| Abstract: |
Electromagnetic plasmadynamic systems are one of the most promising systems for a number of applications including thermal spraying. These systems are capable of accelerating powder particles in the velocity up to 2,5-3 103 m/s . Using these systems the unique coatings from B4C, and WC are formed. Such high particles velocity is not attainable by other spraying. But normally this systems operates only at low pressure of ambient gas (102- 103 Pa) and with low frequency of operation < 0,1 Hz which presents problems for application.
A new hybrid two-stage electromagnetic plasmadynamic system with the first stage in the form of a DC plasma torch with flow temperature ~ 2000 4000 at atmospheric pressure, and with the second stage in a form of a coaxial plasma accelerator has been devised . Plasma of DC torch fill the accelerated channel . A high-voltage impulse is applied to the accelerating gap situated in the beginning of the channel and representing its narrowest zone. As a result, a breakdown occurs, and a plasma current shell is formed and accelerated along the channel. In the area of the formation of the plasma current shell, the density of the DC-induced plasma is up to 0.1 atmosphere and the degree of ionization of DC-induced air plasma up to ~10-6 at 4000 K. Such conditions provide a symmetrical discharge. The results of investigations of such pulsed periodic plasma source are presented and results of its applications are discussed.
The maximum atmospheric plasma flow velocity may be as great as 3 5 103 m/s with the diameter up to 2 cm. Plasma brightness temperature ranges up to 1,5 103K. Frequencies up to 1-4 Hz are realized at energy of pulsed flow 4,5 kJ.
|
|
