ELECTRODE ASSEMBLY FOR PLASMA GENERATION

Abstract

A hollow electrode assembly through which gas from a gas supply can pass and be effused across the casing of the electrode for supplying a gas for a plasma discharge. The gas passing the electrode goes from a higher gas pressure environment inside the electrode to a lower gas pressure environment on the outside of the electrode. The casing of the electrode through which the gas effuses can be a metal or metal allow which provides for a controlled flow of the gas through the wall. The flow rate of the gas can be controlled by one or more of the porosity of the metal or metal alloy used, the type of gas used, the pressure differential between the inside and outside of the electrode, and the temperature of the system. The electrode assembly can be used in and high temperature plasma generators.

Claims

1. An electrode apparatus for plasma generation comprising: a hollow electrode assembly connectable to a gas source, comprising, at least one conduit in the hollow electrode assembly for supplying gas under pressure to the inside of the hollow electrode assembly, a gas permeable membrane on the electrode for permitting gas from inside the assembly to effuse across the membrane for supply gas to a plasma discharge from the electrode.

2. The electrode apparatus of claim 1, wherein the electrode further comprises a plasma discharge head from which the plasma is discharged from the electrode.

3. The electrode apparatus of claim 2, wherein the gas permeable membrane comprises a head composed of a pure element or alloy selected from the group consisting of nickel, iron, carbon, molybdenum, chromium, vanadium, silicon, copper, palladium, platinum, lithium, aluminum, carbon and combinations thereof.

4. A method for generating a plasma comprising: providing a hollow electrode assembly through which a gas from a gas supply can pass and be effused across the casing of the electrode for supplying a gas for a plasma discharge, introducing the gas under pressure into the electrode assembly such that the gas passes and is effused across the casing, and applying a current and a voltage to the electrode assembly for generating a plasma discharge.

Description

BRIEF DESCRIPTIONS OF DRAWINGS

[0008] For the purpose of illustrating the invention, the drawings show aspects of one or more embodiments of the invention. However, it should be understood that the present invention is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:

[0009] FIG. 1 is front elevation view with a partial cut-away of an anode assembly according to an aspect of the present disclosure;

[0010] FIG. 1A is a section view taken along A-A of FIG. 1;

[0011] FIG. 2 is an isometric view of the anode assembly of FIG. 1;

[0012] FIG. 3 is a front elevation view of the anode head of the anode and sleeve of FIG. 1;

[0013] FIG. 3A is a left side elevation view of the anode head and sleeve of FIG. 3;

[0014] FIG. 3B is an isometric view of the anode and sleeve of FIG. 3;

[0015] FIG. 4 is a section view of the anode of FIG. 3 taken along B-B of FIG. 3;

[0016] FIG. 4A is an isometric view of the anode of FIG. 4.

[0017] FIG. 5 is an image of the head of a steel anode according to an aspect of the present disclosure with a high-voltage discharge on the head. The dark striations are the weld seams; and

[0018] FIG. 6 is a graph of the pressure within the anode of FIG. 5 as a function of time when initially charged with (•) hydrogen and (Δ) nitrogen and then the source gas shut off.

DETAILED DESCRIPTION

[0019] Referring initially to FIG. 1, in one implementation, the present disclosure is directed to an electrode assembly including an anode generally indicated at 50 and a gas delivery and cooling assembly generally indicated at 52. The anode 50 includes a hollow bulbous head 54. The anode head 54 includes two cast alloy half spheres 1, 2 welded together along seam 56. The alloy is a steel-based alloy with high nickel content (above ˜20%) but other metals and/or alloys suitable for plasma generation can be used. In certain embodiments, any metal that is castable with porosity can be used. In still further embodiments, noble metals such as palladium, platinum, nickel, etc., may be used since hydrogen dissolves in the lattice and can diffuse from a higher pressure within the anode to the surrounding chamber. Housed in the bulbous head 54 is magnetic core 15 which houses a magnet 58. The magnet 58 may be an electromagnet or permanent magnet which can be used to further customize the plasma characteristics. The charged plasma will follow the field lines from the magnet to the surface of the anode. The magnetic core 15 is located at the free end of inner sleeve 60 which enters the bulbous head 54 through opening 62 is half sphere 2. Sleeve 60 houses conduits indicated generally at 64 that include gas inlet, coolant inlet, and coolant outlet The sleeve 60 is enclosed by insulated outer sleeve 11.

[0020] The sleeves 60 and 62 and conduits 64 extend into insulated sleeve 10 and then insulated sleeve 9 of the gas delivery and cooling assembly 52. The sleeve 9 houses multi-anode tube flow-throughs 19, anode water cooling lines 5, 6 and gas input line 7 which are coupled together by tube unions 8 to internal gas/water cooling lines 14 in order to maintain gas/water pressure and flow. In this manner, in operation, the bulbous anode head 1 remains energized at high electrical potential with no arcing to grounded inlet lines 5, 6, 7. The gas inlet 7 is connected to a pressure gauge and subsequent gas sources. The tapered base 18 ensures the anode assembly is a tight fit to the positive high voltage/high current circuit while allowing multiple styles of anode electrode to be interchanged.

[0021] Electrical charge is delivered via an insulated cable 20 coupled to the multi-anode base/heat exchanger unit 16. Pressurized cooling lines 17 are connected to the multi-anode base/heat exchanger to maintain cooling of the anode and insulated properties.

[0022] Insulated sleeves 9, 10, 11 are utilized to increase arc distance to ground and insulate components from heat.

[0023] In order to further insulate the parts from the high electrical potential when the bulbous head 54 operates as an anode, a polymer bulkhead 13 is used in transition from the gas/cooling/electrical supply-side. Dielectric materials are used whenever possible to prevent discharges across gaps to electrical ground. PEEK polymer, glass, quartz, and refractory materials are common constituents to accomplish such a task. The gas can be any gas, but in this embodiment discharges using hydrogen and deuterium are disclosed. Because of the extremely high temperatures encountered, cooling water lines are distributed throughout the electrode assembly which further strengthen the original nature of this design.

EXAMPLES

Example 1

[0024] FIG. 5 shows a typical electrical discharge in 5 torr hydrogen (chamber pressure) and 200 psi (13.8 kbar) being exerted from the source gas in the anode with a discharge voltage of 300V.

Example 2

[0025] FIG. 6 shows the pressure decay as a function of time for a charged anode surrounded by 1 torr of atmosphere of hydrogen, and a separate experiment with nitrogen. The anode was charged with 250 psi of gas, and the supply valve then closed.

[0026] Accordingly, the present disclosure should only be limited by the scope of the claims that follow.