Glow discharge electron guns with cold cathodes are used for welding, brazing, evaporation, melting of refractory metals, as well as other technological operations which are provided by electron beam in a soft vacuum or controlled gas medium. High voltage glow discharge with anode plasma maintained in pressure range of few Pa and accelerations voltages units-tens of kV is used in such guns for generation of electron beam. Cold cathode from metal is used there as an emitter of free electrons. Therefore, emission of electrons is a result of bombarding of cathode surface by the ions from anode plasma. Plasma have a near-anode potential, so discharge region can be considered as an electron-optical system with a transparent anode. According to wide range of operation voltage and pressure, glow discharge electron gun's power can be in range of from hundreds of watt to hundreds of kilowatt. Minimal diameter of electron beam in crossover can be less then 1 mm2, and so maximum power density - 106 W/cm2. Elaborated electron guns are completed by the electronic control systems.
Main advantages of guns are:
- simplicity of construction;
- high reliability of cold cathodes that operated in the soft vacuum;
- possibility of operation in medium of different gases, including active ones.
Main applications of electron guns today are:
- melting and refusion of titanium, zirconium, molybdenum, tantalum, silicon etc.
- obtaining of oxide, nitride, carbide, other ceramics, metals and polymetals films.
The technological equipment with glow discharge electron guns for welding, evaporation and melting is put into operation in different plants of Ukraine, Russia, Armenia, Germany, Japan, USA. One of elaborated electron gun with 100 kW power, operated in industry today, is presented on photograph.
Parameters of elaborated electron guns
No | Parameter | EH-30 | EH-60 | EH-100 |
1. | Maximal power, kW | 30 | 60 | 100 |
2. | Range of power regulation, kW | 0 – 30 | 0 – 60 | 0 – 100 |
3. | Acceleration voltage, kV | 30 | 30 | 30 |
4. | Maximal angle of beam deflection, degree | 200 | 200 | 200 |
5. | Operation gas | Technical hydrogen | ||
6. | Maximal gas expense, m3∙Pa/sec | 0.1 | 0.15 | 0.3 |
7. | Range of pressure in technological chamber, Pa | 1 – 10-2 | ||
8. | Expense of cooling water, m3/sec | 0.1 | 0.15∙10-3 | 0.3∙10-3 |
9. | Higher, mm | 450 | 450 | 500 |
10. | Weight, kg | 15 | 17 | 22 |
Contacts:
e-mail: imelnik
phbme.kpi.ua
phone: +38-066-981-70-66