# US 10,120,014 B2 · Systems and methods for propagating brush discharge testing

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- Number: US 10,120,014 B2
- Document ID: US10120014B2
- Status: Granted
- Kind: B2
- Application number: 15/414,483
- Filed: 2017-01-24
- Published: 2018-07-26
- Granted: 2018-11-06
- Earliest claimed: 2017-01-24
- Assignees: The Boeing Company
- Applicants: The Boeing Company
- Inventors: Dejan Nikic; Arthur C. Day
- Web page: https://patentgrep.com/patent/US10120014B2

## CPC

- G01R 31/1218: {using optical methods; using charged particle, e.g. electron, beams or X-rays}
- G01N 27/60: by investigating electrostatic variables {, e.g. electrographic flaw testing (G01N27/007 takes precedence)}
- G01N 27/61: Investigating the presence of flaws
- G01R 31/16: Construction of testing vessels; Electrodes therefor
- G01R 15/165: {measuring electrostatic potential, e.g. with electrostatic voltmeters or electrometers, when the design of the sensor is essential (electrometers with passively moving electrodes G01R5/28; measuring electrostatic fields G01R29/12; measuring charge G01R29/24; measuring in circuits with high internal resistance G01R19/0023)}
- G01R 29/24: Arrangements for measuring quantities of charge
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Propagating brush discharge testing systems may include a dielectric layer, an initiation electrode, a high-voltage switch, an optical sensor, and a controller. The initiation electrode has an exposed tip positioned adjacent to a surface of the dielectric layer. The high-voltage switch is configured to selectively isolate the initiation electrode from ground potential. The optical sensor is positioned and configured to sense light generated at the surface due to a propagating brush discharge. The controller is programmed to operate the high-voltage switch to ground the initiation electrode and to operate the optical sensor to collect light from the propagating brush discharge. Propagating brush discharge testing methods include positioning an exposed tip of an initiation electrode with respect to a surface of a dielectric layer, then charging the surface, and then grounding the initiation electrode to neutralize charge on the surface (generally causing a propagating brush discharge).

## Claims

### Claim 1

A system for performing a propagating brush discharge test, the system comprising:
a grounded layer;
a dielectric layer that has a first surface and is backed by the grounded layer opposite the first surface of the dielectric layer;
an initiation electrode with a conductive element that has a body and an exposed tip, wherein the exposed tip is positioned adjacent to the first surface of the dielectric layer such that a voltage differential between the exposed tip and the first surface of less than 50 kV is sufficient to cause an electrical contact between the exposed tip and the first surface, wherein the body of the conductive element is electrically isolated from the dielectric layer;
a high-voltage switch connected to the initiation electrode and configured to selectively isolate the conductive element of the initiation electrode from ground potential;
an optical sensor positioned and configured to sense light generated at the first surface of the dielectric layer due to a propagating brush discharge centered at the exposed tip of the initiation electrode; and
a controller programmed to operate the high-voltage switch to electrically ground the initiation electrode and to operate the optical sensor to collect light from the propagating brush discharge.

### Claim 2 (depends on 1)

The system of claim 1, wherein the first surface of the dielectric layer has a voltage with a magnitude of at least 4 kV, relative to ground potential.

### Claim 3 (depends on 1)

The system of claim 1, wherein the optical sensor is a camera that is configured to image the first surface of the dielectric layer with an exposure time of at most 1 μs.

### Claim 4 (depends on 1)

The system of claim 1, wherein the optical sensor is a camera that is configured to image the first surface of the dielectric layer with a sequence of image frames.

### Claim 5 (depends on 1)

The system of claim 1, wherein a cross sectional area of the exposed tip has an effective diameter of less than 1 mm.

### Claim 6 (depends on 1)

The system of claim 1, wherein a cross sectional area of the initiation electrode along the body of the conductive element has an effective diameter of at most 3 mm.

### Claim 7 (depends on 1)

The system of claim 1, wherein the initiation electrode includes an insulating sheath along the body of the conductive element, wherein the insulating sheath is spaced apart from the first surface of the dielectric layer.

### Claim 8 (depends on 1)

The system of claim 1, wherein the high-voltage switch is configured to selectively isolate the conductive element of the initiation electrode from ground potential at a voltage magnitude of the conductive element of at least 5 kV, relative to ground potential.

### Claim 9 (depends on 1)

The system of claim 1, further comprising a charge source configured to charge the first surface of the dielectric layer to a voltage with a magnitude of at least 4 kV, relative to ground potential.

### Claim 10

A system for performing a propagating brush discharge test, the system comprising:
a grounded layer;
a dielectric layer that has a first surface and is backed by the grounded layer opposite the first surface of the dielectric layer;
an initiation electrode with a conductive element that has a body and an exposed tip, wherein the exposed tip is adjacent to the first surface of the dielectric layer such that a voltage differential between the exposed tip and the first surface of less than 50 kV is sufficient to cause an electrical contact between the exposed tip and the first surface, wherein the body of the conductive element is electrically isolated from the dielectric layer, wherein the initiation electrode includes an insulating sheath along the body of the conductive element, wherein the insulating sheath is spaced apart from the first surface of the dielectric layer;
a high-voltage switch connected to the initiation electrode and configured to selectively isolate the conductive element of the initiation electrode from ground potential;
a flammable gas in contact with the first surface of the dielectric layer;
an optical sensor positioned and configured to detect light generated by ignition of the flammable gas due to a propagating brush discharge centered at the exposed tip of the initiation electrode; and
a controller programmed to operate the high-voltage switch to electrically ground the initiation electrode and to operate the optical sensor to collect light.

### Claim 11

A method for performing a propagating brush discharge test on a dielectric layer, the method comprising:
positioning an exposed tip of an initiation electrode adjacent to a first surface of the dielectric layer, wherein the dielectric layer is backed by a grounded layer opposite the first surface of the dielectric layer;
after positioning, electrically charging the first surface of the dielectric layer to a voltage with a magnitude of at least 4 kV relative to ground potential, while the grounded layer is at ground potential and the initiation electrode is isolated from ground potential; and
after electrically charging, electrically connecting the initiation electrode to ground potential so that the exposed tip of the initiation electrode neutralizes charge on the first surface of the dielectric layer.

### Claim 12 (depends on 11)

The method of claim 11, further comprising collecting light from a region that includes the first surface of the dielectric layer and the exposed tip of the initiation electrode.

### Claim 13 (depends on 12)

The method of claim 12, wherein collecting light includes collecting light generated at the first surface of the dielectric layer due to a propagating brush discharge centered at the exposed tip of the initiation electrode.

### Claim 14 (depends on 12)

The method of claim 12, wherein collecting light includes imaging the first surface within 10 μs of electrically connecting the initiation electrode to ground potential.

### Claim 15 (depends on 12)

The method of claim 12, wherein collecting light includes imaging the first surface with an exposure time of at least 10 μs.

### Claim 16 (depends on 12)

The method of claim 12, wherein collecting light includes imaging the first surface with an exposure time of at most 1 μs.

### Claim 17 (depends on 12)

The method of claim 12, wherein collecting light includes acquiring an image of the first surface and the method further comprises determining a presence of a propagating brush discharge at the first surface based upon the image of the first surface.

### Claim 18 (depends on 11)

The method of claim 11, further comprising electrically isolating the initiation electrode from ground potential with a high-voltage switch and wherein the electrically connecting the initiation electrode to ground potential includes operating the high-voltage switch.

### Claim 19 (depends on 11)

The method of claim 11, wherein electrically charging the first surface includes charging the first surface with at least one of a corona source and a charged fluid.

### Claim 20 (depends on 11)

The method of claim 11, further comprising, after electrically connecting the initiation electrode to ground potential, determining a presence of a propagating brush discharge based upon an electrical current in the initiation electrode.