Radiant energy – Invisible radiant energy responsive electric signalling – Including a radiant energy responsive gas discharge device
Reexamination Certificate
1999-05-07
2001-12-18
Hannaher, Constantine (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
Including a radiant energy responsive gas discharge device
C250S370010, C250S376000
Reexamination Certificate
active
06331706
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns improvements in and relating to ion detection, particularly, but not exclusively to the detection of ions produced by the passage of alpha particles through a medium, such as a gas.
2. Present State of the Art
Alpha particles are only directly detectable a short distance from their source. As a consequence of this longer range detection techniques have been developed based on the ions produced in the air during the passage of alpha particles. These ions are electrostatically attracted towards a detection location and/or forced towards such a detection location by the flow of air within the apparatus. Once within the detector unit, the electric field existing between electrodes and/or between electrodes and the apparatus attracts ions of one polarity. The current arising can subsequently be measured and the level of alpha contamination present be determined from this current.
The number of ions produced is relatively low and as a consequence the currents arising are relatively low. Because of the low signal level, these signals are prone to interference from background noise and are also close to the practical level detectable in certain circumstances. It is therefore desirable to maximise the number of ions actually detected by the apparatus so as to obtain the strongest signal possible.
BRIEF SUMMARY AND OBJECTS OF THE INVENTION
The present invention aims to provide an apparatus and method of detection whereby the maximum number of ions possible are detected due to the increased effective area of detection unit employed.
According to a first aspect of the invention we provide apparatus for detecting ions, the apparatus comprising a plurality of electrodes, the electrodes being spaced from one another and configured with a first outlet electrode and a second outer electrode and an odd number of intermediate electrodes provided there between, the outer electrodes and alternate intermediate electrodes being electrically connected to a source of electrical potential and to current measuring means, the electrode(s) adjacent the outer electrodes and other alternate electrodes being grounded.
Preferably the plurality of electrodes are provided within a housing. Preferably the housing is grounded. Preferably the housing is electrically conductive.
The housing may comprise an elongate chamber. The housing may have a circular or rectilinear cross-section. The housing may be provided with an inlet and an outlet, the electrodes being provided between the inlet and the outlet.
The housing may be provided with medium, such as fluid flow generating and/or assisting means, preferably to cause medium flow from an inlet to an outlet. The medium flow may be assisted or generated by a fan. Preferably the fluid is a gas.
One or more discrete flow paths over a surface or surfaces of the item or a location may be provided. A pipe, for instance, may have an external flow path separated from an internal flow path by the material forming the pipe. Preferably means are provided for regulating the medium flow along one or more of the discrete paths. Detection of ion generating sources on or in one more of the discrete paths alone may be provided by obscuring or inhibiting one or more of the other flow paths. Sealing means may be provided to inhibit flow along one or more of the flow paths, most preferably in a selective manner. Inflatable seals and/or iris seals and/or aperture seals may be provided.
The ions may be generated by the passage of alpha particles and/or beta particles. The apparatus may be used to monitor alpha and/or beta contamination on an item or location. The items(s) to be monitored may be or include tools, pipes, pumps, filters, cables, rods and the like. The location may include surfaces in general, such as floors, walls, ceilings, soil, rubble, material on a conveyor, and include parts of, or surfaces of items, such as glove boxes, tanks, vessels and the like.
Preferably the item or location is provided at a monitoring location relative to the electrodes. The monitoring location is preferably upstream, in flow, relative to the electrodes. Preferably the item is mounted or supported so as to maximise the surface area exposed to the flow.
The apparatus may be provided with one or two plates, but is preferably provided with at least three electrodes. Preferably at least five, and more preferably at least seven electrodes are provided. The apparatus may be provided with less than 15 and more preferably less than 11 electrodes.
One or more, and preferably all, of the electrodes may be planar. Preferably the electrodes are provided parallel to one another. Preferably the electrodes are provided in opposition, an outer electrode being opposed by one electrode, an intermediate electrode being opposed by two electrodes. The spacing between the electrodes is preferably the same between each pair of opposing electrodes. The spacing between the outer electrodes and the housing is preferably the same as between opposing electrodes.
The electrodes may be continuous, such as a plate, or discontinuous, such as a grid.
Preferably the electrodes define an active area, ions entering the active area being attracted towards one or more electrodes. Preferably the active area extends between all of the electrodes. Preferably the active area extends between the outer electrodes and the opposing parts of the housing. Preferably the active area extends between the edges of the electrodes and the parts of the housing opposing those edges. It is particularly preferred that the active area extent across the entire cross-section of the housing, preferably considered perpendicular to the direction of airflow.
The electrodes are preferably arranged parallel to the direction of airflow. Preferably the airflow passes through the spacing between the electrodes.
The electrical potential is preferably provided by an external power source. Potentials of between 10V and 1000V or even 10000V may be provided.
Preferably a single current measuring means is used. Preferably the combined current of all the electrodes connected to the current measuring means is measured. An electrometer, and most preferably a floating point electrometer is preferred for this purpose.
According to a second aspect of the invention we provide a method for detecting ions, the method comprising:
introducing the ions to a detector unit, the detector unit comprising a plurality of electrodes, the electrodes being spaced from one another and configured with a first outer electrode and a second outer electrode and an odd number of intermediate electrodes provided there between;
applying an electrical potential to the outer electrodes and alternate intermediate electrodes and measuring the current passaging through the outer electrodes and alternate intermediate electrodes; and
grounding the electrode(s) adjacent the outer electrodes and other alternate intermediate electrodes and/or those electrodes not connected to the electrical potential source.
Preferably the plurality of electrodes are provided within a housing and the method includes grounding the housing.
The method may include provided an air flow to convey ions into proximity with the electrodes.
The method may be used for detecting ions generated by the passage of alpha particles. The method may be used to monitor alpha contamination on an item or location.
The other options, possibilities, features and details provided elsewhere in the application are equally applicable to the method.
REFERENCES:
patent: 4788430 (1988-11-01), Gonthier
patent: 4814608 (1989-03-01), Dempsey et al.
patent: 4853536 (1989-08-01), Dempsey et al.
patent: 4970391 (1990-11-01), Uber, III
patent: 4992658 (1991-02-01), Ramsey et al.
patent: 5008540 (1991-04-01), Dempsey
patent: 5055674 (1991-10-01), Kotrappa
patent: 5059803 (1991-10-01), Kronenberg
patent: 5107108 (1992-04-01), Ramsey et al.
patent: 5126567 (1992-06-01), Dempsey et al.
patent: 5128540 (1992-07-01), Stieff
patent: 5184019 (1993-02-01), MacArthur et al.
patent: 5187370 (199
Bounds John Alan
Dockray Thomas
Koster James E.
Luff Craig Janson
Macarthur Duncan Whittemore
British Nuclear Fuels PLC
Gabor Otilia
Hannaher Constantine
Workman & Nydegger & Seeley
LandOfFree
Collection of ions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Collection of ions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Collection of ions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2570687