CreaTec - Model TUBO-e- Evaporators - Brochure

Instead of a wire filament, the TUBO sources uses a tubular filament that encloses the entire crucible. The heating current flows along the source axis, up through the heat insulation shields and down through the filament. For extremely high temperatures, the TUBO-e features an electron emission booster heater. In this version of the TUBO source, the crucible is held at a positive high voltage so that a fraction of the heater current provides electron beam heating of the crucible. The source geometry and electrical design are chosen in such a way that the electric emission booster passively follows the filament heater, providing additional heating power at high temperatures. Like this, no separete emission control loop is necessary and the single loop control with the full accuracy of the thermocouple temperature measurement is maintained.