Microwave plasma generating devices and plasma torches

Abstract

The invention relates to a plasma generating device that comprises at least one very high frequency source (> 100 MHz) connected via an impedance adaptation device to an elongated conductor attached on a dielectric substrate, at least one means for cooling said conductor, and at least one gas supply in the vicinity of the dielectric substrate on a side opposite to that bearing the conductor. The invention also relates to plasma torches using said device.

Description

technical field [0001] The present invention relates to devices for generating plasma by coupling electromagnetic power into a gas. Such devices are also referred to as "plasma sources". The terms "plasma generating device" and "plasma source" are used interchangeably in this specification. Background technique [0002] In order for cold plasma surface treatment techniques to become popular, the equipment used to generate these plasmas by coupling electromagnetic power into a gas needs to be improved. These devices or "plasma sources" must be: [0003] - simple and cheap; [0004] - suitable for linear geometries and possibly non-planar geometries; and [0005] - Capable of 10 -2 Operates over a wide range of pressure levels from basic vacuum on the order of mbar to atmospheric pressure or even superatmospheric pressure. [0006] Furthermore, the efficiency with which the electromagnetic power from the generator is delivered to the plasma must be as high as possible, i...

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Problems solved by technology

[0017] - the coupling to the plasma is more precisely of the resonance type, which is best avoided since impedance matching is difficult to achieve and is generally an intolerable limitation in real practical application cases; and

[0018] - In such a configuration, there are not many ways of locating the plasma: the channel can be cut in the dielectric, or the ground plane can be placed at a distance from the lower surface of the dielectric, but in all cases the distance is is limited to a few mm (since, the stripline and the ground plane must be electrically "visible to each other"), which in practice will significantly limit the application of such a configuration

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