Volume 77, Issue 10, October 2006
Index of content:
77(2006); http://dx.doi.org/10.1063/1.2349608View Description Hide Description
We describe new features and results from the previously reported [M. Iqbal et al., Rev. Sci. Instrum.74, 4616 (2003)] thermionic long (up to ) cathode, electromagnetically focused electron beam gun. The gun which was tested up to achieves power density of at the target. The cathode temperature and emission current was uniform over a length of of the cathode. The beam density profile along the line cathode strongly relates to the temperature distribution along the line cathode. The gun has a remarkable application in heat treatment of large surface area and to coat large substrate surfaces at much faster evaporation rates with lower cost.
Electronic frequency modulation for the increase of maximum measurable velocity in a heterodyne laser interferometer77(2006); http://dx.doi.org/10.1063/1.2349607View Description Hide Description
A Zeeman-type He–Ne laser is frequently used as a heterodyne laser due to the simple construction and the small loss of a light. However, the low beat frequency of the Zeeman-type laser limits the maximum measurablevelocity. In this article, an electronic frequency modulation algorithm is proposed to overcome the drawback of the low velocity measurement capability by increasing the beat frequency electronically. The brief analysis, the measurement scheme of the proposed algorithm, and the experimental results are presented. It is demonstrated that the proposed algorithm is proven to enhance the maximum measurablevelocity.
Robust response-compensation scheme for estimating the thermal time-constants of fine-wire temperature sensors77(2006); http://dx.doi.org/10.1063/1.2360965View Description Hide Description
A robust response-compensation scheme has been developed to estimate in situ the thermal time constants of fine-wire temperaturesensors in the frequency domain. The time-constant values can be obtained by maximizing a coherence function of two “compensated” temperature signals measured simultaneously by two sensors having different time constants. The scheme was validated experimentally and showed the highest tolerance to instrumentation noise compared with our previous methods.
77(2006); http://dx.doi.org/10.1063/1.2362721View Description Hide Description
The increased interest in pulsed power field applications has generated the need for development of compact and remotely operated chargers driven by rechargeable batteries. With this objective, a compact and portable dc to dc Converter has been developed which has an output rating of , . The high voltage generation scheme uses a hybrid approach. The overall idea behind implementation of hybrid concept is to optimize voltage upliftment with suitable techniques for maximizing power delivered per unit volume. The proposed converter provides this feature and uses flyback converter in association with Cockcroft-Walton Multiplier [M. Jullian, Cockcroft-Walton Multiplier Optimum Design Guide V2.0, August 2005 (http//www.blazelabes.com)] for the generation of dc from dc source, i.e., normal battery. In the first stage dc is modulated/chopped into series of high frequency pulses by pulse width modulator and then increased in level up to by step up flyback transformer. Further by using stage half wave series Cockcroft-Walton multiplier the voltage is stepped up to the level of . As switching device, state of the art metal-oxide-semiconductorfield-effect transistor has been used. The obtained voltage multiplier cascade efficiency is 82.64%, whereas overall power conversion efficiency of the charging power supply is 85.47%. The control unit has been fiber optically isolated from high voltage unit due to safety consideration. The presented article explores complete design and development approach of compact and portable dc power supply which can be used for a variety of applications such as x-ray generation, ion implantation, charge particle acceleration, radio isotope production, etc.
77(2006); http://dx.doi.org/10.1063/1.2358710View Description Hide Description
We present the implementation of an atomic force microscope(AFM) based on fiber-top design. Our results demonstrate that the performances of fiber-top AFMs in contact mode are comparable to those of similar commercially available instruments. Our device thus represents an interesting alternative to existing AFMs, particularly for applications outside specialized research laboratories, where a compact, user-friendly, and versatile tool might often be preferred.