Patent US4908492A successfully refreshed from Google Patents.
US4908492A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Microwave plasma production apparatus
Assignee: Hitachi Ltd
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Filing: 1989-05-05
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Granted: 1990-03-13
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Expires: 2009-05-05
Abstract
Abstract A microwave plasma production apparatus according to the present invention is so configured that a cylindrical coaxial wave guide is formed by a cylindrical outer conductor and a helical coil shaped inner conductor, and at least a part of a nonconductive discharge tube is disposed inside said inner conductor, microwave being applied between said outer conductor and said inner conductor.
Inventors
- 👤 Yukio Okamoto
- 👤 Seiichi Murayama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 07:55
CPC Classifications
H; H05; H05H; H05H1/00; H05H1/24; H05H1/46
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
77 words
A microwave plasma production apparatus comprising: a cylindrical coaxial wave guide forming a cylindrical bore and including a helical coil shaped inner conductor and a cylindrical outer conductor; an electrically nonconductive discharge tube disposed in said cylindrical bore; and means for introducing microwave power between said inner and outer conductors and for forming a microwave electric field in said cylindrical bore so as to form plasma of a substance to be ionized introduced in said cylindrical bore.
Claim 2
Dependent Claim
77 words
A microwave plasma production apparatus comprising: a cylindrical coaxial wave guide forming a cylindrical bore and including a helical coil shaped inner conductor and a cylindrical outer conductor; an electrically nonconductive discharge tube disposed in said cylindrical bore; and means for introducing microwave power between said inner and outer conductors and for forming a microwave electric field in said cylindrical bore so as to form plasma of a substance to be ionized introduced in said cylindrical bore.
Claim 3
Dependent Claim
39 words
A microwave plasma production apparatus according to claim 1, wherein said discharge tube has an inlet for injecting said substance to be ionized and an opening for utilizing one of said plasma, light and particles emitted from said plasma.
Claim 4
Dependent Claim
33 words
A microwave plasma production apparatus according to claim 1, further comprising magnetic field applying means so disposed around said cylindrical bore as to superimpose an external magnetic field over said microwave electric field.
Claim 5
Dependent Claim
33 words
A microwave plasma production apparatus according to claim 2, further comprising magnetic field applying means so disposed around said cylindrical bore as to superimpose an external magnetic field over said microwave electric field.
Claim 6
Dependent Claim
99 words
A microwave plasma production apparatus according to claim 1, wherein said helical coil shaped inner conductor and said plasma form a transformer with said helical coil shaped inner conductor being a primary coil and said plasma being a secondary coil of the transformer, wherein dimensions and shapes of said helical coil shaped inner conductor and said cylindrical outer conductor are enabled to be selected so that said plasma having a selected diameter is obtainable, a discharge current flowing through said plasma being proportional to the product of an excitation current flowing through said primary coil and an excitation frequency.
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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) | 1993-03-12 | 1993-09-11 | 1994-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-12 | 1997-09-11 | 1998-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-12 | 2001-09-11 | 2002-03-13 | $7700.00 | Window Closed / Lapsed |