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Full-Text Articles in Physics

A Statistical Study Of The Global Structure Of The Ring Current, A. M. Jorgensen, Harlan E. Spence, W. J. Hughes, H. J. Singer Dec 2004

A Statistical Study Of The Global Structure Of The Ring Current, A. M. Jorgensen, Harlan E. Spence, W. J. Hughes, H. J. Singer

Physics & Astronomy

[1] In this paper we derive the average configuration of the ring current as a function of the state of the magnetosphere as indicated by the Dst index. We sort magnetic field data from the Combined Release and Radiation Effects Satellite (CRRES) by spatial location and by the Dst index in order to produce magnetic field maps. From these maps we calculate local current systems by taking the curl of the magnetic field. We find both the westward (outer) and the eastward (inner) components of the ring current. We find that the ring current intensity varies linearly with Dst as …


Mechanisms And Dynamics Of The Metastable Decay In Ar-2(+), J. Fedor, K. Gluch, R. Parajuli, S. Matt-Leubner, Olof E. Echt, P. Scheier, T. D. Mark Oct 2004

Mechanisms And Dynamics Of The Metastable Decay In Ar-2(+), J. Fedor, K. Gluch, R. Parajuli, S. Matt-Leubner, Olof E. Echt, P. Scheier, T. D. Mark

Physics & Astronomy

A detailed experimental as well as theoretical investigation of the properties of the metastable dissociation Ar-2(+)-->Ar++Ar is presented. The mass-analyzed ion kinetic energy (MIKE) scan technique has been performed using a three sector field mass spectrometer. The possible mechanisms of the metastability of Ar-2(+) have been examined and the observed decay process is assigned to the II(1/2)(u)-->I(1/2)(g) bound to continuum radiative transition, in agreement with earlier work. The calculation of the theoretical shape of the kinetic energy release distribution of fragment ions allowed us to construct the theoretical MIKE peak and compare it with the raw experimental data. …


High-Resolution Kinetic Energy Release Distributions And Dissociation Energies For Fullerene Ions C(N)(+), 42 <= N <= 90, K. Gluch, S. Matt-Leubner, Olof E. Echt, B. Concina, P. Scheier, T. D. Mark Aug 2004

High-Resolution Kinetic Energy Release Distributions And Dissociation Energies For Fullerene Ions C(N)(+), 42 <= N <= 90, K. Gluch, S. Matt-Leubner, Olof E. Echt, B. Concina, P. Scheier, T. D. Mark

Physics & Astronomy

We have measured the kinetic energy released in the unimolecular dissociation of fullerene ions, C(n)(+)-->C(n-2)(+)+C(2), for sizes 42less than or equal tonless than or equal to90. A three-sector-field mass spectrometer equipped with two electric sectors has been used in order to ensure that contributions from isotopomers of different masses do not distort the experimental kinetic energy release distributions. We apply the concept of microcanonical temperature to derive from these data the dissociation energies of fullerene cations. They are converted to dissociation energies of neutral fullerenes with help of published adiabatic ionization energies. The results are compared with literature values. …


Relative Timing Of Substorm Onset Phenomena, L. Kepko, M. G. Kivelson, R. L. Mcpherron, Harlan E. Spence Apr 2004

Relative Timing Of Substorm Onset Phenomena, L. Kepko, M. G. Kivelson, R. L. Mcpherron, Harlan E. Spence

Physics & Astronomy

[1] In this paper we examine the temporal ordering of midtail flow bursts, Pi2 pulsations, and auroral arc brightening at substorm onset. We present three substorm events for which the Geotail spacecraft was situated at local midnight, near the inner edge of the plasmasheet. We show that high-speed, convective Earthward directed plasma flows observed by Geotail occurred 1–3 min before auroral onset as observed by the Polar Visible Imaging System and Ultraviolet Imager auroral imagers on board the Polar spacecraft. We also show that the onsets of both nightside Pi2 pulsations and magnetic bay variations were simultaneous with auroral onset. …


Energetic Particle Sounding Of The Magnetopause: A Contribution By Cluster/Rapid, Q. Zong, T. A. Fritz, Harlan E. Spence, K. Oksavik, Z. Y. Pu, A. Korth, P. W. Daly Apr 2004

Energetic Particle Sounding Of The Magnetopause: A Contribution By Cluster/Rapid, Q. Zong, T. A. Fritz, Harlan E. Spence, K. Oksavik, Z. Y. Pu, A. Korth, P. W. Daly

Physics & Astronomy

[1] In this paper we present new results using Cluster/Research with Adaptive Particle Imaging Detectors (RAPID) energetic particle observations to remotely sound the high-latitude magnetopause in three dimensions. We demonstrate that energetic particle flux variations in the vicinity of the magnetopause (inside the magnetosphere) are mainly modulated by the absorbing magnetopause during quiet geomagnetic conditions. Less than two gyro radii from an absorbing boundary a trapped particle distribution becomes nongyrotropic, as particles start to encounter the boundary. Knowing the magnetic field and the particle mass and energy, the direction and distance to the magnetopause can be derived by examining the …


Heliospheric Plasma Sheets, N. U. Crooker, Chia-Lin L. Huang, S. M. Lamassa, D. E. Larson, S. W. Kahler, Harlan E. Spence Mar 2004

Heliospheric Plasma Sheets, N. U. Crooker, Chia-Lin L. Huang, S. M. Lamassa, D. E. Larson, S. W. Kahler, Harlan E. Spence

Physics & Astronomy

[1] As a high-beta feature on scales of hours or less, the heliospheric plasma sheet (HPS) encasing the heliospheric current sheet shows a high degree of variability. A study of 52 sector boundaries identified in electron pitch angle spectrograms in Wind data from 1995 reveals that only half concur with both high-beta plasma and current sheets, as required for an HPS. The remaining half lack either a plasma sheet or current sheet or both. A complementary study of 37 high-beta events reveals that only 5 contain sector boundaries while nearly all (34) contain local magnetic field reversals, however brief. We …


High Resolution Measurements Of Kinetic Energy Release Distributions Of Neon, Argon, And Krypton Cluster Ions Using A Three Sector Field Mass Spectrometer, K. Gluch, S. Matt-Leubner, L. Michalak, Olof E. Echt, A. Stamatovic, P. Scheier, T. D. Mark Feb 2004

High Resolution Measurements Of Kinetic Energy Release Distributions Of Neon, Argon, And Krypton Cluster Ions Using A Three Sector Field Mass Spectrometer, K. Gluch, S. Matt-Leubner, L. Michalak, Olof E. Echt, A. Stamatovic, P. Scheier, T. D. Mark

Physics & Astronomy

Using a newly constructed three sector field mass spectrometer (resulting in a BE1E2 field configuration) we have measured the kinetic energy release distributions of neon, argon, and krypton cluster ions. In the present study we used the first two sectors, B and E1, constituting a high resolution mass spectrometer, to select the parent ions in terms of mass, charge, and energy, and studied the decay of those ions in the third field free region. Due to the improved mass resolution we were able to extend earlier studies carried out with a two sector field machine, where an upper size limit …


On The Solar Wind Control Of Cusp Aurora During Northward Imf, M. G. Bobra, S. M. Petrinec, S. A. Fuselier, E. S. Claflin, Harlan E. Spence Feb 2004

On The Solar Wind Control Of Cusp Aurora During Northward Imf, M. G. Bobra, S. M. Petrinec, S. A. Fuselier, E. S. Claflin, Harlan E. Spence

Physics & Astronomy

[1] The location of cusp aurora during northward interplanetary magnetic field (IMF) conditions and the solar wind control of that location are explored. The cusp aurora is imaged by the Imager for Magnetopause-to-Aurora Global Exploration's (IMAGE) Far Ultraviolet Instrument (FUV). Predicted locations of the cusp aurora were computed by assuming anti-parallel reconnection between the observed IMF orientation and the 1996 Tsyganenko model magnetopause magnetic field. While the majority of anti-parallel reconnection sites tailward of the cusp, when mapped to the ionosphere, coincide with the observed cusp aurora, the anti-parallel merging hypothesis cannot explain certain aspects of the observations, including its …