Wang Chenglong

Design and analysis of a CPC with single vacuum tube for linear Fresnel reflector system

Compound parabolic collector (CPC) plays an important role in optical efficiency of linear Fresnel reflector (LFR) system. In this paper, we designed and optimized a CPC for LFR system. The main element influence on optical performance of CPC was studied, and the maximum acceptance angle and the truncation ratio of CPC were principally reported. Simulation results of the relationship between maximum acceptance angle and convergence ratio show that CPC convergence ratio increased slowly and linearly with the increase of maximum acceptance angle. Experimental results of the relationship between truncation ratio and convergence ratio show that CPC convergence ratio increased sharply until truncation ratio is greater than 0.65. CPC convergence ratio basically achieves a certain value when truncation ratio is greater than 0.7. Ray tracing simulation study illustrated that CPC, with 45° maximum acceptance angle, 0.75 truncation ratio and 475.49 mm opening width, could achieve a high concentrate ratio about 80.1%. Meanwhile, this conclusion was further verified by the experimental measurement results.

Low-Temperature (< 100°C) Poly-Si Thin Film Fabrication on Glass

Polycrystalline silicon (poly-Si) thin-film is fabricated on Al-coated planar glass substrates at the temperature below 100 °C, using aluminium-induced crystallized (AIC) amorphous silicon (a-Si) deposited by dc-magnetron sputtering under an electric field. The properties of NA poly-Si films (AIC of dc-magnetron sputtered silicon non-annealing) are characterized by Raman spectroscopy and x-ray diffraction (XRD) spectroscopy. A narrow and symmetrical Raman peak at a wave number of about 521 cm−1 is observed for samples, showing that the films are fully crystallized. XRD spectra reveal that the films are preferentially (111) oriented. Furthermore, the XRD spectrum of the sample prepared without electric field does not show any XRD peaks for poly-Si, which only appears at about 38° for Al (111) orientation. It is indicated that the electric field plays an important role in crystallization of poly-Si during the dc-magnetron sputtering. Thus, high quality poly-Si film can be obtained at low temperature and separate post-deposition step of AIC of a-silicon can be avoided.