Plasma generator

The arrangement of any one of the preceding claims, wherein the secondary plasma source (25) is arranged for operation at a lower power than the primary plasma source (1).

The arrangement of any one of the preceding claims, wherein the first coil (4) of the primary plasma source (1) and the second coil (26) of the secondary plasma source (25) are RF coils arranged to operate at a radio frequency voltage.

The arrangement of any one of the preceding claims, further comprising a first power supply for supplying a first radio frequency voltage to the first coil (4) of the primary plasma source (1) and a second power supply for supplying a second radio frequency voltage to the second coil (26) of the secondary plasma source (25), and wherein the first voltage is higher than the second voltage.

The arrangement of any one of the preceding claims, wherein, in operation, the primary source (1) is arranged to operate with an input power level being not more than 50% higher than the input power level required to generate enough plasma in the primary source to stabilize the formation of plasma by the secondary plasma source (25).

The arrangement of any one of the preceding claims, wherein the secondary plasma source (25) is arranged for operation with a supply power which is too small to enable stable plasma generation without a supply of plasma from the primary plasma source (1).

The arrangement of any one of the preceding claims, further comprising an electrode (30, 32, 34) located near the outlet of the arrangement, wherein, in operation, the coil (4) of the primary plasma source (1) is capacitively coupled to the electrode via the plasma generated by the primary plasma source and/or the secondary plasma source.

The arrangement of any one of the preceding claims, further comprising a pressure regulator for regulating pressure in the primary source chamber, and wherein a flow or pressure restriction is provided between the primary and secondary source chambers.

The arrangement of any one of the preceding claims, wherein the arrangement is adapted for regulating the pressure in the secondary source chamber.

The arrangement of any one of the preceding claims, wherein the primary source chamber (15) is larger than the secondary source chamber (16).

The arrangement of any one of the preceding claims, wherein the secondary source chamber has a relatively small cross-sectional area in comparison with the primary source chamber.

The arrangement of any one of the preceding claims, wherein the primary source chamber has a diameter of 20 mm or more, and the secondary source chamber has a diameter of less than 20 mm.

The arrangement of any one of the preceding claims, wherein the secondary source chamber has an end section for directing plasma in a desired direction.

The arrangement of any one of the preceding claims, wherein the secondary source chamber is a tube.

The arrangement of any one of the preceding claims, wherein the secondary source chamber has a length longer than the primary source chamber in a direction of the flow of plasma from the primary source chamber.

The arrangement of any one of the preceding claims, wherein the secondary source chamber generates plasma at a position close to an outlet of the arrangement.

The arrangement of any one of the preceding claims, wherein the primary plasma source (1) is located further from the outlet (14) than the secondary plasma source (25).

The arrangement of any one of the preceding claims, wherein, in operation, at least a portion of the plasma generated by the primary plasma source (1) travels through the guiding body (11) to the secondary plasma source (25) to stabilize the formation of plasma by the secondary plasma source (25).

The arrangement of any one of the preceding claims, wherein the hollow guiding body (11) comprises a funnel section (10) located at the outlet of the primary plasma source (1) arranged for guiding plasma generated by primary plasma source into the guiding body.

The arrangement of any one of the preceding claims, wherein the guiding body (11) comprises a quartz material or has an inner surface comprising a quartz material.

The arrangement of any one of the preceding claims, wherein the guiding body (11) is in the form of a tube or duct.

The arrangement of any one of the preceding claims, wherein the guiding body (11) has a bend (13) or elbow (12) to direct plasma from the outlet (14) onto an area to be cleaned by the plasma.

The arrangement of any one of the preceding claims, wherein the primary plasma source (1) comprises a primary source chamber (15) in which the plasma may be formed, the arrangement further comprising an aperture plate (31) positioned between the primary source chamber and the guiding body (11) and the aperture plate having one or more apertures for permitting flow of the plasma from the primary source chamber into the guiding body.

The arrangement of any one of the preceding claims, further comprising an aperture plate (32) at or near the outlet (14) of the guiding body to confine at least a portion of the plasma in the guiding body from exiting through the outlet.

A method for generating a plasma, comprising flowing an input gas into a primary source chamber, energizing a first coil to form a primary plasma in the primary source chamber, flowing at least a portion of the primary plasma into a secondary source chamber, and generating a secondary plasma in the secondary source chamber.