Research on Electromagnetic Field, Eddy Current Loss and Heat Transfer in the End Region of Synchronous Condenser with Different End Structures and Material Properties

Aiming at the problem of end structure heating caused by the excessive eddy current loss of large synchronous condensers used in ultra-high voltage (UHV) power transmission, combined with the actual operation characteristics of the synchronous condenser, a three-dimensional transient electromagnetic field physical model is established, and three schemes for adjusting the end structure of the condenser under rated condition are researched. The original structure has a copper shield and a steel clamping plate. Scheme 1 has no copper shield but has a steel clamping plate. Scheme 2 has no copper shield but has an aluminum clamping plate. By constructing a three-dimensional fluid–solid coupling heat transfer model in the end of the synchronous condenser, and giving the basic assumptions and boundary conditions, the eddy current loss of the structure calculated by the three schemes is applied to the end region of the synchronous condenser as the heat source, and the velocity distribution of the cooling medium and the temperature distribution of each structure under the three different schemes are obtained. In order to verify the rationality of the numerical analysis model and the effectiveness of the calculation method, the temperature of the inner edge of the copper shield in the end of the synchronous condenser is measured, and the temperature calculation results are consistent with the temperature measurement results, which provides a theoretical basis for the electromagnetic design, structural optimization, ventilation and cooling of the synchronous condenser.

Numerical modeling of impacts of twisted-pair data cables

Data wire cable runs are a significant presence on the exterior of the International Space Station (ISS), and continued ISS mission support requires detailed assessment of cables due to micrometeoroid and orbit debris (MMOD) impact. These data wire cables are twisted-pair cables consisting of two 22 gauge stranded conductors inside a tight-fitting, braided-copper shield and jacket having a nominal outer diameter of 3.76 mm. Previous work has documented a total of 97 impact experiments that were performed into these cables to develop an empirical, statistical model for the failure of these cables in reliability studies; however, the experimental work left open the internal behaviors that contribute to the probabilistic findings. To address this shortcoming, numerical impact simulations have been performed to expand the understanding of the acquired dataset. This paper summarizes the dependence of impact location and speed to the penetration of wire jackets based upon particle size and provides an empirical ballistic limit equation based on the assumption that exposed conductors may lead to a short circuit. This work is consolidated with the previous experimental work for design and reliability assessments to cover projectile types, speeds and obliquities.

Energy composition of high-energy neutral beams on the COMPASS tokamak

The COMPASS tokamak is equipped with two identical neutral beam injectors (NBI) for additional plasma heating. They provide a beam of deuterium atoms with a power of up to ~(2 × 300) kW. We show that the neutral beam is not monoenergetic but contains several energy components. An accurate knowledge of the neutral beam power in each individual energy component is essential for a detailed description of the beam- -plasma interaction and better understanding of the NBI heating processes in the COMPASS tokamak. This paper describes the determination of individual energy components in the neutral beam from intensities of the Doppler-shifted Dα lines, which are measured by a high-resolution spectrometer viewing the neutral beam-line at the exit of NBI. Furthermore, the divergence of beamlets escaping single aperture of the last accelerating grid is deduced from the width of the Doppler-shifted lines. Recently, one of the NBI systems was modified by the removal of the Faraday copper shield from the ion source. The comparison of the beam composition and the beamlet divergence before and after this modification is also presented.

Near-Field Electromagnetic Shielding Effect of On-Chip Electroplated Copper Layers

An experimental investigation on the near field electromagnetic loss of thin copper layers has been presented for applications to multi-chip microsystems with on-chip electromagnetic protection. Copper layers in the thickness range of 0.2 μm∼200μm have been electroplated on the silicon substrates. A pair of microwave transceivers has been fabricated using the 3.5mm × 3.5mm nickel microloop antennas, electroformed on the silicon substrates. Electromagnetic radiation loss has been measured for the copper layers placed between the microloop transceivers, resulting in the electromagnetic shield effectiveness of 10dB∼40dB for the wave frequency range of 100MHz ∼ 1GHz. The 0.2μm-thick copper layer provides a shield loss of 20dB at the frequencies higher than 300MHz, whereas showing a predominant decrease of shield loss to 10dB level at lower frequencies. No substantial increase of the shield effectiveness has been found for the copper shield layers thicker than 2μm.