US3885874A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laser plasma diagnostic using ring resonators
Assignee: United States Department of Energy
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Filing: 1974-01-11
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Granted: 1975-05-27
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Expires: 1994-01-11
Abstract
Abstract This invention describes a system for measuring the electron number density of a plasma, which employs a laser interferometric plasma diagnostic technique and which provides significant improved time response compared to conventional laser interferometers. The method of achieving improved time response locates the plasma in one arm of a laser-excited, transmission ring resonator cavity. The response time of the interferometer is then limited only by the Q of the ring resonator cavity and is independent of the gain, the cavity Q, and the collisional lifetimes associated with the laser source.
Inventors
- 👤 Roger A Haas
- 👤 Peter P Chenausky
- 👤 Robert J Freiberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:52
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/41; G01N21/45; H; H05; H05H; H05H1/00; H05H1/0006
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
135 words
Apparatus for measuring the change in the average electron density of a plasma comprising: a. means for producing a laser beam; b. ring resonator means independent of the aforesaid means for receiving said laser beam and propagating the same in a closed system without reflecting laser light into said means for producing said laser beam; said ring resonator means containing at least a portion of said plasma so that said laser beam continuously circulates cyclically through said portion of said plasma; successive portions of said laser beam interfering with the circulating laser beam; c. means for extracting circulating laser light from said ring resonator means; and d. means for presenting the fringe pattern of the extracted laser light, the spacing in said pattern indicating the rate of change of the electron density of said plasma.
Claim 2
Dependent Claim
135 words
Apparatus for measuring the change in the average electron density of a plasma comprising: a. means for producing a laser beam; b. ring resonator means independent of the aforesaid means for receiving said laser beam and propagating the same in a closed system without reflecting laser light into said means for producing said laser beam; said ring resonator means containing at least a portion of said plasma so that said laser beam continuously circulates cyclically through said portion of said plasma; successive portions of said laser beam interfering with the circulating laser beam; c. means for extracting circulating laser light from said ring resonator means; and d. means for presenting the fringe pattern of the extracted laser light, the spacing in said pattern indicating the rate of change of the electron density of said plasma.
Claim 3
Dependent Claim
22 words
The apparatus of claim 1 in which said ring resonator means circulates said laser beam through a plasma that is time varying.
Claim 4
Dependent Claim
24 words
The apparatus of claim 1 in which said ring resonator means has at least one arm containing at least a portion of said plasma.
Claim 5
Dependent Claim
52 words
The apparatus of claim 1 in which said ring resonator means has at least three mirrors, at least two of which are partially reflecting, for receiving, circulating and extracting said laser beam through at least a portion of said plasma without reflecting laser light into said means for producing said laser beam.
Claim 6
Dependent Claim
24 words
The apparatus of claim 1 in which said ring resonator means decouples said circulating laser light from said means for producing said laser beam.
Claim 7
Dependent Claim
76 words
The apparatus of claim 2 in which said means for producing said laser beam produces plane polarized laser light having a gaussian amplitude profile, and the said means for circulating the laser light through a temporally changing plasma is a resonator having two partially reflecting mirrors for receiving, circulating and extracting the circulating laser light, and a third mirror for receiving and totally reflecting the circulating laser light from the second mirror to the first mirror.
Claim 8
Dependent Claim
41 words
The apparatus of claim 1 in which said ring resonator means has a vibrating mirror means for providing a fractional fringe interference pattern in operable association with said circulating laser beam for detection by said means for presenting said fringe pattern.
Claim 9
Dependent Claim
65 words
The apparatus of claim 1 in which said ring resonator means has auxiliary means for receiving and transmitting said circulating laser beam in said ring resonator means, and said auxiliary means has means for rapidly changing the optical length thereof for providing a fractional fringe interference pattern in operable association with said circulating laser beam for presentation by said means for presenting said fringe pattern.
Claim 10
Independent Claim
156 words
The method of measuring the transient, electron density of a temporally varying plasma, comprising the steps of: a. producing said plasma within at least one arm of a light transmission ring resonator adapted to be excited by an external laser source; b. transmitting laser light from an external laser source to excite the resonator by propagating and continuously circulating the laser light through the plasma in the resonator without reflecting the laser light into the external laser source; c. interacting the laser light circulating in the ring resonator with laser light that is injected into the resonator anew as the electron density of the plasma changes to produce an interference the interferenCe produced altering the reflection and transmission of the laser light through the resonator, and d. detecting the laser light as it is progressively reflected or transmitted from the ring resonator due to said interference as a measure of the electron density of the plasma.
Claim 11
Independent Claim
156 words
The method of measuring the transient, electron density of a temporally varying plasma, comprising the steps of: a. producing said plasma within at least one arm of a light transmission ring resonator adapted to be excited by an external laser source; b. transmitting laser light from an external laser source to excite the resonator by propagating and continuously circulating the laser light through the plasma in the resonator without reflecting the laser light into the external laser source; c. interacting the laser light circulating in the ring resonator with laser light that is injected into the resonator anew as the electron density of the plasma changes to produce an interference the interferenCe produced altering the reflection and transmission of the laser light through the resonator, and d. detecting the laser light as it is progressively reflected or transmitted from the ring resonator due to said interference as a measure of the electron density of the plasma.
Claim 12
Dependent Claim
23 words
The method of claim 9 including the step of producing a fractional fringe interference pattern from said light circulating in said ring resonator.
References Cited (Backward Citations)
US3528029A
Cited
US3539262A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |