Examinando por Autor "Ardila-Rey, Jorge"

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  • Miniatura
    Ítem
    Electromagnetic burst measurement system based on low cost UHF dipole antenna
    (Energies, 2017-09) Escalona, Ismael; Avaria, Gonzalo; Díaz, Marcos; Ardila-Rey, Jorge; Moreno, José; Pavez, Cristian; Soto, Leopoldo
    Non-linear high-power devices produce electromagnetic noise (EMN) sources of great intensity that can disrupt and damage the surrounding electrical equipment and devices. This radiative phenomenon is very common at facilities where pulsed power generators are required, particularly those that are needed to produce dense transient plasma experiments. These conditions are found at the Chilean Nuclear Energy Commission (CCHEN), due to the presence of pulsed power generators that switch large currents (kA-MA) in short times (10-100 ns). In order to characterize and establish conditions to mitigate the effects of the EMN on nearby devices, a measurement system based on an ultra-high frequency (UHF) dipole antenna was developed. We evaluated the system measuring the EMN emanated from a plasma focus device, the PF-400J. Measurements at the place indicated broadband and intense electric fields that can couple to nearby cables and equipment (10-300 MHz bandwidth, up to 350 V/MHz spectral intensity, 100 V coupled voltage). Based on these measurements a compact and simple protection system was designed, built and tested, capable of effectively mitigating the high levels of EMN. The proper EMN impact mitigation indicates the correct operation of the suggested system. The developed system can be of interest to the energy community by facilitating EMN measurement produced by arc discharges. © 2017 by the authors.
  • Miniatura
    Ítem
    Hard X-Ray Emission Detection Using Deep Learning Analysis of the Radiated UHF Electromagnetic Signal from a Plasma Focus Discharge
    (Institute of Electrical and Electronics Engineers Inc., 2019) Avaria, Gonzalo; Ardila-Rey, Jorge; Davis, Sergio; Orellana, Luis; Cevallos, Benjamin; Pavez, Cristian; Soto, Leopoldo
    A method to determine the presence of hard X-ray emission processes from a dense plasma focus (205 J, 22 kV, 6.5 mbar H2) using Ultra High Frequency (UHF) measurements and deep learning techniques is presented. Simultaneously, the electromagnetic UHF radiation emitted from the plasma focus was measured with a Vivaldi UHF antenna, while the hard X-ray emission was measured with a scintillator-photomultiplier system. A classification algorithm based on deep learning methods, using two-dimensional convolutional layers, was implemented to predict the hard X-ray signal standard deviation value using only the antenna signal measurement. Two independent datasets, consisting of 999 and 1761 data pairs each, were used in the analysis. Different realizations of the training/validation process using a deep learning model, obtained overall better results in comparison to other machine learning methods like k-neighbors, decision trees, gradient boost, and random forest. The results of the deep learning algorithm, and even its comparison with other machine learning methods, indicate that a relationship between the electromagnetic UHF radiation and hard X-ray emission can be established, enabling the indirect detection of hard X-ray pulses only using the UHF antenna signal. This indirect detection presents the opportunity to have a simple and low-cost diagnostic, compared to the methods currently used to characterize the pulses of X-rays emitted from plasma focus discharges. © 2013 IEEE.
  • Miniatura
    Ítem
    On the Relationship between the Electromagnetic Burst and Inductive Sensor Measurement of a Pulsed Plasma Accelerator
    (Institute of Electrical and Electronics Engineers Inc., 2019) Orellana, Luis; Ardila-Rey, Jorge; Diaz, Marcos; Pavez, Cristian; Schurch, Roger; Soto, Leopoldo
    A remote and non-invasive diagnostic of the plasma focus using antennas is presented in this work. The main motivation is the application of such diagnostic in a miniaturized plasma accelerator, based on the plasma focus architecture, as a cube satellite thruster. The evaluation of this proposal was carried out measuring a hundred of joules plasma focus operation simultaneously with the inductive measurement and antennas. Three different antennas tuned in the ultra high frequency range were tested: a monopole, Vivaldi and helical. The high frequency transients detected with the antennas were time correlated to the known inductive measurement features. The initial dielectric breakdown and later plasma pinch and subsequent disruption (i.e. the source of the propulsion) were identified to be the principal phenomena to be detected. Signal parameter correlations between the inductive sensor and the antennas showed that the pinch phenomena can be correlated with the antenna signals. Good correlation results were obtained with the monopole antenna when using peak value and signal energy parameter from the antenna transient. An improvement in the correlation results, for the helical and Vivaldi antennas, was obtained when calculating the frequency band energy. In this case, the Vivaldi antenna achieved the best results. The results of the monopole antenna make it an alternative remote sensor for plasma focus, but for the application of a miniaturized plasma focus as pulsed plasma thruster, the Vivaldi antenna is a more feasible design to replace the inductive diagnostic due to its compact design in comparison to the monopole. © 2013 IEEE.