Cyclotron Interaction of Lower Hybrid Wave with Charged Particle Beams

Abstract

Theoretical studies of the lower-hybrid-beam-plasma instability have been carried out. A dispersion relation is derived detailing the effect of a population of charged dust grains on the growth of lower hybrid waves excited by an electron beam and an ion beam in dusty plasma. The frequency and the growth rate of the unstable mode increase with the relative density of negatively charged dust grains. The dust charge fluctuations reduce the growth rate of the mode in the presence of beam. No growth of wave is observed for fast cyclotron interaction between the beam modes and lower hybrid mode. The growth rate is comparatively more for ion beam interaction with lower hybrid wave, as the beam is propagating along the wave, perpendicular to the external magnetic field. Keyword: Cyclotron, dispersion, frequency, growth rate, Lower hybrid I. INTRODUCTIONThe instability of waves in a beam-plasma system [1-10] is studied with great interest because their behavior is of physical interest and also because of their possible application to electron acceleration or ion heating. Whenever there is a non-thermal perpendicular distribution of ions or parallel distribution of electrons, lower hybrid waves may play a role in redistributing the energy. Such distributions occur in heliosphere, near magnetic reconnection sites, in the Earth's magnetotail and in the solar corona. The presence of a distribution of charged dust particles can modify the instability. Massive and highly charged grains are quite common in natural systems, such as the plasmas in the planetary atmospheres, rocket exhausts, cometary tails, interstellar clouds, etc. and laboratory plasmas, such as industrial processing plasmas, fusion devices, etc. The dusty plasma can give rise to modifications or additional waves and instabilities [11][12][13][14][15]. It is therefore interesting to study the effect of a dust grain population on the growth of electrostatic waves. Lower hybrid waves can interact resonantly with electrons as well as ions, mediate the transfer of energy between the two plasma species and therefore lead to ion heating or electron acceleration. The lower hybrid waves are generated by different mechanisms such as by electron or ion beams propagating in the plasma. Seiler et al. [1] have studied the excitation of LH wave instability by a spiraling ion beam in the linear Princeton Q-1 device and their frequency measurements show that the instability occurs at just above the cyclotron harmonics due to the coupling of the beam cyclotron mode with the lower hybrid mode. Papadopoulus and Palmadesso [2] have demonstrated that the lower hybrid waves can be generated by an energetic electron beam streaming through plasma along the magnetic fields. Sharma and Tripathi [3] have studied the excitation of lower hybrid waves by a gyrating beam in a magnetized plasma cylinder. Prakash et al. have studied electron beam [4] driven and ion beam [5] driven lower hybrid waves in a dusty plasma and have discussed the dependence of the growth rate on the beam v...

Guidelines for the preparation and isolation of Radionuclides produced with In-house Cyclotrons Bombardments

“…Basic principles of CPAs yield radioisotopes that generally are neutron-defi cient nuclei regarding the nuclear-powered house Cyclotrons Bombardments Open Journal of Chemistry 5(1): 020-029. DOI: http://dx.doi.org/10.17352/ojc.000013 stable line, and that falling-off through positron discharge or even electron seizure [13,14]. RPRI designed by neutron capture are too much neutron, falling-off thru -particle emission [15].…”