Theories of the Origin of Pc 1 Pulsations

  • J. A. Jacobs
Part of the Physics and Chemistry in Space book series (SPACE, volume 1)

Abstract

One model of Pc 1 pulsations is that they are the result of oscillations of bunches of monochromatic particles trapped by the Earth’s magnetic field. In this case the period of Pc 1’s is that of the oscillations of the bunch from one conjugate point to the other, and their amplitude is determined by the density and energy of the charged particles in the group, by the height of the mirror points and by the absorption of hydro-magnetic (hm) waves in the ionosphere. The basis for such a view is the morphological features of Pc 1’s and their connection with other upper atmospheric phenomena. It is further suggested that the spacing between successive “pearls” is the drift time of the particles around the Earth. R. C. Wentworth and L.R. Tepley (1962) assumed the particle bunches to consist of energetic electrons and Table 4.1 shows their calculated and the observed data for Pc 1’s. The mirror points of the particle bunches are thought to be situated above the F-2 layer of the ionosphere. As the ionosphere has high conductivity, the arrival of a diamagnetic bunch of particles at the mirror point cannot be recorded directly at the surface of the Earth. The disturbance must reach the E-layer as a hm wave. Propagation through the ionosphere reduces the disturbance because of absorption due to joule heating.
Table 4.1

Data for Pc 1 Oscillations (after R. C. Wentworth and L. R. Tepley, 1962)

Station

Palo Alto

Victoria

Uppsala

Reykjavik

Geomagnetic latitude

45°

55°

60°

70°

Full length of arc (× 10-9 cm)

5.71

9.42

12.2

22.4

Energy of electrons for 1 Hz oscillations (kev)

9.25

25.2

48.6

260

Electron drift velocity for 1 Hz oscillations (× 10-5 rad/sec)

3.32

12

27

142

Maximum frequency of oscillations (Hz)

5.25

3.18

2.46

1.34

Maximum frequency of oscillations for a point 500 km distant (Hz)

7.8

4.6

3.6

2.1

Maximum observed frequency of hydromagnetic emissions (Hz)

5

3

3

2

Keywords

Attenuation Propa Sine Cross Correlation Geophysics 

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Copyright information

© Springer-Verlag Berlin · Heidelberg 1970

Authors and Affiliations

  • J. A. Jacobs
    • 1
  1. 1.Killam Memorial Professor of ScienceThe University of AlbertaEdmontonCanada

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