Linear theory of current driven ion acoustic instability at the distance 0.3 to 1 AU from the Sun
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ORIGINAL ARTICLE
Linear theory of current driven ion acoustic instability at the distance 0.3 to 1 AU from the Sun Mohammad Javad Kalaee1,2
Received: 23 August 2020 / Accepted: 8 October 2020 © Springer Nature B.V. 2020
Abstract Several kinds of instabilities are often observed in the solar wind. We studied the linear theory of the currentdriven electrostatic ion acoustic instability at frequencies near the ion cyclotron frequency at distances from the Sun over 0.3 to 1 AU. The properties of current driven electrostatic ion-acoustic instability are investigated. The instability parameters, such as angular wave frequency, the critical drift velocity and the growth rate are calculated. We used the dispersion relation in hot magnetized plasma to calculate the current driven ion acoustic instability properties. To determine the critical drift velocity and the growth rate a full numerical solution of the dispersion relation equation is carried out. Since the growth rate of instability depends on the wave normal angle, the drift velocity of the electron along the magnetic field and the ion thermal cyclotron radius, the calculation is carried out for ranging of the wave normal angles, drift velocities and ion thermal cyclotron radius. The results show that the growth rate of instability increases with increasing distance from the Sun. The growth rate of instability increases with decreasing the wave normal angle, but the critical drift velocity decreases with decreasing the wave normal angle. Keywords Instability · Solar wind · Growth rate · Electrostatic ion acoustic
B M.J. Kalaee
[email protected]
1
Space Physics Group, Institute of Geophysics, University of Tehran, Tehran, Iran
2
Solar Physics and Astronomy Section, Institute of Geophysics, University of Tehran, Tehran, Iran
1 Introduction Several types of plasma instabilities occur naturally in various astrophysical and space situations. The most common ones are accretion disks, solar corona (Sharma and Vlahos 1984; Gary et al. 2001) and solar winds in the interplanetary medium. Although plasma instability research is a wellestablished branch of both space physics and astrophysics, owing to the importance of this subject, it is still an active topic in a lot of research. It is well known that the solar wind is composed of approximately equal numbers of ions and electrons that flow at supersonic and super-Alfvénic speeds into planetary space. Solar wind in the interplanetary space is an active laboratory for space plasma experiments because it is available to satellites and space probes. On the other hand, in the solar wind, plasma conditions and parameters can be changed based on the solar activity. Sometimes these changes create the conditions for some kinds of instability events in the plasma. For example, space storms are extreme manifestations of space plasma instabilities. It also varies in response to shocks (Watari et al. 2001; Echer et al. 2003; Kilpua et al. 2015; Kalaee 2020), waves, and turbulence that perturb the interplanetary flow. Instabilitie
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