Topic
Electrical impedance
About: Electrical impedance is a research topic. Over the lifetime, 36015 publications have been published within this topic receiving 371891 citations. The topic is also known as: electrical impedance & complex impedance.
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TL;DR: In this article, the electrical properties of a fluctuating bistable microplasma are specified by three parameters which, in general, are functions of voltage and are independent of time and thus yield simple forms for the pulse rate, average current, differential conductance, and noise spectral density.
Abstract: The electrical properties of a fluctuating bistable microplasma are specified by three parameters which, in general, are functions of voltage. For an ideal low impedance connection, these parameters are independent of time and thus yield simple forms for the pulse rate, average current, differential conductance, and noise spectral density. With a high impedance circuit the phenomenon is more complex, and only an approximate analysis is offered. Measurements on alloyed junctions with breakdown voltages between 7.9 and 10.5 v show that single breakdown regions sometimes occur at low currents. Multistable conduction as well as the simpler bistable conduction is observed. The multistable conduction is characterized by fluctuations among higher current levels which occur at a rate 102–105 times faster than the ``on‐off'' fluctuations. Excellent agreement between measured and calculated current spectral density at low impedance is found. This justifies the assumptions of random events independent of previous ``on'' or ``off'' time and suggests that noise spectrum measurements at low impedance be used as a tool for accurately determining the microplasma parameters. With a high impedance connection, the process is not Markoffian; thus the noise is not simply related to the noise at low impedance. The event which initiates breakdown is found to be field dependent suggesting that field emitted carriers are involved. It is shown that the results do not fully agree with those predicted by Rose's model of a microplasma.
82 citations
Patent•
30 Mar 1999
TL;DR: In this article, a measurement unit (50) is used to determine the impedance between the electrodes which is substantially determined by the electric properties of the tissue which is located between them, and a registration and calculator device (10) forms a control unit which controls the output voltage of the measurement unit, such that the electric field which is formed in the tissue always has a predetermined value.
Abstract: An apparatus (60) according to the present invention includes a voltage generator (1) for generating brief voltage pulses for the impression of voltage on electrodes (6, 15, 16, 24) included in the apparatus, and a measurement unit (50) which is coupled to the electrodes. These are designed to be secured at or inserted in tissue in a restricted region of a human or an animal in order therebetween to form electric fields in the tissue. The measurement unit (50) is disposed to determine the impedance between the electrodes which is substantially determined by the electric properties of the tissue which is located between the electrodes. A registration and calculator device (10) forms a control unit which, based on the impedance determined by the measurement unit, controls the output voltage of the voltage generator such that the electric field which is formed in the tissue always has a predetermined value. The treatment with the electric field realizes a perforation of cell membranes in the tissue which thereby permits the passage of substances fed to the body (e.g. cytostatic or genetic material).
82 citations
TL;DR: In this paper, a measurement method for electrochemical impedance spectroscopy (EIS) using specially designed broadband excitation signals is described, where the impedance, the disturbing noise, the level of non-linear distortions, and the non-stationary behaviour are simultaneously measured.
82 citations
TL;DR: In this article, the authors studied the energy efficiency of a dc helicity injection experiment on the CTX spheromak and showed that the injected magnetic helicity balances the flux lost by resistive decay of the toroidal equilibrium.
Abstract: Electrostatic (dc) helicity injection has previously been shown to successfully sustain the magnetic fields of spheromaks and tokamaks. The magnitude of the injected magnetic helicity balances (within experimental error) the flux lost by resistive decay of the toroidal equilibrium. Hence the problem of optimizing this current drive scheme involves maximizing the injected helicity (the voltage‐connecting‐flux product) while minimizing the current (which multiplied by the voltage represents the energy input and also possible damage to the electrodes). The impedance (voltage‐to‐current ratio) and energy efficiency of a dc helicity injection experiment are studied on the CTX spheromak [Phys. Fluids 29, 3415 (1986)]. Over several years changes were made in the physical geometry of the coaxial magnetized plasma source as well as changes in the external electrical circuit. The source could be operated over a wide range of external charging voltage (and hence current), applied axial flux, and source gas flow rate...
82 citations
15 Jun 2010
TL;DR: In this article, an electrochemical impedance spectroscopy was used to predict the state of charge of a lithium-ion rechargeable battery, which was shown to be suitable for analyzing and predicting the battery parameters.
Abstract: For the purpose of predicting the state of charge of Lithium-ion rechargeable battery accurately, we introduced the method of electrochemical impedance spectroscopy to solve the problem. The experiment data of impedance spectroscopy is comprised of an inductive arc in the high-frequency region and two capacitive arcs in the low-frequency region, and by which the reasonable equivalent circuit of battery was established. The component parameters obtained at several state of charge values of the battery had been analyzed by a non-linear least-squares fitting procedure and some electrochemical knowledge. Through researching the changing regulation of parameters with the different States of charge, the frequency of maximum of the semicircle (f max ), the phase angle o, the equivalent series capacitance (C s ) had been substantiated to be the suitable parameters for analyzing and predicting the state of charge values of the lithium-ion battery.
82 citations