As the efficiency of plasma formation processes and maintaining stable gas discharge are significantly connected with the value of the electric component of the electromagnetic field Еeff intensity in the discharge zone [4,5], microwave resonant type plasmatrons in which significant increase of electromagnetic wave field intensity is provided not by increasing the power of microwave energy source but by design solutions of microwave field formation system, turn to be of vital interest. The following technical design solutions with the use of resonant type devices are possible: partial filling of resonant volume with plasma, complete filling of resonant volume with plasma and a separation of resonant and reaction volumes with vacuum tight partition provided with the elements of electromagnetic connection [6].
Theoretically, the microwave resonant type devices with a characteristic size of discharge zone exceeding the length of a plasma generating electromagnetic wave are studied insufficiently. The information on systematic investigation of parameters , qualitative composition and properties of plasma at microwave discharges of more than 6000 сm3 volume in resonant type reaction-discharge chambers at low
pressure is not available in literature and technical solutions of resonant type devices require comprehensive investigation to develop and improve their design solutions, to develop engineering methods of calculating discharge blocks and to work out scientifically grounded recommendations on their use in various processes of vacuum-plasma treatment of materials.
Working at the processes of treatment of materials with microwave plasma the question of the penetration of microwave fields into the gas discharge zone is of great interest. This effect should be taken into consideration because of the following reasons:
1. microwave fields, in case of presence of high dielectric losses materials in plasma volume, can interact with them that results in the decrease of microwave power supplied into the discharge;
2. microwaves can re-reflect in plasma volume that leads to the change of discharge parameters;
3. microwave fields in this case can initiate plasma reactions on the surface of “ionized gas-solid body” junction.