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A modular electromagnetic railgun accelerator facility named "RAFTAR" (i.e., Railgun Accelerator Facility for Technology and Research) has been commissioned and its performance has been characterized for high velocity impact testing on materials in a single-shot mode. In the first tests, RAFTAR demonstrated an acceleration of more than 1000 m/s for an 8 g solid aluminum-7075 armature projectile. The current fed was 220 kA, having a muzzle time of about 1.75 ms. It is a single pulse breech-fed rectangular bore (14 × 13 mm2) railgun, and its 1.15 m long barrel assembly consists of two parallel copper bars with an inter-gap of 13 mm that are encased within 50 mm thick high strength reinforced fiberglass sheets (Garolite G10-FR4) and bolted from both the sides. RAFTAR is powered by two capacitor bank modules that have a maximum stored energy of 160 kJ each (containing eight 178 μF/15 kV capacitors), two high power ignitron switches, and a pulse shaping inductor. To obtain consistent acceleration of the armature inside the barrel, reversal of driving current is prevented, and its pulse duration is stretched by tactical integration of the crowbar switch and bitter coil inductor in the circuit. Armature projectile velocity measurement in-bore and outside in free space was performed by the time-of-flight technique using indigenously made miniature B-dot sensors and a novel shorting-foil arrangement, respectively. The time resolved measurement of the in-bore armature evidenced a velocity-skin-effect in the high acceleration phase. There is good agreement between the experimentally measured and theoretically predicted efficiency, confirming the optimal choice of operating parameters. The conclusion summarizes important experimental findings and analyzes the underlying causes that limit the performance of railguns. [ABSTRACT FROM AUTHOR]

Characterization results of high-power microwave radiation, from an axial vircator driven by pulsed electron beam accelerator AMBICA-600 are reported in this paper. We present a study on variation in pulsed microwave power output and dominant frequency by discretely varying anode–cathode (A–C) gap. While keeping the cathode diameter fixed at 40 mm, for the A–C gap distance in the range 5–9 mm, dominant frequencies have been measured to be lying in the range 4.7–9.8 GHz. The trend of a subsequent increase in the dominant frequency at lower A–C gap distances (and vice versa) revealed that center frequency is mainly governed by the longitudinal size of the potential well. The highest microwave power of \sim14~MW for \sim75\-ns pulse duration was obtained at A–C gap of 7 mm having the dominant frequency in C-band at \sim6.9~GHz. The beam-to-microwave power conversion efficiency of \sim1.2\% has been demonstrated in our experiments. On the basis of power distribution pattern obtained by the gas breakdown technique, the dominant mode of emission is believed to be transverse magnetic mode. Relative analysis of frequency spectrums obtained for various A–C gap distances evidenced experimental recognition of optimum A–C spacing as a generation of narrowband distinct frequency peak of large magnitude with minimal mode hopping. [ABSTRACT FROM AUTHOR]

High-voltage double pulse of nanosecond duration (\sim hundreds of nanoseconds) with extremely short interval (\sim tens of nanoseconds) between the pulses can be used to study the double pulse effect in nanosecond laser ablation for laser-induced breakdown spectroscopy. A 0.5-GW compact pulsed-power driver is designed using the transmission line characteristics of the pulse forming line to generate two pulses with extremely short repetition interval. The impedance of the pulsed-power driver is 22 \Omega, and it generates two flat top high-voltage pulses of 100 kV, 100 ns duration with a interpulse repetition interval of 30 ns across the matched load. [ABSTRACT FROM AUTHOR]

Aim: To find the prevalence of self-reported diabetes mellitus (DM) in rural Kerala.Methodology: Interview schedule was used to collect the information on pre-designed and pre-tested proforma. Self-reported DM was taken as outcome measure. All these patients were diagnosed by their respective physicians and were on anti-diabetic drugs. Body weight was measured to the nearest 1 kg using bathroom scale; while height was measured using a nonstretchable tape to the nearest 1 mm. Standard classification of obesity and waist circumference was used.Results: The present cross-sectional study was carried out in the Venganoor village of Kerala. Four hundred and sixty four subjects, 64.4% women and 35.6% men, were selected randomly. Nearly half of the subjects were in the age range of 25-54 years, while about one-third of the subjects were over 55 years. Among the men, 38.5% were ever smokers, while 5.5% were in the habit of consuming alcohol. 27.8% of the subjects were found to be obese, while 20.3% of the subjects reported raised waist circumference. The level of physical activity in the majority of the subjects was either sedentary or mild. On multivariate analysis, increasing age was found to be significantly associated with self-reported diabetes (OR = 1.07; 95% CI: 1.04-1.09). The other factors namely sex, smoking habit, alcohol use, obesity, waist circumference and physical activity were found to be statistically nonsignificant.Conclusion: The prevalence of self-reported diabetes was found to be 13.1% and that it was seen to be associated with increasing age. [ABSTRACT FROM AUTHOR]

The experimental results of an air-core pulse transformer are presented, which is very compact (<10 Kg in weight) and is primed by a capacitor bank that is fabricated in such a way that the capacitor bank with its switch takes the shape of single-turn rectangular shaped primary of the transformer. A high voltage capacitor assembly (pulse-forming-line capacitor, PFL) of 5.1 nF is connected with the secondary of transformer. The transformer output voltage is 160 kV in its second peak appearing in less than 2 μS from the beginning of the capacitor discharge. The primary capacitor bank can be charged up to a maximum of 18 kV, with the voltage delivery of 360 kV in similar capacitive loads. [ABSTRACT FROM AUTHOR]