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[en] Owing to a resistive barrier between composites in a superconducting conductor it is possible to share current when composites are broken without important extra losses in pulsed conditions. With a copper oxide obtained by heating in dry air no degradation in DC or AC conditions appears with about 30% of faulty composites
[fr]Lorsqu'on a une barriere resistante entre composes dans un supraconducteur il est possible de partager le courant quand les composes sont casses sans pertes importantes en regime pulse. Avec un oxyde de cuivre obtenu par chauffage en air sec, aucune degradation en regime continu et pulse n'apparait avec environ 30% de composes defectueux
[en] Electronics devices when designed to meet specific requirements, the designers do not generally envisage the amount of electromagnetic interference that this particular device may give as power line conducted noise and radiated noise. After the product is developed, the quantification of the same is carried out in certified EMI-EMC set-up to get these figures of conducted emissions (CE) and radiated emissions (RE), and its mitigation as per limits of the chosen standard. In the latest TM embodiment of Fault Tolerant Power Distribution System ECPS"T"M (Electronics Corporation Power Supply) developed for NPCIL (PHWR700MW plant) we carried out CE and RE tests and quantified the spectrum obtained for CE and RE, and mitigated them as per CISPR22 standards. In this short article we bring out the CE and RE results of the latest product ECPS, done at EMI-EMC Centre of ECIL Hyderabad. (author)
[en] X-ray fluorescence from thin foils inserted into the Naval Postgraduate School linac has been used to measure the integrated electron beam intensity when the accelerator is operating with dark current. The measured x-ray flux, the known inner shell ionization cross sections and radiative transition probabilities are used to obtain measurements of dark currents of the order of 10-14 Amperes. The same arrangement allows continuous, in-situ energy calibration of their SiLi detector in the electromagnetic noise environment of the linac. This technique was originally developed to perform absolute production efficiency measurements of parametric x-ray generation in the 5 - 50 keV range
[en] Some results on planar diode structure creation by the method of a plasma-immersion ion implantation is presented in this paper. Obtained leakage current ∼ 1 μA/cm2 at reverse voltage -1 V. (paper)
[en] The total ionizing dose effects of novel vertical channel double-gate nMOSFETs (DGMOS) are experimentally investigated and compared with conventional planar nMOSFETs firstly in this paper. The radiation-induced off-state leakage current and subthreshold slope are greatly suppressed in vertical DGMOS devices compared with conventional nMOSFETs. The performance of vertical DGMOS devices under irradiation does not change apparently even when the dose is up to 1 Mrad(Si), which is attributed to its unique device structure for separating the channel from the thick oxide isolation region and preventing the formation of a leakage path. The results indicate that the vertical channel device structure is a promising candidate for future space applications
[en] The CMS Preshower is part of the CMS Electromagnetic Calorimeter (ECAL) system. It is a sampling calorimeter that was installed to improve π0 rejection in the forward direction. It is composed of two layers of lead, each followed by a layer of silicon sensors. The Preshower is installed at each end of CMS, at about ±310 cm from the CMS interaction point. The sensors are exposed to a wide spectrum of ionizing and non-ionizing radiation, causing an increase of the bulk leakage current and a change of the effective doping concentration, resulting in a change of the full depletion voltage. This paper presents the measurements of the bulk current increase from the 2010 and 2011 LHC runs, corresponding to an integrated luminosity of 6.17 fb−1, including luminosity taken outside stable beam conditions, at a centre-of-mass energy of 7 TeV. A computer program based on the Hamburg model was developed for calculating the effects of simultaneous irradiation and annealing on the bulk leakage currents. The calculated currents, as a function of time, were found to be in good agreement with the bulk leakage currents measured in 2011. The program will be used to estimate the long-term evolution of the bulk leakage currents. The absolute level of the bulk leakage current, and its radial dependence, is in good agreement with the predictions obtained with the Hamburg model folded with the FLUKA simulation of the CMS radiation field.
[en] 10-kV 4H–SiC p-channel insulated gate bipolar transistors (IGBTs) are designed, fabricated, and characterized in this paper. The IGBTs have an active area of 2.25 mm2 with a die size of 3 mm × 3 mm. A step space modulated junction termination extension (SSM-JTE) structure is introduced and fabricated to improve the blocking performance of the IGBTs. The SiC p-channel IGBTs with SSM-JTE termination exhibit a leakage current of only 50 nA at −10 kV. To improve the on-state characteristics of SiC IGBTs, the hexagonal cell (H-cell) structure is designed and compared with the conventional interdigital cell (I-cell) structure. At an on-state current of 50 A/cm2, the voltage drops of I-cell IGBT and H-cell IGBT are 10.1 V and 8.3 V respectively. Meanwhile, on the assumption that the package power density is 300 W/cm2, the maximum permissible current densities of the I-cell IGBT and H-cell IGBT are determined to be 34.2 A/cm2 and 38.9 A/cm2 with forward voltage drops of 8.8 V and 7.8 V, respectively. The differential specific on-resistance of I-cell structure and H-cell structure IGBT are and , respectively. These results demonstrate that H-cell structure silicon carbide IGBT with SSM-JTE is a promising candidate for high power applications. (paper)
[en] We present a liquid phase post synthesis self-assemble protocol that transforms trillions of carbon nanotubes (CNTs) in powder form into densely packed flexible, robust and binder-free macroscopic membranes with a hierarchical pore structure. We employ charge transfer engineering to spontaneously disperse the CNTs in a liquid medium. The processing protocol has limited or no impact on the intrinsic properties of the CNTs. As the thickness of the CNT membrane is increased, we observed a gradual transition from high flexibility to buckling and brittleness in the flexural properties of the membranes. The binder-free CNT membranes have bulk mass density greater than that of water (1.0 g cm–3). We correlate the mass of the CNTs in the membrane to the thickness of the membrane and obtained a bulk mass density of ∼1.11 g cm–3 ± 0.03 g cm–3. We demonstrate the use of the CNT membranes as electrode in a pristine and oxidized single/stacked solid-state capacitor as well as pristine interdigitated microcapacitor that show time constant of ∼32 ms with no degradation in performance even after 10 000 cycles. The capacitors show very good temperature dependence over a wide range of temperatures with good cycling performance up to 90 °C. The specific capacitance of the pseudocapacitive CNT electrode at room temperature was 72 F g–1 and increased to 100 F g–1 at 70 °C. The leakage current of bipolar stacked solid state capacitor was ∼100 nA cm−2 at 2.5 V when held for 72 h. (paper)
[en] The paper presents the design of the active feedback used in a charge-sensitive amplifier. The predominant advantages of the presented circuit are its ability for setting wide range of pulse-time widths, small silicon area occupation and low power consumption. The feedback also allows sensor leakage current compensation and, thanks to an additional DC amplifier, it minimizes the output DC voltage variations, which is especially important in the DC coupled recording chain and for processes with limited supply voltage. The paper provides feedback description and its operation principle. The proposed circuit was designed in the CMOS 130nm technology.
[en] One channel electron multiplier (Galileo No. 4501) and one 14 stage Be/Cu multiplier (Dumont No. SPM3) were exposed to tritium pressures between approx. 10-7 Torr to 10-3 Torr in amounts from approx. 10-5 Torr-s to 60 Torr-s and the β-decay caused currents in the multipliers measured. The background currents in both multipliers consisted of two components: (1) a high, reversible current which was proportional to the tritium exposure pressure; and (2) a lower, irreversible background current which increased with increasing cumulative tritium exposure. The β-decay caused currents in each multiplier increased the same way with exposure, suggesting the detected electrons arose from decaying tritium adsorbed on surfaced external to the multipliers