Journal of Kufa - physics

Computer simulation of orbit estimation satellites has been developed. The combined
effects of the 2 J zonal harmonics of the Earth gravitational field and the sun and moon
attraction effects on the orbital elements , the right ascension of ascending nodes and the
argument of perigee ,were investigated. Orbit estimation is based on the iterative solution of
Kepler\'s equation by using Newton method.

In this work, we applied the nuclear shell model to study the energy levels for 18F nucleus which contain two nucleons ( proton and neutron ) outside 16O core and occupy the ( d5/2 s1/2 d3/2 ) shell . In this calculations used the Surface Delta Interaction ( SDI ) is employed as a residual inter- action. Comparison with experimental values and found to be rather good agreement , and determined some of the total angular momentum values that were undetermined experimentally .

In this work the side lobes of the radiation pattern emitted by circular aperture antenna is reduced by controlling the current distribution function to higher order power equation of parabolic function. The results shows that one can be get a pattern of side lobe below -55 dB.Also we get that the side lobe levels can be reduce using the tapering current distribution across the aperture.

The Nd:YAG laser system at 1.064 μm has been operated. The BDN-I dye has been prepared and dissolved in many pure polar organic solvent such as ( Carbon-tetra-chloride,Chloroform,Acetone,Dioxane and Pyridine ), and in a mixture of Carbon-tetra-chloride with other solvent at 1:1 , and 2:1 mixing ratios, to act as liquid passive Q-Switch for Nd:YAG laser. The energy and duration of Q-Switching laser pulse has been measured at different molar concentration of the dye dissolved in solvents which mentioned above. Thevalues of ground-state absorption cross-section σ of the saturable absorber (S.A) at different values of dye molar concentration ( M).The effect of ( M) on (σ) , and its relation with giant laser power (P , have been studied .The increasing of (M)causes (P) increasing and (σ) decreasing. The (σ) results have been interpreted according to polarity of used solvent. However the giant laser power results may be explained according to used solvent density. Pyridine solvent is an efficient solvent ,has been concluded because there is no need to higher (M) of dye by using it , and its mixture has high (σ) compared to other solvents . The main conclusion is the mixing way of Carbon-Tetra-Chloride with other solvent at different mixing ratios , is an ideal way for improving the giant laser pulse power higher , and obtaining high (σ) of (S.A).

An analysis was carried out to examine the conduction mechanism in poly crystal violet terephrthalate (PCVT) synthesized by condensation polymerization .Electrical measurement including (current-voltage) characteristics .The effect of temperature on conductivity with range(300-368)K ,also investigated the activation energy (Ea) was estimated from conductivity as a function of reciprocal temperature about 0.47eV.The deviation from Ohm\'s law has been analyzed in term of hopping available range conduction theories .Hopping conducting mechanism was concluded to be the most probable one interpreting the behavior of charge transport that was supplied by injector electrodes .Optical properties of polymer was also investigated by using thin film of polymer on a glass substrates .The type of transition and energy gap determined depending on data of absorption spectrum of this sample . Indirect allowed band gap can be calculated equalto about 1.56eV and phonon energy assistance in transition about 0.06eV. The value of energy gap indicated that polymer have semiconductive properties.

The aim of this research is to prepare ( CdSe0.5Te0.5) thin films by vacuum thermal evaporation method ,and study the direct electrical conductivity and calculating activation energy values of thin films which prepared at different rates of deposition (0.25,0.50,0.75) nm/s .The study of relation ship between electrical conductivity and temperature has shown that the electrical conductivity increase with temperature increasing ,and the study of relation ship between electrical conductivity with rate of deposition has shown that the electrical conductivity increase with rate of deposition increasing ,while the activation energy values decrease.

Silicon nano-structure has been prepared in this work viaLaser-induced etching process (LIE)onn-type silicon wafer (3Ω.cm resistivity)in hydrofluoric acid (HF) (24.5% concentration)at different etching times(5 –25min.).The irradiation has been achieved using laserbeamof 2W power and 810 nm wavelength.Themorphologicaland photoluminescence characteristics of these material such as porosity,surfacemorphologyand nanocrystallite size havebeen investigated using scanning electron microscope (SEM),photoluminescence(PL)measurements,and the gravimetric method.

This paper contain the fabrication of metal-oxide-semiconductor field-effect transistor MOSFET by using the lithography technique and studying of (C-V) characteristics in the reveres and forward bias and the effect of frequency variation on it, withcalculate some important physical variable parametersfor it.The fabricated transistor by using p-type silicon as a substrate has n-type channel (n-MOSFET) its length and width equal to L=50 μm ,Z = 1000μm . The results showed that the capacity (CG) was decreases with the increasing of the gate voltage VGin the reverse bias with frequencies (100,200,400,500) KHz, and the capacity decreases with the increasing of the applied current frequency. The results also showed that the capacity CGincreases with the increasing of the gate voltage VGin the forward bias with the same frequencies and the capacity decreases with the increasing of the applied current frequency. The behavior of capacity-voltage in the forward and reveres biases is in good agreement with the theoreticalbehavior of the transistor.