Plasma Nozzle Array for Providing Uniform Scalable Microwave Plasma Generation

Abstract

The present invention provides microwave plasma nozzle array systems ( 10, 70, 230 , and 310 ) and methods for configuring microwave plasma nozzle arrays ( 37, 99 , and 337 ). The microwaves are transmitted to a microwave cavity ( 323 ) in a specific manner and form an interference pattern ( 66 ) that includes high-energy regions ( 69 ) within the microwave cavity ( 32 ). The high-energy regions ( 69 ) are controlled by the phases and the wavelengths of the microwaves. A plurality of nozzle elements ( 36 ) is provided in the array ( 37 ). Each of the nozzle elements ( 36 ) has a portion ( 116 ) partially disposed in the microwave cavity ( 32 ) and receives a gas for passing therethrough. The nozzle elements ( 36 ) receive microwave energy from one of the high-energy regions ( 69 ). Each of the nozzle elements ( 36 ) includes a rod-shaped conductor ( 114 ) having a tip ( 117 ) that focuses on the microwaves and a plasma ( 38 ) is then generated using the received gas.

1 . A method for configuring a microwave plasma nozzle array, comprising the steps of: 
 directing microwaves into a microwave cavity in opposing directions such that the microwaves interfere and form a standing microwave pattern that is stationary within the microwave cavity;    adjusting a phase of at least one of the microwaves to control high-energy regions generated by the standing microwave pattern; and    disposing a nozzle array at least partially in the microwave cavity so that one or more nozzle elements of the nozzle array are configured to receive microwave energy from a corresponding one of the high-energy regions.    
     
     
         2 . A method as defined in  claim 1 , wherein said step of directing microwaves includes the steps of: 
 transmitting microwaves to the microwave cavity; and    reflecting microwaves using a sliding short circuit operatively connected to the microwave cavity.    
     
     
         3 . A method as defined in  claim 1 , wherein said step of directing microwaves includes the step of: 
 transmitting microwaves generated by two microwave power heads to the microwave cavity.    
     
     
         4 . A method for configuring a microwave plasma nozzle array, comprising the steps of: 
 directing a first pair of microwaves into a microwave cavity in opposing directions along a first axis;    directing a second pair of microwaves into the microwave cavity in opposing directions along a second axis, the first axis being normal to the second axis such that the first and the second pairs of microwaves interfere and form high-energy regions that are stationary within the microwave cavity;    adjusting a phase of at least one of the microwaves to control the high-energy regions; and    disposing a nozzle array at least partially in the microwave cavity so that one or more nozzle elements of the nozzle array are configured to receive microwave energy from a corresponding one of the high-energy regions.    
     
     
         5 . A method as defined in  claim 4 , wherein said step of directing the first pair of microwaves includes the steps of: 
 transmitting microwaves to the microwave cavity; and    reflecting microwaves using a sliding short circuit operatively connected the microwave cavity.    
     
     
         6 . A method as defined in  claim 4 , wherein said step of directing the first pair of microwaves includes the step of: 
 transmitting microwaves generated by two microwave power heads to the microwave cavity.    
     
     
         7 . A method as defined in  claim 4 , further comprising the steps of: 
 generating the microwaves by a microwave power head; and    providing a power splitter connected to the microwave power head.    
     
     
         8 . A method as defined in  claim 4 , wherein said step of adjusting a phase of at least one of the microwaves includes adjusting phases of the first pair of microwaves.  
     
     
         9 . A method as defined in  claim 4 , wherein said step of adjusting a phase of at least one of the microwaves includes adjusting phases of the second pair of microwaves.  
     
     
         10 . A method as defined in  claim 4 , wherein said step of adjusting a phase of at least one of the microwaves includes adjusting phases of both the first pair and the second pair of microwaves.  
     
     
         11 . A microwave plasma nozzle array unit, comprising: 
 a microwave cavity; and    an array of nozzles, each of said nozzles including: 
 a gas flow tube adapted to direct a gas flow therethrough and having an inlet portion and an outlet portion; and  
 a rod-shaped conductor axially disposed in said gas flow tube, said rod-shaped conductor having a portion disposed in said microwave cavity to receive microwaves and a tip positioned adjacent said outlet portion.  
   
     
     
         12 . A microwave plasma nozzle array unit as defined in  claim 11 , wherein each of said nozzles further includes: 
 a vortex guide disposed between said rod-shaped conductor and said gas flow tube, said vortex guide having at least one passage for imparting a helical shaped flow direction around said rod-shaped conductor to a gas passing along said at least one passage.    
     
     
         13 . A microwave plasma nozzle array unit as defined in  claim 12 , wherein said microwave cavity includes a wall, said wall of said microwave cavity forming a portion of a gas flow passage operatively connected to the inlet portion of said gas flow tube.  
     
     
         14 . A microwave plasma nozzle array unit as defined in  claim 11 , wherein each of said nozzles further includes: 
 a shield disposed adjacent to a portion of said gas flow tube for reducing a microwave power loss through said gas flow tube, said shield being made of a conducting material.    
     
     
         15 . A microwave plasma nozzle array unit as defined in  claim 11 , wherein each of said nozzles further includes: 
 a grounded shield disposed on an exterior surface of said gas flow tube for reducing a microwave power loss through said gas flow tube, said grounded shield having a hole for receiving the gas flow therethrough.    
     
     
         16 . A microwave plasma nozzle array unit as defined in  claim 15 , wherein each of said nozzles further includes: 
 a position holder disposed between said rod-shaped conductor and said grounded shield for securely holding said rod-shaped conductor relative to said grounded shield.    
     
     
         17 . A microwave plasma nozzle array unit as defined in  claim 11 , wherein said gas flow tube is made of quartz.  
     
     
         18 . A microwave plasma nozzle array unit as defined in  claim 11 , wherein each of said nozzles further includes a pair of magnets disposed adjacent to said gas flow tube, said pair of magnets having a shape approximating a portion of a cylinder.  
     
     
         19 . A microwave plasma nozzle array unit as defined in  claim 11 , wherein each of said nozzles further includes: 
 an anode disposed adjacent to a portion of said gas flow tube; and    a cathode disposed adjacent to another portion of said gas flow tube.    
     
     
         20 . A microwave plasma nozzle array unit as defined in  claim 11 , wherein said microwave cavity includes: 
 a microwave inlet; and    a sliding short circuit configured to reflect microwaves transmitted through said microwave inlet.    
     
     
         21 . A microwave plasma nozzle array unit as defined in  claim 11 , wherein said microwave cavity includes: 
 two microwave inlets disposed in opposite sides of said microwave cavity.    
     
     
         22 . A microwave plasma nozzle array unit as defined in  claim 11 , wherein said microwave cavity includes: 
 two microwave inlets disposed in sides of said microwave cavity which are non-nal to each other; and    two sliding short circuits configured to reflect microwaves received by said inlets.    
     
     
         23 . A microwave plasma nozzle array unit as defined in  claim 11 , wherein said microwave cavity includes: 
 a first pair of microwave inlets disposed in opposite sides of said microwave cavity along a first axis;    a second pair of microwave inlets disposed in opposite sides of said microwave cavity along a second axis, the second axis being substantially normal to the first axis.    
     
     
         24 . A microwave plasma nozzle array unit as defined in  claim 11 , wherein said microwave cavity is configured to generate a plurality of stationary high-energy regions using microwaves directed thereto and wherein said portion of said rod-shaped conductor is disposed within the space occupied by said stationary high-energy regions.  
     
     
         25 . A microwave plasma system, comprising: 
 a microwave source;    a pair of isolators operatively connected to said microwave source;    a microwave cavity having a pair of inlets;    a pair of waveguides, each of said waveguides being operatively connected to a corresponding one of said isolators and to a corresponding one of said inlets of said microwave cavity; and    a pair of non-rotating phase shifters, each of said non-rotating phase shifters being operatively connected to a corresponding one of said waveguides and to a corresponding one of said isolators; and    an array of nozzles, each of said nozzles including: 
 a gas flow tube adapted to direct a gas flow therethrough and having an inlet portion and an outlet portion; and  
 a rod-shaped conductor axially disposed in said gas flow tube, said rod-shaped conductor having a portion disposed in said microwave cavity to receive microwaves and a tip positioned adjacent said outlet portion.  
   
     
     
         26 . A microwave plasma system as defined in  claim 25 , wherein each of said nozzles further includes: 
 a vortex guide disposed between said rod-shaped conductor and said gas flow tube, said vortex guide having at least one passage for imparting a helical shaped flow direction around said rod-shaped conductor to a gas passing along said at least one passage.    
     
     
         27 . A microwave plasma system as defined in  claim 26 , wherein said microwave cavity includes a wall, said wall of said microwave cavity forming a portion of a gas flow passage operatively connected to the inlet portion of said gas flow tube.  
     
     
         28 . A microwave plasma system as defined in  claim 25 , wherein each of said nozzles further includes: 
 a shield disposed adjacent to a portion of said gas flow tube for reducing a microwave power loss through said gas flow tube, said shield being made of a conducting material.    
     
     
         29 . A microwave plasma system as defined in  claim 25 , wherein each of said nozzles further includes: 
 a grounded shield disposed on an exterior surface of said gas flow tube for reducing a microwave power loss through said gas flow tube, said grounded shield having a hole for receiving the gas flow therethrough.    
     
     
         30 . A microwave plasma system as defined in  claim 29 , wherein each of said nozzles further includes: 
 a position holder disposed between said rod-shaped conductor and said grounded shield for securely holding said rod-shaped conductor relative to said grounded shield.    
     
     
         31 . A microwave plasma system as defined in  claim 25 , wherein said gas flow tube is made of quartz.  
     
     
         32 . A microwave plasma system as defined in  claim 25 , wherein each of said nozzles further includes a pair of magnets disposed adjacent to said gas flow tube, said pair of magnets having a shape approximating a portion of a cylinder.  
     
     
         33 . A microwave plasma system as defined in  claim 25 , wherein each of said nozzles further includes: 
 an anode disposed adjacent to a portion of said gas flow tube; and    a cathode disposed adjacent to another portion of said gas flow tube.    
     
     
         34 . A microwave plasma system as defined in  claim 25 , wherein said microwave cavity is configured to generate a plurality of stationary high-energy regions using microwaves directed thereto and wherein said portion of said rod-shaped conductor is disposed within the space occupied by said stationary high-energy regions.  
     
     
         35 . A microwave plasma system as defined in  claim 25 , wherein each of said isolators includes: 
 a circulator operatively connected to at least one of said waveguides; and    a dummy load operatively connected to said circulator.    
     
     
         36 . A microwave plasma system as defined in  claim 25 , further comprising: 
 a pair of tuners, each of said tuners being operatively connected to a corresponding one of said waveguides and said microwave cavity.    
     
     
         37 . A microwave plasma system as defined in  claim 25 , further comprising: 
 a pair of circulators, each of said circulators being operatively connected to a corresponding one of said waveguides and configured to direct microwaves to a corresponding one of said non-rotating phase shifters.    
     
     
         38 . A microwave plasma system as defined in  claim 25 , further comprising: 
 a pair of couplers, each of said couplers being operatively connected to a corresponding one of said waveguides and a power meter for measuring microwave fluxes.    
     
     
         39 . A microwave plasma system as defined in  claim 25 , wherein said microwave source includes a pair of microwave power heads, each of said microwave power heads being operatively connected to a corresponding one of said isolators.  
     
     
         40 . A microwave plasma system as defined in  claim 25 , wherein said microwave source includes: 
 a microwave power head for generating microwaves; and    a power splitter for receiving, bisecting and directing the microwaves to said isolators.    
     
     
         41 . A microwave plasma system, comprising: 
 a microwave source;    an isolator operatively connected to said microwave source;    a microwave cavity having an inlet;    a waveguide operatively connected to said isolator and to said inlet of said microwave cavity;    a non-rotating phase shifter operatively connected to said waveguide and said isolator;    a circulator operatively connected to said waveguide and configured to direct microwaves to said non-rotating phase shifter;    a sliding short circuit operatively connected to said microwave cavity; and    an array of nozzles, each of said nozzles including: 
 a gas flow tube adapted to direct a gas flow therethrough and having an inlet portion and an outlet portion; and  
 a rod-shaped conductor axially disposed in said gas flow tube, said rod-shaped conductor having a portion disposed in said microwave cavity to receive microwaves and a tip positioned adjacent said outlet portion.  
   
     
     
         42 . A microwave plasma system as defined in  claim 41 , wherein each of said nozzles further includes: 
 a vortex guide disposed between said rod-shaped conductor and said gas flow tube, said vortex guide having at least one passage for imparting a helical shaped flow direction around said rod-shaped conductor to a gas passing along said at least one passage.    
     
     
         43 . A microwave plasma system as defined in  claim 42 , wherein said microwave cavity includes a wall, said wall of said microwave cavity forming a portion of a gas flow passage operatively connected to the inlet portion of said gas flow tube.  
     
     
         44 . A microwave plasma system as defined in  claim 41 , wherein each of said nozzles further includes: 
 a shield disposed adjacent to a portion of said gas flow tube for reducing a microwave power loss through said gas flow tube, said shield being made of a conducting material.    
     
     
         45 . A microwave plasma system as defined in  claim 41 , wherein each of said nozzles further includes: 
 a grounded shield disposed on an exterior surface of said gas flow tube for reducing a microwave power loss through said gas flow tube, said grounded shield having a hole for receiving the gas flow therethrough.    
     
     
         46 . A microwave plasma system as defined in  claim 45 , wherein each of said nozzles further includes: 
 a position holder disposed between said rod-shaped conductor and said grounded shield for securely holding said rod-shaped conductor relative to said grounded shield.    
     
     
         47 . A microwave plasma system as defined in  claim 41 , wherein said gas flow tube is made of quartz.  
     
     
         48 . A microwave plasma system as defined in  claim 41 , wherein each of said nozzles further includes a pair of magnets disposed adjacent to said gas flow tube, said pair of magnets having a shape approximating a portion of a cylinder.  
     
     
         49 . A microwave plasma system as defined in  claim 41 , wherein each of said nozzles further includes: 
 an anode disposed adjacent to a portion of said gas flow tube; and    a cathode disposed adjacent to another portion of said gas flow tube.    
     
     
         50 . A microwave plasma system as defined in  claim 41 , wherein said microwave cavity is configured to generate a plurality of stationary high-energy regions using microwaves directed thereto and wherein said portion of said rod-shaped conductor is disposed within the space occupied by said stationary high-energy regions.  
     
     
         51 . A microwave plasma system as defined in  claim 41 , wherein said isolator includes: 
 a circulator operatively connected to said waveguide; and    a dummy load operatively connected to said circulator.    
     
     
         52 . A microwave plasma system as defined in  claim 41 , further comprising: 
 a tuner operatively connected to said waveguide and said microwave cavity.    
     
     
         53 . A microwave plasma system as defined in  claim 41 , further comprising: 
 a coupler operatively connected to said waveguide and a power meter for measuring microwave fluxes.    
     
     
         54 . A microwave plasma system, comprising: 
 a microwave source;    a pair of isolators operatively connected to said microwave source;    a microwave cavity having a pair of inlets;    a pair of waveguides, each of said waveguides being operatively connected to a corresponding one of said isolators and to a corresponding one of said inlets of said microwave cavity;    a pair of non-rotating phase shifters, each of said non-rotating phase shifters being operatively connected to a corresponding one of said waveguides and to a corresponding one of said isolators;    a pair of sliding short circuits, each of said sliding short circuits being operatively connected to said microwave cavity; and    an array of nozzles, each of said nozzles including: 
 a gas flow tube adapted to direct a gas flow therethrough and having an inlet portion and an outlet portion; and  
 a rod-shaped conductor axially disposed in said gas flow tube, said rod-shaped conductor having a portion disposed in said microwave cavity to receive microwaves and a tip positioned adjacent said outlet portion.  
   
     
     
         55 . A microwave plasma system as defined in  claim 54 , wherein each of said nozzles further includes: 
 a vortex guide disposed between said rod-shaped conductor and said gas flow tube, said vortex guide having at least one passage for imparting a helical shaped flow direction around said rod-shaped conductor to a gas passing along said at least one passage.    
     
     
         56 . A microwave plasma system as defined in  claim 55 , wherein said microwave cavity includes a wall, said wall of said microwave cavity forming a portion of a gas flow passage operatively connected to the inlet portion of said gas flow tube.  
     
     
         57 . A microwave plasma system as defined in  claim 54 , wherein each of said nozzles further includes: 
 a shield disposed adjacent to a portion of said gas flow tube for reducing a microwave power loss through said gas flow tube, said shield being made of a conducting material.    
     
     
         58 . A microwave plasma system as defined in  claim 54 , wherein each of said nozzles further includes: 
 a grounded shield disposed on an exterior surface of said gas flow tube for reducing a microwave power loss through said gas flow tube, said grounded shield having a hole for receiving the gas flow therethrough.    
     
     
         59 . A microwave plasma system as defined in  claim 58 , wherein each of said nozzles further includes: 
 a position holder disposed between said rod-shaped conductor and said grounded shield for securely holding said rod-shaped conductor relative to said grounded shield.    
     
     
         60 . A microwave plasma system as defined in  claim 54 , wherein said gas flow tube is made of quartz.  
     
     
         61 . A microwave plasma system as defined in  claim 54 , wherein each of said nozzles further includes a pair of magnets disposed adjacent to said gas flow tube, said pair of magnets having a shape approximating a portion of a cylinder.  
     
     
         62 . A microwave plasma system as defined in  claim 54 , wherein each of said nozzles further includes: 
 an anode disposed adjacent to a portion of said gas flow tube; and    a cathode disposed adjacent to another portion of said gas flow tube.    
     
     
         63 . A microwave plasma system as defined in  claim 54 , wherein said microwave cavity is configured to generate a plurality of stationary high-energy regions using microwaves directed thereto and wherein said portion of said rod-shaped conductor is disposed within the space occupied by said stationary high-energy regions.  
     
     
         64 . A microwave plasma system as defined in  claim 54 , wherein each of said isolators includes: 
 a circulator operatively connected to at least one of said waveguides; and    a dummy load operatively connected to said circulator.    
     
     
         65 . A microwave plasma system as defined in  claim 54 , further comprising: 
 a pair of tuners, each of said tuners being operatively connected to a corresponding one of said waveguides and said microwave cavity.    
     
     
         66 . A microwave plasma system as defined in  claim 54 , further comprising: 
 a pair of couplers, each of said couplers being operatively connected to a corresponding one of said waveguides and a power meter for measuring microwave fluxes.    
     
     
         67 . A microwave plasma system as defined in  claim 54 , further comprising: 
 a pair of circulators, each of said circulators being operatively connected to a corresponding one of said waveguides and configured to direct microwaves to a corresponding one of said non-rotating phase shifters.    
     
     
         68 . A microwave plasma system, comprising: 
 a microwave source;    a microwave cavity having four inlets;    four waveguides, each of said waveguides being operatively connected to a corresponding one of said inlets of said microwave cavity and said microwave source;    four non-rotating phase shifters, each of said non-rotating phase shifters being operatively connected to a corresponding one of said waveguides and said microwave source;    four circulators, each of said circulators being operatively connected to a corresponding one of said waveguides and configured to direct microwaves generated by said microwave source to at least one of said non-rotating phase shifters; and    an array of nozzles, each of said nozzles including: 
 a gas flow tube adapted to direct a gas flow therethrough and having an inlet portion and an outlet portion; and  
 a rod-shaped conductor axially disposed in said gas flow tube, said rod-shaped conductor having a portion disposed in said microwave cavity to receive microwaves and a tip positioned adjacent said outlet portion.  
   
     
     
         69 . A microwave plasma system as defined in  claim 68 , wherein each of said nozzles further includes: 
 a vortex guide disposed between said rod-shaped conductor and said gas flow tube, said vortex guide having at least one passage for imparting a helical shaped flow direction around said rod-shaped conductor to a gas passing along said at least one passage.    
     
     
         70 . A microwave plasma system as defined in  claim 69 , wherein said microwave cavity includes a wall, said wall of said microwave cavity forming a portion of a gas flow passage operatively connected to the inlet portion of said gas flow tube.  
     
     
         71 . A microwave plasma system as defined in  claim 68 , wherein each of said nozzles further includes: 
 a shield disposed adjacent to a portion of said gas flow tube for reducing a microwave power loss through said gas flow tube, said shield being made of a conducting material.    
     
     
         72 . A microwave plasma system as defined in  claim 68 , wherein each of said nozzles further includes: 
 a grounded shield disposed on an exterior surface of said gas flow tube for reducing a microwave power loss through said gas flow tube, said grounded shield having a hole for receiving the gas flow therethrough.    
     
     
         73 . A microwave plasma system as defined in  claim 72 , wherein each of said nozzles further includes: 
 a position holder disposed between said rod-shaped conductor and said grounded shield for securely holding said rod-shaped conductor relative to said grounded shield.    
     
     
         74 . A microwave plasma system as defined in  claim 68 , wherein said gas flow tube is made of quartz.  
     
     
         75 . A microwave plasma system as defined in  claim 68 , wherein each of said nozzles further includes a pair of magnets disposed adjacent to said gas flow tube, said pair of magnets having a shape approximating a portion of a cylinder.  
     
     
         76 . A microwave plasma system as defined in  claim 68 , wherein each of said nozzles further includes: 
 an anode disposed adjacent to a portion of said gas flow tube; and    a cathode disposed adjacent to another portion of said gas flow tube.    
     
     
         77 . A microwave plasma system as defined in  claim 68 , wherein said microwave cavity is configured to generate a plurality of stationary high-energy regions using microwaves directed thereto and wherein said portion of said rod-shaped conductor is disposed within the space occupied by said stationary high-energy regions.  
     
     
         78 . A microwave plasma system as defined in  claim 68 , wherein said microwave source includes: 
 four microwave power heads; and    four isolators, each of said isolators being operatively connected to a corresponding one of said microwave power heads and to at least one of said waveguides, each of said isolators including:    a circulator operatively connected to said waveguide; and    a dummy load operatively connected to said circulator.    
     
     
         79 . A microwave plasma system as defined in  claim 68 , wherein said microwave source includes: 
 two microwave power heads;    two isolators, each of said isolators being connected to a corresponding one of said microwave power heads, each of said isolators including: 
 a circulator operatively connected to said waveguide; and  
 a dummy load operatively connected to said circulator; and  
   two power splitters, each of said power splitters being operatively connected to a corresponding one of said isolators, each of said power splitters being configured for receiving, bisecting and directing the microwaves to a corresponding two of said waveguides.    
     
     
         80 . A microwave plasma system as defined in  claim 68 , wherein said microwave source includes: 
 a microwave power head;    an isolator operatively connected to said microwave power head, said isolator including: 
 a circulator operatively connected to said waveguide; and  
 a dummy load operatively connected to said circulator; and  
   a power splitter connected to said isolator, said power splitter being configured to receive, split and direct the microwaves to a corresponding one of said waveguides.    
     
     
         81 . A microwave plasma system as defined in  claim 68 , further comprising: 
 four tuners, each of said tuners being operatively connected to a corresponding one of said waveguides and said microwave cavity.    
     
     
         82 . A microwave plasma system as defined in  claim 68 , further comprising: 
 four couplers, each of said couplers being operatively connected to a corresponding one of said waveguides and a power meter for measuring microwave fluxes.