Improvements in equipment for the evaporation of subliming materials in reactive gas conditions

摘要

While materials which evaporate from the liquid phase present little difficulty in electron beam sources, those which sublime present unique problems. The electron beam tends to form a ole bin the sublimer which, once formed, no amount of beam steering can dislodge. A number of materials which have this problem are particularly useful for optical and industrial coatings and include silica, chromium and thermal barrier coatings such as yttria stabilized zirconia. An improved source is desicribed which will evaporate material continuously from a rod of sublmimer and avoids the formation of bored holes. A new rod height control is also described which will work for non-melting materials. The source also provides material more efficiently in terms of mass per kW power applied.