Coaxial cavity type, radiofrequency wave, plasma generating apparatus

In a plasma generating apparatus including a plasma source employing a radio frequency, including UHF or microwave, wave coupler means which is metallic and in the shape of a hollow cavity and which is excited in one or more modes of resonance and optionally including a static magnetic field around the plasma which aids in coupling radiofrequency energy at electron cyclotron resonance and aids in confining ions in the plasma in an electrically insulated chamber means in the coupler means, and wherein the chamber means has a central longitudinal axis in common with the coupler means and is mounted in closely spaced and sealed relationship to an area of the coupler means with an opening from the chamber means at one end;

• gas supply means for providing a gas which is ionized to form the plasma in the chamber means, wherein the radio frequency wave applied to the coupler means creates and maintains the plasma around the central longitudinal axis in the chamber means;
• movable metal plate means in the cavity mounted in the coupler means perpendicular to the central longitudinal axis and movable along the central longitudinal axis towards and away from the chamber means;
• and a movable probe means connected to and extending inside the coupler means for coupling the radio frequency waves to the coupler means, the improvement which comprises:
• (a) probe means which is elongate mounted in the coupler means in line with the central longitudinal axis of the chamber means and coupler means with an end of the probe in spaced relationship to the chamber means;
• (b) plate means having an opening in line with the central longitudinal axis of the chamber means which supports the probe means so that the probe means can be moved in the opening in the plate means along the central longitudinal axis;
• (c) a co-axial conductor means mounted along the longitudinal axis of the cavity such that a distal end of the conductor means is adjacent to a closed end of the chamber means opposite the opening from the chamber means;
• (d) support means for the probe means mounted on an outside portion of the coupler means including adjustable holding means which allows movement of the probe means in line with the central longitudinal axis of the chamber means so as to vary the spacing means between the chamber means and the end of the probe means;
• and
• (e) rod means adjustably mounted on the support means and connected to the plate means so as to allow the plate means to be moved towards and away from the chamber means, wherein movement of the plate means and the probe means in the coupler mean achieves a selected mode of resonance and varies the resonance of the mode of the radiofrequency wave in the chamber means.