Abstract The search for a reliable source of energy has been a challanging task to manking while conventional energy resorces are diminishing nuclear fusion, especially laser fusion, promises to be the source of the future. Experimental costs in laser fusion are astronomical and computer modeling drastically minimizes such costs and gives a chance for less fortunate Gauntries to gain insight into the scientific and technical aspects of the subject since a large portion of information involved is classified. This work deals with the spatial and temporal evolution of the laser fusion produced by different laser pulses It is based on a computer code called MEDUSA which takes into account the variation in the wavelength, power density pulse duration, target geometry and material. It assumes a target which is divided into 20 cells each of 24 urn width. Inverse-Bremsstrahlung and resonance absorption are the two main mechanisms responsible for absorption of energy from the incident laser pulse. Fusion takes place in the plasma as a result of ablation of the plasma corona where the formed shock waves compress the plasma cells and heat them. The rate of energy deposited into and radiated from the plasma ,which causes variation of the plasma internal energy, is expressed by the energy equation. This equation is transformed into a finite difference form and solved by Gauss Elimination Method to calculate the plasma parameters such as electron(T e) and ion ternperatures(Ti), pressure(P) and density(p) and the different processes of energy absorption and losses. The temporal evolution of these parameters is studied through the divisions of the pulse into chosen time steps at which the evolution is clear. The results have shown that by increasing laser power the energy deposited into and radiated from the plasma increases. The electron and ion temperatures the plasma pressure and density also increase. This is because of the geadual propagation of the shock wave from the surface of the pellet towards its center causing compression of the plasma cells. The optimum value of such parameters are obtained close to the end of the pulse where the incident laser power is maximum and so as the energy deposited into the plasma center where heating and compression causes the consumption of the whole target After the end of the pulse duration, the plasma cells coordinates expand and the plasma parameters decrease, a process known as diminishing of the plasma The effect of the laser parameters of four diffterent lasers namely CO2, KrF, Nd-glass and Ruby of 5ns, 15ns and 45ns pulse duration was studied. It was found that: (1) the maximum value of the plasma parameters decrease by increasing the pulse duration of a certain power and wavelength, (2) the maximum value of the plasma parameters increase by increasing the wavelength because of increasing the energy deposited into the plasma by resonance absorption process. At the optimum implosion time, the plasma parameters show a strong spatial variation. However, a strong temporal variation of the plasma parameters was observed at the pellet center.
هناء محمد حسن موسي (1994)

In this research paper it was studied the electric behaviour of ferrite zinc material[1][3][5] [9][12][16][19][24] added to it manganese iron (Mn+2) [2][4][11][13][19][20][25] according to the chemical formula: Mnx, Zn1-x, Fe2O4; X= 0.0, 0.2, 0.4 and 0.6, which was prepared by the traditional ceramic method. This matter is classified as one of the ferromagnetic [9][14][16][17] materials of multi-crystalline structure. X-ray diffraction technology was used for all samples and the electric conductivity [1][3][5][6][7] was measured at a certain range of temperatures and frequencies. arabic 23 English 107
Abdusalam Emhemed Ibrahim Abubkr(8-2019)

Abstract In this work, study was performed using Amorphous polymer – based composites consisting of polystyrene (PS) and carbon black (CB) . Five samples have been prepared with different weight percentage which are (0%CB+100%PS) , (5%CB+95%PS) , (15%CB+85%PS) , (25%CB+75%PS) and (35%CB+65%PS) . The electrical properties have been studied for these samples as follows : Electrical conductivity , relative dielectric constant and the dielectric loss tangent were measured at alternating electric field in temperature range between (30C°) and (60C°) and at four different constant frequencies (100HZ, 1KHZ, 10KHZ and 100KHZ ) . It is noted that the highest value of alternating electrical conductivity at (30C°) is for the sample of composition (25%CB+75%PS) which was (1.25x10 S/m ) and the highest value at temperature (60C°) was for same sample with value of (3.2x10 S/m ) , it should be noted that in general the electrical conductivity increases as the temperature increases where this result shows the behaviour of semiconductors. The relative dielectric constant in the pure sample (0%CB+100%PS) and the other samples with low percentage of carbon black increases as the temperature increases however it decreases as frequency increases. And the samples with higher percentage of carbon black which are (25%CB+75%PS) and (35%CB+65%PS) it was noted that the relative dielectric constant decreases as temperature increases. The lowest value was (1.26) at temperature (30C°) and frequency (10KHZ) for the sample with composition of (15%CB+85%PS), while the highest value at same temperature is (410.2) at (100HZ) for the sample with composition of (25%CB+75%PS), for the relative dielectric constant the highest result it was for the sample (5%CB+95%PS) at (607) at (100HZ) and (45C°). The dielectric loss tangent increases as the carbon black increases in all samples and it was found that the temperature influence will be at high percentage of the carbon black where the temperature of (55C°) the dielectric loss tangent increased to the highest value (1.2X10 ) for the sample of composition (35%CB+65%PS). at the high level of the carbon black it was found that the dielectric loss tangent decreases as the frequency increases.
عادل محمد التميمي (2013)