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The main objective of the study is focusing primarily on the acquisition of the V-I characteristic curve under applied magnetic field conditions through the design and implementation of cryogenic HTS measurements apparatus is discussed. In the conclusion the overall operation and output of the measurement apparatus appeared to meet the design goals and produced a vast amount of characteristics data that is useful for the development of power applications involving HTS tape technology.

Research was conducted to perform electrical measurements of alternating current losses at power frequencies through the use of a dual channel digital lock-in. A complete view of the loss behavior under direct current applied field was achieved with the application of a direct current magnetic field between 2 and 400 mT with a varying angle from parallel to perpendicular to the tape surface. The voltage was measured and average by means of a triangular input current. Calculations were repeated for the magnetic field and angle domain.

Research was conducted to examine AC transport losses in multifilamentary BSCCO-2223 silver sheathed tapes as a function of the applied external magnetic field and its direction in terms of the plane of the samples. AC transport current values and DC critical current angular characteristics were measured. Results illustrate that the magnetic field changes the transport losses only through the changing of the critical current of the superconductor.

Calculations of the dc voltage-current characteristics and the ac loss were conducted on Southwire Co cable no 7 in the original four-layer configuration and by sequentially stripping the outer layer to make a three-, two- and one-layer cable. Results illustrate that the four-layer cable carried the highest current. The electrical and calorimetric calculations were in agreement for the one-layer cable to within a factor of two.

Research was conducted to measure the transport current alternating current losses of different structures and different materials. Their dependence on the frequency and direct current background field was also examined. Results were compared with the Norris' elliptical and strip models. It was observed that there were discrepancies between the theoretical measurements and experimental data.

A simple circuit for direct current (dc) measurement using a transformer is proposed. The circuit is based on nonlinear effects in the transformer ferromagnetic core, and it provides information about the current magnitude and polarity. The circuit is analyzed applying piecewise-linear model of the core magnetization curve. An averaged-circuit model and the circuit transfer function are presented. Good linearity and wide measurement range are obtained. Design guides for reduction of the output voltage ripple are given. Measurement error within 0.25% of the full scale is achieved.

A direct-current current-voltage uses gate-controlled parasitic bipolar junction transistor of a metal-oxide-silicon field-effect transistor in a p/n junction isolation well to study the variations of the oxide and interface trap density. The process of interface and oxide traps on oxidized silicon is discussed. The technique is more effective and dependable than many of the traditional alternating current methods for finding fundamental kinetic rates and transistor degradation mechanism.

Standard semiconductor fabrication techniques help produce large arrays of silicon field emitters having good tip-to-tip uniformity and fair device yield. Application of gate electrode potentials below 250 V on the arrays leads to the generation of significant levels of total emitted current and current density. These devices show more than 99% efficiency and their performance indicates their applicability in RF and microwave amplifiers and other high intensity electron beam source applications.

A rigorous method of applying observability criteria to the estimation of winding currents in brushless dc drives is presented. Observability is related to both the drive's operating condition, both motoring and regenerating, and to the PWM switching strategy being employed. The precise conditions under which motor winding currents can be estimated from measurements of de link current are clearly defined. A modified single current sensor arrangement, in which switching device currents are measured, is shown to improve the observability of currents with complementary switching, but to have an adverse effect on observability with the basic switching strategy. An arrangement involving two current sensors allows discontinuous estimation of the winding currents for all operating conditions and both switching strategies. The primary advantage of this technique is that measurements by each sensor are made equally on all three phases of the motor.

A new algorithm for calculating HVDC corona based on Boundary Element Method (BEM) is presented. The new algorithm takes a different approach to the process of updating the space charge density during the iteration. The iteration process is convergent even for a uniform initial space charge distribution. It takes into account the effect of wind.

It has been proposed recently [1] that the lowest level of dc field, above which electrical degradation may occur, is associated with the formation of space charges in insulation. Therefore, inference of field levels above which space charge accumulates in a given material may provide fundamental information for material characterization and system design. Threshold field values were estimated through evidence of space charge accumulation derived from conduction current, space charge amplitude and electroluminescence (EL) counts vs. electrical field characteristics. Press-molded plates of polyethylene-based materials were used for this investigation. In order to be able to detect even by EL experiments the presence of the space charge accumulated at low fields, measurements were carded out during both polarization and short-circuit of specimens. It is shown that the threshold corresponding to the onset of EL upon grounding the specimen is close to the space charge accumulation threshold derived from space charge and conduction current measurements. This earlier value is considerably lower than the one previously detected from constant dc-voltage EL measurements, thus confirming that even at low fields and in the presence of voltage reversals or transients, space charges can trigger luminescence phenomena. The methodology developed in this paper enlarges the applicability of the EL technique to accommodate a wider electrical field range in view of insulation characterization.