Browsing by Author "Silva, P."
Now showing 1 - 11 of 11
Results Per Page
Sort Options
- ItemCharacteristics of a small plasma focus device(IET, 1996) Favre Domínguez, Mario Benjamin; Silva, P.; Chuaqui, Hernán; Wyndham Hodder, Edmund Sydenham; Choi, P.; Dumitrescu-Zoita, C.We report on experimental observations in PFP-I, a small 3.8 kJ plasma focus, which is operated in Hydrogen-Argon mixtures to investigate the effect of parameter modifications on the overall performance of the device. An extensive array of diagnostics is been used, which includes voltage and current probes in the external circuit, a novel small magnetic probes array located along the cathode rods, filtered PIN diodes located side and end on, and multi-pinhole X-ray camera. EX1ended operated range from below 0.2 Torr upwards has been achieved with the implementation of the auxiliary discharge circuit. Despite the low voltage and low energy operation, energetic beam formation has been observed at the time of the final compression, prior to disruption. Current sheath formation and evolution has been characterised using the magnetic probes array, in correlation with beam formation and plasma emission. Time integrated visible plasma spectroscopy is performed to investigate impurity effects on focus performance and plasma dynamics at the collapse phase.
- ItemComparison of two identification and susceptibility test kits forUreaplasmaspp andMycoplasma hominisin amniotic fluid of patients at high risk for intra-amniotic infection(2020) Kusanovic, Juan Pedro; Vargas Innocenti, Paula Andrea; Ferrer Márquez, Fernando Andrés; Díaz, F.; Córdova, V.; Martinovic, C.; Valdés, R.; Rosas, A.; Luna Fernández, Daniela Fanny; Silva, P.; Silva, K.; Nilo, M. E.; Silva, M. J.; Espejo, E.; Zambrano, M. A.; García, J.; Parra Lara, L. G.; Escobar, M. F.
- ItemElectrical characteristics of a small plasma focus device(IET, 1996) Choi, P.; Favre Domínguez, Mario Benjamin; Silva, P.; Chuaqui, Hernán; Wyndham Hodder, Edmund SydenhamEfficient plasma focus operation relies on uniform initial breakdown across the insulator surface. In this paper, we discuss basic plasma focus electric circuit, in order to highlight circuit modifications that produce high voltage oscillation at initial breakdown time. Superimposed on the main discharge voltage such oscillating voltage has been found in real systems to enhance the initial gas breakdown by localizing the initial current path across the insulator surface. PSpice circuit simulations are compared with electric signals from different operational plasma focus devices.
- ItemExperimental investigations of hotspots in a low energy plasma focus operating in hydrogen-argon mixtures(IEEE, 1998) Favre Domínguez, Mario; Silva, P.; Choi, P.; Chuaqui, Hernán; Dumitrescu-Zoita, C.; Wyndham, EdmundWe present experimental results on the investigation of hotspot formation in PFP-I, a small 3.8 kJ plasma focus device operating in hydrogen-argon mixtures, at pressures from below 0.2 torr upward. A combination of multipinhole and slit-wire X-ray photography is used to measure the characteristic size and temperature of the hotspots, over a range of pressure and gas mixing ratios. Filtered p-i-n diodes and a beam-target detector are used to investigate the time evolution of the hotspots. Typical size for the hottest emitting region, at temperatures between 200 and 400 eV, is found to be around 150 /spl mu/m, with a typical duration of the high temperature phase of the order of 10 ns. In general, the temperature in the final phase of the time evolution of the hotspots reaches values which are nearly twice those of the plasma column where they are formed. Characteristic size of the hotspots is about half of that of the initial plasma column.
- ItemExperimental Observations on a Small Plasma-Focus Operating With Hydrogen/Gas Mixtures(1998) Silva, P.; Favre Domínguez, Mario; Chuaqui, Hernán
- ItemIon beam measurements in a small plasma focus operating in hydrogen/gas mixtures(IEEE, 1998) Silva, P.; Favre Domínguez, Mario; Choi, P.; Dumitrescu-Zoita, C.; Chuaqui, Hernán; Wyndham Hodder, Edmund SydenhamDense transient plasmas of high energy density, can be easily produced in a plasma focus device, on a cost effective basis. High energy ion beam emission is one, among several others, of the very interesting transient plasma phenomena observed in plasma focus discharges. Although some of the properties of these ion beams have been investigated in the past, the physical mechanisms involved in their generation are still not clear, and further investigations are required on order to establish the exact correlations of the ion beam emission with other plasma focus phenomena. We present a preliminary series of measurements on ion beams in a plasma focus operating with hydrogen/gas mixtures, using an XRD probe array, which allows the characteristic ion energy to be determined from the time of flight across the probe array, and the time of the ion beam emission to be correlated with plasma emission events associated with the soft X-ray pulses detected by the probes.
- ItemPalmitic acid reduces the autophagic flux in hypothalamic neurons by impairing autophagosome-lysosome fusion and endolysosomal dynamics(2020) Hernández Cáceres, María Paz; Cereceda, K.; Hernández, S.; Li, Y.; Rivera Reyes, Patricia Ximena; Toledo Valenzuela, Lilian Alejandra; Cifuentes Araneda, Flavia Dominique; Pérez Leighton, Claudio; Bertocchi, Cristina; Morselli, Eugenia; Narro, C.; Silva, P.; Avalos, Y.; Jara, C.; Burgos, P.; Lagos, P.; Clegg, D. J.; Criollo, A.; Tapia Rojas, C.; Burgos, P. V.
- ItemPatients with acute cervical insufficiency without intra-amniotic infection/inflammation treated with cerclage have a good prognosis(2019) Monckeberg, M.; Valdes, R.; Kusanovic, Juan Pedro; Schepeler, M.; Nien, J.K.; Pertossi, E.; Silva, P.; Silva, K.; Venegas, P.; Guajardo, U.; Romero, R.; Illanes, S.E.
- ItemStress during Lactation Induces Insulin Resistance Associated with an Increase in Type 1 Cannabinoid Receptors in Liver and Adipose Tissue(2019) Fonseca, L.; Castillo, V.; Aguirre Polanco, Carolina; Silva, P.; Ronco, A. M.; Llanos, M.
- ItemStudies of current sheath evolution in a small plasma focus device(IET, 1996) Silva, P.; Favre Domínguez, Mario Benjamin; Chuaqui, Hernán; Wyndham Hodder, Edmund Sydenham; Choi, P.We present preliminary time and space resolved studies of current sheath formation in Plasma Focus discharges, using a novel array of non invasive magnetic field probes. The experiments are performed in a Mather type plasma focus, which is powered by a 9 µf capacitor bank, operating at 30 kV. The discharge is formed between a hollowed anode and six symmetrically arranged cathode rods. The array of small magnetic probes is located along the cathode rods. The probes are of millimeter size. They are shielded behind the rods, as to minimize capacitive coupling to the anode electrode, and allow nonperturbing measurements to be made. The array probe signals are recorded simultaneously, with 2 ns time resolution. Other available diagnostics include voltage and current probes in the ex1emal circuit, filtered PIN diodes located side and end on, and a multi-pinhole x-ray camera. A simple analytical model of current sheath evolution is used to interpret the probe signals. The experiments have been performed in pure Hydrogen and Hydrogen with Argon mixture, at pressures from below 0.2 Torr upwards. The effect of the Argon mixture on the current sheath structure is investigated with the probe array. It is found that at constant mass density operation, the increase in the percentage of Argon results in a thinner sheath, with steeper current profile.
- ItemStudies of Plasma Dynamics in a Small Plasma Focus Operating in Hydrogen-Argon Mixtures(1998) Favre Domínguez, Mario; Silva, P.; Chuaqui, Hernán; Wyndham, Edmund