Zaheer Abbas Gilani

Improvement of Solar Cell Performance After Oxygen Removal by Electron Beam Melting

Two 450 kg multicrystalline silicon ingots were obtained by mixing and melting high purity silicon and silicon from the edges and the bottom of the casted ingots together in a casting furnace. For one of the ingot, the silicon from casted ingots was refined in an electron beam melting furnace to remove oxygen. The oxygen content was reduced from 10 to less than 0.0517 ppmw when silicon was refined at 500 kW with removal efficiency up to 99.429% in the most areas. The life time of the ingot after oxygen removal was measured to be far better than another one, whereas in the central parts the value was almost 6.7 µs. The efficiencies of both solar cells were initially 17.55% but after 4 h decreased to 17.05% and 15.55%, respectively. The solar cell after oxygen removal shows a better performance in degradation.

Removal of SiC from Silicon After Electron Beam Melting Technique on Industrial Scale

Carbon and their compounds were removed successfully through electron beam melting (EBM), so that those areas (contaminated with carbon) of ingot were recycled and reused. During EBM process, the numerical simulation results show that there is great temperature gradient existing in the melt. During EBM, the melt near copper crucible shows low temperature and bad fluidity. Carbon in silicon melt flows, precipitated and gathered in this area so that it is separated. The flow mechanism of SiC in silicon melt was investigated. After EBM, carbon enriches in the form of SiC at the bottom of the ingot but not in the center. This technology is applied on industrial scale EBM equipment. The results show that a majority of SiC was deposited in the bottom of the refining crucible and the carbon contaminations are not found in the most of the area of the solidified ingot in crucible.

Intensity modulated radiation therapy: A review of current practice and future outlooks

Abstract Intensity Modulated Radiotherapy (IMRT) is a modern type of external beam radiotherapy that conforms high radiation dose to the target with minimum dose to the organs at risk (OARs), making it an embellishment of every developed institution. The earlier publications didnt have much proofs of the clinical superiority of IMRT over other radiotherapy techniques. It was considered a complicated and expensive treatment technique but the advent of modern treatment and imaging modalities have made its rapid clinical implementation unquestionable. Now IMRT have grown up, it is not the technique in which non uniform beam intensities were generated just by metal compensators, now it has multileaf collimators (MLCs), rotational fan and cone beam delivery systems and robotic arm linear accelerators to cure the life threatening cancer diseases. IMRT with all its advances have some limitations including its high cost, increased staff work, increased time for its planning, and risks of marginal misses.