Department of Physics
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Item Oxygen Cyclotron Harmonic Waves in the Inner Magnetosphere(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Abdul Waheed; CIIT/FA17-RPH-037/LHR; Dr. Muhammad Jamil; LHR TP 5726The Banded emission of Oxygen cyclotron harmonic waves has been observed by Van Allen probes in the Earth inner magnetosphere. The general dispersion relation for electrostatic Oxygen cyclotron harmonic waves is derived by using Lerche-Newberger sum rule for Maxwellian and Kappa distributions. Oxygen ion kappa spectral index (𝜅𝑖𝑂) has a significant impact on the Oxygen cyclotron harmonic waves. The quasi Maxwellian behavior is being observed as 𝜅𝑖𝑂 ≥ 5. The curves shift toward the higher value of wavenumber, as the value of 𝜅𝑖𝑂 reduce. There is an increase in super-thermal particles as we reduce the value of 𝜅𝑖𝑂. By decreasing the value of 𝜅𝑖𝑂, the super-thermal particles reduce the frequency , 𝜔𝑝𝑒𝑎𝑘, where the group velocity vanish and the associated 𝑘𝑝𝑒𝑎𝑘 get increase. These cyclotron harmonic waves may be useful for the diagnostic for the velocity distribution characteristics. Oxygen cyclotron harmonic waves can be helpful for the diagnostic of Van Allen Radiation Belts.Item Study of Landau quantization effect over Jeans- Alfven Instability in Dense Plasmas(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) ZAHRA SHAHID; CIIT/SP17-RPH-004/LHR; Dr. Muhammad Jamil; LHR TP 5708Quantum plasmas have gained significance due to its applications in magnetized/un- magnetized semiconductor and astrophysical plasmas. Quantum effects are usually incorporated through exchange and correlation potential, Bohm potential, Fermi degenerate pressure in the presence or absence of external magnetic field. The electromagnetic waves of low frequency are commonly known as Alfven waves. The modification in the electronic properties of materials as a function of the applied magnetic field are Landau quantization. Henceforth in this thesis studied the Landau Quantization effect over Jeans Instability in Dense Plasma. The self-gravitational or Jeans instability come to play due to the gravitational characteristics of massive species in plasmas. This thesis deals with two scales competing with each other. First, the gravitational time scale associated with massive particles called ion. Second, acoustic time scale. The source of acoustic scale is the lighter particles like electron fluid that exert acoustic pressure outward. If the two scales are comparable then the system will be at equilibrium. On other case, if the acoustic time scale is larger, then the gravitational collapse will take case and if the gravitational time scale is larger than the explosion will take place. In this work the comparative analysis of Jeans and quantum plasmas have analyzed under different conditions. In other words, the macroscopic effects evolvedItem Electromagnetic Wave Instability with Dynamic Charge Fluctuation in Semiconductor(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) UZMA MAQSOOD; CIIT/FA17-RPH-063/LHR; Dr. Muhammad Jamil; LHR TP 5737In nature, the gravitational tragedy has been observed. Electromagnetic perturbations are the only reason of these gravitational tragedies. In quantum plasmas, these types of perturbations (electromagnetic) are propagated by cause of magnetic densities along with the manifestation of magnetic field. This study will cover the analytical and numerical features of electromagnetic waves in semiconductor quantum plasmas in the presence of external magnetic field including the quantum effects. The discussion will be based on the quantum effects like Fermi statistical pressure, Bohm tunneling potential and spin-based exchange correlation effects. The dust charging will be dynamical with respect to the time. The plasmas are omnipresent in space, inter- stellar and the dense astrophysical environment as well as in the metals and the semiconductors. The presence of charge species in plasmas ensures the plasma system to host variety of waves and the instability features. This work evolves around the semiconductor medium as a plasma system. In the semiconductor systems, the dust is produced in fabrication. The dust is charged either positive or negative. The dust charging is source of new features evolved at micro and nano scales. This study will cover the analysis of electromagnetic waves in semiconductor electron-hole plasmas in the presence of charge variation. The quantum effects will be included on taking different terms used in plasma which explain the quantum effect in equation of motion like Bohm criterion, exchange correlation and fermi pressure. The quantum features of plasma physics explored up a new area of research due to its wide range of application.Item Alfven Instability in Charge Fluctuating Quantum Plasma(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) IQRA NAEEM; CIIT/fa17-RPH-062/LHR; Dr. Muhammad Jamil; LHR TP 5736The interest of plasma researchers has been shifted towards quantum plasma due to its abundant occurrence in space. The physical processes of the common ion-electron plasma changes to a large scale due to highly charged dust particles. This field is fascinating for researchers due to wide range of waves and instabilities. Dusty magneto plasma with number of species like ions, electrons and dust particles which are highly charged is considered. The low frequency, long wavelength electromagnetic waves, viz., Shear Alfven waves in quantum dusty magneto plasmas, has been examined using quantum magneto hydrodynamic model. The time dependent charging effects on dust particles around its equilibrium charge are taken into account. A modified dispersion relation of the shear Alfven waves by the magnetized electrons and ions and unmagnetized dust is derived. The dispersion relation is then explained by graphical representation. The external magnetic field and size of the dust particles have new physical effects over the propagation of such waves.Item Temperature Contributions on Large Amplitude High Frequency Oscillations in Quantum Plasmas(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) MUBEEN ALI; CIIT/FA17-RPH-027/LHR; Dr. Muhammad Jamil; LHR TP 5721The development of plasma physics theory is closely related to the investigations of various nonlinear phenomena. Most of this theory concerns rather small disturbances which can be treated by means of perturbation techniques, such as quasi-linear theory, wave-wave interactions, etc. Although much effort has been devoted to the search for exact solutions, there are, however, comparatively few results in this field. Therefore, at least for pedagogical purposes, it is still vitally important to look for new exact large amplitude solutions. Most of the previous studies concern cold plasmas. However, the present work will demonstrate that somewhat analogous non-trivial exact solutions also can be found in classical as well as in quantum system where temperature effects are taken into account. Firstly, we find solution of amplitude of oscillating wave in classical plasma and after that at certain condition when classical plasma unable to find amplitude of electron plasma oscillation than we switch towards quantum plasma.