No abstract

Measurements of the thickness dependence of the electrical resistance of two very thin Cr films deposited at substrate temperatures of 385 and 360°C and pressures of 4 X 10-7 and 10-6 Torr are reported. Preliminary measurements of the thickness dependence of the Nee! temperature ( TN) of the film deposited at 360 °C at thicknesses;> 10 nm are also presented. In these two films the resistance in the thickness region 2<.d<.7.5 nrn can be very wen described by R a: [(d Ide) --!]t with de equal to 1.64 ± 0.20 and 1.03 ± 0.20 nm, respectively, and t = 1.34 ± 0.1 L The NeeI temperatures show a turning point around 14 nm in agreement with the known thickness dependence of the stress. dT N IdS, has been found to be -100 K/kbar where St is the internal tensile stress in the film,

Quasi-disruption of the discharge current has been occurred in an electrode discharge system. The discharge takes place between two T-shaped electrodes, a copper central cylindrical rod and a molybdenum cylindrical transverse rod. The capacitor bank used has 52 kJ. maximum stored energy, which consists of two capacitors 680tIF capacitance each, triggering spark gap system, micro processor control system, and the power supply. The discharge current was a fast rising single pulse one, with a peak value at 500 p, then it decayed exponentially in 7.5 ms. The peak discharge current increases linearly with the charging potential of the capacitor banks, which was 14 kA at 15 kV. The discharge current disruption starts early with the increasing of the capacitor bank charging voltage in a linear relation. This indicates that the diamagnetic effect of the plasma k the main source of such disruption.

This paper studies the use of laser diodes and single element photo-detectors in mechanical alignment. Considering Gaussian beam theoretical model, the effect of laser beam diameter is studied using computer simulation. Optimum conditions that give the highest sensitivity are proved to be where: (i) the laser beam diameter matches the diameter of the sensitive area of the detector. (ii) the laser beam waist is located at the sensitive area of the detector. The photo-detector with two-complement sensitive area has been studied as a better replacement of a single area photodetector. It was proved that the use of this type of detectors , with all of the other parameters unchanged, doubles the alignment sensitivity. Finally, an experimental verification has been performed which gives a good agreement with the results obtained by computer simulation, where an alignment sensitivity of ± 0.3558 ttm was obtained.