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No abstract available

[en] This article discusses the basic concepts of magnetic resonance (MRI) with intention to introduce the subject to uninitiated. The MRI technique is a powerfull noninvasive probe of body's internal anatomy. In MRI the images are produced not by X-rays, but through the use of non-ionizing radio waves that stimulate transitions between spin states of nuclei in a magnetic field when passed through the body. The time required for the nucleus to return to equilibrium gives information about the environment of the nucleus. In this way tissue abnormalities can be determined in vivo. This article covers the basis of MRI phenomena, the concept of magnetic moment of the sample, NMR exalation and emission and the equipment necessary to observe these NMR properties. The primary agents increased tissue contrast in MRI are also mentioned. Finally the importance and prospects of this technique in Pakistan have been discussed. (author)

No abstract available

[en] The maximum current of a superconducting solenoid is restricted by the maximum magnetic field. Therefore current density in low magnetic field regions becomes much smaller than the critical current density at those magnetic fields. This means that the superconductors are used inefficiently. A simple way to use superconductors more efficiently is to divide the solenoid into several sections according to their magnetic field strength. A method of minimizing the winding volume of the superconducting solenoid by such a division is described using certain approximations. This method is also very convenient for designing the solenoid with the highest current density or the most economical solenoid made with different superconducting materials. (author)

[en] Magnetic field and force equations for lumped solenoids, fields off-axis, iron-bound solenoids, and Helmholtz magnets are generally complex. Many of these problems are readily solvable, with reasonable accuracy and speed, by a programmable calculator. Six typical problems are selected, and the approach to solving each one is discussed. All of the problems have been programmed for an HP-97 calculator, using no more than 224 program steps in any case. The principles discussed here are not specific to any calculator, and the purpose is to prepare these problems for general calculator solution. 7 refs

[en] Preliminary seismic deflection response analyses of a toroidal field (TF) coil design for General Atomic (GA) Company's Power Generating Fusion Reactor (PGFR) concept have been performed to aid in determining whether sufficient clearance was available between the TF coils and adjacent shield structure

[en] Thermally actuated shims designed for the Large Coil Test Facility (LCTF) provide passive clamping capability for inaccessible structural interfaces. These shims were designed to hold the test coils tightly in place against the bucking post. This particular interface is relatively inaccessible, tends to loosen as the structure cools down, and experiences high loads due to magnetic interaction of the test coils. As designed, the shims are loose at assembly and tighten as the temperature of the structure decreases. These devices utilize the difference in the thermal coefficient of expansion of materials to drive a double acting wedge which causes an increase in shim thickness as the temperature is decreased. These magnets are for fusion applications. 1 ref

[en] Owing to the strong magnetic field disturbance, it is very difficult to measure in field the pulse stress of the magnetic coil of controlled fusion set by using the resistance wire strain gauge. However, we have succeeded in performing this measurement by using reflection hologram of a single beam light. We have come to the conclusion that the set can operate safely under designed conditions and the fact that it has been running well for three successive years proves the correctness of our conclusion. The principle of holographic interferometry by using a single beam light is put forward and the pulse stress holography equipment and the results of the pulse stress measurement are described. The results of non-destruction test are also given. (orig.)