CA1121069A - Electron beam-capillary plasma flash x-ray device - Google Patents
Electron beam-capillary plasma flash x-ray deviceInfo
- Publication number
- CA1121069A CA1121069A CA000330520A CA330520A CA1121069A CA 1121069 A CA1121069 A CA 1121069A CA 000330520 A CA000330520 A CA 000330520A CA 330520 A CA330520 A CA 330520A CA 1121069 A CA1121069 A CA 1121069A
- Authority
- CA
- Canada
- Prior art keywords
- electrode
- plate
- ray device
- passage
- capillary passage
- 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
Links
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05G—X-RAY TECHNIQUE
- H05G2/00—Apparatus or processes specially adapted for producing X-rays, not involving X-ray tubes, e.g. involving generation of a plasma
- H05G2/001—X-ray radiation generated from plasma
- H05G2/003—X-ray radiation generated from plasma being produced from a liquid or gas
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J35/00—X-ray tubes
- H01J35/22—X-ray tubes specially designed for passing a very high current for a very short time, e.g. for flash operation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
Abstract
ELECTRON BEAM-CAPILLARY PLASMA FLASH X-RAY DEVICE
Abstract A method and device for the generation of x-rays is described.
X-rays can be generated by establishing a high density plasma in a capillary passage and then passing an electron beam there-through. The device has a cylindrical passage, the ends of which are maintained at a potential difference. An electrode is main-tained at the potential and is slightly displaced from the higher potential end. when ions are supplied to the passage, the higher potential end is discharged and a high density plasma is created in the cylindrical passage. The discharge of the higher potential end of the cylindrical passage causes a discharge of the electrode into the passage forming an electron beam which interacts with the plasma, generating x-rays.
Abstract A method and device for the generation of x-rays is described.
X-rays can be generated by establishing a high density plasma in a capillary passage and then passing an electron beam there-through. The device has a cylindrical passage, the ends of which are maintained at a potential difference. An electrode is main-tained at the potential and is slightly displaced from the higher potential end. when ions are supplied to the passage, the higher potential end is discharged and a high density plasma is created in the cylindrical passage. The discharge of the higher potential end of the cylindrical passage causes a discharge of the electrode into the passage forming an electron beam which interacts with the plasma, generating x-rays.
Description
E:LI~CTRON B~l-C~PILL.~RY Pl.AS~ Fl.~SH ~ Y DE;VI(:~ ~
Description ~ecllnical Eield ~ device for generating flash lligll intensity sofc x-rays is 5 described. ~lore particularly the device is designed to generate a tizlltly focused electron beam and a high density, high temperature plasma. The interaction of the plasma and tlle electron beam creates sott x-rays.
~ackground Art lO ~igll intensity x-rays have been generated by the flash x-ray techlliques, and generally speaking these have been used for the purpose of quality control. Radiographs of thick sections can be proauced in reasonably short times by emploving flash x-rays with appro;imately ;00 kv excitation. Flasll x-ray 15 techniques have also been used for radiating materials to induce physical cllarlges in the rnaterial properties. The spectrum of radiation generated by thc current flash x-ray machines in gener.31 llas wavelengths less tllan 2~.
In general the same type of machines may be used for medicl1 20 e~amirlation, however, for medical e~aminatiol, tlle volLagc is usually reduced to 150 kv. Using x-r1ys generated in thLs manner, one can readily observe fractures in bones. t~gclLll tllC
ma:~imum wavelength for .c-rays so generated is in the nei~hbor-hood of 2A. U. S. Patent 4,053,~02 is illustr~tive of one of the 25 current x-ray tubes that is usable for the above described uses.
ile generation of flash x-rays in the hard x-ray segment of thc spectrum llas allowed one to observe relatively thick sections of both or~anic and inorganic materials, these ~-ra~s are not particularly effective whe!l used to study thinner 30 sections of material. If, for e~ample, one were to use hara Y~9,8-~30 ~rays (e.g., wavelengtll of less than about 20~) to study a thin section of biological material such as a cell, the radio-graph ~ould have essentially no contrast since these hard x-rays would penetrate through all sections of the sample with equal intensity. It is therefore necessary to develop softer ~-rays that have longer wavelengtlls and are less energetic, for biological microscopy. The soft x-ray spectrum strongly exposes x-ray photoresists making this soft portion of the spectrum desirable for x-ray lithography.
It is appreciated that there is a need for the production of a broader spectrum of x-ray radiation, and in particular for softer :~-rays. In order to produce a broader spectrum, tlle usual approach has been to drop tlle voltage and lower the Z number of LhC ma~erlal uscd as .1 ~argct. lhesc ch.ll~es ~,cner;llLy ro.sllL~
in a lack of x-ray intensity. Tl)c intensity of the ~-rays generated can be increased by increasing the current while either water cooling the tube or usinX a rotating anode. ~
further discussion of these techniques is contained in X-Rav Optics, ~pplications to Solids, Vol. 2, High Brilliance ~C-Ray Source, by ~ oshimatsu and S. Ko7aki, Springer-Verlag Berlin, Heidelberg, New York, 1977. While these techniques have broaden-ed the spcctrum of x-ray emlssions they have beell Eound to be generally ineffective for use in x-ray lithography and x-ray microscopy due to the fact that the required exposure times are extremely l~ng.
The exposure time may be reduced by employing a svllchrotron.
~hile the synchrotron will substantially reduce ~he time oE
exposure such an instaïlation is costly, and requires appreciable operational overhead and main~.enance. .~ further discussion of synchrotron is contained in Science, Vol. 199, January 1978, pp. 411-413. ~urthermore, the use of tlle synchrotroll will still require several minutes of e:~posure time. I~len one is working b9 with living organisms these times may be unduly long and allow the structure to change during the exposure. In lithography, a similar problem e~ists in that there may be a shift between a mask and an underlying substrate during the exposure.
In order to further reduce the exposure times plasma techniques have been used to generate soft x-rays. With the advent of high powered lasers generated by Q-switching, it is possible to focus intense radiation onto a material and thereby generate soft x-rays. This system is both costly and difficult to construct, and furthermore, suffers from the fact that the radiation contains an appreciable component of hard ~-rays. These hard x-rays are undesirable for uses with biological samples, as well as, for x-ray lithography for tlle reasons stated above. This latter point is more fully discussed in an article "Diagnostic Techniques in Laser Fusion Research" by P. J. ~lalloz~.i and H. ~. Epstein~ Research/Development, pp. 30-42 (Feb. 1976).
An inexpensive and reproducible source of soft x-rays can be produced by a spar~ discharge method. This is described in an article entitled "Continum Radiation Source of High Intensity", printed in the Journal of Optical Society of ~merica, Vol. 58, No. 2, pp. 203-206, 1968. This device will produce the desired range of radiation but the intensity is insufficient to allow either the exposure of biological samples or exposure of photo-resist used in lithography with a single flash.
~hile other high intensity radiation generating sources are available (e.g., U. S. Patent 3,512,G30), the spectrum of radiation generated by these devices are more heavily weighted towards the ultraviolet segment of the s?ect um and therefore not particularly applicable or uses in either x-ray lithography or biological microscopy.
_.. , Disclosure of Inventioll It is the object of this invention to provide a soft ~-ray source wherein the principal portion of the radiation lies between lO~
and 400A.
~nother object of this invention is to provide a high intensity source which acts over a short period of time.
further object of this invent on is to provide a stable concen-trated source of radiation (e.z., a point source).
Still a further object of ~his lnvention is a de~ice which generates x-rays that are compatible for use in microscopy oE
biological samples.
The final object of the invention is a device for ~eneratin~
:c-ravs which are compatible with ~-ray lithography.
~ method and device for accomplishing the above objectives and for 2eneratin~ flash, high intensity soft ~-rays is described.
The device has a first plate of a conductive material, an -illter-medlate layer of an insulatin~ material attached to tlle first conductive plate and a second plate of a conductive material attached to the intermediate layer and electrically isolated '0 from the first conductive plate. ~ capillary opening wllich e:~tends througll the first conducting plate, the ir.sulatillz lajer and the second conductill~ plate forms a cy;indr cal p.lssage.
A first electrode is aligned ~ith the passage. Ihe first electrode has a tapered end wnich is adjacent to and spaced apart from the second plate. The second plate is maintained at a potential with respect to the first plate by a first capacitive ~0978-030 ~", _ . . _. .. .
stora~e mealls. Likewise the first electrode is maintained at a potential with respect to the first plate by a second capacitive storage mealls. The first electrode is electrically connected to the second plate by a Means for electrical connection that under . C. operatin2 conditions equalizes the potentiai between the second plate and the first electrode but prevents equalization under pulse operating conditions. A means for triggering a discharge between the first and second plates allows the discharge of the second plate to the first plate. ~Then this discharge occurs and a means to supply ions to the cylindrical passage is provided, an ioni~ed plasma is established in the cylindrical passage. Tlle electrode discharges through the cylindrical passage interacting with the plasma and generating an intense burs, of x-rays.
~hile the invention may be described in terms of the above-mentioned devlce, alternatively it may be de~scribed by the following process. ~ gas is ionized. The ionized gas is subject to an electric field. The ionized gas is constrained in a capillary passage and is subject to an electric field. A plasma is created whicll is constrained by the passage. ~n electron beam is passe~ through the plasma and interacts Wittl the plasma to generate -,c-rays.
~rief Description of tlle Drawings rigure 1 is a schematic represeiltation of one embodimellt o~ t~,e flash x-ray device wherein the first electrocie ~ cL~c~rically connected to the second conducting plate thr.u2.h an inductive co il .
Fi~ure 2 is a scllematic representation of a second embodiment of the flash ~-ray device ~inerein the first electrode i5 electrical-I~: conllected to the secolld conducting plate through a resistiveelement.
,~,_ ..
~est ~lode of Carrying Out the Lnvention Fig. 1 depicts one embodiment of the present invention, wherein a first conductive plate 10 is attached to an intermediate layer 12 of insulating material which in turn is attached to a second conductive plate 14. A first capillary opening 15 which e:~tends through the first conductive plate 10, the intermediate layer 12 and the second conductive plate 14 for~s a cylindrical capillary passage 16. L~ first electrode 18 having a tapered end 18A is aligned with the cylindrical capillary passage 16 and is spaced apart from the second conductive plate 14. A first capacitGr 20 serves as a means for storing energy between the first plate 10 and the second plate 14. It should be appreciated that a first bank of capacitors could be substituted Eor the capncitor 20. In this case the indivi~ual capacitors sl~ould be arrall~ed so that the charge is sylnmetrically disposed about the cylindrical capillary passage 16. The capacitor can be charged by a DC power supply not shown through a resistive element 22 which is appropriately selected to prevent unwarranted dis-charge of capacitor 20. ~ second capacitor 24 connected to the electrode 18 and the first plate 10 serves as a means for storing energy between these elements. The comment made Witil respect to the ~irst capacitor 20 applies with equaL force to the second capacitor 24 and a second bank of capacitors could replace the second capacitor ~4. ~tn inductive co l 26L~ serves ~5 as a means for electrically connectin~ the second conductive plate 14 WitLl the first electrode 18.
It is preferred tha, the inductive coii 25L be matc~ed with the second capacitor 24. This allows ample current ~low between the second conducting plate 14 and the first elec~rode 18 and providcs for chargin~ oî the second capacitor 24 without creatin~
a signi~lcant potelltial between tlle second conductive plate 14 alld tl~e elecLrode 18 Ihe inductive coil ~6L~ and the second capacitor 24 will be appropriately matched wllen the product of the square root of the inductance of the coil 26A and the ~_ , .
capacitance o~ the second capacitor ~4 is between about 10 microsecor.d and 100 .nicroseconds.
Fig. 2 shows an alternati~e embodiment where rather than an inductive coil 26A a resistor 26~ is employed to proviae the electrical connection bet~een the second plate 14 and Lhe electrode 18.
For the reasons set forth above, the resistor 26B and the second capacitor 24 sllould be matched. In this case the product of the resistance of the resistor 26~ and the capacitance of the second capacitor 24 should be between about 10 microseconds and 1000 microseconds.
The discharge may be tri~gered by a second electrode 34 as shown in Fig. l. This electrode 34 is separated frotn the first plate and may have an insulator 36 between the first plate 10 and the electrode 34.
~hen discllarge occurs in the capillary passage 16, erosion oL the insulating material is caused by a spark flash over between plate 14 and plate 10 and allo~s the insulato~ to serve as a me3lls for supplying ions to the passage.
Alternati~ely injecting gas into the cylindrical capillary passage 16 througll a second opening 38 illustrated in Fig. ~, will trigger a discllarge betweell tlle first conductive pl.lte 10 and the second conductive plate 14. ~ny stand-rd injection sy~tem may be employed to su~ply gas to the secold ope;ling 38 one such system being described in an article entitled "Fast Valve for Gas Injection into Vacuum" by A. Fisl;er, F. ~lalzo and J. Shiloll, Rev. o Scientific Inst., Vol. 49, No. 6, June 197~3, pp. S7 -873. Ihe injected gas t~ l be ionized by the disclldr~e and isl addition co ser~ing as the trigger means serv~s as tbe ion supply. It is also possible to inject gas into the capillary passage 16 through the openillg 15 of irst end ~late 10.
Preferably energy storage capacities of either the individual capacitors 20 and 24 or the respective banks oE capacitors for the present invention should be from appro~imately 10 joules to about 1~ joule. When the operating voltages are between about 20 kv ancl about 100 kv, the capacitors should be connected to the plates by synunetrical low inductance paths.
Furthermore preferably the cylindrical capillary passage 16 should be from about 0.1 millimeters to 3 millimeters in diameter and the length of the insulatinz section of the capillary passage ]O 16 should be from about 0.1 cm to 5 cm. The limited size of the capillary will assure a stable concentrated source of radiation.
Conductive plates 10 and 1~l should have a thickness from about 0.25 millimeters to 3 millimeters. The tip l~A of the electrode 18 should have a smzll radius preferably less than a tenth of a ~S milli~Deter. The preferrecl material for the electrode 18 and for the conductive plates lG and 1~ is high density carbon such as poco gracle. It shoulci also be appreciated that the design of the capillary chamber must be constructed with the principals of higll voltaze technology, as is further discussed in R. Hawley's article "Solid Insulators in Vacuum:~ Review,l' Vacuum, ~'ol. 18, No. 7, pp. 383-90.
The above described device is designed to operate in a low pressure environment. ~ypically, the pressure should be 10 5 torr or less. Preferably these pressures may be maintaillecj by enca!)sulatinz the devlce save the capaci~ors in a vacuum chamber as is sllown l>y the dottecl lines ~ iz. L ;Ind 2. ;he vacuum chamber is continuously pumped [o maintaill a ,ow pressure by a device such as an oil diffusion pump. Once the chamber has been evacuated the capacitors 20 and 24 may be charged by a DC
supply througll a resistive element 22. Once the capacitors are fullv charged the plates 10 and lL may be discharged by tlle second el~ctrocle 3~ wllich is employed to generate a spark betweell tlle second electrocle and the first conductive plate 10.
Y~978-03~
This spark in turn will illuminate the capillary chamber with sufficient ultraviolet radiation to initiate discharge between the conducting plates 10 and l4. The discharge spark travelling down the capillary ~ubes from 14 and lO causes erosion of the surface of the insulating material 12 creating a desired plasma.
'l'his insulating material should have at least one eleMent with a Z number (atomic number) which is less tl-an eighteen. While it would be possible to ionize heavier elements than Argon (Z = 18), ionization of the heavier ions would not expose the ~-shell electrons and therefore limit .~-ray generation. To maximize the radiation it is preferred that all elements in the insulating material have a Z number whicll is less than eighteen. Tlle discharge of second plate 14 results in a potential between the first electrode 18 and the second plate 14 which in turn,draws electrons fro~ the electrode 18 creating an electron beam.
The electron beam may be tuned to optimize the radiatioll pulse output by matching the impedance of the elec~ron beam with the impedance of the capacitor 24, and its connection to the fi,rst plate 10 by adjusting the spacing between the second plate 14 and the electrode 13. ~s the beam travels through the capillary it interacts with the plasma generating soft ~-rays.
The plasma can be made self-triggered by reducing the thick-ness of the insulating material. The thickness of tllis zone will determine at what voltage a discharge will occur across the insulating material layer 12 which is between the conducting plates 10 and 14. Thereafter all the steps being similar to the preceding described steps.
- It is also possible to introduce various gases into the capillary passage 16. These gases in addition to serving to trigger the discharge between the conductive plates 10 and 14 YO97~-030 ~_ _ .. .
lo are the ion source for the plasma. The plasma being character-istic of the gas introduced into the capillary passage 16.
variety of x-ray spectrum can be generated by the proper selection of either the gas introduced into the capillary opening or alternatively in the case of the spark discharge process by the proper selection of the insulating material.
Further refinement of the spectrum is ?ossible by adjusting the size of the cylindrical capillary passage 16. The si~e of the passage 16 will effect the temperature of the plasma and thereby the resulting ~-ray spectrum.
While I have illustrated and described the preferred embodi-ments of my invention, it is to be understood that I do not limit myself to the precise constructions herein disclosed and the right is reserved to all challges and modifications coming within the sccpe of the invention as defined in the appended claims.
Description ~ecllnical Eield ~ device for generating flash lligll intensity sofc x-rays is 5 described. ~lore particularly the device is designed to generate a tizlltly focused electron beam and a high density, high temperature plasma. The interaction of the plasma and tlle electron beam creates sott x-rays.
~ackground Art lO ~igll intensity x-rays have been generated by the flash x-ray techlliques, and generally speaking these have been used for the purpose of quality control. Radiographs of thick sections can be proauced in reasonably short times by emploving flash x-rays with appro;imately ;00 kv excitation. Flasll x-ray 15 techniques have also been used for radiating materials to induce physical cllarlges in the rnaterial properties. The spectrum of radiation generated by thc current flash x-ray machines in gener.31 llas wavelengths less tllan 2~.
In general the same type of machines may be used for medicl1 20 e~amirlation, however, for medical e~aminatiol, tlle volLagc is usually reduced to 150 kv. Using x-r1ys generated in thLs manner, one can readily observe fractures in bones. t~gclLll tllC
ma:~imum wavelength for .c-rays so generated is in the nei~hbor-hood of 2A. U. S. Patent 4,053,~02 is illustr~tive of one of the 25 current x-ray tubes that is usable for the above described uses.
ile generation of flash x-rays in the hard x-ray segment of thc spectrum llas allowed one to observe relatively thick sections of both or~anic and inorganic materials, these ~-ra~s are not particularly effective whe!l used to study thinner 30 sections of material. If, for e~ample, one were to use hara Y~9,8-~30 ~rays (e.g., wavelengtll of less than about 20~) to study a thin section of biological material such as a cell, the radio-graph ~ould have essentially no contrast since these hard x-rays would penetrate through all sections of the sample with equal intensity. It is therefore necessary to develop softer ~-rays that have longer wavelengtlls and are less energetic, for biological microscopy. The soft x-ray spectrum strongly exposes x-ray photoresists making this soft portion of the spectrum desirable for x-ray lithography.
It is appreciated that there is a need for the production of a broader spectrum of x-ray radiation, and in particular for softer :~-rays. In order to produce a broader spectrum, tlle usual approach has been to drop tlle voltage and lower the Z number of LhC ma~erlal uscd as .1 ~argct. lhesc ch.ll~es ~,cner;llLy ro.sllL~
in a lack of x-ray intensity. Tl)c intensity of the ~-rays generated can be increased by increasing the current while either water cooling the tube or usinX a rotating anode. ~
further discussion of these techniques is contained in X-Rav Optics, ~pplications to Solids, Vol. 2, High Brilliance ~C-Ray Source, by ~ oshimatsu and S. Ko7aki, Springer-Verlag Berlin, Heidelberg, New York, 1977. While these techniques have broaden-ed the spcctrum of x-ray emlssions they have beell Eound to be generally ineffective for use in x-ray lithography and x-ray microscopy due to the fact that the required exposure times are extremely l~ng.
The exposure time may be reduced by employing a svllchrotron.
~hile the synchrotron will substantially reduce ~he time oE
exposure such an instaïlation is costly, and requires appreciable operational overhead and main~.enance. .~ further discussion of synchrotron is contained in Science, Vol. 199, January 1978, pp. 411-413. ~urthermore, the use of tlle synchrotroll will still require several minutes of e:~posure time. I~len one is working b9 with living organisms these times may be unduly long and allow the structure to change during the exposure. In lithography, a similar problem e~ists in that there may be a shift between a mask and an underlying substrate during the exposure.
In order to further reduce the exposure times plasma techniques have been used to generate soft x-rays. With the advent of high powered lasers generated by Q-switching, it is possible to focus intense radiation onto a material and thereby generate soft x-rays. This system is both costly and difficult to construct, and furthermore, suffers from the fact that the radiation contains an appreciable component of hard ~-rays. These hard x-rays are undesirable for uses with biological samples, as well as, for x-ray lithography for tlle reasons stated above. This latter point is more fully discussed in an article "Diagnostic Techniques in Laser Fusion Research" by P. J. ~lalloz~.i and H. ~. Epstein~ Research/Development, pp. 30-42 (Feb. 1976).
An inexpensive and reproducible source of soft x-rays can be produced by a spar~ discharge method. This is described in an article entitled "Continum Radiation Source of High Intensity", printed in the Journal of Optical Society of ~merica, Vol. 58, No. 2, pp. 203-206, 1968. This device will produce the desired range of radiation but the intensity is insufficient to allow either the exposure of biological samples or exposure of photo-resist used in lithography with a single flash.
~hile other high intensity radiation generating sources are available (e.g., U. S. Patent 3,512,G30), the spectrum of radiation generated by these devices are more heavily weighted towards the ultraviolet segment of the s?ect um and therefore not particularly applicable or uses in either x-ray lithography or biological microscopy.
_.. , Disclosure of Inventioll It is the object of this invention to provide a soft ~-ray source wherein the principal portion of the radiation lies between lO~
and 400A.
~nother object of this invention is to provide a high intensity source which acts over a short period of time.
further object of this invent on is to provide a stable concen-trated source of radiation (e.z., a point source).
Still a further object of ~his lnvention is a de~ice which generates x-rays that are compatible for use in microscopy oE
biological samples.
The final object of the invention is a device for ~eneratin~
:c-ravs which are compatible with ~-ray lithography.
~ method and device for accomplishing the above objectives and for 2eneratin~ flash, high intensity soft ~-rays is described.
The device has a first plate of a conductive material, an -illter-medlate layer of an insulatin~ material attached to tlle first conductive plate and a second plate of a conductive material attached to the intermediate layer and electrically isolated '0 from the first conductive plate. ~ capillary opening wllich e:~tends througll the first conducting plate, the ir.sulatillz lajer and the second conductill~ plate forms a cy;indr cal p.lssage.
A first electrode is aligned ~ith the passage. Ihe first electrode has a tapered end wnich is adjacent to and spaced apart from the second plate. The second plate is maintained at a potential with respect to the first plate by a first capacitive ~0978-030 ~", _ . . _. .. .
stora~e mealls. Likewise the first electrode is maintained at a potential with respect to the first plate by a second capacitive storage mealls. The first electrode is electrically connected to the second plate by a Means for electrical connection that under . C. operatin2 conditions equalizes the potentiai between the second plate and the first electrode but prevents equalization under pulse operating conditions. A means for triggering a discharge between the first and second plates allows the discharge of the second plate to the first plate. ~Then this discharge occurs and a means to supply ions to the cylindrical passage is provided, an ioni~ed plasma is established in the cylindrical passage. Tlle electrode discharges through the cylindrical passage interacting with the plasma and generating an intense burs, of x-rays.
~hile the invention may be described in terms of the above-mentioned devlce, alternatively it may be de~scribed by the following process. ~ gas is ionized. The ionized gas is subject to an electric field. The ionized gas is constrained in a capillary passage and is subject to an electric field. A plasma is created whicll is constrained by the passage. ~n electron beam is passe~ through the plasma and interacts Wittl the plasma to generate -,c-rays.
~rief Description of tlle Drawings rigure 1 is a schematic represeiltation of one embodimellt o~ t~,e flash x-ray device wherein the first electrocie ~ cL~c~rically connected to the second conducting plate thr.u2.h an inductive co il .
Fi~ure 2 is a scllematic representation of a second embodiment of the flash ~-ray device ~inerein the first electrode i5 electrical-I~: conllected to the secolld conducting plate through a resistiveelement.
,~,_ ..
~est ~lode of Carrying Out the Lnvention Fig. 1 depicts one embodiment of the present invention, wherein a first conductive plate 10 is attached to an intermediate layer 12 of insulating material which in turn is attached to a second conductive plate 14. A first capillary opening 15 which e:~tends through the first conductive plate 10, the intermediate layer 12 and the second conductive plate 14 for~s a cylindrical capillary passage 16. L~ first electrode 18 having a tapered end 18A is aligned with the cylindrical capillary passage 16 and is spaced apart from the second conductive plate 14. A first capacitGr 20 serves as a means for storing energy between the first plate 10 and the second plate 14. It should be appreciated that a first bank of capacitors could be substituted Eor the capncitor 20. In this case the indivi~ual capacitors sl~ould be arrall~ed so that the charge is sylnmetrically disposed about the cylindrical capillary passage 16. The capacitor can be charged by a DC power supply not shown through a resistive element 22 which is appropriately selected to prevent unwarranted dis-charge of capacitor 20. ~ second capacitor 24 connected to the electrode 18 and the first plate 10 serves as a means for storing energy between these elements. The comment made Witil respect to the ~irst capacitor 20 applies with equaL force to the second capacitor 24 and a second bank of capacitors could replace the second capacitor ~4. ~tn inductive co l 26L~ serves ~5 as a means for electrically connectin~ the second conductive plate 14 WitLl the first electrode 18.
It is preferred tha, the inductive coii 25L be matc~ed with the second capacitor 24. This allows ample current ~low between the second conducting plate 14 and the first elec~rode 18 and providcs for chargin~ oî the second capacitor 24 without creatin~
a signi~lcant potelltial between tlle second conductive plate 14 alld tl~e elecLrode 18 Ihe inductive coil ~6L~ and the second capacitor 24 will be appropriately matched wllen the product of the square root of the inductance of the coil 26A and the ~_ , .
capacitance o~ the second capacitor ~4 is between about 10 microsecor.d and 100 .nicroseconds.
Fig. 2 shows an alternati~e embodiment where rather than an inductive coil 26A a resistor 26~ is employed to proviae the electrical connection bet~een the second plate 14 and Lhe electrode 18.
For the reasons set forth above, the resistor 26B and the second capacitor 24 sllould be matched. In this case the product of the resistance of the resistor 26~ and the capacitance of the second capacitor 24 should be between about 10 microseconds and 1000 microseconds.
The discharge may be tri~gered by a second electrode 34 as shown in Fig. l. This electrode 34 is separated frotn the first plate and may have an insulator 36 between the first plate 10 and the electrode 34.
~hen discllarge occurs in the capillary passage 16, erosion oL the insulating material is caused by a spark flash over between plate 14 and plate 10 and allo~s the insulato~ to serve as a me3lls for supplying ions to the passage.
Alternati~ely injecting gas into the cylindrical capillary passage 16 througll a second opening 38 illustrated in Fig. ~, will trigger a discllarge betweell tlle first conductive pl.lte 10 and the second conductive plate 14. ~ny stand-rd injection sy~tem may be employed to su~ply gas to the secold ope;ling 38 one such system being described in an article entitled "Fast Valve for Gas Injection into Vacuum" by A. Fisl;er, F. ~lalzo and J. Shiloll, Rev. o Scientific Inst., Vol. 49, No. 6, June 197~3, pp. S7 -873. Ihe injected gas t~ l be ionized by the disclldr~e and isl addition co ser~ing as the trigger means serv~s as tbe ion supply. It is also possible to inject gas into the capillary passage 16 through the openillg 15 of irst end ~late 10.
Preferably energy storage capacities of either the individual capacitors 20 and 24 or the respective banks oE capacitors for the present invention should be from appro~imately 10 joules to about 1~ joule. When the operating voltages are between about 20 kv ancl about 100 kv, the capacitors should be connected to the plates by synunetrical low inductance paths.
Furthermore preferably the cylindrical capillary passage 16 should be from about 0.1 millimeters to 3 millimeters in diameter and the length of the insulatinz section of the capillary passage ]O 16 should be from about 0.1 cm to 5 cm. The limited size of the capillary will assure a stable concentrated source of radiation.
Conductive plates 10 and 1~l should have a thickness from about 0.25 millimeters to 3 millimeters. The tip l~A of the electrode 18 should have a smzll radius preferably less than a tenth of a ~S milli~Deter. The preferrecl material for the electrode 18 and for the conductive plates lG and 1~ is high density carbon such as poco gracle. It shoulci also be appreciated that the design of the capillary chamber must be constructed with the principals of higll voltaze technology, as is further discussed in R. Hawley's article "Solid Insulators in Vacuum:~ Review,l' Vacuum, ~'ol. 18, No. 7, pp. 383-90.
The above described device is designed to operate in a low pressure environment. ~ypically, the pressure should be 10 5 torr or less. Preferably these pressures may be maintaillecj by enca!)sulatinz the devlce save the capaci~ors in a vacuum chamber as is sllown l>y the dottecl lines ~ iz. L ;Ind 2. ;he vacuum chamber is continuously pumped [o maintaill a ,ow pressure by a device such as an oil diffusion pump. Once the chamber has been evacuated the capacitors 20 and 24 may be charged by a DC
supply througll a resistive element 22. Once the capacitors are fullv charged the plates 10 and lL may be discharged by tlle second el~ctrocle 3~ wllich is employed to generate a spark betweell tlle second electrocle and the first conductive plate 10.
Y~978-03~
This spark in turn will illuminate the capillary chamber with sufficient ultraviolet radiation to initiate discharge between the conducting plates 10 and l4. The discharge spark travelling down the capillary ~ubes from 14 and lO causes erosion of the surface of the insulating material 12 creating a desired plasma.
'l'his insulating material should have at least one eleMent with a Z number (atomic number) which is less tl-an eighteen. While it would be possible to ionize heavier elements than Argon (Z = 18), ionization of the heavier ions would not expose the ~-shell electrons and therefore limit .~-ray generation. To maximize the radiation it is preferred that all elements in the insulating material have a Z number whicll is less than eighteen. Tlle discharge of second plate 14 results in a potential between the first electrode 18 and the second plate 14 which in turn,draws electrons fro~ the electrode 18 creating an electron beam.
The electron beam may be tuned to optimize the radiatioll pulse output by matching the impedance of the elec~ron beam with the impedance of the capacitor 24, and its connection to the fi,rst plate 10 by adjusting the spacing between the second plate 14 and the electrode 13. ~s the beam travels through the capillary it interacts with the plasma generating soft ~-rays.
The plasma can be made self-triggered by reducing the thick-ness of the insulating material. The thickness of tllis zone will determine at what voltage a discharge will occur across the insulating material layer 12 which is between the conducting plates 10 and 14. Thereafter all the steps being similar to the preceding described steps.
- It is also possible to introduce various gases into the capillary passage 16. These gases in addition to serving to trigger the discharge between the conductive plates 10 and 14 YO97~-030 ~_ _ .. .
lo are the ion source for the plasma. The plasma being character-istic of the gas introduced into the capillary passage 16.
variety of x-ray spectrum can be generated by the proper selection of either the gas introduced into the capillary opening or alternatively in the case of the spark discharge process by the proper selection of the insulating material.
Further refinement of the spectrum is ?ossible by adjusting the size of the cylindrical capillary passage 16. The si~e of the passage 16 will effect the temperature of the plasma and thereby the resulting ~-ray spectrum.
While I have illustrated and described the preferred embodi-ments of my invention, it is to be understood that I do not limit myself to the precise constructions herein disclosed and the right is reserved to all challges and modifications coming within the sccpe of the invention as defined in the appended claims.
Claims (14)
1. An x-ray device for employment in a vacuum chamber comprising:
a first plate of a conductive material;
an intermediate layer of an insulating material attached to said first conductive plate;
a second plate of a conductive material attached to said intermediate layer and electrically isolated from said first conductive plate;
a cylindrical capillary passage formed by a first capil-lary opening which extends through said first conductive plate, said layer of insulating material and said second conducting plate;
a first electrode having a tapered end, said electrode spaced apart from said second conducting plate and aligned with said cylindrical capillary passage;
means for supplying ions to said cylindrical capillary passage;
first means for storing capacitive energy so that said second plate is maintained at a potential with respect to said first plate;
second means for storing capacitive energy so that said first electrode is maintained at a potential with respect to said first plate;
means for electrically connecting said first electrode and said second conducting plate allowing passage of a current to equalize the potential between said second conductive plate and said first electrode; and means for triggering a discharge between said first con-ductive plate and said second conductive plate, where an ionized plasma is established in said cylindrical capillary passage and said electrode discharges an electron beam into said plasma causing the generation of x-rays.
a first plate of a conductive material;
an intermediate layer of an insulating material attached to said first conductive plate;
a second plate of a conductive material attached to said intermediate layer and electrically isolated from said first conductive plate;
a cylindrical capillary passage formed by a first capil-lary opening which extends through said first conductive plate, said layer of insulating material and said second conducting plate;
a first electrode having a tapered end, said electrode spaced apart from said second conducting plate and aligned with said cylindrical capillary passage;
means for supplying ions to said cylindrical capillary passage;
first means for storing capacitive energy so that said second plate is maintained at a potential with respect to said first plate;
second means for storing capacitive energy so that said first electrode is maintained at a potential with respect to said first plate;
means for electrically connecting said first electrode and said second conducting plate allowing passage of a current to equalize the potential between said second conductive plate and said first electrode; and means for triggering a discharge between said first con-ductive plate and said second conductive plate, where an ionized plasma is established in said cylindrical capillary passage and said electrode discharges an electron beam into said plasma causing the generation of x-rays.
2. The x-ray device of Claim 1 wherein said first means for storing capacitive energy further comprises a first bank of capacitors symmetrically disposed about said cylindrical capil-lary passage.
3. The X-ray device of Claim 2 wherein said second means for storing capacitive energy further comprises a second bank of capacitors symmetrically disposed about said cylindrical capillary passage.
4. The X-ray device of Claim 3 wherein said means for connection between said first electrode and second plate further comprises an inductive coil coaxially and symmetrically disposed about said first electrode.
5. The X-ray device of Claim 3 wherein said means for electrically connecting said first electrode and said second conducting plate further comprises a resistor, said resistor being selected such that the product of the resistance of said resistor and the capacitance of said second bank of capacitors is between about 10 microseconds and 1000 microseconds.
6. The X-ray device of Claim 3 wherein said means for electrically connecting said first electrode and said second conducting plate further comprises an inductive coil, said inductive coil being selected such that the product of the square root of the inductance of said inductive coil and the capacitance of said second bank of capacitors is between about 10 microseconds and 1000 microseconds.
7. The x-ray device of Claim 1 wherein said means for supplying ions to said cylindrical capillary passage further comprises a second capillary opening connected to and radiating away from said cylindrical capillary passage through which gas is passed into said cylindrical capillary passage, said gas serving to trigger a discharge between said first plate and second plate thereby ionizing said gas.
8. The x-ray device of Claim 1 wherein said triggering means further comprises a second electrode, and an insulator separating said second electrode from said first plate.
9. The x-ray device of Claim 1 wherein said cylindrical capillary passage is between about 0.1 mm and 3 mm in diameter and the length of said passage should be between about 0.1 cm and 5 cm while the thickness of said electrode should be between 0.25 mm and 3 mm.
10. The x-ray device of Claim 1 wherein said tapered end of said first electrode has a radius of curvature of less than 1/10 mm and further wherein said electrode is of high density carbon.
11. The X-ray device of Claims 4 and wherein said storage capacity of each of said banks of capacitors is about 10 joules to 1000 joules and the potential at which said bank of capacitors is maintained is between about 20 kv and 500 kv.
12. The X-ray device of Claim 1 wherein said capacitors are mounted external to the vacuum chamber.
13. The x-ray device of Claim 1 wherein said insulating material has at least one element with a Z number of less than eighteen, said material being susceptible to ionization by a spark discharge and serves as means for supplying ions to said capillary Passage.
14. The X-ray device of Claim 12 wherein said insulating material consists of elements selected from those elements with Z less than or equal to eighteen.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/927,238 US4201921A (en) | 1978-07-24 | 1978-07-24 | Electron beam-capillary plasma flash x-ray device |
| US927,238 | 1978-07-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1121069A true CA1121069A (en) | 1982-03-30 |
Family
ID=25454445
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000330520A Expired CA1121069A (en) | 1978-07-24 | 1979-06-25 | Electron beam-capillary plasma flash x-ray device |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4201921A (en) |
| CA (1) | CA1121069A (en) |
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| US4368538A (en) * | 1980-04-11 | 1983-01-11 | International Business Machines Corporation | Spot focus flash X-ray source |
| US4536884A (en) * | 1982-09-20 | 1985-08-20 | Eaton Corporation | Plasma pinch X-ray apparatus |
| US4618971A (en) * | 1982-09-20 | 1986-10-21 | Eaton Corporation | X-ray lithography system |
| US4633492A (en) * | 1982-09-20 | 1986-12-30 | Eaton Corporation | Plasma pinch X-ray method |
| US4504964A (en) * | 1982-09-20 | 1985-03-12 | Eaton Corporation | Laser beam plasma pinch X-ray system |
| CA1239487A (en) * | 1985-10-03 | 1988-07-19 | National Research Council Of Canada | Multiple vacuum arc derived plasma pinch x-ray source |
| CA1239486A (en) * | 1985-10-03 | 1988-07-19 | Rajendra P. Gupta | Gas discharge derived annular plasma pinch x-ray source |
| DE4208764C2 (en) * | 1992-03-19 | 1994-02-24 | Kernforschungsz Karlsruhe | Gas filled particle accelerator |
| CA2241116C (en) | 1998-06-19 | 2009-08-25 | Liyan Zhang | Radiation (e.g. x-ray pulse) generator mechanisms |
| US6912356B2 (en) * | 1999-06-07 | 2005-06-28 | Diversified Industries Ltd. | Method and apparatus for fracturing brittle materials by thermal stressing |
| CA2310883A1 (en) | 1999-06-07 | 2000-12-07 | Norman L. Arrison | Method and apparatus for fracturing brittle materials by thermal stressing |
| US6815668B2 (en) * | 1999-07-21 | 2004-11-09 | The Charles Stark Draper Laboratory, Inc. | Method and apparatus for chromatography-high field asymmetric waveform ion mobility spectrometry |
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| US6690004B2 (en) * | 1999-07-21 | 2004-02-10 | The Charles Stark Draper Laboratory, Inc. | Method and apparatus for electrospray-augmented high field asymmetric ion mobility spectrometry |
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| DE10207835C1 (en) * | 2002-02-25 | 2003-06-12 | Karlsruhe Forschzent | Channel spark source for a stable electron beam e.g. an electron gun, has a conical sleeve in the hollow cathode with a gas feed and an adjusted pressure drop to give a large number of shots without loss of beam quality |
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| EP1690074A2 (en) * | 2003-11-25 | 2006-08-16 | Sionex Corporation | Mobility based apparatus and methods using dispersion characteristics, sample fragmentation, and/or pressure control to improve analysis of a sample |
| WO2005060696A2 (en) * | 2003-12-18 | 2005-07-07 | Sionex Corporation | Methods and apparatus for enhanced ion based sample detection using selective pre-separation and amplification |
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| US7456394B2 (en) * | 2004-02-02 | 2008-11-25 | Sionex Corporation | Compact sample analysis systems and related methods of using combined chromatography and mobility spectrometry techniques |
| EP1756561A1 (en) * | 2004-04-28 | 2007-02-28 | Sionex Corporation | System and method for ion species analysis with enhanced condition control and data interpretation using differential mobility spectrometers |
| WO2006060807A1 (en) * | 2004-12-03 | 2006-06-08 | Sionex Corporation | Method and apparatus for enhanced ion based sample filtering and detection |
| EP1920243B1 (en) * | 2005-04-29 | 2015-09-09 | DH Technologies Development Pte. Ltd. | Compact gas chromatography and ion mobility based sample analysis systems, methods, and devices |
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| US3022444A (en) * | 1958-03-28 | 1962-02-20 | Fischer Heinz | Ultra short light pulse generation |
| US2972698A (en) * | 1958-09-08 | 1961-02-21 | Union Carbide Corp | High-intensity light source |
| US3280360A (en) * | 1963-02-28 | 1966-10-18 | Westinghouse Electric Corp | High intensity radiation source |
| DE1589312B2 (en) * | 1967-04-12 | 1971-04-01 | INJECTION BURNER FOR GENERATING A HIGH INTENSITY ULTRAVIOLET RADIATION | |
| US3512030A (en) * | 1967-06-16 | 1970-05-12 | Vitro Corp Of America | High intensity source of selected radiation |
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| US3588590A (en) * | 1969-04-07 | 1971-06-28 | Ibm | Gas discharge plasma tube having a multiturn primary winding |
| US3596128A (en) * | 1969-05-01 | 1971-07-27 | Spectrametrics Inc | Excitation source for spectroscopic analysis |
| US4042848A (en) * | 1974-05-17 | 1977-08-16 | Ja Hyun Lee | Hypocycloidal pinch device |
| US4027185A (en) * | 1974-06-13 | 1977-05-31 | Canadian Patents And Development Limited | High intensity radiation source |
| DE2506841C2 (en) * | 1975-02-18 | 1986-07-03 | Philips Patentverwaltung Gmbh, 2000 Hamburg | High voltage vacuum tube |
-
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- 1978-07-24 US US05/927,238 patent/US4201921A/en not_active Expired - Lifetime
-
1979
- 1979-06-25 CA CA000330520A patent/CA1121069A/en not_active Expired
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| Publication number | Publication date |
|---|---|
| US4201921A (en) | 1980-05-06 |
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