Microwave plasma torch generating laminar flow for materials processing

• US 20130270261A1
• Filed: 04/13/2012
• Published: 10/17/2013
• Est. Priority Date: 04/13/2012
• Status: Active Grant

• Current Assignee: 6K Incorporated
• Original Assignee: Amastan Technologies LLC
• Inventors: Hadidi, Kamal, Redjdal, Makhlouf
• Granted Patent: US 10,477,665 B2
• Time in Patent Office: Days
• US Class Current: 219/686
• 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 torch providing two laminar flows is described. Two laminar flows are created using a set of at least three concentric, staggered dielectric tubes connected to a pressurized gas source. An inner laminar flow entrains injected particles entering the plasma. An outer laminar flow creates a sheath around the plasma and prevents it from attaching to the walls of the plasma torch. The entry point of the gas source is designed to ensure laminar flow for both the entrainment of the particles and for the shielding of the plasma plume. The uniform processing conditions results in uniform particles and a homogenous materials distribution. This enables a final product with improved thermal properties, improved corrosion and wear resistance and a higher tolerance to interface stresses. The microwave plasma torch can be used for producing nanomaterial powder and for spray coating materials onto various substrates.

Claims

1. A microwave plasma torch comprising:

a set of staggered concentric tubes, an outer tube, an inner tube and a middle tube, said tubes comprising a dielectric material, said outer tube having an open end for passage of plasma, said middle tube disposed within and concentric to said outer tube and extending towards said open end but not beyond said outer tube, said inner tube disposed within said middle tube and extending towards said open end but not beyond said middle tube, said inner tube having a tapered end;

a first injection port for injecting gas between said outer and middle tubes towards said open end;

a second injection port for injecting gas between said middle and inner tubes towards said open end;

2. The plasma torch of claim 1 wherein there are at least three concentric tubes.

3. The plasma torch of claim 1 wherein a means is provided for inducing processing gas at said open end of said middle tube to form plasma using microwave energy generated from a source for microwave energy, said microwave energy propagated using a waveguide.

4. The plasma torch of claim 1 wherein laminar flow is created between said outer tube and said middle tube, said laminar flow shielding the plasma torch from plasma heat.

5. The plasma torch of claim 1 wherein laminar flow is created between said middle tube and said inner tube which permits a higher entrainment velocity for particles injected for deposition exiting said open end of inner tube and shields said particles from turbulent flow effects.

7. The plasma torch of claim 1 wherein the dielectric material is comprised of fused quartz.

8. The plasma torch of claim 1 wherein the three tubes are fused together using high heat.

9. The plasma torch of claim 1 wherein the tapered angle of the inner tube is between 0°

and 45°

.

10. The plasma torch of claim 1 wherein the middle tube is longer than the inner tube by at least 1 inch.

11. The plasma torch of claim 1 wherein the maximum outer diameter of the outer tube is no more than 3 cm when used with microwave radiation of frequency 2.45 GHz.

12. The plasma torch of claim 1 wherein the maximum outer diameter of the outer tube is no more than 9 cm when used with microwave radiation of frequency 915 MHz.

13. The plasma torch of claim 1 wherein the gas injection port to the outer tube is at an angle relative to a central axis of the torch and is substantially tangential to an inner surface of the outer tube.

14. The plasma torch of claim 1 wherein the gas injection port to the outer tube is at an angle relative to a central axis of the torch and is perpendicular to an inner surface of the outer tube.

15. The plasma torch of claim 1 wherein the gas injection port to the middle tube is at an angle relative to a central axis of the torch and is substantially tangential to an inner surface of the middle tube.

16. The plasma torch of claim 1 wherein the gas injection port to the middle tube is at an angle relative to a central axis of the torch and is perpendicular, to an inner surface of the middle tube.

17. The plasma torch of claim 1 wherein the material to be processed is injectable through the inner tube.

18. The plasma torch of claim 1 wherein the material to be processed is injectable through the annular gap between the inner and middle tubes.

19. A method for using the plasma torch of claim 1, said method comprising introducing material to be processed through said inner tube and also through annular gap between the inner and middle tubes.

20. The method of claim 19 wherein at least two materials are introduced.

21. The plasma torch of claim 1 wherein the material to be processed is selected from the group consisting of solid, liquid and gas.

6. (canceled)