Development of Transparent Diamond Plates Synthesis Apparatus by magnetic field assisted Arc Discharge Plasma Jet

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Diamond films were synthesized by are discharge plasma jet CVD that is suitable for high rate synthesis. However, this method has drawbacks such as distributions of thickness and quality occurs in diamond plates. Thus, a newly type of an apparatus were designed and developed in order to control the plasma state by magnetic field. This apparatus were prepared an electromagnet movable along the axs of the plasma torch and a plasma jet. As a result of application of magnetic field to an arc and a plasma jet generated with methane, hydrogen and argon gases, the diameter of a plasma jet increases, and the distributions of the substrate temperature and the thickness and quality are improved in the range of 7-8 mm in diameter.The deposition conditions were also discussed for synthesizing transparent diamond plates. Diamond films that have high transmittance are obtained at lower methane concentration of 1% independently of nucleation density. Transmittance of the diamond plates that were polished with diamond wheel was measured with FTIR and was approximately 68% at the wavelength of 10 mum. This transparent diamond film was found to have random orientation by X-ray diffraction analysis and less defects and impurities by the observation of the structure of its cross section. Since it takes long time to synthesize thick transparent diamond films under the determined deposition conditions, CVD apparatuses need to generate a stable and long-life time plasma jet.