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Solar Physics

, Volume 44, Issue 1, pp 173–193 | Cite as

Generation of intermediate drift bursts in solar type IV radio continua through coupling of whistlers and Langmuir waves

  • Jan Kuijpers
Article

Abstract

The possible generation of intermediate drift bursts in type IV dm continua through coupling between whistler waves, traveling along the magnetic field, and Langmuir waves, excited by a loss-cone instability in the source region, is elaborated. We investigate the generation, propagation and coupling of whistlers.

It is shown that the superposition of an isotropic background plasma of 106K and a loss-cone distribution of fast electrons is unstable for whistler waves if the loss-cone aperture 2α is sufficiently large (sec α⩾4); a typical value of the excited frequencies is 0.1 ωce (ωce is the angular electron cyclotron frequency).

The whistlers can travel upwards through the source region of the continuum along the magnetic field direction with velocities of 21.5–28 vA (vA is the Alfvén velocity).

Coupling of the whistlers with Langmuir waves into escaping electromagnetic waves can lead to the observed intermediate drift bursts, if the Langmuir waves have phase velocities around the velocity of light.

In our model the instantaneous bandwith of the fibers corresponds to a frequency of 0.1–0.5 ωce and leads to estimates of the magnetic field strength in the source region. These estimates are in good agreement with those derived from the observed drift rate, corresponding to 21.5–28 vA, if we use a simple hydrostatic density model.

Keywords

Source Region Drift Rate Cyclotron Frequency Electron Cyclotron Langmuir Wave 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© D. Reidel Publishing Company 1975

Authors and Affiliations

  • Jan Kuijpers
    • 1
  1. 1.Sterrekundig InstituutUtrechtThe Netherlands

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