US3311775A - Gaseous discharge lamp with stabilizing arrangement - Google Patents
Gaseous discharge lamp with stabilizing arrangement Download PDFInfo
- Publication number
- US3311775A US3311775A US304878A US30487863A US3311775A US 3311775 A US3311775 A US 3311775A US 304878 A US304878 A US 304878A US 30487863 A US30487863 A US 30487863A US 3311775 A US3311775 A US 3311775A
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- United States
- Prior art keywords
- tube
- prod
- lamp
- discharge lamp
- electrodeless discharge
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J65/00—Lamps without any electrode inside the vessel; Lamps with at least one main electrode outside the vessel
- H01J65/04—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
- H01J65/042—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 by an external electromagnetic field
- H01J65/048—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 by an external electromagnetic field the field being produced by using an excitation coil
Definitions
- An electrodeless gaseous discharge tube or lamp is one which contains a gas or vapor whose atoms are excited by an oscillating electric field to produce light.
- Optical pumping lamps employing electrodeless discharge tubes are used in gas cell type atomic frequency standards, magnetometers, atomic gyroscopes, and the like. In use the electrodeless discharge tube is driven by an applied electromagnetic field at a selected frequency in order to produce the desired optical discharge.
- the electrodeless discharge lamps are so-called because they do not employ any internally mounted electrodes to initiate or maintain the optical discharge. Rather, the driving electromagnetic field is induced within the discharge region of the tube from an externally positioned generator which is commonly in the form of a solenoid encompassing a portion of the discharge tube and which may be energized at a radio frequency.
- Discharge tubes of this type usually contain some quantity of inert gas such as argon or neon and a small amount of alkali metal raised to a temperature above the melting point of this metal. The contained gases are electrically excited to provide an ionized plasma which is the source of the optical pumping radiation.
- an optical pumping lamp incorporates an electrodeless discharge tube within a parabolic reflector for proper concentration and direction of the generated light.
- Most of the useful light derived from such an arrangement originates in the near vicinity of the focal point of the parabolic reflector. It is most desirable that the light originate at a point source located at the focus of the parabola in order that a beam of collimated light be provided. Should the plasma vary in position within the electrodeless discharge lamp during operation, the light which is available from the parabolic reflector will fiuctuate, depending upon the position relative to the focus, with the adverse result of an unwanted variation in light intensity at any particular point within the beam.
- electrodeless discharge lamps are in common use in the applications mentioned above, many workers in the field have found these lamps prone to plasma oscillations which, in turn, cause the light to fluctuate in intensity at any given point of observation along the plasma.
- One approach has been to drive the electrodeless discharge lamp at increased power levels in order to minimize the adverse effect of plasma oscillations. This, however, unfortunately diminishes the useful life of the discharge tube, due to excessive heat and ion bombardment, and also necessitates the use of higher powered oscillators for driving the lamp.
- Another approach is to energize the lamp with electromagnetic radiation at higher frequencies. This introduces the difficulty of generating the desired radiation at very high frequencies and does not entirely eliminate the plasma oscillations.
- a further object of the present invention is elimination of plasma oscillations encountered in an electrodeless discharge lamp without the necessity of resorting to higher power or higher frequency radiation for energizing the lamp.
- An additional object of the present invention is to provide an electrodeless discharge lamp capable of operation with improved stability over an extended period at reduced power input.
- the present invention comprises an electrodeless discharge lamp incorporating a discharge tube which is in the general form of a right circular cylinder with closed ends.
- the tube includes a prod, preferably of the same material as the walls of the tube for ease of fabrication, extending coaxially from one end of the tube toward the center thereof. This prod is configured so that it extends into the plasma which is ionized when the tube is in operation but terminates short of the focal point of the associated parabolic reflector in which the tube is mounted.
- the tube and the enclosed prod are fabricated of glass, and rubidium vapor, along with an inert gas such as argon or neon, are utilized as the active elements within the tube.
- an inert gas such as argon or neon.
- an electrode is aflixed to the outside of the tube adjacent the base of the prod and a pulse source is connected thereto which is capacity coupled through the glass to trigger the ionization of the gases within the tube to initiate operation of the electrodeless discharge lamp.
- the lamp is used in conjunction with a metallic reflector which is commonly connected to ground or a point of reference potential.
- this connection effectively completes the capacitive circuit for the triggering pulse from the pulse source.
- the higher dielectric constant of the glass prod relative to the surrounding plasma within the tube more effectively carries the high voltage trigger pulse which is applied to the rear of the lamp to the interior of the tube and therefore makes the lamp easier to ignite.
- the dielectric material of the glass prod effectively pro vides a coupling path for the triggering pulse to the interior of the lamp tube.
- the glass prod may be of the same material and dielectric constant vof the walls of the tube envelope, this merely means that multiple paths exist which provide somewhat diiferent impedances for the triggering pulse as it is capacitively coupled between the electrode 'afiixed to the outside of the tube adjacent the base of the prod and the lamp reflector.
- FIG. 1 is a sectional representation of an electrodeless discharge lamp in accordance with the present invention.
- FIG. 2 is a cross-sectional view taken along the line 2-2 in the lamp shown in FIG. 1.
- an electrodeless discharge lamp comprising a discharge tube or bulb 12 mounted within a ferrule 14 which in turn is aflixed to a parabolic reflector 16.
- a solenoid winding 18 is represented surrounding the right-hand end of the tube 12 for applying an electromagnetic field to ionize the gases within the tube 12.
- Such a solenoid is conventionally driven from an associated RF generator by leads which are connected through the holes of the parabolic reflector 16, but these connections and associated driving equipment have been omitted for the sake of simplicity.
- the point 17 represents the focal point of the parabolic reflector from which various rays of optical radiation are represented as emanating to form the desired beam of light after reflection from the interior surface of the parabolic reflector 1s.
- a prod 13 is shown extending interiorily from one end of the tube 12 to terminate short of the focal point 17.
- an electrode is shown adjacent the base of the prod 13.
- the electrode 20 may be affixed to the tube 12 by a quantity of silver epoxy resin 21.
- a pulse source 24 is shown connected to the electrode 20.
- FIG. 2 represents a cross-sectional view of the tube 12 taken along the lines 2-2 of FIG. 1 to show the generally circular configuration of the cross section of the tube 12 and its prod 13.
- oscillating current of a suitable frequency is applied to the solenoid 18 and a trigger pulse is transmitted from the pulse source 24 to the electrode 20 at the base of the prod 13.
- This pulse is transmitted to the interior of the tube 12 by the prod 13 and effectively serves to initiate ionization of the gases therein which are thereafter maintained as an ionized plasma by the oscillating electromagnetic field from the solenoid 18.
- the prod 13 advantageously serves to maintain the ionized plasma, represented by the outline 22, in a stable configuration so that the light which is present at the focus 17 is maintained virtually constant in intensity.
- this arrangement of the present invention additionally serves to eliminate a further source of interference with the purity and stability of the ionized plasma light source.
- an electrodeless discharge tube is fabricated of Pyrex glass and filled with rubidium vapor plus an inert gas before sealing.
- the tube is formed with a glass prod extending from one end thereof.
- the tube 12 is cemented within the ferrule 14 by silver epoxy which is cured at C. for thirty minutes.
- the electrode 20 is formed by making a loop from one strand of a coaxial cable. The loop is cemented to the end of the tube 12 by silver epoxy which is then cured at C. for one hour. The arrangement is then fitted within the parabolic reflector 16. The outer end of the prod 13 is approximately 0.1 inch from the focus of the reflector 15.
- An electrodeless discharge lamp comprising a discharge tube closed at both ends and consisting of a dielectric material, a solenoidal coil positioned around a portion of the discharge tube for establishing an electromagnetic field therein, and stabilizing means including a prod consisting essentially of the same material as the discharge tube afiixed to one of the closed ends of said tube and extending within the discharge tube for maintaining the intensity of light generated in the tube substantially constant at a predetermined point therein.
- An electrodeless discharge lamp comprising a discharge tube closed at bath ends, a solenoidal coil positioned around a portion of the discharge tube for establishing an electromagnetic field therein, stabilizing means including a non-conductive prod of a dielectric material aifixed to one of the closed ends of said tube and extending within the discharge tube for maintaining the intensity of light generated in the tube substantially constant at a predetermined point therein, and means coupled to the prod for initiating an electrical discharge within said tube.
- An electrodeless discharge lamp in accordance with claim 2 wherein said last mentioned means comprises a terminal afiixed to said tube adjacent the prod and a trigger pulse source connected to said terminal.
- An electrodeless discharge tube for use as a light source comprising a glass cylinder closed at both ends and containing a quantity of rubidium vapor, means for initiating and maintaining an ionized plasma within said tube, and means for stabilizing the ionized plasma to minimize oscillations thereof comprising a substantially solid, glass prod extending interiorly of said tube from one of the closed ends thereof along the axis of the cylinder.
- An electrodeless discharge tube for use as a light source comprising a glass cylinder closed at both ends to contain a predetermined quantity of rubidium vapor and an inert gas, a substantially solid, glass prod extending interiorly from one of the closed ends of said tube concentrically positioned therein, and an electrical connection atfixed to said tube adjacent the base of said prod for facilitating the initiation of an ionic discharge within the tube.
- An electrodeless discharge tube for use as a controlled source of light from a focal point thereof comprising a substantially transparent symmetrical envelope closed at both ends to contain a predetermined quantity of an ionizable material, said material being subject to plasma oscillations when ionized by an applied oscillating electromagnetic field, and means for minimizing said plasma oscillations comprising a substantially solid prod extending inwardly from one of the closed ends along the major axis of the tube concentrically therewith to a point short of the focal point of the tube.
- An electrodeless discharge tube for use as a light source comprising a substantially transparent cylindrical envelope of a dielectric material closed at both ends to enclose an ionizable material, means for applying an oscillating electromagnetic field to maintain an ionized plasma once established within said tube, and a dielectric prod consisting essentially of the same material as the cyclindrical envelope extending into said tube concentrically therewith from one of the closed ends for both transmitting an applied trigger pulse to initiate ionization of the enclosed vapor and for stabilizing the resulting ionized plasma to maintain a constant light intensity at a predetermined point within the tube.
- An electrodeless discharge lamp for use as a light DAVID J. GALVIN,
- a source comprising a reflector having a fixed focal point, a sealed glass tube closed at both ends and mounted therein and containing an ionizable material, means for initiating and maintaining an ionized plasma Within said tube, and means for stabilizing the ionized plasma to minimize oscillations thereof comprising a solid, glass prod extending interiorly of said tube from one of the closed ends thereof along the axis of the tube and terminating a predetermined distance from the focal point of the reflector.
Description
Claims (1)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US304878A US3311775A (en) | 1963-08-27 | 1963-08-27 | Gaseous discharge lamp with stabilizing arrangement |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US304878A US3311775A (en) | 1963-08-27 | 1963-08-27 | Gaseous discharge lamp with stabilizing arrangement |
Publications (1)
Publication Number | Publication Date |
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US3311775A true US3311775A (en) | 1967-03-28 |
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US304878A Expired - Lifetime US3311775A (en) | 1963-08-27 | 1963-08-27 | Gaseous discharge lamp with stabilizing arrangement |
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3497767A (en) * | 1966-04-14 | 1970-02-24 | Csf | Constant intensity monochromatic light source |
US4035691A (en) * | 1975-08-04 | 1977-07-12 | The United States Of America As Represented By The Secretary Of The Navy | Pulsed laser excitation source |
US4766351A (en) * | 1987-06-29 | 1988-08-23 | Hull Donald E | Starter for inductively coupled plasma tube |
EP0447852A2 (en) * | 1990-03-12 | 1991-09-25 | General Electric Company | Luminaire for an electrodeless high intensity discharge lamp with electromagnetic interference shielding |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1698691A (en) * | 1926-07-01 | 1929-01-08 | Cooper Hewitt Electric Co | High-intensity induction lamp |
US2974243A (en) * | 1959-11-12 | 1961-03-07 | Space Technology Lab Inc | Light source |
US3122676A (en) * | 1961-04-26 | 1964-02-25 | Space Technology Lab Inc | Lamp striking arrangement |
US3138739A (en) * | 1961-12-26 | 1964-06-23 | Gen Technology Corp | Electrodeless lamp having a sheathed probe |
US3227923A (en) * | 1962-06-01 | 1966-01-04 | Thompson Ramo Wooldridge Inc | Electrodeless vapor discharge lamp with auxiliary radiation triggering means |
-
1963
- 1963-08-27 US US304878A patent/US3311775A/en not_active Expired - Lifetime
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1698691A (en) * | 1926-07-01 | 1929-01-08 | Cooper Hewitt Electric Co | High-intensity induction lamp |
US2974243A (en) * | 1959-11-12 | 1961-03-07 | Space Technology Lab Inc | Light source |
US3122676A (en) * | 1961-04-26 | 1964-02-25 | Space Technology Lab Inc | Lamp striking arrangement |
US3138739A (en) * | 1961-12-26 | 1964-06-23 | Gen Technology Corp | Electrodeless lamp having a sheathed probe |
US3227923A (en) * | 1962-06-01 | 1966-01-04 | Thompson Ramo Wooldridge Inc | Electrodeless vapor discharge lamp with auxiliary radiation triggering means |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3497767A (en) * | 1966-04-14 | 1970-02-24 | Csf | Constant intensity monochromatic light source |
US4035691A (en) * | 1975-08-04 | 1977-07-12 | The United States Of America As Represented By The Secretary Of The Navy | Pulsed laser excitation source |
US4766351A (en) * | 1987-06-29 | 1988-08-23 | Hull Donald E | Starter for inductively coupled plasma tube |
EP0447852A2 (en) * | 1990-03-12 | 1991-09-25 | General Electric Company | Luminaire for an electrodeless high intensity discharge lamp with electromagnetic interference shielding |
EP0447852A3 (en) * | 1990-03-12 | 1992-10-21 | General Electric Company | Luminaire for an electrodeless high intensity discharge lamp with electromagnetic interference shielding |
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Owner name: B.C. RESEARCH COUNCIL, 3650 WESBROOK MALL, VACOUVE Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:YAMAMOTO, MASANOBU;REEL/FRAME:004169/0641 Effective date: 19830824 |
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Owner name: TRACOR AEROSPACE AUSTIN INC Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:TRACOR INC A TX CORP;REEL/FRAME:004188/0864 Effective date: 19830901 |
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Owner name: TORONTO-DOMINION BANK, THE, AS AGENT Free format text: SECURITY INTEREST;ASSIGNOR:TRACOR, INC.;REEL/FRAME:004810/0283 Effective date: 19871216 |
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Owner name: TORONTO-DOMINION BANK, THE Free format text: SECURITY INTEREST;ASSIGNORS:TRACOR, INC.;LITTLEFUSE, INC.;TRACOR AEROSPACE, INC.;AND OTHERS;REEL/FRAME:005234/0127 Effective date: 19880801 Owner name: BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIA Free format text: SECURITY INTEREST;ASSIGNOR:TRACOR INC.;REEL/FRAME:005217/0224 Effective date: 19880801 Owner name: BANK OF AMERICA AS AGENT Free format text: SECURITY INTEREST;ASSIGNOR:TORONTO-DOMINION BANK, THE;REEL/FRAME:005197/0122 Effective date: 19880801 Owner name: BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIA Free format text: SECURITY INTEREST;ASSIGNOR:TRACOR, INC.;REEL/FRAME:005217/0247 Effective date: 19880801 Owner name: BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIA Free format text: SECURITY INTEREST;ASSIGNOR:TORONTO-DOMINION BANK THE;REEL/FRAME:005224/0751 Effective date: 19880801 Owner name: BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIA Free format text: SECURITY INTEREST;ASSIGNORS:TORONTO-DOMINION BANK;TRACOR, INC.;REEL/FRAME:005224/0276 Effective date: 19880801 |
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Owner name: TRACOR, INC. Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIATION AS COLLATERAL AGENT;REEL/FRAME:005957/0562 Effective date: 19911220 Owner name: TRACOR, INC. Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIATION AS COLLATERAL AGENT;REEL/FRAME:005957/0542 Effective date: 19911227 |