US3439209A - Positive column gas discharge lamp employing an alloy of two metals with impedance-free terminal connections - Google Patents
Positive column gas discharge lamp employing an alloy of two metals with impedance-free terminal connections Download PDFInfo
- Publication number
- US3439209A US3439209A US572513A US3439209DA US3439209A US 3439209 A US3439209 A US 3439209A US 572513 A US572513 A US 572513A US 3439209D A US3439209D A US 3439209DA US 3439209 A US3439209 A US 3439209A
- Authority
- US
- United States
- Prior art keywords
- alloy
- metals
- lamp
- positive column
- current
- Prior art date
- 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.)
- Expired - Lifetime
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/12—Selection of substances for gas fillings; Specified operating pressure or temperature
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/70—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr
- H01J61/72—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr having a main light-emitting filling of easily vaporisable metal vapour, e.g. mercury
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/70—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr
- H01J61/74—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr having a main light-emitting filling of difficult vaporisable metal vapour, e.g. sodium
Definitions
- FIG-.1 POSITIVE COLUMN GAS DISCHARGE LAMP EMPLOYING AN ALLOY OF TWO METALS WITH IMPEDANCE-FREE TERMINAL CONNECTIONS Filed Aug. .15, 1966 Sheet 0f 2 FIG-.1
- Substantially impedance-free connections to an energy source are provided and the lamp is operated at a wall temperature at which at least of the metal having the lower ionization potential is ionized at the place of the positive column in each cross-sectional area of the lamp where the positive column is located while the density of the other metal has a value favorable to the radiation generation.
- the invention relates to a device comprising a gas discharge lamp having a filament cathode, in which an arc discharge with radiation emission from the positive column occurs, the lamp containing, apart from a rare gas, at least two volatile metals, at least one of which is an alkalimetal.
- the invention furthermore relates to a lamp intended for use in such a device.
- the radiation emission may lie in the invisible part as well as in the visible part of the spectrum.
- the invisible radiation for example ultraviolet radiation, may be converted by luminescence into light.
- the lamp filled with a rare gas, an alkali-metal and mercury is operated so that all gas and vapour is ionised.
- the idea underlying this lamp is that the vapour pressure of the mercury is so low due to its being alloyed with an alkali-metal that by the depletion of the number of ionisible atoms the number of charge carriers does not or substantially not increase with an increase in current.
- the rare gas is ionised, a positive characteristic can be obtained only when the pressure of the rare gas is very low, mm. or less. At this pressure, however, no positive column can appear, but there does occur a ditferent type of discharge, the light output of which is low.
- the low gas pressure gives rise to difliculties in the ignition and to disintegration of the electrodes.
- a device comprising a gas discharge lamp with a thermionic cathode, in which an arc discharge with radiation emission from the positive column occurs, said lamp containing, apart from a rare gas, at least two volatile metals, at least one of which is an alkali-metal, the two volatile metals are provided, in accordance with the invention, in the form of an alloy and the wall temperature under the operational conditions of the lamp is chosen so that the component of the alloy having the lower ionisation potential at the place of the positive column, is ionised for at least 20% on an average in the cross-sectional area of the lamp, whereas the density of the constituent of the higher ionisation potential has a value which is favourable for the radiation emission and the pressure of the rare gas is about 0.1 to 10 torr.
- the raregas serves to enable the positive column to occur, to facilitate the ignition and to counteract the disintegration of the electrodes.
- the ionisation potential of the rare gases is always higher than that of the volatile metals, which will preferably be selected from the alkali-metals, cadmium, zinc and mercury.
- the invention is based on the idea that due to the low pressure of the constituent of the lower ionisation potential a certain degree of saturation of the ionisation in the positive column is reached under the operational conditions.
- the longitudinal voltage gradient in the positive column must increase, in order to raise the number of charge carriers, so that the characteristic becomes positive; this positive characteristic disappears only when the voltage gradient in the positive column has reached such a high value that also the second constituent, and, as the case may be, also the rare gas are ionised to a noticeable extent.
- the advantage obtainable by a lamp in a device according to the invention consists not only in the positive current-voltage characteristic, due to which the series impedance may be omitted, but also in that the pressure of the constituent producing the radiation may be so chosen that the optimum value for the radiation generation is obtained.
- the diameter of the lamp should thereby be taken into account.
- the vapour pressure of the radiation emitting metal also had to fulfill the conditions for current conduction, which means that the requirements for current conduction and radiation production had to be compromised.
- the invention can be applied to lamps having mercury as the radiation producing element, in which one or more of the five alkali-metals caesium, rubidium, potassium, sodium and lithium can be added alone or in the form of an alloy.
- the invention may furthermore be applied to socalled sodium lamps, in which then the current conduction is mainly provided by caesium, rubidium, potassium or alloys thereof.
- any other metals are admixed, any influence on the vapour pressure of the metal providing mainly the current conduction and of the metal providing mainly the radiation has to be taken into account, while the additional metals may contribute to current conduction and to radiation emission.
- the pressure of the current conducting constituent can be determined by the formula:
- drift velocity is to be understood to mean the current density (j) divided by the total charge per cubic centimetre of the movable electrons.
- the temperature can be chosen so that the desired pressures are obtained.
- the vapour pressure of the constituent of an alloy is, in general, the vapour pressure of the pure metal multiplied by the fraction of said constituent in the alloy, :1 coelfcient being added, which is the activity coefiicient, which may be higher or lower than 1.
- the activity coefiicients are known for many alloys.
- Advantageous combinations for a lamp according to the invention are caesium or sodium as current-conducting constituent and mercury as a radiation emitting constituent, the rare gas being argon, krypton or xenon.
- a combination of caesium as the current-conducting constituent and of sodium as the radiation emitting constituent with argon, krypton or xenon as the rare gas also is advantageous.
- the radiation generation will extend gradually from the portion around the axis towards the wall at an increase in current intensity and at an increase of the degree of ionisation. In many cases this appears first at the anode end of the discharge space.
- the most favourable compromise between the stability without ballast and a low self-absorption in the positive column is obtained when the boundary between the radiation generation throughout the sectional area and in the portion around the axis is located approximately at the middle of the discharge space.
- FIG. 1 shows a lamp according to the invention and FIG. 2 shows voltage-current curves at different temperatures for this lamp.
- the lamp comprises a hard-glass tube 1 having an inner diameter of 30 mms. and a length of 750 mms.
- the tube comprises two cathodes 2 and 3, surrounded by nickel rings 4 and 5 respectively.
- the tube has a filling of 3 mms. argon and furthermore a quantity of 200 mgs. of an alloy of 45 atom percent of mercury and 55 atom percent of caesium.
- the pressure of the mercury is about 2 10- torr and that of the caesium 2 10 torr.
- FIG. 2 the voltage in volts of the lamp shown in FIG. 1 is illustrated at a direct-current discharge varying between about 100 and 500 ma.
- the measurement showed that the tube wall assumed the temperature indicated in the current-voltage characteristics; this temperature was controlled by a second tube 6 surounding the lamp and having a heating wire. It is apparent that the total voltage of the tube strongly increases with an increasing current and that the maximum in this characteristic appears at a current which increases with an increasing wall temperature.
- the caesium portion may vary between 40 and 75 atom percent whilst the mercury portion is varied simultaneeously.
- the composition is 98 atom percent of sodium and 2 atom percent of mercury.
- the temperature is then about 483 K.
- alternating current discharge may be used instead of direct-current discharge, which is more important for practical purposes.
- the alloy chosen contains less than 1% of caesium at a temperature of 483 K. to 543 K., the pressure of the caesium being 2 10- torr and the pressure of the sodium being 2 10 torr.
- the precise composition of the alloy and the choice of the temperature depend upon the requirements imposed: either maximum efiiciency or maximum light output or a compromise thereof.
- a device comprising a gas discharge lamp having a thermionic cathode and emitting radiation from a positive column, the lamp containing a rare gas at a pressure of the order of 0.1 to 10 torr and an alloy of at least two volatile metals having different ionization potentials, at least one of said metals being an alkali-metal, and means to energize the lamp to produce therein a wall temperature at which at least 20% of the metal having the lower ioniaztion potential has a value favorable to the radiation column in each cross-sectional area of the lamp at said place while the density of the metal having the higher ionization potential has a value favorable to the radiation generation, said energizing means including means substantially free of impedance for connecting said lamp to an energy source.
- a device as claimed in claim 1 in which at the anode end of the positive column the radiation is produced throughout the cross-sectional area and over part of the cross-sectional area at the cathode end.
Landscapes
- Discharge Lamp (AREA)
- Discharge Lamps And Accessories Thereof (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL6511266A NL6511266A (hu) | 1965-08-28 | 1965-08-28 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3439209A true US3439209A (en) | 1969-04-15 |
Family
ID=19794002
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US572513A Expired - Lifetime US3439209A (en) | 1965-08-28 | 1966-08-15 | Positive column gas discharge lamp employing an alloy of two metals with impedance-free terminal connections |
Country Status (11)
Country | Link |
---|---|
US (1) | US3439209A (hu) |
AT (1) | AT266259B (hu) |
BE (1) | BE686073A (hu) |
CH (1) | CH477090A (hu) |
DE (1) | DE1539498C3 (hu) |
ES (1) | ES330611A1 (hu) |
FI (1) | FI41416B (hu) |
GB (1) | GB1152719A (hu) |
NL (1) | NL6511266A (hu) |
NO (1) | NO120120B (hu) |
SE (1) | SE303334B (hu) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3806747A (en) * | 1973-03-08 | 1974-04-23 | Gte Sylvania Inc | Sodium vapor lamp having an improved grooved alumina arc tube |
US3806748A (en) * | 1973-03-08 | 1974-04-23 | Gte Sylvania Inc | Sodium vapor lamp having a grooved alumina arc tube with side rod heater retainer |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL7405871A (nl) | 1974-05-02 | 1975-11-04 | Philips Nv | Inrichting voorzien van een gas- en/of dampontladingsbuis. |
NL168993C (nl) * | 1975-01-17 | 1982-05-17 | Philips Nv | Werkwijze voor het bedrijven van een zelfstabiliserende ontladingslamp. |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1961750A (en) * | 1932-12-31 | 1934-06-05 | Gen Electric | Gaseous electric discharge device |
US2016111A (en) * | 1933-10-30 | 1935-10-01 | William J Hitchcock | Gas discharge lamp, especially mercury lamp |
US2042261A (en) * | 1931-11-06 | 1936-05-26 | Gen Electric | Gaseous electric discharge device |
US2733371A (en) * | 1950-05-12 | 1956-01-31 | Internally conducttvely coated | |
US3219869A (en) * | 1963-07-01 | 1965-11-23 | Gen Electric | Cesium vapor discharge lamp |
-
1965
- 1965-08-28 NL NL6511266A patent/NL6511266A/xx unknown
-
1966
- 1966-08-15 US US572513A patent/US3439209A/en not_active Expired - Lifetime
- 1966-08-23 DE DE1539498A patent/DE1539498C3/de not_active Expired
- 1966-08-25 FI FI2233/66A patent/FI41416B/fi active
- 1966-08-25 GB GB38114/66A patent/GB1152719A/en not_active Expired
- 1966-08-25 NO NO164439A patent/NO120120B/no unknown
- 1966-08-25 AT AT807566A patent/AT266259B/de active
- 1966-08-25 SE SE11491/66A patent/SE303334B/xx unknown
- 1966-08-25 CH CH1232866A patent/CH477090A/fr not_active IP Right Cessation
- 1966-08-26 BE BE686073D patent/BE686073A/xx unknown
- 1966-08-26 ES ES0330611A patent/ES330611A1/es not_active Expired
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2042261A (en) * | 1931-11-06 | 1936-05-26 | Gen Electric | Gaseous electric discharge device |
US1961750A (en) * | 1932-12-31 | 1934-06-05 | Gen Electric | Gaseous electric discharge device |
US2016111A (en) * | 1933-10-30 | 1935-10-01 | William J Hitchcock | Gas discharge lamp, especially mercury lamp |
US2733371A (en) * | 1950-05-12 | 1956-01-31 | Internally conducttvely coated | |
US3219869A (en) * | 1963-07-01 | 1965-11-23 | Gen Electric | Cesium vapor discharge lamp |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3806747A (en) * | 1973-03-08 | 1974-04-23 | Gte Sylvania Inc | Sodium vapor lamp having an improved grooved alumina arc tube |
US3806748A (en) * | 1973-03-08 | 1974-04-23 | Gte Sylvania Inc | Sodium vapor lamp having a grooved alumina arc tube with side rod heater retainer |
Also Published As
Publication number | Publication date |
---|---|
ES330611A1 (es) | 1967-12-16 |
NL6511266A (hu) | 1967-03-01 |
DE1539498C3 (de) | 1975-09-25 |
SE303334B (hu) | 1968-08-26 |
FI41416B (hu) | 1969-07-31 |
BE686073A (hu) | 1967-02-27 |
AT266259B (de) | 1968-11-11 |
DE1539498A1 (de) | 1969-11-06 |
DE1539498B2 (de) | 1975-02-13 |
NO120120B (hu) | 1970-08-31 |
CH477090A (fr) | 1969-08-15 |
GB1152719A (en) | 1969-05-21 |
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