CA2128682A1 - Electrodeless lamp with thin shell power applicator - Google Patents

Abstract

Abstract of the Disclosure An electrodeless lamp with a thin shell first power applicator having a lamp capsule, first power applicator, second power applicator, first power lead, second power lead, and means for powering the lamp is disclosed. The thin shell first power applicator does not touch the lamp capsule, but is closely adjacent, and generally conformal with the capsule surface. The first power applicator efficiently couples power to the capsule, but does not drain heat from the capsule, thereby enhancing overall lamp efficiency, and limiting thermal stress to the support and power delivery structures. The thin shell applicator also reduces capacitive interference with the lamp plasma, thereby improving plasma position, shape, and stability.

Description

- 2~286~2 El~ctrodele ~ Lamp With A Thin Shell Pow~r Applicator 1. Technical Field The invention relatQ~ to electric lamps and particularly to electrodele~9 high inten~ity dl charge lamp~. More particularly the invention i3 concerned with a power applicator for an electrodeless high inten~ity discharge lampc 2. Background Art Electrodeless, high inten~ity lamp~ are efficient producers of vi~ible llght. The bright, inten~e light emitted by electrodele~ lamp~ exceeds many common need~, ~o the lamp~ are commonly ~caled to have relatively ~mall ~ize.
For example, a lamp powerful enough to form a Yehicle hea~lamp might use a lamp capsule only a few millimeters in diameter and only a few centimeter~ long. For 5uch a ~mall capsule, the power applicator and lamp need to b~ accurately aligned, as mi~alignment result~ in mismatch and power loss.
There i~ a similar n~ed to control the thermal flux of the cap~ule. ~he high liyht output i~ a result of th~ hi~h temperature o the enclosed plasma, but wi~h such a ~mall lamp body, heat 19~s can be rapid and substantial.
In the past, power ha~ been applied to the lamp capsule by machined metal cups, metalized ceraMic cups ~ and me~al coils. The Applicant has found that th~ mach~ned metal cup~
conduct he8~ away from the lamp cap~ule, coollng ~h~ cap~ule and ~hereby reducing ~he energy Pf f iciency of the lamp .
Al~o, the heat conducted into the power applicator may detrimentally affect the power coupling to the capsule, the mechanical ~ntegrity of the applicator, the applicator ~upport structure, and the electrical conn~ction o~ the applicator. In particular, the Applicant has found that the hiqh heat experienced by the machined cup~ when in clo~e prox~mity to th~ lamp capsule cau~d the ~olid metal - , ,, ~ . .

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:, ,, . - ~ ;, 2~286lg2 surface~ to darken, or ~pall, while the coatings of ceramic material~ evaporated, or ~caled off. The hlgh heat al~o caused the soldered connection hetween the applicator and the ~icrostripline power lead to soften or melt, allowing the applicator to shift po~ition~ in the ~older thereby al~ering the conductivity of the connection and the power delivery to the capsule. The high heat loss under any condition represented a los8 of power efficiency. There i~
a need for a power coupler that minimally conduct3 heat from the lamp capsule.
Machined metal cup type applicators al~o compri~e electrical capacitors with unwanted alectrlcal characteristics. The Appllcant has found the regular metallic ~urface of a machined block ~upport~ a stray capacitance with respect to the rest of the block's surroundings. The stray capacitance alters the tuning between the concave field ~haping ~urface and the lamp, causing movament of thz lamp pla~ma, and flicker and color irregularitie~ in the light outpu~. Without accurate sh~ping, the lamp plasma may be displaced, and may thereby detrimentally interact with the capYule wall, shortening lamp life, or reducing lamp quality. There i8 a need for a power applicator, that has reduced or no stray capacitance to interfere with lamp operation.
Machined cups ~re also relatively heavy, thereby requirlng heavier supports to resi~t vibration. The heavy support~ have similar adver~e heat and capacit~ve affect~ a~
do the machined CUp8 . There ~ then a need for a small power applicator ~hat can be inexpensively manufactured, that may be held in po~ition accurately.
Example~ of the related art are shown in the following U.S. patents:
U.S. patent 4,041,352 i~ ued to William H. McNeill et al on August 9, 1977 for a starting system for an electrodeles~ lamp shows a singled ended excitation source.

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al on Augu~t 9, 1977 for a ~tarting ~ystem for an electrodele~ lamp show~ a capsule held in a cup radlator, which is then enclo~ed by a container and mesh screen radiator.
U.S. patent 4,266,162 is~ued ~o William H. McNeill et al on August 9, 1977 for a starting system for an electrodeless lamp shows a doubled ended excitation ~ource.
In claim 1 Mc~eill cite~ the termination load approach, and in claim 5 cites the need to conkrol the electric field in the vicinity of the lamp envelope.
U.S. 5,113,121 issued to Walter P. Lapatovich et al, on May 12, 1392 for Electrodeless HID Lamp with Lamp Cap~ule ~hows a doubled ended cap~ule ~upported on a circuit board structure, having two coil power applicators. In ~olumn 6, line~ 34 et s~q. the coils are de~cribed as being o~fset from the lamp cap~ule. By not touching the cap~ule, the heat lo~ from tho capsule is limited.
U.S. 5,130,612 issued to i~sued as to Walter P.
Lapatovich e~ al, on July 14, 1992 for Loop Applicator for Hi~h Frequency Electrodele~s Lamp~ ~how~ a doubled ended capsule supported on circuit board structur~, havlng two hairpin wire power applicators. In column 3, line~ 13 et eq. the coils are de~cribed as belng offset from tha lamp cap~ule. An advantags of the hairpin coll is de~cribed to be the minimal coupling of heat conducted back to the solder ~oint~.
U.S. 5,130,612 l~ued to i ~ued a3 ~o Sco t Butler, Walter P. Lapatovich, and Jason 80chin~ki September 1, 1992 for Electrodeless HID ~amp Coupling Strueture with Integral Matching Network, shows a doubled ended capsule supported on a circuit board structure, having two coil power applicators. A matching impedance network structure is de~cribed.

21286~2 U. S, S. N. 07/757,095 issued to Walter P. Lapatovlch, for End Cup Applicator for High Frequency Electrodele~
Lamps disc10-~2s solid metal block applica~ors with concave openings. The block3 are altsrnatively formed from a metali2ed ceramic. The concavity ls offset from the lamp capsule by from 0.1 to 10 millimeters.

Disclosure_of the Invention An ~lectrodele~s lamp may be formed with an electrodeles~ lamp capsule, the cap~ule having an axis, an enclosed volume containing a mlxture of gas and chemical dopant material excitable by radio frequency electromagnetlc radiation to a state of luminous em~ sion, and a mechanical support coupling, a first power appllcator, a second power applicator, and radio frequency power connection. The lamp capsule l~ generally positioned coaxial with ~he fir~t power applicator ~o the enclosed volume of the lamp capsule i3 intermediate the fir~t power applicator and the 3econd pow~r applicator. A support coupled ~o the lamp capsule may be formed to hold the lamp capsule intermedia~e the f~r~t power applicator and the second power applicator. The fir~t preferred power appllcator i~ formed a~ a thin metal ~hell having a concaYe wall ad~acent, while off~et from the lamp cap~ule 30 as to not touch the lamp capsule, while being approximately conformal with a portion of the exterior surface of the lamp capaule.

Brief Deacri~tion of the Drawin~
0 FIG. 1 show~ a slde, cross sectional view, partially broken away of a preferred embodiment of a thin sh~ll pow~r applicator and lamp capsule.
FIG. 2 shows a ~op view of an ~lectrodeless lamp.
FIG. 3 show a front vi~w of a preform for a power applicator with a wide tab.

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FIG. 4 shows a front view of a preform for a power applicator with a moderately wide tab.
FIG. 5 shows a front view of a preform fox a power applicator with a narrow tab.
Best Mode for Carrvin~ Out the Invention FIG. 1 shows a side~ cros~ sectional view, partially broken away of a preferred embodiment of a thin shell power appllcator, and lamp capsule. Like reference number~ are used throughout the drawings and specification to designate like or corresponding parts. The electrodeless lamp 10 may be assembled from a lamp capsule 12, a fir~t power applicator 26, a secvnd power applicator 58, a fir~t power lead, a ~econd power lead~ and a support structuxe. FIG. 2 shows a top view of an electrodeless lamp 10.
Th~ lamp cap~ule 12 may be made out of quartz to have the general form of a elongated, closed tube with a lamp cap~ule axis 14. The lamp capsule 12 ~hereby defines an enclosed volume 16 that may be filled with any of the well known combinations of ga~e~ and chemical dopants u~ed in ~lectrodeless l~mps. The lamp cap3ule 12 in the region of the enclosed volume 16 has a fir~t outside diameter 18. ~he fir~t outside diameter 1~ typically varie~ from perhaps a~
little as 2 millimeters to a3 much a~ 10 or more millimeter~, The pre~erred fir~t out~ide diameter 18 i~ 4.0 millimeter~, while the ad~acent wall~ are 1.0 millimeters th~ck, giv~ng an in~ide diameter of about 2.0 millimeter~.
~he lamp capsule 12 may b~ rounded, at a fir~t end 20 to generally have a hemispherical form. Pro~ecting axially from one or both of the ends of the lamp cap~ule 12, the preferred embodi~ent further includes one (or two) rod or tubular extension(s) 22. The lamp capsule 12 may be ~upport by the extension(s) 22. The preferred lamp cap~ule 12 has a tubular rod extension 22 wi~h an ou~side diameter 24, les~

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2~2~82 D 93~1-445 -6- PATEN~

than th~ first outside diameter l~. The preferred exten~ion 22 i~ open at the end far~hest from the lamp capsule 12. ~y way of example, the lamp cap~le 1~ iq ~hown a~ a s~raight tube with a larger diameter middle region, saaled at each end, with a ~maller diameter, axially aligned, tubular extension 22 that may be used to support the lamp capsule 12.
FIG. 3 ~hows a front view of a prPform for a fir~t power applicator 26 with a wide tab 28 with a width 30.
FIG. 4 show~ a front view of an alternative preform for a first power applicator 32 with a modexately wide tab 34 with a width 36. FIG. 5 shows a front view of a still further alternative preform for a fir~t power applicator 38 with a narrow tab 40 wlth a width 42. The first power applicator 26, 32, 38 may be made out of conductive metal1 abl~ to withstand the high temperature of nearly 900 Cel~ius resulting from being po~itionsd close the oparating lamp cap~ule 12. Metal~ such as nickel, molybdenum, titanium, and tung~ten are sugge~ted. Alternatively a high temperature ~uper conducting ceramic, ~uch a~ a yttium-barium-copper-oxide formed a~ a thln foil ~s thought to be potentially useful, e~pecially for lamps with fill chemistries requiring only low operating temperatures. In such a ca3e, the high temperature ~uperconduc or may remain ~uperconductive.
The preferred $irst power applicator 26 is formed from a thin nickel foil, with a concave wall 44 that i~ ~ized and shaped to fit around an end of t~e lamp capsule 12 to be near an axial end o the enclosed volum~ 16. The wall thicknes~ 46 ~hould be substantially le~ than th~ width 47 of the whole power applicator 26, perhaps one tenth of the whole applicator w~dth, to reduce capacitance, and i~
preferably about the thicknes~ of the mircostripline 64 for minimal impedance mismatch. Nonetheless~ the first power applicator 26 must still be thick 46 enough to mechanically ., , . . . , , , - , , ,............................. . . ~. - ~ - .-.

2 12'3 ~?, ~tand in place. The preferred wall thickness 46 of the power applicator 26 i9 les3 than 1.0 millimeter, and more preferably is about 0.5 millimeters thick. By limiting the power applica~or 26's thickne~s 46, the adverse capac1tive affect~, heat content, and thermal conductlvity of the fir~t power applicator 26 are limited.
The fir~t power applicator 26 is preferably formed with a concave wall 44, with the concave wall 44 facing the lamp capsule 12's enclosed volume 16. Further, the concave wall 44 may have a similar or the same shape a~ the exterior wall of the adjacent first end 20 of the lamp capsule 12. The lamp capsule 12 is preferably rotationally symmetric about the lamp cap~ule axis 14. Similarly the preferred first power applicator 26 in the concave wall 44 region i8 al~o rotationally symmetr$c around the fir~t power applicator axis 48. Where the lamp capsule 12 i5 formed wlth an approximately hemispherical first end 20, the preferred power applicator 26 is formed with a similar heml~pherical concave wall 44 that then ha~ a slightly larger hemispherical appllcator d~ameter 50. The hemi~pherical ~hell then define~ an appllcator axis 48, that is preferably parallel with, and even collinear with the lamp cap~ule axis 14. The first power applicator 26 may have a ~imilar general form, that o~ a thin walled, hemi~pherical 3hell, roughly conformal with shape of the exterior of the sealed end of the lamp cap~ule 12. The preferred concave wall 44 ha~ an axial depth that i~ at lea~t a tenth of the applicator diameter 50. The shape of the concave wall 44 forces an electrlc field concentra~ion in the vicinity of the fir~t end 20 and in the gap between the opposing fir t power applicator 26 and the ~econd power applicator 58.
While hemispherical form8 have been used, elliptic~l, and hyperbolic surface~ of revolution about the lamp axis may also be used. Even planar flat wall structures may be used, but these are believed to be le~s efficient power coupler3.

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212~6~2 Where the fir3t power applicator 26 i~ concave, the end of the lamp capsule 12 may be ins~rted in~o the concave region of ~he first power applicator 26. The fir~t power applicator 26 may then be po~ltioned in a clo~e, ~ymmetric, but evenly offset relation to the first end 20 of ~he lamp capsule 12. The stand off 52 distance is considered to be the least axial distance from lamp capsule's fir~t end 20 to the first power applicator 26. The preferred ~tand off 52 i5 in the range of from 0.1 to 10.0 millimeter~. The preferred stand off 52 ls about 0.5 millimeters for lamps with hemispherical ends, 4.0 millimeters iJI outside diameter, and operated at about 35 watts. The applicator diameter 50 of the concave wall 44 may then equal the first outside diame~er 18 of the lamp capsule 12, plu3 twice the expected stand off 52 distance, say 0.5 millimeter~, for a total inside applicator diameter 50 of 5.0 millimeter~.
Where the lamp cap~ule 12 includes a pro~ecting tubular extension 22, the f~rst power applicator 26 may deflne an included through hole 54, of sufficien~ly large diameter to allow the tubular exten~ion 22 to pass through, while leaving ~uf f icient separation ~pace, so the tubular extension 22 and fir~t power applicator 2~ do not touch, particularly during lamp operation. The fir~t power applicator 26 then does not act a3 an effective heat sink for the lamp cap ule 12. The preferred fir~t power applicator 26 i~ then positloned to be clo~e to the first end 20 of the lamp cap~ule 12, les~ than a quarter wave lengSh o~ the power to be applied, or le~. G2nerally, for good coupl~ng of the appliad power into the lamp cap~ul0 12, the fir~t power applicator 26 i~ positioned a3 clo~ely as possible, but wi~hout actually touching the lamp capsule 12.
A ~tand off 52 distance between the lamp capsule 12 and the first power applicator 26 of f;ve or less millimeters is preferred~ from 0.5 to 1.0 mlllimeters being most preferred.
Similarly the lamp cap~ule 12 and flrst power applicator 26 - . . -~,: ~: , .

212~6~2 are preferably parallely aligned and even collinearly allgned.
The concave wall 44 of the fir~t power applicator 26 may be ~upported by an elongated tab 28 having a width 30 approximately equal to the applicator diameter 50. The length of the tab 28 may be conveniently cho~en to allow the tab 28 to be held and connected to th~ radio frequency power lead, ~uch as mlcrostripline 64. In one form, the tab 28 was bent to provide a solderable ba~e portion for the power applicator. By bending the tab 28 at about 90, a stand with a flat base 72 may be formed that i~ readily po~itioned agains~ and then soldered to a microstripline 64. The thin walled first power applicator 26 even w~th a wide tab 28 i9 effective in llmiting heat conduction and improving lamp performance.
The tab 28 is inherently a heat conductor. ~y also limiting the width of the tab 28 to less than the applicator diameter 50, les~ heat may flow from the concave wall 44 ad~acent the lamp capsule, down the length of the tab 28 to the radio frequ0ncy power source ~tructure, which in on~
case wa~ a circuit board. FIG. 4 shows a ~imilar power applicator 32 wlth a tab 34 whose width 36 i~ about 70 percent of the applicator diameter 50, or in one example about 3.5 millimeters. The narrower tab 34 resi~t~ heat conduction bett~r than the wider tab 28. FIG. 5 show~ a ~imllar pow~r applicator 38 with a ~till narrower tab 40 whose width 42 is about 40 percent of the applicator diameter 50, or in one example about 2.0 millimeters. The narrower the tab width 30, 36, 4~, the less heat may be conducted through the tab to the support for the power applicator. The tab 28 ~34, 40) also serve~ as a radio frequency power connection. By matchlng the tab width 30 (36, 423 to the width of the radio frequency input source, such as the microstripline S4 width, an e~ficient el~ctrical connection i~ made. The preferred tab width i~ fir~t . . . ;.
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21~86~2 D 93-1-445 -10- PA~EN~

ad~u3ted to match the width of the micro~tripline. The preferred tab width then depends indirectly on the impedance characteri3tics of the miorostripline, the lamp capsule, the power frequency, and the power source.
As shown ln Fig. 2, a sQcond power applicator 58 may be ~imilarly formed and 3imilarly po~it~oned with re~pect to the lamp capsule 12, but at the opposLte axial end, the second end, of the lamp capsule 12. The preferred first power applicator 26 and the second power applicator 58 are symmetric, so the power distributed by them is even acros~
the length of the lamp capsule 12, and the enclosed volume 16. Th~ first power applicator 26, the lamp capsule 12, the enclos~d volume 16, and the second power applicator 58 are preferably parallely align~d, and even collinearly aligned.
The enclosed volume 16 then receives the electromagnetic energy radiated between the first power applicator 26 and second power appli~ator 58 evenly.
The first pow~r applicator 26 receive~ a radio fre~uency power lnput from a first power lead, ~uch a~ a microstripline 64, connected to a power source (not ~hown).
Applicant~ prefer a planar tran~mlssion line, as constructed on a circuit board structure with a microstripline 64 on one side, an insulating intermsdiate layer 66, and a conductive plane 68 on the opposite side, the second side. The first power applicator 26 may then be soldered to the microstriplin2 64, while being braced by th0 circuit board material. The second power appl~cator 58 may be slmllArly electrically coupl~d to a ~econd m~crostripline connection, whlle al50 being mechanically ~upported by the circuit board material. The micro~tripline connectlons may lead back throu~h circuit patterns, such a~ a balun~ (not ~hown) to a power source (not hown) as is known in the art. The preferred circuit allows power transmission to the two power applicators with the vol~age~ in each power applicator 180 out of pha~e with the other.

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,: . , -212~2 In a working example, the lamp cap~ule was made of quartz, and had an outside diameter of 4.0 millime~er~, a wall thicknes~ of 1.0 millimeters, an inside dlameter of 2 millimeter~, and an in~ide length of about 10.0 millimeters.
The enclosed volume was about 0.03 cubic centim~ter~. The ends were closed to have approximately hemispherical ~hape~
and had a tubular rod extended axially ~rom one end. The tubulax exten~ion had an outside diameter of 1.8 millimeters, an in~ide diameter of 1.0 millimeter~, and a length of about 20.0 mlllimeters. The first power applicator was formed a~ a thin, flat, elon~ated, nickel foil rectangle. The foil was 0.25 millimeter~ (0.01 inch~
thick. One end of the rectangle was spun pr2~sed with a hemispherical tool to form a deep dimple, or concave wall.
The cavity was 5.0 millimeters in diamet~r. An axial through hole was drilled through the middle of the concave wall, and had a diameter of 2.25 millimeter~, ~lightly larger than the outside diameter of the tubular exten~ion.
At about 1.0 millimeters from the rim of the formed cavi~y, the foil tab wa~ bent at a right angle to parallel the cavity axl~, in the directlon away from the cavity opening.
The bent right angl~ portion o~ the foil provided a ~upport staAd (foot), and solder point for the form~d Aemlspher$cal ravity. ~ notched circuit board, with micro~tripline circuitry, provided the mechanical ~upport and electrical connection for thQ fir3t power applicator. ~ ~imilar second power applicator, wi~h a center through hole, was formed for the second end of the lamp capsule. The two power applicator~ were then thin walled, and still self ~tanding.
The two power applicators were positioned ad~acent the lamp capsule with the tubular extenYion passing through the axial through hole. The feet of ths two fir3t power applicator~
were ~oldered to the microstripline circuitry of the circuit board to thereby receive the power to be directed to the lamp caps~le. ~he tab~ of the power applicator~ were formed - :., - ~

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to have approximately the ~ame widths and thicknesses as the micro~tripline had. A ceramic V-block was attached to the circult board, and a bead of silicone rubber wa~ placed in the V of the support block. The ~ubular exten~ion wa3 placed across the V-block, and a second bead of ~ilicone rubber was place on top of the tubular exten~1on in the V-block. The tubular exten~ion positioned by the V-block then collinearly aligned the enclosed cavity and the fir~t power applicator. ~he power applicator~ recelved radio frequency power from the ~icrostripline circuitry to thereby power the lamp capsule. The applied power wa~ ~upplied through a micro~tripline structure at 2.45 GHz. Similar devLces have been operated at 915 Mhz, and still other frequencies may be u~ed. The reduction of the metal mas3 of the power applicator reduced the stray capacitances of the power applicators, making the power appl~cator easier to tune to the lamp operating impedance. The th~n foil al~o reduced the thermal conductivity of the power applicator. While heavier, solld metal cup applicators tended to float on a pool of ~oft or even molten solder after contlnued operation, le~ heat was conducted lnto the solder ~olnt by the thi~ walled applicator~, go the hin walled applica~ors stayed ~n place. ~he disclo~ed dimen~ion~, configurations and embodlment~ are as example~ only~ and other ~uitable configurations and relatlons may be us~d to implement the inv~ntlon.
The operatlon of the lamps was also found to be more l~othermal, than with heavy end cup structure~. For example, oth~r field applicators u~ed with a 4 millimeter diameter lamp and operated at 2.45 GHz showed an end to end temperature difference of 65 to 70 Celsiu~ and a top to bottom temperature difference of about 50 Celsius. With the thln walled power applicators, the end to end ~emperature difference was ahout 55 Celsius and the top to bottom difference was about 7 Cel~ius. Being more .. : ~: . . . . . :

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i~othermal contributed to the stabili~y of the discharge, and to a more uniform lumlnance along the arc. The close to isothermal operation give~ a better condensate distribution and mora light output. The nearly lsothermal opera~ion 1 thought to result ~rom power being delivered to the di~charge more uniformly.
In operation, the lamp was found to have le~s flicker and similar distortion of the arc due to the reduced capacitive affects. The power applicator~ did not over heat, and did not change poYition due to ~older softening.
The lamp capsule with the thin walled power applicator wa~
found to produce 124 lumen~ per watt, while a similar lamp capsule, with a coil type applicator was found to produce 88 lumens per watt. Thl~ amounted to a forty percen~ increase in efficiency. The greater lumen efficiency 1~ thought to b~ due to the improved capacltive coupling to the discharge lamp capsule.

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Claims (18)

1. An electrodeless lamp comprising:
a) an electrodeless lamp capsule, the capsule having an axis, an enclosed volume containing a mixture of gas and chemical dopant material excitable by radio frequency electromagnetic radiation to a state of luminous emission, and a mechanical support coupling, b) a first power applicator comprising a thin metal shell having a wall adjacent, while offset from the lamp capsule so as to not touch the lamp capsule, and having a radio frequency power connection, c) a second power applicator, and having a radio frequency power connection, and generally positioned with the first power applicator so the enclosed volume of the lamp capsule is intermediate the first power applicator and the second power applicator; and d) a support coupled to the lamp capsule to hold the lamp capsule intermediate the first power applicator and the second power applicator.

2. The electrodeless lamp in claim 1, wherein the first power applicator has a concave wall symmetric positioned about the lamp capsule axis.

3. The electrodeless lamp in claim 2, wherein the concave wall is conformal with a portion of the adjacent, exterior surface of the lamp capsule.

4. The electrodeless lamp in claim 1, wherein the first power applicator has a wall thickness less than 1.0 millimeters.

5. The electrodeless lamp in claim 1, wherein the first power applicator has a wall thickness less than 0.3 millimeters.

6 The electrodeless lamp in claim 2, wherein the first power applicator has a support with a width that is not greater than 70 percent of the concave wall diameter.

7. The electrodeless lamp in claim 2, wherein the first power applicator has a support with a width that is not greater than 40 percent of the concave wall diameter.

8. The electrodeless lamp in claim 1, wherein the first power applicator has a support with a width that is not greater than 2.0 millimeters.

9. The electrodeless lamp in claim 2, wherein the first power applicator has a support with a width that is less than the concave wall diameter.

10. The electrodeless lamp in claim 1, coupled to a first radio frequency power lead, and wherein the first power applicator has a tab support with a width that is approximately equal to the width of the power lead.

11. The electrodeless lamp in claim 2, wherein the first power applicator defines a concave wall axially facing the lamp capsule, the concave wall having a diameter equal to or greater than the capsule diameter, the first power applicator having a wall thickness less than or equal to one tenth of the concave wall diameter.

12. The power applicator in claim 11, wherein the concave wall comprises a surface of revolution about the power applicator axis.

13. The power applicator in claim 12, wherein the concave wall comprises a section of a sphere.

14. The power applicator in claim 11, wherein the concave wall comprises a section an elliptical surface of revolution.

15. The power applicator in claim 11, wherein the concave wall has an axial depth of equal to or greater than one tenth of the power applicator diameter.

16. An electrodeless high intensity lamp comprising:
a) a lamp capsule having a tubular form, having an axis extending from a first end to a second end, and having an enclosed a chemical fill;
b) a first power applicator, formed as a thin walled concave shell in the form of a surface of revolution about the lamp capsule axis, having a diameter greater than the diameter of the lamp capsule, an axial depth of at least one tenth of the diameter, a wall thickness less than one tenth the diameter, and facing and axially aligned with the first end of the lamp capsule;
c) a second power applicator, positioned opposite the second end of the lamp capsule;
d) a first power lead, electrically coupled to the first power applicator; and e) a second power lead, electrically coupled to the second power applicator.

17. The lamp in claim 16, wherein the first end of the lamp capsule, and the shell concave wall are similarly formed, and the lamp capsule is positioned with respect to the shell concave wall to be offset by a constant distance throughout the region of insertion.

18. Each and every novel feature or novel combination of features herein disclosed.