RSI Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Jul 1999

Volume 70, Issue 7, pp. 2899-3187

Return to All Sections
back to top
RSS Feeds
back to top ELECTRONICS; ELECTROMAGNETIC TECHNOLOGY; MICROWAVES

Wide-band low-noise tunnel current measurements in laser assisted experiments

J. Jersch, F. Demming, I. Fedotov, and K. Dickmann

Rev. Sci. Instrum. 70, 3173 (1999); http://dx.doi.org/10.1063/1.1149882 (4 pages) | Cited 6 times

Full Text: | Download PDF

Show Abstract
A composite current-to-voltage converter that shows a superior bandwidth and signal-to-noise ratio (bandwidth ∼ 50 MHz at 410 kΩ transimpedance) was designed. Two options for the input stage were tested: a high input impedance wide-band operational amplifier (OP) OPA655 (Burr–Brown) and a differential cascade which is based on the junction field effect transistors SST440 (Siliconics). By using a wideband current feedback OPA658 in the second stage the achieved bandwidth gain product is ∼ 10 GHz. A method for testing the performance of the preamplifier by using laser induced electron emission is described. The technique’s possibility for measurements of laser induced acoustic waves with high sensitivity and nanometer local resolution is demonstrated. For further applications the design of a wide-bandwidth, low-noise, single tunneling electron counting capable preamplifier is discussed. © 1999 American Institute of Physics.
Show PACS
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
07.68.+m Photography, photographic instruments; xerography
84.30.Le Amplifiers

A method for measuring low capacitance for tomography

FuQun Shao and QinGuo Mong

Rev. Sci. Instrum. 70, 3177 (1999); http://dx.doi.org/10.1063/1.1149883 (3 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
The applications of electrical capacitance tomography (ECT) to image multiphase flows in pipelines, fluidization process, interfaces in separation vessels, and combustion phenomena in internal combustion engines have been studied for some years. In these applications, none of the equipment imaged has an inner diameter exceeding 1 m. When ECT techniques for large industrial equipment like blast furnaces are explored, the existing methods for measuring low capacitance have some limitations. This article proposes a method for measuring low capacitance which is suitable to construct ECT systems for imaging large industrial equipment. The method is based on single high-voltage excitation and magnetic C/V converting principle which can resist interference by stray capacitance. Experiment results indicated that the method has good performance in regard to resolution, linearity, and stability. Though the method was designed for imaging large equipment, it can also be applicable to other fields where low capacitance measurements are required. © 1999 American Institute of Physics.
Show PACS
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
07.68.+m Photography, photographic instruments; xerography
47.80.-v Instrumentation and measurement methods in fluid dynamics
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing

The operation and modeling of transmission line transformers using a referral method

P. N. Graneau, J. O. Rossi, and P. W. Smith

Rev. Sci. Instrum. 70, 3180 (1999); http://dx.doi.org/10.1063/1.1149884 (6 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
This article describes the modeling of transmission line transformers using methods which are analogous to the methods used to analyze both the ac frequency and transient response of conventional transformers. Transformers in which the lines used to construct them are wound inductively, in order to suppress parasitic short circuit paths within the transformers, are analyzed. It is shown that by using this technique the resulting inductive isolation of the secondary circuit from the primary substantially reduces pulse droop and pulse distortion. Despite the apparent complexity of these transformers, a method by which circuit models of these transformers can be deduced is given. From these models very simple equivalent circuits can be derived which can then be used to calculate accurately the performance characteristics of the transformers and, in particular, predict the pulse distortion characteristics of these devices. Different winding configurations are also considered and it is shown that, by the use of mutually coupled winding of the transmission lines in the transformer, it is possible to minimize pulse droop. Finally it is shown that the modeling technique can be used, in modified form, to analyze the ac frequency response of this type of transformer. © 1999 American Institute of Physics.
Show PACS
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
84.32.Hh Inductors and coils; wiring
84.40.Az Waveguides, transmission lines, striplines
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close