Development of ultraviolet resonance lamp with improved transmission of radiatio

Bass, A. M.

English

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https://ntrs.nasa.gov/search.jsp?R=19710003046 2020-03-17T02:31:54+00:00Z
Feb. 3, 1970 A* M. B A S S  
ULTRAVIOLET RESONANCE LAMP 
F i l ed  Nov. 1, 1967 
, R E S O N A N T  
M I C R O W A V E  
24 - C A V I T Y  
P R I O R  A R T  
IN VENII'OR 
ARNOLD M. BASS 
United States Patent Office 3,493,805 Patented Feb. 3, 1970 
An object of this invention is the provision of an ultra- 
3,493,805 violet resonance lamp which may be operated with dis- 
ULTRAVIOLET RESONANCE LAMP charge at the window without rapid reduction in the ultra- Arnold M.  ass, Silver Spring, Md., assitznor to the United violet transmission through the window due to vaporiza- States of as represented by the tion and/or decomposition of the window sealing means. of the National Aeronautics and space Ad~iofrfration 5 The above and other objects and of the in- Filed Nov. 1,1967, Ser. NO. 679,885 
bt .  CI. HOlj 5/16,61/40 vention are obtained by means of a resonance lamp com- 
U.S. C1. 313-110 1 Claim prising a body in the form of a tube which is onen at 
one end. A skirt or sleeve-like member is formed-on or 
30 attached to the outside of the tube a spaced distance from 
ABSTRACT OF THE DISCLOSURE the open end. The skirt surrounds the tube and the ouen 
-- 
tube end terminates in substantially the plane of the open An ultraviolet monance lamp comprising a tube con- 
end of the skirt. A window is attached to the open end of taining a gas such as xenon, krypton, or the like, which the skirt in sealing engagement which window gas is excited so as to produce atomic resonance lines 15 also closes the tube end in 
manner. With this of relatively high intensity. 
arrangement, even if the tube is operated with the dis- The tube contains an ultraviolet wave-permeable win- 
charge impinging on the window, the discharge terminates 
through which radiation from the excited gas is at the tube end at a spaced distance from the sealing transmitted. Decomposition and/or vaporization of the 
means between the skirt and window. Consequently, 
window seal, particularly with impingement of the gase- 20 vaporization and,or decomposition of the sealing means 
ous discharge on the window, is prevented by means of is eliminated. a chamber which surrounds the tube adjacent the win- The invention will be better understood from the fol- dow. The window is in sealing engagement with the sur- lowing description when taken in conjunction with the 
rounding chamber and in non-sealing engagement with 
accompanying drawings. In the drawings: the tube. With this arrangement, even when the discharge 25 FIGURE is a generally diagrammatic view of a prior is allowed to impinge upon the window, it is terminated 
a spaced distance from the window seal to substantia~ly art resonance lamp excited by a microwave source; and FIGURE 2 is an enlarged fragmentary cross-sectional 
eliminate decomposition and/or vaporization of the win- 
view of a resonance lamp embodying the novel window dow seal. 
mounting arrangement of this invention. 
30 There are basically two different types of discharge re- 
The invention described herein may be made by an SOnanCe lamps, i.e. lamps which are excited by an arc volt- 
employee of the United States Government and may be age applied to electrodes within the tube, and lamps with- 
manufactured and us& by or for the Government for Out electrodes, which lamps are excited by microwaves. 
Governmental purposes without the payment of any royal- In FIGURE 1 of the drawings there is shown a prior 
ties thereon or therefor. 35 art resonance lamp 10 which is microwave operated by 
Resonance lamps for the production of monchromatic waves from a nkrowave source 12- The i ~ u r c e  12 may 
light of hi& intensity in the ul~aviolet range are well comprise a & O W ~ V ~  generator operating for example 
known and include a tube of glass, or like fused silica at 2450 mc-/sec. and supplying 125 watts of Power. 
material; which tube is filled with a suitable gas. The Microwaves from the generator 12 are fed to a resonant 
gas, when excited, produces resonance lines which are cavity 14 into or through which cavity the resonance 
useful in photochemical work, such as photolysis, and lamp 10 extends for excitation of the gas therewith. 
the like. Gases such as xenon, kryton, argon, neon, he- A conventional ultraviolet resonance lamp includes a 
lium, and the like, and mixtures of gases have been used. body comprising a tube 16 made of fused silica or like 
The tube is provided with an ultraviolet wave-permeable material such as glass, ''P~rex'' or the like, which tube 
window through which the radiation is transmitted, a win- p5 is ~ h ~ s e d  at one end 18. An opening is formed at the other 
dew of lithium fluoride (L~F)  often being used, which end of the tube which is closed by an Ultraviolet wave- 
window filters out radiation which is shorter than ap- permeable window 20 of lithium fluoride, Or other suitable 
proximately 1040 A. material. Seal means 22 such as "Apiezon W wax, epoxy 
The windows of prior art arrangements are secured di- cement, or like material, is used to secure the window to 
rectly to the tube as by cement, sealing compound, or 50 the tube. 
other suitable sealing means. Often, when such lamps are The tube 16 is first evacuated and then supplied with 
operated with the gaseous discharge impinging on the a suitable gas as through a line 24 which is subsequently 
window, the action of the discharge thereat weakens the sealed off as illustrated. A suitable getter, not shown, may 
seal or causes the seal to decompose. Also, the reaction be included in the lamp for the absorption of impurity 
products of the decomposition and/or vaporization may 65 gases, and the tube may be cooled if desired, to rm~ove 
coat the window, thereby adversely affecting the ultraviolet condensible impurities such as water vapor which may 
transmission therethrough. In addition, impurity atomic be present in the gas or desorbed from the tube walls 
emission lines may be produced by the gases which re- during operation. 
4 sult from the decomposition of the sealing composition. Both high and low pressure resonance lamp systems are An object of this invention is the provision of an ultra- known. With a low pressure system, gas at a pressure of 
violet resonance lamp which eliminates the above-men- O0 approximately 1 mm. Hg is employed. with the tube 
tioned problems encountered in the operation of prior art exposed to microwaves from the source 12, discharge is 
resonance lamps. initiated by a spark from a Tesla coil not shown. For 
An object of this invention is the provision of an im- maximum intensity output from the lamp, the power 
proved ultraviolet resonance lamp in which impingement 65 source 12 is adjusted so that the visible discharge within 
of the gaseous discharge on the lamp window seal is pre- the tube contacts the window 20. However, as noted 
vented. above, decomposition and/or vaporization of the sealing 
An object of this invention is to provision of an im- means 22 is particularly rapid when the discharge con- 
proved window mounting arrangement for resonance tacts the window, whereby the window seal is weakened 
lamps which substantially eliminates decomposition and/ 7O and the window is coated with the reaction products. 
or vaporization of the window seal often produced when A novel lamp construction which eliminates these prob- 
the discharge impinges on the window. lems is shown in FIGURE 2 to which Egure reference is 
now made. There, a i'~agmi.,nia;y portion of a lamp 28 ?he electrode type as ivc!! as to :he ill~is!m!ed electrode- 
is shown comprising a tube 30 of fused silica or like less lamp. It is intended that the above arrd other such 
matel-ial such as "Pyrex," or the like. The tube 30, as changes and modifications shall fall within the spirit 
with the tube 10, is closed at the one end not shown, and and scope of the invention as defined in the appended 
open at the end 30A. A jacket, or skirt member 32 sur- claim. 
rounds the tube at the open end thereof and is attached 5 I claim: 
thereto or formed thereon at a spaced distance from the 1. A gaseous discharge lamp including, 
open end 3@A. The jacket is generclly coaxially located a tube with first and second ends, said first end being 
with the tube 38, and may be provided with an inwardly sealed and said second end being substaatiafly co- 
directed lip or rim 32A at the one end thereof. The forward planar, 
ends of the jacket and tube are substantially coplanar, 10 a skirt sorrounding said tube, said skirt having a fil-st 
and a windovv 34 of lithium fluoride, or the like serves to end and a second end, said first end of sajd skirt 
close the open ends of the tube and jacket. Fastening being secured to said tube near said second end of 
and sealing means 36 such as "Apiezon W" wax, epoxy said tube, said second end of mid skirt substantially 
cement, or the like, is used to secure the window to the occupying the plane described by said second end 
jacket. The sealing means is shown applied to the annu- l5 of said tube, 
lar groove formed between the window and jacket by the a planar window, 
inturned lip 32A. No sealing means are provided between seal means to provide a sealing engagement between 
the window 34 and the tube end. said window and said second end of said skirt, said 
With this arrangement the tube end 30A abuts or is window being in abutting relationship with said sec- 
closely spaced from the window 34 at the central portion 20 ond end of said tube, 
of the window. A chamber 40 is formed at the end of the said skirt, the portion of said tube coextensive there- 
tube 30 between the jacket 32, tube 30, and window 34, with and the portion of said window between said 
which chamber con~municates with the interior of the skirt and said tube forming a chamber, 
tube 30 through the space between the unsealed end of 25 a gas within said tube and said chamber, 
the tube and the window. Thus, it will be understood means for generating an electrical discharge inside of 
that when the tube is evacuated and then supplied with said tube, said chamber isolating said discharge from 
gas, the chamber is sim~~ltaneously evacuated and filled. said seal means to reduce decomposition of said seal 
It will be seen that the seal means 36 at the edge of the means. 
window is spaced from the tube end. Even when the 
lamp is operated with sufficient excitation for the dis- 
charge to impinge upon the central portion of the win- 
References Cited 
UNITED STATES PATENTS 
dow, the discharge thereby is maintained at a sufficient 2,763.806 9/1956 Anderson -------- 313-220 X 
distance from the seal 36 such that the seal is substantially 3,374,383 3/1968 Bergen et al. ------ 313-1 12 X 
unaffected thereby. 35 
The invention having been described in detail in ac- JAMES W. LAWRENCE, Primary ~ x a m i r ~ e r  
cordance with the requirements of the patent statutes, RAYMOND F. HOSSFELD, Assistant Examiner 
various changes and modifications may suggest them- 
selves to those skilled in this art. For example, it will be U.S. C1. X.R. 
Rpparent that the invention may be applied to lamps of 40 313-112, 161, 220 


Ultraviolet Resonance Lamp-Patent

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