Browsing by Author "Dr. Zahida Ehsan"

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    Analytical And Numerical Study Of KdV Burger
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Samia Zafar; FA19-RPH-037; Dr. Zahida Ehsan; LHR TP 7256
    Analytical And Numerical Study Of KdV Burger
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    Modulation Instability of Lower Hybrid Waves in Piezoelectric Semiconductor Plasma
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Sumreen Fatima; FA19-RPH-004; Dr. Zahida Ehsan; LHR TP 7242
    In this thesis, we have discussed the piezoelectric effect on linear and non-linear coupling and constructed Zakharov and Schrödinger equation. Longmuir and lattice ion waves propagating in the semiconductor plasma. For this semi-classical model has been used. In the linear regime, coupling of waves was not relevant. Therefore, we studied the non-linear the coupling a set of Zakharov and Schrödinger equations were constructed. This coupling leads to the cusp type of solitons. We have also studied modulation instability for this system of plasma. Later, we constructed the Zakharov and Schrödinger equation for the modulation instability of the lower hybrid wave propagated in quantum plasma. Later, we also discussed cusp soliton for the lower hybrid waves where Bohm potential, spin Fermi pressures, and piezoelectricity is incorporated. These equations have numerically been examined for the typical n-type piezoelectric semiconductor plasma parameters.
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    Study of Black Body Radiation in Astrophysical Plasma Environments
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2020) Waqar Ahmed; CIIT/SP19-RPH-026/LHR; Dr. Zahida Ehsan; LHR TP 7232
    Black body radiation in a plasma is altered due to cut off frequency which highly depends upon the plasma density. Mass energy of the photon in plasma indeed the chemical potential. As 2 2 m c h p T T       if  0 we recover the Stefan Boltzmann law from total kinetic energy equation form equation of Black body radiation in plasma, however in plasma  is different from form zero. The value of chemical potential may be now positive. Kinetic energy of the plasma body radiation exceeds the one given by the Stefan-Boltzmann law; the larger the value of, the larger this excess, which, when  is larger than unity become much, larger in vacuum. In plasmas the total all Thermodynamical parameter are altered drastically form vacuum, like total photon energy, total kinetic energy, the total number of photon, free energy, entropy and pressure, changes in all these Thermodynamical parameters are discussed here and changes are expressed
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    Study of Capillary-Gravity (Surface Jeans) Waves at the Dusty Plasma-Vacuum Interface
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Hafsa Akhtar; CIIT/FA19-RPH-016/LHR; Dr. Zahida Ehsan; LHR TP 7257
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    Study of Nonlinear Stationary Structures of Dust Acoustic Waves(DAW)
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Naveed Ahmad; CUI/FA17-RPH-064/LHR; Dr. Zahida Ehsan; LHR TP 5738
    The effect of steady dust charge and weak magnetic field on small but finite amplitude nonlinear dust acoustic wave in electronegative dusty plasma are investigated. The electronegative plasma constituents are an electron, ions (negative or positive) and negatively charged dust particle. The electrons and ions are Boltzmann. The dynamics of nonlinear wave are governed by a Korteweg- de Vries (KdV) equation that possesses the solitary wave (solitons). Propagation of ion acoustic solitary waves (solitons) in electronegative magnetized dusty plasma in the presence of Maxwellian electron. These constituents support dust acoustic solitary wave (solitons) with the negative potential. The magnetic field is responsible for the dispersive term. The coefficient of the dissipative term depends only on the obliqueness of the magnetic field.
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    Study of Shock Waves Structures in the Comet Halley Plasma
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Muhammad Abdul Ghani; CUI/FA17-RPH-014/LHR; Dr. Zahida Ehsan; LHR TP 5715
    Weak dust-acoustic waves (DAWs) are addressed in a nonthermal charge varying electronegative magnetized dusty plasmas with application to the Halley Comet. The dynamics of the nonlinear wave are governed by a Korteweg–de Vries Burger equation that possesses dispersive shock wave. A weakly nonlinear analysis is carried out to derive a Korteweg-de Vries-Burger equation. The weak magnetic field is responsible for the dispersive term, whereas nonsteady dust charge variation is responsible for dissipative term, i.e., the Burger term. The positive and negative ion nonthermality, the obliqueness, and magnitude of the magnetic field are found to modify the dispersive and dissipative properties of the DA shock structure. Our results may aid to explain and interpret the nonlinear oscillations that may occur in the Comet Halley Plasma.