US3817622A
Expired / Lapsed
US
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Measurement of plasma temperature and density using radiation absorption
Assignee: National Aeronautics and Space Administration
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Filing: 1972-12-26
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Granted: 1974-06-18
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Expires: 1992-12-26
Abstract
Abstract A light beam of predetermined wavelength, preferably monochromatic, is directed through a plasma to be measured. The absorption of the light by the plasma is detected for deriving an absorption coefficient of the plasma. Knowing the absorption coefficient of the plasma and independently measuring either the electron density or temperature of the plasma allows solution of an equation to derive the other unknown quantity, i.e. either electron density or temperature. In a preferred method, the absorption coefficient of the plasma is derived simultaneously for two probing light beams of substantially different predetermined wavelengths. Knowing these two coefficients allows solution of two simultaneous equations to derive the electron density and temperature of the plasma.
Inventors
- 👤 J Stallcop
- 👤 L Presley
- 👤 K Billman
- 👤 P Rowley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:58
CPC Classifications
G; G01; G01J; G01J5/00; G01J5/60; G01K; G01K1/00; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/314; G01N21/3151; H; H05; H05H; H05H1/00; H05H1/0006
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
115 words
In a method of deteRmining properties of a plasma by radiation absorption, the steps of selecting a first radiation with a wavelength lambda 1 for radiating said plasma wherein the dominant absorption in said plasma will be photoionization, selecting a second radiation with a wavelength lambda 2 for radiating said plasma wherein lambda 2 is longer than lambda 1, and the photoionization absorption in said plasma will be insignificant, directing said first and second radiations into said plasma, detecting the absorption of said first and second radiations to derive first and second absorption coefficients, respectively, and graphically determining from the absorption coefficient plots for said two wavelengths the temperature and electron density of the plasma.
Claim 2
Dependent Claim
115 words
In a method of deteRmining properties of a plasma by radiation absorption, the steps of selecting a first radiation with a wavelength lambda 1 for radiating said plasma wherein the dominant absorption in said plasma will be photoionization, selecting a second radiation with a wavelength lambda 2 for radiating said plasma wherein lambda 2 is longer than lambda 1, and the photoionization absorption in said plasma will be insignificant, directing said first and second radiations into said plasma, detecting the absorption of said first and second radiations to derive first and second absorption coefficients, respectively, and graphically determining from the absorption coefficient plots for said two wavelengths the temperature and electron density of the plasma.
Claim 3
Dependent Claim
15 words
The method of claim 1 wherein the second radiation is absorbed by electron-ion inverse bremsstrahlung.
Claim 4
Dependent Claim
16 words
The method of claim 1 wherein the second radiation is absorbed by electron-neutral atom inverse bremsstrahlung.
Claim 5
Dependent Claim
20 words
The method of claim 1 wherein the second radiation is absorbed by electron-ion inverse bremsstrahlung and electron-neutral atom inverse bremsstrahlung.
Claim 6
Dependent Claim
14 words
The method of claim 1 wherein said radiations are other than a resonance line.
Claim 7
Dependent Claim
95 words
In a method of determining the electron density of a plasma wherein the temperature is known, the steps of: selecting a radiation with a specific wavelength lambda 1 that will produce a predetermined type of absorption in said plasma; choosing the type of absorption from the group of photoionization, electron-ion inverse bremsstrahlung, and electron-neutral atom inverse bremsstrahlung, directing said radiation on said plasma, detecting the absorption of said radiation at wavelength lambda 1 to derive an absorption coefficient, and graphically determining from the absorption coefficient plot for said wavelength the electron density of said plasma.
Claim 8
Dependent Claim
95 words
In a method of determining the electron density of a plasma wherein the temperature is known, the steps of: selecting a radiation with a specific wavelength lambda 1 that will produce a predetermined type of absorption in said plasma; choosing the type of absorption from the group of photoionization, electron-ion inverse bremsstrahlung, and electron-neutral atom inverse bremsstrahlung, directing said radiation on said plasma, detecting the absorption of said radiation at wavelength lambda 1 to derive an absorption coefficient, and graphically determining from the absorption coefficient plot for said wavelength the electron density of said plasma.
Claim 9
Dependent Claim
94 words
In a method of determining the temperature of a plasma wherein the electron density is known, the steps of: selecting a radiation with a specific wavelength lambda 1 that will produce a predetermined type of absorption in said plasma; choosing the type of absorption from the group of photoionization, electron-ion inverse bremsstrahlung, or electron-neutral atom inverse bremsstrahlung, directing said radiation on said plasma, detecting the absorption of said radiation at wavelength lambda 1 to derive an absorption coefficient, and graphically determining from the absorption coefficient plot for said wavelength the temperature of said plasma.
Claim 10
Dependent Claim
94 words
In a method of determining the temperature of a plasma wherein the electron density is known, the steps of: selecting a radiation with a specific wavelength lambda 1 that will produce a predetermined type of absorption in said plasma; choosing the type of absorption from the group of photoionization, electron-ion inverse bremsstrahlung, or electron-neutral atom inverse bremsstrahlung, directing said radiation on said plasma, detecting the absorption of said radiation at wavelength lambda 1 to derive an absorption coefficient, and graphically determining from the absorption coefficient plot for said wavelength the temperature of said plasma.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-17 | 1977-12-17 | 1978-06-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-17 | 1981-12-17 | 1982-06-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-17 | 1985-12-17 | 1986-06-18 | $7700.00 | Window Closed / Lapsed |