2000

OSTI ID:783563

Hansen, Alexander K ^[1]

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1. Department of Physics

Plasmas play host to a wide variety of instabilities. For example, tearing instabilities use finite plasma resistivity to exploit the free energy provided by plasma currents parallel to the magnetic field to alter the magnetic topology of the plasma through a process known as reconnection. These instabilities frequently make themselves known in magnetic confinement experiments such as tokamaks and reversed field pinches (RFPs). In RFP plasmas, in fact, several tearing instabilities (modes) are simultaneously active, and are of large amplitude. Theory predicts that in addition to interacting linearly with magnetic perturbations from outside the plasma, such as field errors or as resistive wall, the modes in the RFP can interact nonlinearly with each other through a three-wave interaction. In the current work investigations of both the linear (external) and nonlinear contributions to the kinematics of the tearing modes in the Madison Symmetric Torus (MST) RFP are reported Theory predicts that tearing modes will respond only to magnetic perturbations that are spatially resonant with them, and was supported by experimental work done on tokamak devices. The results in this work verified that the theory is still applicable to the RFP, in spite of its more complicated magnetic mode structure, involving perturbations of a single poloidal mode number.

• Research Organization: University of Wisconsin-Madison (US)
• Sponsoring Organization: USDOE Office of Policy and International Affairs (PO) (US)
• DOE Contract Number: FG02-96ER54345
• OSTI ID: 783563
• Report Number(s): DOE/ER/54345-332
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
FREE ENERGY
MAGNETIC CONFINEMENT
MAGNETIC FIELDS
MAGNETIC RECONNECTION
MST DEVICE
PLASMA INSTABILITY
PLASMA WAVES
REVERSE-FIELD PINCH
TOKAMAK DEVICES