Global Alfvén eigenmode studies

Abstract

Impedance measurements and magnetic probes are used to study driven global Alfvén eigenmodes in a small tokamak. The probes measure the field amplitudes in the outer region of the plasma, complementing earlier laser measurements in the plasma interior. An approximate analytic model is used to help determine mode numbers. The measured field profiles and impedance values are found to compare favorably with the predictions of a cylindrical, kinetic theory calculation. Measured widths of resonances are consistently found to be larger than theoretical predictions.

The Texas Experimental Tokamak: A plasma research facility. A proposal submitted to the Department of Energy in response to Program Notice 95-10: Innovations in toroidal magnetic confinement systems

“…This is troubling as Compass did not achieve H-mode with an inner x-point. 7 In at least one device, TCV, that has produced H-mode,s shapes close to that of Figure 11.2 can be reproduced. It would be interesting to know whether this device can produce H-mode in a TEXT-like configuration.…”

“…Phase contrast imaging (PCI) of plasmas is a relatively new technique which we expect will yield a great deal of new information. Our group has the potential to definitively characterize interior turbulence in collaboration with the other powerful turbulence diagnostics on TEXT-U (RPI heavy ion beam probe [6], UCLA F'IR scattering [7], and UWM beam emission spectroscopy [ 8 I) and the FRC/IFS modeling expertise.…”

The discrete Alfvén wave spectrum observed in the TORTUS tokamak

“…These results serve to quantify the qualitative observations made thus far; namely the lower Q values at lower density and the highest Q values at intermediate frequency through the range. Despite the uncertainty in the Q measurements, it is clear that these quality factors are far lower than predicted by kinetic cylindrical models [9,14,15]. Possible causes for this discrepancy are discussed in the following sections.…”