Thermal vaporization sources resistively heated

Fig. 5. Thermal vaporization sources (a) hairpin (b) spiral (c) basket (d) boat and (e) canoe, which ate all resistively heated sources and (f) focused...

Figure 6.7 Resistively Heated Thermal Vaporization Source Configurations...

Vacuum Deposition. Vacuum deposition, sometimes called vacuum evaporation, is a PVD process in which the material is thermally vaporized from a source and reaches the substrate without coUision with gas molecules in the space between the source and substrate (1 3). The trajectory of the vaporized material is therefore line-of-sight. Typically, vacuum deposition takes place in the pressure range of 10 10 Pa (10 10 torr), depending on the level of contamination that can be tolerated in the resulting deposited film. Figure 3 depicts a simple vacuum deposition chamber using a resistively heated filament vaporization source. 

Because evaporation of a liquid phase usually requires addition of large amounts of thermal energy, the method of transferring this heat to the liquor tends to dominate evaporator capital cost. The source of heat for evaporators is usually a medium such as hot combustion gases or a condensing vapor, typically steam. Molten salts and electrical resistance heaters are less commonly used sources of thermal energy. 

Source fixturing involves making good electrical contact with the resistively heated vaporization source (wire, sheet, etc.). Thermal expansion requires that the fixture be somewhat flexible. If the fixture is rigid, the vaporization source can be stressed and break. If the source is flexible, as with a wire or coil, the source can distort, producing changes in the... 

This document is intended to provide a ready source of the thermal characteristics, availability, safety and other pertinent information for the selected types of insulation. The compilation covers all commonly used types of products whose primary purpose is to provide thermal resistance to heat flow through the building envelope. Due to the importance of controlling the migration of moisture to the insulating material, vapor barriers are also included. 

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