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[en] A novel shorted anode lateral-insulated gate bipolar transistor (SA LIGBT) with snapback-free characteristic is proposed and investigated. The device features a controlled barrier V barrier and resistance R SA in anode, named CBR LIGBT. The electron barrier is formed by the P-float/N-buffer junction, while the anode resistance includes the polysilicon layer and N-float. At forward conduction stage, the V barrier and R SA can be increased by adjusting the doping of the P-float and polysilicon layer, respectively, which can suppress the unipolar mode to eliminate the snapback. At turn-off stage, the low-resistance extraction path (N-buffer/P-float/polysilicon layer/N-float) can quickly extract the electrons in the N-drift, which can effectively accelerate the turn-off speed of the device. The simulation results show that at the same V on of 1.3 V, the E off of the CBR LIGBT is reduced by 85%, 73%, and 59.6% compared with the SSA LIGBT, conventional LIGBT, and TSA LIGBT, respectively. Additionally, at the same E off of 1.5 mJ/cm2, the CBR LIGBT achieves the lowest V on of 1.1 V compared with the other LIGBTs. (paper)
[en] The investigation of electric contacts by neutron radiography allows the visualization of the contact interface when contacts are closed and of the effective zones of current path with a precision of the order of a fraction of millimeter. Before closure, the contact surfaces are coated with a neutron absorber (grease containing boron, colloidal boron, etc..) and the absorber is driven away into zones without elementary contacts
[fr]La methode d'analyse des contacts electriques par neutronographie permet de visualiser l'interface des contacts maintenus fermes et les zones effectives de passage du courant avec une definition de l'ordre d'une fraction de millimetre. Avant fermeture, on enduit les surfaces en contact d'un produit absorbant les neutrons (graisse boree, bore colloidal etc..), ce produit est chasse dans les zones ne presentant pas de contacts elementaires
[en] Highlights: • Study valley dependent transport in L junction consists of an armchair and a zigzag leads. • At some Fermi energies, the current in the zigzag lead is highly valley polarized. • An electrical potential applied to the junction increases the energy range where highly valley polarized current is found. • Scaling behavior is founded in the results; conclusion can be extended to larger junctions. • The junction can be used a generator of highly valley polarized current. We studied the valley dependent transport in graphene L junctions connecting an armchair lead and a zigzag lead. The junction can be used in valleytronic devices and circuits. Electrons injected from the armchair lead into the junction is not valley polarized, but they can become valley polarized in the zigzag lead. There are Fermi energies, where the current in the zigzag lead is highly valley polarized and the junction is an efficient generator of valley polarized current. The features of the valley polarized current depend sensitively on the widths of the two leads, as well as the number of dimers in the armchair lead, because this number has a sensitive effect on the band structure of the armchair lead. When an external potential is applied to the junction, the energy range with high valley polarization is enlarged enhancing its function as a generator of highly valley polarized current. The scaling behavior found in other graphene devices is also found in L junctions, which means that the results presented here can be extended to junctions with larger dimensions after appropriate scaling of the energy.
[en] Point-contact spectroscopy was originally developed for the determination of the electron-phonon spectral function in normal metals. However, in the past 20 years it has become an important tool in the investigation of superconductors. As a matter of fact, point contacts between a normal metal and a superconductor can provide information on the amplitude and symmetry of the energy gap that, in the superconducting state, opens up at the Fermi level. In this paper we review the experimental and theoretical aspects of point-contact spectroscopy in superconductors, and we give an experimental survey of the most recent applications of this technique to anisotropic and multiband superconductors. (topical review)
[en] Given are the simple methods to connect the thin indium conductors without changing considerably the cross-section in the contact point. The method is based on the fact, noticed during the squeezing out of the long indium wire with a plunger die in the female die through the aperture. The die is being placed on the base freely. The wire loops are welded in the place of contact. This happens owing to the large energy of the distorted lattice, cleanliness of the wire surface and the low indium recrystallization temperature. The ''active'' state ends quickly - after 15 minutes the wire loses the mentioned ability, i.e. the regression processes occur in the metal lattice
[en] Boundary pillars are important symbols of the junction, and at present, the most common way of managing boundary pillars in China is to employ a full-time boundary pillar maintainer in order to maintain the pillars themselves better. Damage to or loss of reference materials such as the "borders" can cause considerable problems in resolving boundary disputes and controversies. In recent years, the Geographical Information System (GIS) has been in a stage of rapid development, both theoretically and in terms of application. With the advancement of network information technology and the increasing maturity of GIS technology, WebGIS combining the two has gradually been widely used in various industries, while the Internet of Things (IoT) is also developing rapidly, on which a more complete set of intelligent electronic boundary pillars based on IoT technology has the theoretical basis to emerge. (paper)
[en] Application of ceramic high temperature superconductor (HTSC) to cryogenic current leads has successfully demonstrated the ability to significantly reduce the refrigeration requirements associated with current leads. Westinghouse Science ampersand Technology Center has participated in this technology development from the very beginning and has now brought this technology into commercialization with a line of HTS (High Temperature Superconducting) vapor-cooled current lead products. In the process of developing this technology, Westinghouse has performed design analysis; tested prospective HTSC of various composition and geometry from half a dozen vendors; developed designs of low resistance, high current capacity HTSC/copper contact joints; fabricated and extensively tested several current lead test models and prototypes; and performed application and cost/benefits analyses. These efforts, together with HTS current lead design parameters and performance data are discussed
[en] The evaluation of the electrical contact resistances of thermoelectric legs is important to predict the performance of thermoelectric modules. Thermoelectric modules can be divided into devices operating at high and low temperatures. In the former, the electrical contact resistance can change with temperature. However, many research groups have only analyzed the electrical contact resistance at mainly room temperature. In this study, an electrical contact resistance measurement system for thermoelectric legs of thermoelectric devices at high operating temperature (400 to 600 °C) is proposed, which provides a more accurate performance prediction. The measurement conditions are determined according to the amplitude and frequency of the current to minimize the measurement errors caused by the Peltier effect. Skutterudite thermoelectric legs with a Ti metallization layer are used to understand the specific contact resistance at high temperatures. Based on the obtained results, the thermoelectric module is analyzed through a simulation to investigate the power outputs with the specific contact resistances at both room and high operation temperatures.
[en] The invention concerns a current supply device for a superconducting magnet coil to be shortcircuited, with a separating device per coil end, which contains a fixed cooled contact and a moving contact connected to a power supply device and a mechanical actuating device for closing and opening the contacts. When closing the heated contact on to the cooled contact, relatively large quantities of heat can be transferred to the cooled contact and therefore to the connected superconducting coil end and can cause normal conduction there. The invention therefore provides that the mass ratio of the cooled contact to the moving contact is at least 5:1, preferably at least 10:1, and that the cooled contact part is provided, at the end away from the contact area, with means for increasing the area, for example cooling fins and is connected to the coil end has a thermal resistance between the contact area and the coil end of at least 0.2 k/W, preferably at least 0.5 k/W per 1000 A of current to be transmitted. (orig.)
[de]Die Erfindung betrifft eine Stromzufuehrungsvorrichtung fuer eine supraleitende, kurzzuschliessende Magnetspule mit einer Trennvorrichtung pro Spulenende, die ein ortsfestes, gekuehltes Kontaktteil und ein bewegliches, mit einer Stromversorgungseinrichtung verbundenes Kontaktteil sowie eine mechanische Betaetigungsvorrichtung zum Aneinanderfuegen bzw. Trennen der Kontaktteile enthaelt. Beim Aneinanderfuegen des erwaermten Kontaktteils an das gekuehlte Kontaktteil koennen jedoch verhaeltnismaessig grosse Waermemengen auf das gekuehlte Kontaktteil und somit auf das mit ihm verbundene supraleitende Spulenende uebertragen werden und dort Normalleitung hervorrufen. Die Erfindung sieht deshalb vor, dass das Massenverhaeltnis von gekuehltem Kontaktteil zu beweglichem Kontaktteil mindestens 5:1, vorzugsweise mindestens 10:1 betraegt und dass das gekuehlte Kontaktteil an seinem dem Kontaktbereich abgewandten Ende mit Mitteln zur Oberflaechenvergroesserung wie beispielsweise Waermewiderstand zwischen dem Kontaktbereich und dem Spulenende pro 1000 A zu uebertragenden Strom von mindestens 0,2 K/W, vorzugsweise mindestens 0,5 K/W hat. (orig.)
[en] We measure the thermal conductance of GaAs pillars that are only a few nanometers long. Our observations can be understood with a simple model, in which the pillars constitute thermal point contacts between 3D phonon reservoirs. Moreover, first measurements of the electronic transport through these pillars are presented