JOURNAL OF SCIENCES (ISLAMIC AZAD UNIVERSITY)
Year:2007 | Volume:17 | Issue:63 (PHYSICS ISSUE)|Papers Count:9

In this research the Kardar-Parizi- Zhang equation for surface growth has been analyzed in the regime where the nonlinear coupling constant,l, is small (Edwards-Wilkinson equation) and also by using Fourier Transformations the finite size correction on the mean-square width has been calculated. It has found that the calculated interface width for t@0 behaves as W(L,t)~tb+t 2+d/2 /L2d and for t→¥ behaves as W(L,t) ~La– L6-d/2/t.

This study is executed and written based on one large scale simulation model based on smolakiewicz and margolion in 1995 in Caspian sea. This is non-hydrostatic model which is used by Boussinesq approximation. With using Gal-Chen coordination transfer model is solved by effective of out of flatness. For solving advection equation we use upwind weighted MPDATA algorithm. In this algorithm for balancing of antidiffusive velocity is used upstream scheme. For solving elliptic equation enveloped from model we use generalized residual method. The information is collected from navigation patrol by Hydrology research ship of Metrology organization of azarbayejan and supported by atomic international agency with sharing of seaside countries. The information samples are taken from 13 stations.Velocity variation profile of vertical and horizontal and flow field is drawn in different distances.

A semi industrial cylindrical magnetron discharge is designed and fabricated and experimental results which we are going to discuss in this paper are reported. This system which usually called CMD contains of two coaxial metallic cylinders with different diameters, serving as the cathode and the anode. In post magnetron mode the inner one is cathode and the other is anode. Two magnetic coils are placed around the outside of the anode and inside the cathode. The working gas in this investigation is Argon. By this system, copper thin films are sputtered at different pressures and then are analyzed by different methods and finally the dependence of thickness of thin films on pressure is obtained.

Heat budget has always been one of the most important issues in sea and oceanic physical research. Different parameters influence exact heat budget calculation including: solar radiation, long wave radiation, direct heat transfer between air and water and heat transfer through evaporation. But the issue wind and sea intraction and energy exchange between sea and air is one of the complex parameters in exact heat budget calculation. In this research considering closed Gorgan Bay area wich is very important from the geological, environmental and physical oceanography point of view and we have derived the local coefficients and their relations to the heat budget in this Bay. The average heat budget in Gorgan Bay is about - 118 w/m2. The results shows that the short wave radiation flux is about 154 w/m2, net long wave radiation flux is about -67 w/m2, sensible heat flux is about -21 w/m2 and latent heat flux is about -185 w/m2 (the negative sign shows the heat loss), and heat balance is related to heat loss from the river flows, heat exchange between Caspian Sea and Gorgan Bay gaps, and have been analysied in different seasons. The results of all data analysis shows that governing coefficients are as follows: Drag coefficient (CD=1.88×10-3) latent heat flux coefficient (CL=1.60×10-3) and sensible heat flux coefficient(CS 1.62×10-3) Comparison of different parameters in other seas and oceans have good correction with this results.

A two dimensional molecular dynamic (atomistic) simulation model was used to investigate the relationship between the nano-structure and the deposition parameters; namely, substrate temperature, deposition rate, angle of incidence, surface roughness. Qualitative agreements with the predictions of the structure zone model (SZM) and the theoretical results of Srolovitze and coworkers (1988), as well as expectations through changes in the activated processes during film growth due to changes in deposition parameters (Grovenor and coworkers (1984)) are obtained. It is shown that by enhancing the atomic mobility (i.e., increasing the substrate temperature or/and lowering the deposition rate) films of higher density with fewer voids are produced. By increasing the deposition angle, the nano-structure of the film changes from a dense film with few voids, to a nano-structure with columns/boundless inclined with the same angle (b) towards the incidence atoms with elongated voids. The angle b increases with increasing the deposition angle (a), and in agreement with the tangent rule (Dirks and Leamy (1977)). The angle of bundles (or the angle of the formation of the voids between atomic bundles), and columnar structure are caused by shadowing effects. Results showed that b decreases slowly with increasing surface mobility (i.e., increasing the substrate temperature or/and reducing the deposition rate). In general, the model provides almost all predicted results and agrees well with observations.

In every Tokomak there are several coils for plasma heating, displacement & confinement. It is necessary to produce large currents of several kilo amps in very short time duration of about several milliseconds. For this purpose and avoiding problems with such high currents, a large capacitor bank is changed and discharged by high current ignitron switches through the coils. If this ignitron switches do not work property it is necessary to discharge the capacitors through other high voltage keys and relays. If these keys are not designed properly they would cause some further problems. The original high voltage relays on IR-T1 Tokomak were not functioning properly because of design and aging problems. A new design of such relays was used and these relays were build, mounted with special consideration of the contact material and shapes. The relay control circuited was also modified and successfully tested with new high voltage relays on IR-T1 Tokomak.

To achieve the edge plasma properties, 2 electronic circuit have been fabricated and a set of 4 single Langmuir probes installed in Iran –Tokamak1 (IR-T1). The Floating Potential has been measured without applying any voltage, Ion Saturation Current by a negative DC power supply and then by applying a sweep voltage to tips, I-V curve and so electron temperature is obtained. Then we compare these results to investigate of some properties of edge plasma.

In this paper we are going to explain how we made hot superconductor samples which are based on Bismuth with general formula bi2 Sr2 Can-1 Cun O2n+4 (n=1, 2, 3) and analyze different parameter effects like temperature, calcinations time and required pressure for making samples and also time and temperature for sintering. By studying XRD and electrical measuring critical temperature and transmission band width we found out both 2212 and 2223 phases are existed simultaneously and we can change those ratio by changing making parameters. Samples were made at Tabriz University, electrical measuring was done at Sharif University and XRD was done at geology organization in west of country.