A NEW-TYPE OF DC ARC PLASMA TORCH FOR LOW-COST LARGE-AREA DIAMOND DEPOSITION

In the present paper, a new type of DC are plasma torch is disclosed. The principles of the new magnetic and fluid dynamic controlled large orifice long discharge tunnel plasma torch is discussed. Large area un iformity is achieved through the externally applied magnetic field whi ch stabilizes the are jet and the proper magnetic and fluid dynamic co ntrol which guarantees the dynamic mixing of gases before impinging on to the substrate. The 100 kW high power jet which is newly developed based on the experience of the low power model is equipped with a Phi 120 mm orifice torch, and is capable of depositing diamond films over a substrate area of Phi 110 mm at a growth rate as high as 40 mu m/h, and can be operated in gas recycling mode, which allows 95% of the gas es to be recycled. It is demonstrated that the new type DC plasma torc h can be easily scaled-up to an even higher power jet. It is estimated that even by the 100 kW jet, the cost for tool grade diamond films ca n be as low as less than $4/carat. (C) 1998 Elsevier Science S.A.