1,721,058 research outputs found
The structure of the power supplies for ITER-FEAT additional heating and current drive systems
No full textDifferent systems are foreseen for the plasma additional heating and current drive of ITER-FEAT, to provide preionization, assisted current startup, bulk central heating and on- and off-axis current drive. Three different systems of radio frequency (RF) heating (ion cyclotron (IC), electron cyclotron (EC) and lower hybrid (LH)) and a couple of neutral beam injectors (NBI) were designed. The RF generators employ a number of different types of high power vacuum tubes (tetrode (IC), gyrotron (EC) and klystron (LH)) while the neutral injectors consist of coordinated ion production, acceleration and neutralization systems. All these equipments require dedicated dc power supplies PSs; their description and the discussion of their characteristics is done in the paper
Development and commissioning of a test system based on a TEM cell for RF exposure
No full textIn the development of a low-cost two-port TEM cell, a new analytical model of the capacitance of the terminations has been performed. The model has been verified by calculating the termination capacitance by means of a commercial 3D code. A TEM cell modified in accordance with the obtained results has been tested, with reference to the voltage standing wave ratio (VSWR) parameter, and the obtained improvements on VSWR versus frequency are reported. The TEM cell is the principal part of a test system for RF exposure (up to 230 MHz), including signal generator, power amplifier, dual directional coupler, 50 Ω load attenuator and 1 GHz bandwidth oscilloscope, whose commissioning has been performed. A numerical analysis has been performed also for calculating the stationary electric field in the TEM cell. Experimental measurements of electric field inside the TEM cell, by means of an electric field meter (100 kHz – 6 GHz broadband) were done, and the results are in good agreement with the numerical data
Development of a simple and low cost magnetic field measurement equipment up to 400 kHz
No full textIn this paper the design, realization and operative ratings of a new simple and low cost magnetic field measurement equipment in the frequency range from 10 Hz to 400 kHz are reported. The design specifications of this device have been chosen following the indications given for the magnetic field reference sensor in Standard EN 50366, concerning emissions of household and similar electrical appliances with reference to human exposure to electromagnetic fields. The developed equipment consists of three mutually perpendicular concentric coils, each one of two turns, for magnetic field analysis up to 400 kHz. By using operational amplifiers, an electronic elaboration of the coil signals has been done and is described. The characterization of the equipment has been performed by using a laboratory set-up, where the test magnetic field configuration has been obtained with a single layer solenoid in house developed
Closed-loop control of plasma current and toroidal field in RFX
No full textIn the paper the design of a control loop for both plasma current and toroidal field for RFX machine is presented. The requirements of the loads are described and both the static and dynamic performances of the control schemes in terms of precision, response time and stability are discussed. Simulations with different plasma models are then performed to test the behaviour of the control loops under different operating conditions
Design Criteria for the switching units of the RFX experiment
No full textThe results of the optimization work on the parameters of the switching units of RFX are referred in the paper. In particular, due to the use of at least two vacuum circuit breakers in parallel, attention has been paid to the problems related tothe jitter in the opening time of the different breakers. The effects of the choice of charging voltage of the counterpulse bank and of the way of connecting transfer resistor and saturable reactors have also been investigated. Finally some considerations have been done about a double opening circuit arrangement, that could be required in some operating conditions of the experiment
Influence of electrode materials on arc voltage waveforms in pressurized field distortion spark gaps
No full textA new version of coaxial holder with continuous conductor for tests on planar films
No full textA new version of coaxial transmission line sample holder with continuous conductor for measurement of shielding effectiveness of planar films has been developed. The inner conductor of the sample holder is divided in two parts; at one end of the two parts an internal and an external straight thread respectively have been realized. The connection of the inner conductor is done by screwing the two parts, pressing the film and its substrate between two flat annular surfaces. The contact is simple, reliable and effective. Contact resistance value of the order of milliohm has been obtained with a copper film deposited on PEEK substrate. With the deposited copper film, shielding effectiveness measurements in the frequency range 10 kHz – 300 MHz have been done and are reported
Magnetic field emissions up to 400 kHz from a welding equipment
No full textThis paper reports on the experimental characterization of a commercial industrial welding equipment with respect to magnetic field emissions up to 400 kHz. The frequency range of this analysis is due to the fact that the equipment under test is a manual metal arc (MMA) welding power source using inverter technology and an active dynamic control, resulting in frequency components in the tens and hundreds of kHz range. A simple and low cost new measurement probe consisting of three mutually perpendicular concentric coils for magnetic field analysis up to 400 kHz has been developed. This equipment has been combined with a commercial one for the analysis at low frequencies down to 5 Hz. Experimental data have been obtained at 400 A, maximum current for the equipment under test, with a resistive load corresponding to an MMA conventional load voltage of 36 V, in agreement with Standard EN 60974-1. Further analysis has been performed on the emissions from the welding cables. Frequency-selective field measurements have been obtained and the results are discussed with respect to occupational exposure limits
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