US3794875A - Neutron generators - Google Patents
Neutron generators Download PDFInfo
- Publication number
- US3794875A US3794875A US00099331A US3794875DA US3794875A US 3794875 A US3794875 A US 3794875A US 00099331 A US00099331 A US 00099331A US 3794875D A US3794875D A US 3794875DA US 3794875 A US3794875 A US 3794875A
- Authority
- US
- United States
- Prior art keywords
- pump
- envelope
- gas
- sputterable
- metal
- 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
Links
- 229910052751 metal Inorganic materials 0.000 claims abstract description 33
- 239000002184 metal Substances 0.000 claims abstract description 33
- 239000007789 gas Substances 0.000 claims abstract description 32
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 19
- 239000001257 hydrogen Substances 0.000 claims abstract description 19
- 229910052722 tritium Inorganic materials 0.000 claims abstract description 17
- 239000001307 helium Substances 0.000 claims abstract description 16
- 229910052734 helium Inorganic materials 0.000 claims abstract description 16
- YZCKVEUIGOORGS-NJFSPNSNSA-N Tritium Chemical compound [3H] YZCKVEUIGOORGS-NJFSPNSNSA-N 0.000 claims abstract description 14
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims abstract description 12
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910052802 copper Inorganic materials 0.000 claims abstract description 8
- 239000010949 copper Substances 0.000 claims abstract description 8
- 239000000126 substance Substances 0.000 claims abstract description 8
- -1 helium ions Chemical class 0.000 claims description 9
- 238000004544 sputter deposition Methods 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 5
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 4
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 4
- 229910052737 gold Inorganic materials 0.000 claims description 4
- 239000010931 gold Substances 0.000 claims description 4
- 229910052709 silver Inorganic materials 0.000 claims description 4
- 239000004332 silver Substances 0.000 claims description 4
- 238000004891 communication Methods 0.000 claims description 3
- 229910052805 deuterium Inorganic materials 0.000 abstract description 9
- SWQJXJOGLNCZEY-BJUDXGSMSA-N helium-3 atom Chemical compound [3He] SWQJXJOGLNCZEY-BJUDXGSMSA-N 0.000 abstract description 7
- 238000006243 chemical reaction Methods 0.000 abstract description 4
- 150000002431 hydrogen Chemical class 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 230000005258 radioactive decay Effects 0.000 abstract description 2
- 238000005086 pumping Methods 0.000 description 11
- 150000002500 ions Chemical class 0.000 description 9
- 125000004429 atom Chemical group 0.000 description 7
- 150000002739 metals Chemical class 0.000 description 7
- YZCKVEUIGOORGS-OUBTZVSYSA-N Deuterium Chemical compound [2H] YZCKVEUIGOORGS-OUBTZVSYSA-N 0.000 description 6
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 6
- 229910001220 stainless steel Inorganic materials 0.000 description 6
- 239000010936 titanium Substances 0.000 description 6
- 229910052719 titanium Inorganic materials 0.000 description 6
- 230000009471 action Effects 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 3
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- 229910000792 Monel Inorganic materials 0.000 description 2
- 238000009933 burial Methods 0.000 description 2
- 238000012937 correction Methods 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J41/00—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas; Discharge tubes for evacuation by diffusion of ions
- H01J41/12—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps
- H01J41/18—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of cold cathodes
- H01J41/20—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of cold cathodes using gettering substances
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H3/00—Production or acceleration of neutral particle beams, e.g. molecular or atomic beams
- H05H3/06—Generating neutron beams
Definitions
- ABSTRACT ln a sealed-off neutron generator containing tritium, for the production of neutrons by the D-T reaction, helium-3 gas accumulates owing to radioactive decay of the tritium and interferes with the proper operation of the generator.
- a sputter-ion pump is sealed to the generator to remove the helium- 3 from the envelope prior to admitting hydrogen isotope gas from the usual replenisher before use.
- the pump is adapted to remove only the unwanted helium- 3 and not the wanted D and T, by having its sputterable cathodes made of, or coated with, a metal which has a low chemical affinity for hydrogen but is readily sputtered by helium, such as copper.
- This invention relates to neutron generators and relates particularly to generators comprising a sealed-offv envelope or tube in which deuterium and/or tritium ions from an ion source are accelerated to strike a target containing deuterium and/or tritium to produce neutrons by the D-D and/or D-T reactions.
- a generator of this type is described, for example, in U.K. Specification No. 1,088,088 and corresponding US. Pat. No. 3,448,314.
- a low pressure (e.g., about 0.02 mTorr) of deuterium and/ortritium is present throughout the tube during operation.
- This is obtained from a gas replenisher containing a hydrogen-occluding metal (such as titanium) in which deuterium and/or tritium gas has been previously absorbed.
- the desired pressure in the tube is maintained by controlling the temperature of the replenisher. When the replenisher is switched off the gas is reabsorbed by the replenisher and the pressure should fall to approximately zero.
- He-3 is a chemically inert atom, it is not chemically bonded to the target, replenisher and walls in the same way as its parent tritium atom. There is thus a gradual release of l-Ie-3 atoms, which build up a gas pressure in the free space within the tube.
- This free He-3 gas can cause reduction of neutron output in several ways:
- the He-3 gas within the ion source is ionized so that the pressure within the ion source is incorrect and the extracted deuterium and/or tritium ions are contaminated with He-3 ions.
- the deuterium and/or tritium ions undergo various electronic interactions with the neutral l-Ie-3 atoms, which, in general, reduce their velocity of impact on the target.
- a pump in continuous communication with the generator envelope for removing helium from the envelope, said pump being adapted to pump gas from the envelope when the pump is oper- B2,;tnrsssurstnlbqiqnso e can in thibri ated, and substantially not to absorb hydrogen gas from the envelope when the pump is not operated.
- the pump is preferably a sputter-ion pump having sputterable electrode means whereof the sputterable metal has a low chemical affinity for hydrogen.
- the sputterable metal has a high sputtering coefficient for helium ions.
- the sputter-ion pump is preferably of the triode type, the sputterable electrode means comprising at least one multi-apertured, eg grid or mesh, cathode located between an anode and a further electrode on to which, in operation, metal is sputtered from the cathode.
- the pump may be external to the envelope and permanently sealed thereto.
- Sputterable metals suitable for the sputterable electrode include copper, silver and gold.
- the sputterable metal may be a deposit on a stronger metal such as stainless steel, monel or molybdenum, eg, plated on to a grid or mesh of such metals.
- the sputter-ion pump serves to remove the accumulated gaseous He-3 periodically.
- the pressure in the tube is checked. A reading other than zero indicates the presence of He-3 gas and the I-Ie-3 pump is oper ated until a zero indication is obtained. The pump is then switched off, and the replenisher operated to give the working hydrogen isotope pressure.
- conventional sputter-ion pumps are unsuitable for use in the present invention because such pumps comprise metals, such as titanium, which have a high chemical affinity for hydrogen and which would therefore remove the wanted D and T as well as the unwanted He-3.
- the drawing shows the ion-source end of a neutron generator tube of the kind described in U.K. Specification No. 1,088,088. It comprises a glass tube or envelope 1 surrounded by a radiofrequency exciting winding 2. Within the tube analuminum-coated copper electron-stopper 3 is supported on a metal tube 4. At-
- tached to the tube 1 are a gas replenisher 5, a sealingoff tube 6 and a Pirani pressure gauge, the latter being hidden behind sealing-off tube 6.
- the envelope 1 includes a metal portion 7 to which, in accordance with the present invention, there is sealed a triode-type of sputter-ion pump 8 (sometimes called a getter-ion pump).
- Pump 8 comprises an envelope 9 of non-magnetic stainless steel surrounded by hollow cylindrical permanent magnet 10 to provide an axial magnetic field.
- a cylindrical anode 11 Within the envelope 9 are mounted a cylindrical anode 11, a pair of mesh cathodes 12 and a pair of further elecrodes formed as enddiscs 13.
- the anode and the end-discs are earthed to the envelope 9 and are also of stainless steel.
- the mesh cathodes l2 and 12 are mounted on a lead-through connection 14 sealed to an insulating bush 15, and in use are connected to a negative potential, suitably about 4.5 kV.
- the upper mesh cathode 12 is made of stainless steel wire 0.0148 inch in diameter with wires per inch, and is plated with copper to a thickness of 0.002 inch.
- the lower mesh cathode 12' is made of copper wire 0.0124 inch in diameter with 24 wires per inch.
- the use of plated stainless steel wire for cathode 12 prevents it distorting under the weight of cathode 12', which is suspended from it by the narrow flat strips 16.
- Anode 11 and discs 13 are mounted on envelope 9 by further narrow flat strips (omitted for clarity) in a conventional manner.
- the sputterable mesh cathode is usually made of titanium.
- the pump should not pump or absorb gaseous D or T which are present during operation of the generator. Otherwise (a) it would tend to empty the gas replenisher, and (b) its pumping action for He-3 would be impaired by saturation effects. It has been found that such a conventional sputter-ion pump will continue to absorb hydrogen even when the cathode voltage is switched off. This is because, once the titanium film has been deposited, its chemical sorption action does not depend on the presence of electrical voltages.
- the hydrogen absorption problem is alleviated by making the cathode meshes of a metal which does not readily react chemically with hydrogen.
- the film sputtered over the end-discs is relatively chemically inactive and the pumping action substantially ceases immediately the voltage applied to the cathodes is switched off.
- the cathode meshes are made of a metal having a high sputtering coefficient for helium ions. In this way, maximum I-Ie-3 pumping speeds can be obtained and, because of the deeper burial of ions and excited atoms, the re-emission of pumped He-3 is minimised.
- Examples of high-sputtering metals which do not readily react with hydrogen are copper, silver and gold.
- these metals can advantageously be deposited, e.g., by plating, on meshes made of stronger metals such as stainless steel, monel and molybdenum.
- the pump operates satisfactorily at 180 mTorr helium pressure.
- ii. lt pumps down from this pressure to zero in approximately 7 hours and from 50 mTorr in 1 /2 hours, in a volume of about 1 litre.
- the pump does not absorb hydrogen gas at a measurable rate when the cathode voltage is switched off thereafter.
- a sealed-off neutron generator which contains tritium and which includes a replenisher for providing hydrogen isotope gas, wherein there is provided a pump in continuous communication with the generator envelope for removing free helium gas from the envelope, said pump being adapted to pump gas from the envelope when the pump is operated, and substantially not to absorb hydrogen gas from the envelope when the pump is not operated.
- a neutron generator as claimed in claim 3 wherein the sputterable metal is selected from copper, silver and gold.
- a neutron generator as claimed in claim 3 wherein 8.
- a method of operating a neutron generator as the sputterable metal is a deposit on a stronger metal. Claimed in claim 1 comprising operating said pump to 7 A neutron generator as claimed in claim 1 wherein remove helium from the envelope before admitting hy' the pump is external to said envelope and sealed 5 drogen isotope gas from replemsherthereto.
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- High Energy & Nuclear Physics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Electron Tubes For Measurement (AREA)
- Particle Accelerators (AREA)
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB6257069 | 1969-12-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3794875A true US3794875A (en) | 1974-02-26 |
Family
ID=10488272
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US00099331A Expired - Lifetime US3794875A (en) | 1969-12-23 | 1970-12-18 | Neutron generators |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US3794875A (nl) |
| DE (1) | DE2062918C3 (nl) |
| FR (1) | FR2072027B1 (nl) |
| GB (1) | GB1325685A (nl) |
| NL (1) | NL154048B (nl) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5103134A (en) * | 1988-08-26 | 1992-04-07 | U.S. Philips Corporation | Reconditionable particle-generating tube |
| US20090146052A1 (en) * | 2007-12-10 | 2009-06-11 | Schlumberger Technology Corporation | Low Power Neutron Generators |
| CN101978429A (zh) * | 2008-02-27 | 2011-02-16 | 星火工业有限公司 | 寿命长的高效中子发生器 |
| US9734926B2 (en) | 2008-05-02 | 2017-08-15 | Shine Medical Technologies, Inc. | Device and method for producing medical isotopes |
| US10734126B2 (en) | 2011-04-28 | 2020-08-04 | SHINE Medical Technologies, LLC | Methods of separating medical isotopes from uranium solutions |
| US10978214B2 (en) | 2010-01-28 | 2021-04-13 | SHINE Medical Technologies, LLC | Segmented reaction chamber for radioisotope production |
| US11361873B2 (en) | 2012-04-05 | 2022-06-14 | Shine Technologies, Llc | Aqueous assembly and control method |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2964665A (en) * | 1955-12-01 | 1960-12-13 | Tracerlab Inc | Pressure control system |
-
1969
- 1969-12-23 GB GB6257069A patent/GB1325685A/en not_active Expired
-
1970
- 1970-12-18 US US00099331A patent/US3794875A/en not_active Expired - Lifetime
- 1970-12-21 DE DE2062918A patent/DE2062918C3/de not_active Expired
- 1970-12-22 NL NL707018680A patent/NL154048B/nl not_active IP Right Cessation
- 1970-12-22 FR FR7046336A patent/FR2072027B1/fr not_active Expired
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2964665A (en) * | 1955-12-01 | 1960-12-13 | Tracerlab Inc | Pressure control system |
Cited By (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5103134A (en) * | 1988-08-26 | 1992-04-07 | U.S. Philips Corporation | Reconditionable particle-generating tube |
| US7978804B2 (en) * | 2007-12-10 | 2011-07-12 | Schlumberger Technology Corporation | Low power neutron generators |
| US20090146052A1 (en) * | 2007-12-10 | 2009-06-11 | Schlumberger Technology Corporation | Low Power Neutron Generators |
| CN101978429B (zh) * | 2008-02-27 | 2015-04-29 | 星火工业有限公司 | 寿命长的高效中子发生器 |
| US9607720B2 (en) * | 2008-02-27 | 2017-03-28 | Starfire Industries Llc | Long life high efficiency neutron generator |
| US20110091000A1 (en) * | 2008-02-27 | 2011-04-21 | Starfire Industries Llc | Method and system for in situ depositon and regeneration of high efficiency target materials for long life nuclear reaction devices |
| US20110044418A1 (en) * | 2008-02-27 | 2011-02-24 | Starfire Industries Llc | Long life high efficiency neutron generator |
| US9008256B2 (en) | 2008-02-27 | 2015-04-14 | Starfire Industries, Llc | Method and system for in situ depositon and regeneration of high efficiency target materials for long life nuclear reaction devices |
| CN101978429A (zh) * | 2008-02-27 | 2011-02-16 | 星火工业有限公司 | 寿命长的高效中子发生器 |
| CN101990686B (zh) * | 2008-02-27 | 2015-11-25 | 星火工业有限公司 | 长寿命核反应装置高效靶材的原位沉积和再生方法及系统 |
| CN101990686A (zh) * | 2008-02-27 | 2011-03-23 | 星火工业有限公司 | 长寿命核反应装置高效靶材的原位沉积和再生方法及系统 |
| US10366795B2 (en) * | 2008-02-27 | 2019-07-30 | Starfire Industries Llc | Long-life high-efficiency neutron generator |
| US9734926B2 (en) | 2008-05-02 | 2017-08-15 | Shine Medical Technologies, Inc. | Device and method for producing medical isotopes |
| US11830637B2 (en) | 2008-05-02 | 2023-11-28 | Shine Technologies, Llc | Device and method for producing medical isotopes |
| US10978214B2 (en) | 2010-01-28 | 2021-04-13 | SHINE Medical Technologies, LLC | Segmented reaction chamber for radioisotope production |
| US11894157B2 (en) | 2010-01-28 | 2024-02-06 | Shine Technologies, Llc | Segmented reaction chamber for radioisotope production |
| US10734126B2 (en) | 2011-04-28 | 2020-08-04 | SHINE Medical Technologies, LLC | Methods of separating medical isotopes from uranium solutions |
| US11361873B2 (en) | 2012-04-05 | 2022-06-14 | Shine Technologies, Llc | Aqueous assembly and control method |
Also Published As
| Publication number | Publication date |
|---|---|
| GB1325685A (en) | 1973-08-08 |
| NL7018680A (nl) | 1971-06-25 |
| DE2062918A1 (de) | 1971-07-01 |
| DE2062918B2 (nl) | 1974-03-28 |
| NL154048B (nl) | 1977-07-15 |
| FR2072027B1 (nl) | 1975-01-10 |
| FR2072027A1 (nl) | 1971-09-24 |
| DE2062918C3 (de) | 1974-10-24 |
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