Electric lamp and discharge devices: systems – Discharge device load with fluent material supply to the... – Plasma generating
Patent
1998-07-30
2000-09-05
Bettendorf, Justin P.
Electric lamp and discharge devices: systems
Discharge device load with fluent material supply to the...
Plasma generating
31511171, 118723MW, 118723AN, 156345, H05H 146
Patent
active
061148113
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to an electromagnetic radio-frequency or microwave device having a treatment chamber with a transmission wall, which is permeable for the electromagnetic waves, to an adjacent chamber and with a design of the transmission chamber for influencing the intensity distribution of the transmission of the electromagnetic waves into the treatment chamber.
BACKGROUND OF THE INVENTION
It is known for the intensity distribution of microwaves which are transmitted through a transmission wall from a chamber into a treatment chamber to be influenced by a special design of the transmission wall. DE 94 05 808 U discloses a plasma processing device in which a plasma is produced in a treatment chamber by means of microwaves that are introduced, for example for surface processing of objects which are introduced into the treatment chamber. In this case, the microwaves are produced in a rectangular hollow waveguide of elongated design, and are output at the side via a waveguide which projects into the hollow waveguide. In this case, the waveguide is designed in the form of a disk and forms a boundary wall for the treatment chamber. In order to introduce the microwave energy uniformly into the treatment chamber, a screen of conductive material is located between the waveguide and the treatment chamber, which screen is designed as a perforated metal sheet, the size of the through-holes increasing as the distance from the hollow waveguide increases, in order in this way to make it possible to compensate for the decrease in the microwave energy as the distance from the hollow waveguide increases.
The use of such a screen as a transmission wall of the treatment chamber leads, however, to a considerable reduction in the microwave energy introduced into the treatment chamber. The introduction of energy into the treatment chamber is thus made uniform at the expense of a considerable reduction in the microwave energy.
It is furthermore known for it to be possible to produce a plasma in a treatment chamber by radio-frequency excitation as well.
SUMMARY OF THE INVENTION
The invention is thus based on the problem of designing an electromagnetic radio-frequency or microwave device of the type mentioned initially such that it is possible to transmit electromagnetic waves into the treatment chamber with a predetermined intensity profile or as uniformly as possible without as a consequence having to accept a considerable reduction in the transmitted electromagnetic energy.
Based on this problem, an electromagnetic radio-frequency or microwave device of the type mentioned initially is characterized in that the transmission wall has a large number of antenna elements which are directed at an angle to the wall plane of the adjacent chamber, are in the form of rods, and project centrally through through-openings which are bounded by electrically conductive material.
According to the invention, the excitation energy is injected from the adjacent chamber into the antenna elements and is emitted by them in the direction of the treatment chamber. Together with the through-openings which surround them and are composed of electrically conductive material, the antenna elements form a type of coaxial conductor. The electromagnetic energy transmitted via the antenna element into the treatment chamber can be adjusted by adjusting the coupling conditions of the antenna elements for the excitation energy in the adjacent chamber.
For the transmission of microwaves, this can be done in a simple manner by means of the length of the antenna elements, which projects out of the through-openings. The through-openings are in this case preferably designed as through-chambers which are connected directly, or with an intermediate space, to a plate, which is permeable for microwaves, of the transmission wall.
It is possible to design the length of the various antenna elements to be different over the surface of the transmission wall in order in this way, if necessary, to unify or produce a desired intensity profile ove
REFERENCES:
patent: 5149375 (1992-09-01), Matsuyama
patent: 5637150 (1997-06-01), Wartski et al.
patent: 5700326 (1997-12-01), Takatsu et al.
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