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Concept

Reflections of signals on conducting lines

Publications associées (28)

Validation of short-pulse reflectometry turbulence measurements with a synthetic diagnostic

Stefano Coda, Stephan Brunner, Oleg Krutkin, Samuele Mazzi, Umesh Kumar, Mackenzie Peter-Fulford Van Rossem

Experimental measurements of the turbulence amplitude utilizing a short pulse reflectometry method are presented. Two discharges with shaped plasma possessing opposite signs of triangularity are considered and a higher turbulence amplitude is found in the ...

IOP Publishing Ltd2024

Electromagnetic time reversal for online partial discharge location in power cables: Influence of interfering reflections from grid components

Farhad Rachidi-Haeri, Marcos Rubinstein

In online single-sided partial discharge (PD) location, the measured PD reflection patterns are affected by the characteristics of all the components of the associated power network. This paper analyses the performance of a PD location method based on elec ...

2024

Exact Expressions for Lightning Electromagnetic Fields: Application to the Rusck Field-To-Transmission Line Coupling Model

Farhad Rachidi-Haeri, Marcos Rubinstein

An exact analytical expression for the electric field of the return stroke as excited by a propagating step current source is derived in this paper. This expression could be advantageously used to evaluate the disturbances caused by lightning on overhead l ...

2023

Biomaterial devices on Arecanut palm leaf for microwave applications

Anja Skrivervik, Sujith Raman

This paper presents an investigation on the possibility of arecanut palm leaf as a biomaterial substrate for various microwave devices such as transmission lines, antenna, filter and a radio frequency identification device (RFID). The dielectric properties ...

IEEE2023

High power mm-wave loss measurements of ITER ex-vessel waveguide components at the FALCON test facility at the Swiss Plasma Center

Timothy Goodman, René Chavan, Avelino Mas Sanchez, Anastasia Xydou, Cinta Lucia Marraco Borderas, Humberto Torreblanca Quiroz

Many future fusion devices will rely heavily, if not solely, on electron cyclotron (EC) heating subsystems to provide bulk heating, instability control (neoclassical tearing mode (NTM) stabilization), and thermal instability control. Efficient use of the i ...

E D P SCIENCES2023

Distributed Scheme for Line Overload Mitigation With Linearized AC Power Flow

Ping Hu

The transmission overload after a disturbance poses significant security risk to the power system. Once it happens, an efficient remedial action must be taken to relieve the line overloads as quickly as possible. The line overload mitigation problem become ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2022

Interaction of lightning-generated electromagnetic fields with overhead and underground cables

Farhad Rachidi-Haeri, Marcos Rubinstein, Carlo Alberto Nucci

In this chapter, we discussed the TL theory and its application to the problem of lightning electromagnetic field coupling to transmission lines. After a short discussion on the underlying assumptions of the TL theory, we described seemingly different but ...

IET2022

On the Solution of the Optimal Power Flow for Three-Phase Radial Distribution Networks With Energy Storage

Jean-Yves Le Boudec, Cong Wang, Eleni Stai

We study a multiperiod optimal power flow (OPF) problem in unbalanced three-phase radial distribution networks with batteries. To address this problem, we first take the resistance-line battery model that treats lossy batteries by adding resistive lines an ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2021

A Closed Time-Reversal Cavity for Electromagnetic Waves in Transmission Line Networks

Farhad Rachidi-Haeri, Marcos Rubinstein, Mario Paolone, Reza Razzaghi, Zhaoyang Wang

A closed time-reversal (TR) cavity has been considered a purely theoretical concept whose experimental realization was assumed to be impossible. In this article, we demonstrate that it is, in fact, possible to realize a closed TR cavity using a network of ...

2021

Prototype mitre bends of the ex-vessel waveguide system for the ITER upper launcher: Thermal hydraulic simulations and experiments with off-center mm-wave beams

Timothy Goodman, René Chavan, Anastasia Xydou, Matteo Vagnoni, Humberto Torreblanca Quiroz

On ITER, long pulse gyrotrons are required as a power source for electron cyclotron heating (ECH) and current drive (CD). The microwaves are guided from the gyrotrons, which are placed far from the Tokamak, into the plasma by transmission lines (TLs) and a ...

Elsevier2021

An Effective EMTR-Based High-Impedance Fault Location Method for Transmission Lines

Farhad Rachidi-Haeri

This article summarizes the electromagnetic time-reversal (EMTR) technique for fault location, and further numerically validates its effectiveness when the fault impedance is negligible. In addition, a specific EMTR model considering the fault impedance is ...

2021

A Method for the Improvement of the Stability in FDTD-Based Numerical Codes Evaluating Lightning-Induced Voltage

Farhad Rachidi-Haeri

Dealing with realistic networks, the solution of lightning electromagnetic field coupling to transmission lines is generally obtained through a Finite-Difference Time-Domain (FDTD) algorithm interfaced with an electromagnetic simulator. As well known, the ...

2021

Simulation of High-Frequency Transients in Overhead Lines Including Frequency-Dependent Soil Parameters: an FDTD Aproach

Farhad Rachidi-Haeri, Rafael Silva Alipio

This paper investigates the effect of frequency-dependent soil parameters on the simulation of electromagnetic transients on overhead lines, based on the application of the FDTD method to solve the telegrapher’s equations. The ground return impedance is ca ...

2021

Design and Thermal-Structural Analyses of Ancillary Components for the Optical Steering Mirror (M4) for the ITER ECH Upper Launcher

Timothy Goodman, René Chavan, Avelino Mas Sanchez, Matteo Vagnoni, Phillip Miguel Santos Silva

Each of the four ITER Electron Cyclotron Heating Upper Launcher (ECHUL) features eight transmission lines (TLs) that are used to inject 170-GHz microwave power into the plasma at a level of up to 1.31 MW (at the TL diamond window) per line. The millimeter ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2020

The Upper Bound of the Speed of Propagation of Waves along a Transmission Line

Farhad Rachidi-Haeri, Marcos Rubinstein

According to theory, once certain conditions are fulfilled, current and voltage pulses propagate along ideal transmission lines with the speed of light. One can reach such a conclusion only when the conductors are assumed to be perfectly conducting, which ...

2020

Megawatt power generation of the dual-frequency gyrotron for TCV at 84 and 126 GHz, in long pulses

Timothy Goodman, Stefano Alberti, Minh Quang Tran, Jean-Philippe Hogge, Damien Fasel, Ioannis Pagonakis, Blaise Marlétaz, Ugo Siravo, Jérémy Genoud, Jérémie Dubray, Matthieu Toussaint, Jonathan Sylvain Masur, Christian Moura

In the frame of the TCV Tokamak upgrade, two 84/126 GHz/2 s dual frequency gyrotrons designed by SPC and KIT and manufactured by THALES will be added to the existing EC-System. The first unit has been delivered to EPFL-SPC and tested. In the commissioning ...

2020

Active Phase-Conjugating Rotman Lens With Reflection Amplifiers for Backscattering Enhancement

Pouyan Keshavarzian

Active retrodirective antenna arrays find a variety of use in applications involving wireless communication and sensing systems. This article presents a novel active version of the phase-conjugating Rotman lens with negative conductance amplifiers for appl ...

Institute of Electrical and Electronics Engineers2020

High-Power Testing of Guided-Wave Components for the ITER ECH Upper Launcher at the FALCON Test Facility

Timothy Goodman, René Chavan, Matteo Vagnoni

Each of the four ITER electron cyclotron heating (ECH) upper launchers (ULs) features eight transmission lines (TLs) made of guided-wave components used to inject 170-GHz microwave power into the plasma at a level of up to 1.31 MW per line, at the TL diamo ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2020

Electromagnetic Time Reversal: Theory, Application to Fault Location in Power Networks and Experimental Validation

Zhaoyang Wang

The time-reversal invariance is readily described and universally embodied in most laws of nature, either in a strict or in a soft sense. Based on this underlying physical principle, time-reversal theory has been theoretically and experimentally studied in ...

EPFL2020

Finite element modeling of dynamic frictional rupture with rate and state friction

Jean-François Molinari, Fabian Barras, Roozbeh Rezakhani

Numerous laboratory experiments have demonstrated the dependence of the friction coefficient on the interfacial slip rate and the contact history, a behavior generically called rate and state friction. Although numerical models have been widely used for an ...

PERGAMON-ELSEVIER SCIENCE LTD2020