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A compact matching network couples an RF power supply to an RF antenna in a plasma generator. The simple and compact impedance matching network matches the plasma load to the impedance of a coaxial transmission line and the output impedance of an RF amplifier at radio frequencies. The matching netwo

A compact matching network couples an RF power supply to an RF antenna in a plasma generator. The simple and compact impedance matching network matches the plasma load to the impedance of a coaxial transmission line and the output impedance of an RF amplifier at radio frequencies. The matching network is formed of a resonantly tuned circuit formed of a variable capacitor and an inductor in a series resonance configuration, and a ferrite core transformer coupled to the resonantly tuned circuit. This matching network is compact enough to fit in existing compact focused ion beam systems.

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The invention claimed is: 1. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising: a resonantly tunable circuit formed of a variable capacitor and inductor in a series resonance configuration; a ferrite core transformer, said resonantly tunable circu

The invention claimed is: 1. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising: a resonantly tunable circuit formed of a variable capacitor and inductor in a series resonance configuration; a ferrite core transformer, said resonantly tunable circuit being connected to one end of a winding of said ferrite core transformer and said RF antenna being connected to another end of the winding of said ferrite core transformer. 2. The matching network of claim 1 wherein the transformer comprises a secondary winding which couples the transformer to both the tunable circuit and RF antenna and a primary winding. 3. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising: a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration: a ferrite core transformer coupled to the resonantly tunable circuit, wherein a secondary winding of the transformer is a single-turn winding and a primary winding of the transformer is a multi-turn winding, the secondary winding is coupled to the tunable circuit. 4. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising: a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration; a ferrite core transformer having a single-turn secondary winding and a multi-turn primary winding, and the resonantly tunable circuit being connected to the secondary winding, wherein the transformer further comprises a core which is made of a plurality of ferrite cores. 5. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising: a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration; a ferrite core transformer having a secondary winding that couples the transformer to the resonantly tunable circuit, and also having a primary winding, wherein the transformer further comprises a core which is made of a plurality of ferrite cores. 6. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising: a resonantly tunable circuit formed of a variable capacitor and inductor in a series resonance configuration; and, a ferrite core transformer, said resonantly tunable circuit being connected to one end of a winding of said ferrite core transformer, the one end of a winding of said ferrite core transformer being a secondary winding that couples said ferrite core transformer to said resonantly tunable circuit and said ferrite core transformer also having a primary winding, wherein the turn ratio between the primary winding and the secondary winding ranges from 3:1 to 8:1. 7. The matching network of claim 6 wherein the turn ratio between the primary winding and the secondary winding is selected to transform the plasma impedance of the plasma generator to 50 Ω. 8. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising: a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration; a ferrite core transformer having a secondary winding that couples the transformer to the resonantly tunable circuit, and also having a primary winding, wherein the turn ratio between the primary winding and the secondary winding ranges from 3:1 to 8:1, and the transformer comprises a core made of 12 ferrite cores with a 1.25 inch OD and 0.75 inch ID, made of M-type ferrite. 9. The matching network of claim 8 wherein the variable capacitor has a capacity range of 5-125 pF. 10. The matching network of claim 9 wherein the network fits within a cylindrical volume 6 inches in diameter and 8 inches long. 11. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising: a resonantly tunable circuit formed of a variable capacitor and inductor in a series resonance configuration; a ferrite core transformer, said resonantly tunable circuit being connected to one end of a winding of said ferrite core transformer; and, an RF power supply connected through a 50 Ω coaxial cable to an input of the matching network and the RF antenna (inductive coil) connected to an output of the matching network. 12. A plasma ion or electron source, comprising: an RF power supply; a coaxial cable connected to the RE power supply; a matching network having an input connected to the coaxial cable, the matching network comprising; a resonantly tunable circuit formed of variable capacitor and an inductor in a series resonance configuration; a ferrite core transformer, said resonantly tunable circuit being connected to one end of a winding of said ferrite core transformer; an RF antenna connected to an output of the matching network; a plasma ion or electron generator having the RF antenna mounted therein for inductively generating a plasma. 13. The plasma ion or electron source of claim 12 wherein the transformer comprises a secondary winding which couples the transformer to the tunable circuit and a primary winding. 14. A plasma ion or electron source, comprising: an RF power supply; a coaxial cable connected to the RF power supply; a matching network having an input connected to the coaxial cable, the matching network comprising; a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration; a ferrite core transformer coupled to the resonantly tunable circuit; an RF antenna connected to an output of the matching network; and, a plasma ion or electron generator having the RF antenna mounted therein for inductively generating a plasma, wherein a secondary winding of the transformer is a single-turn winding and a primary winding of the transformer is a multi-turn winding, and the secondary winding couples the transformer to the resonantly tunable circuit. 15. A plasma ion or electron source, comprising: an RF power supply; a coaxial cable connected to the RF power supply; a matching network having an input connected to the coaxial cable, the matching network comprising: a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration; and, a ferrite core transformer having a single-turn secondary winding and a multi-turn primary winding, and the resonantly tunable circuit being connected to the secondary winding; wherein there is an RF antenna connected to an output of the matching network; and, a plasma ion or electron generator having the RF antenna mounted therein for inductively generating a plasma; and, wherein the transformer further comprises a core which is made of a plurality of ferrite cores. 16. The plasma ion or electron source of claim 14 wherein the turn ratio between the primary winding and the secondary winding ranges from 3:1 to 8:1. 17. The plasma ion or electron source of claim 14 wherein the coaxial cable has an impedance of 50 Ω and the turn ratio between the primary winding and the secondary winding is selected to transform the plasma impedance of the plasma generator to 50 Ω. 18. A plasma ion electron source comprising: an RF power supply; a coaxial cable connected to the RF power supply; a matching network having an input connected to the coaxial cable, the matching network comprising: a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration; and, a ferrite core transformer coupled to the resonantly tunable circuit, wherein there is an RF antenna connected to an output of the matching network; and, a plasma ion or electron generator having the RF antenna mounted therein for inductively generating a plasma; and, wherein the plasma ion or electron generator is a multicusp plasma generator. 19. The plasma ion or electron source of claim 18 wherein the source is a part of a compact focused ion beam system. 20. The plasma ion or electron source of claim 19 wherein the matching network fits within a cylindrical cavity 6 inches in diameter and 8 inches long. 21. A plasma ion or electron source, comprising: an RF power supply; a coaxial cable connected to the RF power supply; a matching network having an input connected to the coaxial cable, the matching network comprising; a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration; a ferrite core transformer coupled to the resonantly tunable circuit; an RF antenna connected to an output of the matching network; and, a plasma ion or electron generator having the RF antenna mounted therein for inductively generating a plasma, wherein the transformer comprises both a single-turn secondary winding that couples the transformer to the tunable circuit and a multi-turn primary winding, and the transformer further comprises a core that is made of a plurality of ferrite cores. 22. A plasma ion or electron source, comprising: an RF power supply; a coaxial cable connected to the RF power supply; a matching network having an input connected to the coaxial cable, the matching network comprising; a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration; a ferrite core transformer coupled to the resonantly tunable circuit; an RF antenna connected to an output of the matching network; and, a plasma ion or electron generator having the RF antenna mounted therein for inductively generating a plasma, wherein the plasma ion or electron generator is a multicusp plasma generator. 23. The plasma ion or electron source of claim 22 wherein the source is a part of a compact focused ion beam system. 24. The plasma ion or electron source of claim 23 wherein the matching network fits within a cylindrical cavity 6 inches in diameter and 8 inches long.