ISSN: 2277-9655 [Prakash, 7(2): February, 2018] Impact Factor: 5.164 IC™ Value: 3.00 CODEN: IJESS7 http: // www.ijesrt.com © International Journal of Engineering Sciences & Research Technology [656] IJESRT INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY EFFECT OF DUST CHARGE FLUCTUATIONS ON EXCITATION OF LOWER HYBRID WAVES IN STREAMING DUSTY PLASMA Ved Prakash India Meteorological Department, Ministry of Earth Sciences, Lodi Road, New Delhi-110 003, India DOI: 10.5281/zenodo.1184044 ABSTRACT The linear theory of excitation of electrostatic lower hybrid waves by streaming electrons is presented. The dispersion relation for the lower hybrid mode is obtained for a warm plasma containing electrons, ions and negatively charged dust grains with dust charge fluctuations. The frequency of the lower hybrid mode increases with the number density of negatively charged dust grains. It is found that the instability has the largest growth rate when the velocity of electron beam in the direction of the magnetic field is comparable to the parallel phase velocity of the mode. An increase in the dust population enhances the growth rate of the lower hybrid wave instability through the effect of capturing electrons. The dust charge fluctuations give rise to an additional unstable damping mode in plasma. However, the maximum growth rate decreases with an increase in the velocity of the streaming electrons travelling parallel to the magnetic field. KEYWORDS: Lower hybrid, frequency, dispersion, growth rate. I. INTRODUCTION Lower hybrid waves, unlike other wave modes, can interact resonantly with electrons as well as ions. This allows lower hybrid waves to mediate the transfer of energy between the two plasma species and therefore lead to ion heating or electron acceleration, making them of considerable interest in many different laboratory [1,2] and space plasma environments [3-10]. The lower hybrid waves are generated by different mechanisms such as by electron or ion beams propagating in the plasma. A perpendicular ion-beam-driven lower hybrid mode has been observed by Chang [1]. Seiler and Yamada [2] have studied the excitation of lower hybrid wave instability by a spiraling ion beam in the linear Princeton Q-1 device. Papadopoulus and Palmadesso [3] have demonstrated that the lower hybrid modes can be generated by an energetic electron beam streaming through plasma along the magnetic fields. There has been a great deal of interest in studying the collective properties of dusty plasma [11- 18], particularly for low frequency wave propagation. The dust charge may fluctuate due to a variety of reasons. Several authors have tried to incorporate the effect of these charge fluctuations on wave propagation and found interesting results [19-24]. Tsytovich [19] has considered a novel kinetic effect arising from inhomogeneities in dust charges and demonstrated collisionless drift wave instability. Mahanta et al. [20] have showed that dust charge fluctuation lead to damping of lower-hybrid like waves in cold dusty plasma. In this paper, we study the excitation of lower hybrid waves by streaming electrons in magnetized dusty plasma. The streaming electrons propagating through the dusty plasma drive electrostatic lower hybrid waves to instability. In Sec. II, the instability analysis for lower hybrid wave excitation by streaming electrons is carried out. Results and discussions are given in Sec. III. Finally, the conclusion part is given in Sec. IV. II. INSTABILITY ANALYSIS We consider a collisionless and uniformly magnetized dusty plasma whose constituents are electrons, ions and negatively charged dust grains, with respective number densities neo, nio and ndo, immersed in a static magnetic field Bs in the z-direction. The electrons are streaming along the magnetic field direction with a constant electron drift velocity veo ˆ z . The quasineutrality condition at equilibrium is given by