HR: 0830h
AN: SM51B-0521    [PDF]
TI: Determination of the Quiet-Time Current Sheet Thickness Using Geotail CPI Data and Nonlinear Dynamics Modeling
AU: * Holland, D L
EM: holland@phy.ilstu.edu
AF: Illinois State Univetsity, Department of Physics, Normal, IL 61790-4560 United States
AU: Richards, B H
EM: harry-the-wombat@excite.com
AF: University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242-1479 United States
AB: Computer simulations of nonlinear charged particle dynamics in magnetotail-like magnetic fields have pointed towards the existence of an ion distribution function signature that manifests itself as a series of peaks and valleys. The separation between the peaks and valleys scales as the fourth root of the normalized particle energy. The normalization in turn depends on parameters that describe the magnetic field structure, i.e. the current sheet half-thickness and the ratio of the magnetic field strength at the midplane, $B_z$, to the magnetic field strength far from the field reversal but still in the plasma sheet, $B_0$. This signature has been identified in both ISEE-1 and Geotail data. Using Geotail CPI and magnetometer data, it has been shown that the signature may be used to determine the current sheet thickness during quiet-times. In this paper we present the results of a survey of the quiet (Kp $\le$ 1+) current sheet thickness for $X_{GSE}$ between $-20 R_E$ and $-50 R_E$ as determined from the ion distribution signature and magnetic field data. We have found clear evidence of the distribution function signature throughout the entire region of interest. Analysis of the data shows a weak general trend for the current sheet to thicken and become flatter (i.e. $B_z/B_0$ becomes smaller) as we move down tail. An average of all of the data yields a mean current sheet thickness for the region as $0.81\pm 0.69 R_E$.
DE: 2744 Magnetotail
DE: 2764 Plasma sheet
DE: 2794 Instruments and techniques
DE: 7839 Nonlinear phenomena
DE: 7894 Instruments and techniques
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting