MICROWAVE PLASMA APPARATUS AND METHOD FOR MATERIALS PROCESSING

• US 20080173641A1
• Filed: 01/17/2008
• Published: 07/24/2008
• Est. Priority Date: 01/18/2007
• Status: Active Grant

• Current Assignee: 6K Incorporated, University of Connecticut (State of Connecticut)
• Original Assignee: Amastan Technologies LLC
• Inventors: Jordan, Eric, Hadidi, Kamal, Cetegen, Baki M., Woskov, Paul
• Granted Patent: US 8,748,785 B2
• Time in Patent Office: Days
• US Class Current: 219/690
• CPC Class Codes: B05B 7/226 the material being originally a particulate material
• CPC Class Codes: C23C 16/511 using microwave discharges
• CPC Class Codes: C23C 16/513 using plasma jets
• CPC Class Codes: C23C 4/134 Plasma spraying
• CPC Class Codes: H05H 1/30 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/28 takes precedence

Abstract

A microwave plasma apparatus for processing a material includes a plasma chamber, a microwave radiation source, and a waveguide guiding microwave radiation from the microwave radiation source to the plasma chamber. A process gas flows through the plasma chamber and the microwave radiation couples to the process gas to produce a plasma jet. A process material is introduced to the plasma chamber, becomes entrained in the plasma jet, and is thereby transformed to a stream of product material droplets or particles. The product material droplets or particles are substantially more uniform in size, velocity, temperature, and melt state than are droplets or particles produced by prior devices.

Claims

1. A microwave plasma apparatus for processing a material comprising:

a plasma chamber;

a microwave radiation source for generating microwave radiation;

a waveguide guiding the microwave radiation from the microwave radiation source to the plasma chamber;

a supply in fluid communication with the plasma chamber for providing a gas to the plasma chamber; and

a material feeding system in communication with the plasma chamber for introducing a process material to the plasma chamber,

wherein the microwave radiation couples to the gas to form a plasma jet, and wherein the process material, through contact with the plasma jet, forms a product material.

2. The apparatus according to claim 1, wherein the gas is a process gas.

3. The apparatus according to claim 2, wherein a portion of the process gas is used as a shrouding gas.

4. The apparatus according to claim 2, further comprising a second supply in fluid communication with the plasma chamber for providing a shrouding gas to the plasma chamber.

5. The apparatus according to claim 4, further comprising a swirl structure that causes the shrouding gas to flow in a laminar and substantially helical swirl between the plasma jet and an inner surface of the plasma chamber.

6. The apparatus according to claim 5, wherein the plasma chamber includes an outlet, and the swirl of the shrouding gas continues past the outlet.

7. The apparatus according to claim 1, wherein the plasma chamber includes an outlet, and the plasma jet extends past the outlet.

8. The apparatus according to claim 1, further comprising an inlet sleeve and an outlet sleeve.

9. The apparatus according to claim 8, configured for modular assembly.

10. The apparatus according to claim 8, further comprising an inlet assembly mounted to the inlet sleeve and in fluid communication with the supply and with the material feeding system.

11. The apparatus according to claim 1, wherein the plasma chamber includes a gas injector that causes the gas to flow laminarly and substantially parallel to an axis of the plasma chamber.

12. The apparatus according to claim 1, wherein the material feeding system suspends the process material in a carrier gas for introduction to the plasma chamber.

13. The apparatus according to claim 12, wherein the material feeding system further comprises:

a droplet maker; and

a source of the carrier gas,

wherein the droplet maker produces droplets containing the process material,

wherein the source of the carrier gas is in fluid communication with an inner volume of the plasma chamber via the material feeding system, and

wherein a flow of the carrier gas toward the plasma chamber entrains the droplets containing the process material, so that the process material enters the plasma chamber suspended in the carrier gas.

14. The apparatus according to claim 13, wherein the droplet maker is a piezoelectric multi-orifice droplet maker.

15. The apparatus according to claim 12, wherein the process material is suspended in the carrier gas as particulates.

16. The apparatus according to claim 1, wherein the material feeding system comprises:

an emitter rod comprising the process material and protruding into the plasma chamber;

a gas injector that imparts to the gas a velocity into the chamber and substantially along a surface of the emitter rod; and

means for advancing the emitter rod into the plasma chamber,

wherein the plasma jet comes into contact with at least a portion of the emitter rod,

wherein the gas and the plasma jet cooperate to erode at least a part of the portion of the emitter rod, and

wherein the emitter rod is advanced into the chamber as the part of the portion of the emitter rod erodes, thereby maintaining at least a portion of the emitter rod in contact with the plasma jet.

17. The apparatus according to claim 1, wherein the plasma chamber includes an outlet, and wherein a target is arranged proximate the outlet so that the product material impacts on the target.

18. The apparatus according to claim 17, wherein the target is a substrate to be coated.

19. A method for processing a material in a plasma chamber, comprising the steps of:

generating a plasma jet in the plasma chamber;

supplying the material to the plasma chamber; and

entraining the material in the plasma jet.

20. The method according to claim 19, further comprising a step of discharging the material from the plasma chamber.

21. The method according to claim 19, wherein the step of generating a plasma jet includes the steps of:

supplying a gas to the plasma chamber;

ionizing the gas; and

coupling microwave radiation to the ionized gas.

22. The method according to claim 19, wherein the step of supplying the material includes a step of suspending the material in a gas.

23. A microwave plasma apparatus for processing a material comprising:

a plasma chamber;

a microwave radiation source generating microwave radiation;

a waveguide guiding the microwave radiation from the microwave radiation source to the plasma chamber;

a first supply in fluid communication with the plasma chamber for providing a process gas to the plasma chamber;

a second supply in fluid communication with the plasma chamber for providing a shrouding gas to the plasma chamber; and

a material feeding system in communication with the plasma chamber for introducing a process material to the plasma chamber,

wherein the microwave radiation comes into contact with the process gas to form a plasma jet, and

wherein the process material, through contact with the plasma jet, forms a product material.