Astron. Astrophys. 358, 776-788 (2000)

Saturation of electron cyclotron maser by lower-hybrid waves

G. Fleishman ¹ and K. Arzner <sup>2

1</sup> Ioffe Institute for Physics and Technology, 194021 St. Petersburg, Russia (gregory@sun.ioffe.rssi.ru)
² Institut für Extraterristrische Physik, P.O. Box 1603, 85740 Garching, Germany (kja@mpe.mpg.de)

Received 22 July 1999 / Accepted 2 March 2000

Abstract

We perform a numerical study on the quasilinear relaxation of an electron cyclotron maser on the initially dominant mode. We focus thereby on a situation where the initially dominant modes are quasi-electrostatic lower hybrid (lh) waves, which have not been treated in preceding studies. To this end, we chose (: plasma-, : electron cyclotron frequency) and an initial losscone distribution of energetic electrons of the form (p: momentum, µ: pitch angle cosine). Superimposed on this is a damping Maxwellian background. From our calculations, we find that multiple peaks in the lower-hybrid wave intensity can occur if the initial loss cone distribution is sufficiently broad. We also find that quasilinear relaxation with respect to lower-hybrid waves does not destroy the capability of the electron distribution to amplify transverse (XOZ) waves, which therefore become dominant at a later stage. The comparison with observations shows that the calculated shape of a single peak in the lower-hybrid energy density displays a remarkable similarity to solar radio spikes.

Key words: Sun: radio radiation masers

Send offprint requests to: K. Arzner

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Contents

• 1. Introduction
• 2. Definition of the model
  • 2.1. Simplified model
  • 2.2. Properties of and
• 3. Numerical code
  • 3.1. Test of the code
• 4. Simulations and initialisation
• 5. Results
• 6. Summary and discussion
• Acknowledgements
• Appendices
  • A: numerical implementation of the cyclic Crank-Nicholson scheme
• References

© European Southern Observatory (ESO) 2000

Online publication: June 8, 2000
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