# US 8,749,139 B2 · Microwave driven plasma light source

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- Number: US 8,749,139 B2
- Document ID: US8749139B2
- Status: Granted
- Kind: B2
- Application number: 13/807,320
- Filed: 2011-07-05
- Published: 2013-04-25
- Granted: 2014-06-10
- Earliest claimed: 2010-07-05
- Assignees: Ceravision Limited
- Applicants: Andrew Simon Neate; Barry Preston
- Inventors: Andrew Simon Neate; Barry Preston
- Web page: https://patentgrep.com/patent/US8749139B2

## CPC

- H01J 65/04: Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating {plasma display panels}
- H01J 65/044: {the field being produced by a separate microwave unit}
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

A lucent crucible of a Lucent Waveguide Microwave Plasma Light Source (LWMPLS) comprising a Light Emitting Resonator (LER) in form of a crucible (1) of fused quartz which has a central void (2) having microwave excitable material (3) within it. In one example, the void is 4 mm in diameter and has a length (L) of 21 mm. The LWMPLS is operated at a power (P) of 280 W and thus with a plasma loading P/L of 133 w/cm and a wall loading of 106 w/cm2. The lamp is thus operated with a high efficiency—in terms of lumens per watt—while having a reasonable lifetime.

## Claims

### Claim 1

A Lucent Waveguide Microwave Plasma Light Source (LWMPLS) comprising:
a magnetron of a power such that the light source has a rated power P and
a body of solid-dielectric lucent material having a closed void length L,
wherein:
a plasma loading of the rated power divided by the void length (P/L) is at least 100W per cm,
a wall loading of rated power divided by internal surface area of the void is between 100 W per cm2 and 300 W per cm2,
the void length being the overall void length minus two radii of a central portion of the void and
the internal surface area of the part being measured between one radius of a central portion from each end of the void.

### Claim 2 (depends on 1)

A LWMPLS as claimed in claim 1, wherein the plasma loading of the rated power divided by the void length is at least 125W per cm.

### Claim 3 (depends on 1)

A LWMPLS as claimed in claim 1, wherein the plasma loading of the rated power divided by the void length is at least 140 W per cm.

### Claim 4 (depends on 1)

A LWMPLS as claimed in claim 1, wherein the plasma void is directly in the lucent crucible.

### Claim 5 (depends on 1)

A LWMPLS as claimed in claim 1, wherein the plasma void is in a lucent bulb within a lucent waveguide.

### Claim 6 (depends on 1)

A LWMPLS as claimed in claim 1, wherein the wall loading of rated power divided by internal surface area of the void is between 125 W per cm2 and 300 W per cm2.

### Claim 7 (depends on 6)

A LWMPLS as claimed in claim 6, wherein the wall loading of rated power divided by internal surface area of the void is between 150 W per cm2 and 250 W per cm2.