Stabilisation of plasma generation using electron beam evaporator for metals - focusing electron beam on evaporator material within housing and monitoring intensity of light emission above surface, to control power supply to electron gun

摘要

The housing (1) has an electron gun (2) coupled to a high voltage supply (3). The electron gun is controlled to provide a constant output power (4). The beam is focused on to the evaporator surface (5) and produces a high vapour pressure over the surface. Typically the evaporation material is aluminium oxide. A reaction gas is introduced through a side valve (7). Optical sensors (8) set above the surface measure the intensity of the emission in different zones. The sensor signals are processed (9) and compared with a reference with the output used to control the power supply (11). USE/ADVANTAGE - For surface treatment, e.g. in metallurgy, engineering, optics, and packaging and glass industries. Provides stabilised plasma generation at high vaporisation rates.