[1] In this paper, we discuss the effects of magnetospheric activity (as measured by Kp) on an ion distribution function signature of nonlinear particle dynamics in current sheet-like magnetic fields. The signature manifests itself as a series of peaks in the ion distribution function whose separation depends on the fourth root of the energy and parameters that describe the current sheet structure. We have found that the signature is evident in Geotail CPI data for Kp 3+ and that the larger the value of Kp, the closer the peaks are together. We have also used the energy resonance signature in conjunction with measurements of the magnetic field to determine a lower bound on the current sheet thickness and have found that this lower bound decreases for increasing levels of magnetospheric activity. For values of Kp > 4À, there are frequently peaks in the ion distribution function; however, their separations do not follow a simple rule.Citation: Holland, D. L., C. J. Bush, and W. R. Paterson (2008), Effects of magnetospheric activity on the current sheet energy resonance ion distribution function signature,

In stellarator-type magnetic confinement devices (of which the torsatron is one), the magnetic field is produced entirely by external, current-carrying coils. Two methods for mapping magnetic surfaces in the Auburn torsatron were tested and compared, both of which involve the use of highly transparent screens. The first method consists of coating the screen with a phosphor that emits light when struck by electrons emitted by an electron gun. A pattern representative of a magnetic surface is formed on the screen, and this pattern is recorded photographically. The second method uses an uncoated screen to collect electrons emitted from an emissive probe, which is scanned over a poloidal cross section of the torus. Under certain conditions, the collected current is a constant over a particular magnetic surface so that a contour plot of the current versus position is equivalent to a plot of the magnetic surfaces. Parametric studies of the two methods are presented, and the effectiveness of each technique is discussed.

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