WO1997050160A1

WO1997050160A1 - Ionization apparatus

Info

Publication number: WO1997050160A1
Application number: PCT/GB1996/001559
Authority: WO
Inventors: Matthew Mccann; Thomas Diamond Mccann
Original assignee: Matthew Mccann; Thomas Diamond Mccann
Priority date: 1996-06-26
Filing date: 1996-06-26
Publication date: 1997-12-31
Also published as: AU6462796A

Abstract

The invention provides ionization apparatus for providing ion concentrations in air several orders of magnitude greater than prior art ionizers. Ion concentrations produced may be of the order 109 ions per cubic centimetre or more, in comparison to previously used maximum concentrations of 5000 - 6000 ions per cubic centimetre. The apparatus preferably includes a large number of discharge points formed by providing a large area, preferably of the order of square metres, of material having a large number of discharge points per unit area (typically 1000 discharge points per square centimetre). Arcing is preferably prevented by using a pulsed electrical current. Very high ion concentrations have various applications such as rapid and effective removal of smoke caused by fire, inhibition of corrosion and air scrubbing: methods and apparatus for these applications are provided. Particle precipitation may be enhanced by providing a strategically placed good earth or a high voltage anode onto which charged particles precipitate. This increases the speed of particle or smoke precipitation and allows the precipitated matter to be easily collected.

Description

IONIZATION APPARATUS

This invention relates to ionization apparatus and especially but not exclusively to ionization apparatus for smoke precipitation.

Room ionizers which release streams of negatively charged ions into the atmosphere are known. Such room ionizers use a sharp point or other elements coupled to a high voltage source, for example 7000 volts, to produce negative ions as a result of corona discharge. Typically the aim of such ionizers is to increase the concentration of negative ions in the air from about 500 or 1000 per cubic centimetre (which is typical for a poorly ventilated building interior) to about 5000 per cubic centimetre (which is typical of some outdoor environments such as near a waterfall). These relatively high concentrations provide air conditioning by removal of positively charged particles of dust and cigarette smoke. This technique has been applied successfully, for example, for home and aircraft air conditioning. Use has essentially been for comfort purposes in an environment where the concentration of particles to be removed has been low, such as only a fraction of one percent. The present invention -is directed towards the production and use of much higher negative ion concentrations than have previously been used and especially to precipitate the constituents of smoke so as to enable smoke reduction or elimination along escape routes in buildings, in the case of fire.

Smoke and exhaust gases comprise small particles of burnt material which move through the air under the influence of draughts, convection and Brownian motion. These small particles are generally positively charged.

It has been shown that positively charged dust, cigarette smoke and dirt particles can be removed by negative ions. One aspect of the present invention is based on the realisation that it is possible to increase the concentration of negative ions very substantially to a level necessary to counteract the rapid production of positively charged particles generated, for example, in a fire. In such circumstances the concentration of particles may rise to greater than ten percent relatively rapidly. In particular this aspect of the invention is directed towards providing structures that may be released and activated to clear smoke from escape routes such as corridors and stairways of buildings. For this purpose ion concentrations many orders of magnitude greater than in the prior art become necessary.

Other aspects of the present invention are based on the realisation that extremely high negative ion concentration may be used for many other purposes such as to inhibit the corrosion (oxidisation) of materials such as metals .

According to a first aspect of the present invention there is provided an air ionizer adapted to produce ion concentrations at least of the order 10⁶ ions per cm³.

Preferably, said air ionizer is adapted to produce ion concentrations in excess of 10⁷, 10⁸, 10⁹, 10¹⁰, 10^u or 10¹² ions per cm³.

Preferably, said air ionizer is adapted to produce said ion concentrations over a relatively large volume of air.

Preferably, said relatively large volume of air is at least of the order of 60000 cm³.

Preferably, said ionizer includes an ionizer element which may be stored in a contracted configuration and which may be deployed in an extended configuration for ion generation.

Preferably, said ionizer element is a flexible member which is retained packed, preferably in folds or gathers, whilst stored in said contracted configuration and which, when released, drops into said extended configuration.

Preferably, said air ionizer includes an ionizer element comprising a large number of conductive fibres with ends which form discharge points.

Preferably, said ionizer element has an active emission surface with at least 100 discharge points per cm² and more preferably with at least 500 or 1000 discharge points per cm².

Preferably, the active surface area of said ionizer element is at least 100 cm² and is more preferably at least of the order 10\ 10*, 10⁵, 10⁶, 10⁷ or 10⁸ cm².

Preferably, said ionizer includes at least 10⁵ and more preferably in excess of 10⁶, 10⁷, 10⁸, 10⁹, 10¹⁰ or 10^H discharge points.

Preferably, said ionizer is adapted to generate ions at a rate of at least 10¹² ions per second, and more preferably at a rate of at least 10¹³, 10^u, 10¹⁵, 10¹⁵, 10¹⁷' 10¹⁸, 10¹⁹, 10²⁰ or 10²¹ per second.

Preferably, there is provided pulsing means to pulse the supply of current.

Preferably, said pulsing means is adapted to pulse current at a frequency of at least 50 Hz and more preferably more than 100 Hz.

Preferably, said ionizer is adapted to produce negative ions at a rate sufficient to precipitate smoke resulting from a fire from the air.

According to a second aspect of the present invention there is provided an air ionizing system for ionizing air and influencing the direction of drift of said ions or other charged particles, said system comprising an air ionizer and an attraction member adapted to attract said ions or charged particles.

Preferably, said attraction member is an electrically conductive earthed or charged member.

According to a third aspect of the present invention there is provided a method of clearing smoke from the air in the event of fire comprising the use of an air ionizer or an ionizing system in order to create an ion density in the vicinity of said smoke high enough to precipitate a substantial amount of said smoke.

According to a fourth aspect of the present invention there is provided a method of inhibiting oxidisation of a subject comprising the use of an air ionizer to produce a negative ion density in the vicinity of the subject high enough to substantially inhibit the oxidation of said subject.

Preferably, said method comprises the further step of negatively charging at least part of the surface of said subject.

Preferably, said subject is a metallic, and in particular a ferrous, object.

According to a fifth aspect of the present invention there is provided a method of cleaning air comprising passing said air to be cleaned through a region in which the air is ionized by an ionizer as claimed in any of Claims 1 to 14 or by an air ionizing system as claimed in either of Claims 15 or 16.

According to a sixth aspect of the present invention there is provided a method of reducing the likelihood of an object being struck by lightning comprising ionization of air in the vicinity of said object.

Preferably, said object is an aircraft.

According to a seventh aspect of the present invention there is provided a method of detecting smoke in a system with gas flowing therethrough comprising the steps of using an ionizer to provide ions at an upstream part of said system and using ion detection o means at a downstream -part of said system to detect variations of the ion concentrations in the vicinity thereof which correspond to the existence of smoke at or between said upstream and downstream parts.

Preferably, said system comprises at least part of a jet engine.

According to an eighth aspect of the present invention there is provided a method of producing ozone in the atmosphere comprising: mounting an ionizer on an aircraft; flying said aircraft in the atmosphere; and using said ionizer to produce ozone by electrostatic discharge.

According to a ninth aspect of the present invention there is provided a method of facilitating the removal of gases from the atmosphere comprising use of an ionizer to hydroxylate molecules of said gases, thereby increasing the solubility of said gases and facilitating their removal by precipitation.

Embodiments of the invention are now described by way of example with reference to the accompanying drawings in which:

Fig. 1 is a schematic circuit and layout diagram of an embodiment of ionization apparatus in the form of an ionizer in accordance with the present invention.

Fig. 2 is a schematic diagram of an embodiment of ionization apparatus in accordance with the present invention;

Fig. 3 is a schematic circuit and layout diagram of an embodiment of ionization apparatus in the form of an ionizer and smoke detector unit in accordance with the present invention;

Figs . 4a and 4b are schematic diagrams of an embodiment of ionization apparatus for fire smoke precipitation having a drop down ionization member;

Figs. 5a, 5b and 5c are schematic diagrams of a further embodiment of ionization apparatus for fire smoke precipitation having a drop down ionization member;

Fig. 6 is a schematic diagram of an embodiment of an ionization apparatus illustrating a control sequence;

Fig. 7 is a schematic diagram illustrating an embodiment of ionization apparatus servicing dual sites;

Fig. 8 is a table showing ion concentrations under various conditions;

Fig. 9 is a table showing experimental results;

Fig. 10a is an illustration of smoke motion by convection; and

Fig. 10b is an illustration of a system for smoke precipitation in accordance with the present invention.

Essential to the invention is to provide very high concentrations of negative ions. Where such high concentrations are to be provided over a relatively large area it is necessary to provide an ion generator, or ionizer, with a high output of negatively charged particles (e.g. electrons). In the described embodiments this is achieved by providing a large 6 number of discharge points, in contrast to the single discharge point provided in some prior art ionizers. The large number of discharge points is preferably obtained by providing a discharge element, or ionizer element with a large number of discharge points per square centimetre of surface (typically of the order of 1000 discharge points per cm²) and a large surface area (at least of the order of square metres in the described embodiments).

Fig. 1 shows schematically the basic construction of an embodiment of a circuit for ionization apparatus in accordance with the present invention. This embodiment uses the mains supply 5. A transformer 6 converts the mains supply to 9000 volts, which in turn is fed to a pulsing unit 7 and DC conversion unit 8. The pulses of DC current of around 0.5 mA are supplied to ionizer element 1 which may have various structural forms described later. In the described embodiments the ionizer element 1 is preferably a sheet of large size formed of a material including a large number of fibres that provides a large number of discharge points from which corona discharge can occur. A high rate of ion production is achieved by virtue of the very large number of discharge points. The large size of the ionizer element increases the risk of arcing which would lead to breakdown in ion production and also potential hazard. Use of high voltages also increases the risk of arcing. The risk of arcing can however be reduced or eliminated by ensuring that the power is supplied to the ionizer element in a pulsed, rather than a continuous manner. Therefore to prevent arcing the circuit is arranged to supply pulses via pulsing unit 7. The output pulses are of a fixed short duration, with a pulsed negative voltage being supplied to the ionizer element 1. The pulse frequency is about 100 Hz in a preferred embodiment but the required speed of pulsing varies with the other parameters of the ionizer. Frequencies of about 50 Hz to over 300 Hz may be appropriate in different embodiments.

Referring to Fig. 2, the basic elements of an embodiment of ionization apparatus adapted to act as a fire smoke precipitation unit comprise an ionizer element 1, shown generally as occupying area 19, with a fan 2 directing air from an inlet over the ion generating circuit to an outlet. Such a unit is not intended to run continuously, but to be triggered to start in the event of a fire. Hence a smoke detector 3 is mounted externally of the unit and is provided with a warning light 4, and/or an audible alarm, which indicates when the unit has been activated and provides an alarm indication to personnel.

Fig. 3 illustrates a suitable circuit for operating the unit of Fig. 2.

The supply to the ionizer element is very similar to that shown in Fig. 1. However, the mains supply is also applied through a second transformer 9 with zener diode circuit 10 converting to DC to supply a relay in a smoke detector circuit 3. When the smoke alarm responds the relay is energised and the ionizer circuit is switched on. An audible alarm 12 is provided, and is activated when smoke is detected. A warning light 4 is also provided.

Figs. 4a and 4b show a first embodiment of a structure for the ionizer element 1. In this embodiment the ionizer element comprises a screen 11, preferably of fire metal meshing or a carbon or graphite textile such as felt or cloth. These materials can provide a large surface area having a very high number of end points from which corona discharge can occur, and exhibit low thermal inertia and low outgassing.

The screen is adapted to fold or be gathered in a concertina manner, as shown in Fig. 4a, and this configuration is maintained while the unit is on standby. It will be appreciated that in the folded configuration the screen is unobtrusive or may even be concealed. When the associated smoke detector 3 senses smoke, or when some other associated triggering mechanism such as a fire alarm is activated, the screen 11 is released to drop into the open configuration shown in Figure 4b. Screens of this nature may be installed in workplaces and along escape routes. The current in the screen is at very low amperage, of the order of 0.5 mA. Units for use in large areas such as shopping malls or arcades, warehouses or large retail outlets may include screens with linear dimensions of tens of metres. As with all described embodiments, to reduce the possibility of arcing the current is pulsed.

In the standby mode the unit may be powered by a battery 20, and the screen held and released by electromagnetic catches 21. The unit includes an audible alarm 22. It will be appreciated that all described embodiments include an insulating casing of plastics or other suitable material. The circuitry is housed in the area referenced 23.

Figs. 5a, 5b and 5c show a further embodiment of a folded ionizer element. In this embodiment strips 12 replace the screen 11 of the previous embodiment. Fig. 5a shows the general appearance of the unit from below when concealed in a ceiling space. Fig. 5b shows the strips held in folded configuration. When the associated smoke alarm is activated, or other triggering occurs, electromagnetic switches holding the strips in the folded configuration are released and the strips fall under their own weight to the configuration shown in Fig. 5c.

Plastic separator strips 13 keep the strips 12 apart, assist the dropping action and stabilise the deployed configuration. The separator strips 13 may also be used for holding and folding purposes. Use of thin strips 12 instead of a screen increases the surface area and hence the number of discharge points, which may be fitted into a given allocated space.

Fig. 6 schematically illustrates a link between the smoke detector, a first relay 14 which closes to activate an alarm 22 and light 4, and a second relay 15 that activates an ionizer. The supply for the ionizer is preferably mains, transformed as described earlier, the supply for the smoke detector may be mains, battery or mains with a battery backup.

A further embodiment of a fire smoke precipitation device in accordance with the invention is shown in Fig. 7. In this embodiment more than one ion generating site is activated by the sensor 3. As in other embodiments the unit comprises an alarm 22 and light 4 in addition to smoke detecting apparatus.

The primary ion generating site 16 comprises an ionizer element in the form of a carbon composite material that both conveys current to the secondary site or site 17 and produces ions via electron emission from its surface. Preferably or alternatively copper or other high conductivity wires running through the material also carry the current to the secondary site. This ionizer element may extend for some distance, or more than one such link may be provided.

One or more secondary sites 17 of ion generating material are provided of significantly larger surface area to produce hyper ionization levels that will effectively remove fire smoke particles from other locations, which may be remote from the detection apparatus. For example, escape route ionizers may become activated irrespective of the location of fire detection as a precautionary measure. It will be appreciated that a modification of this system is for the link provided by the primary ion generating site to be replaced by a purely electrical or signalling link.

The secondary site ion generating material may be any of those previously described or, for example, a large area of carbon composite material on a non-earthing backing. Other possible structures include hessian type weave wall coverings that incorporate small electrically conducting carbon fibres or composite gel materials such as polysaccharide gels impregnated with loose carbon filaments that upon drying provide a conductive medium with ion generating end points . Such gels are presently made incorporating carbon and graphite powders and used in scanning electron microscopy where the electron beam generates an electric current across the gel compound. Filament addition could be achieved by air blasting wet gels with carbon/graphite fibres that on drying provide a coating of fine ion generating filaments or discharge points.

Supplementary highly electrically conductive elements or auxiliary units may also be incorporated to ensure dispersion of current throughout the structures. In experiment, embodiments of fire smoke precipitation devices in accordance with the present invention have been demonstrated to clear fire smoke rapidly. Smoke is cleared by the donation of negative charge to the smoke particulates which causes at least two main mechanisms to occur - precipitation of particles which are caused to clump together by the ionization process; and the moving to ground of negatively charged particulates because of their tendency to earth.

As previously mentioned ion concentrations several orders of magnitude greater than those produced by prior art ionizers are required to clear high concentrations of smoke.

Fig. 8 gives examples of various concentrations levels of negative ions under various conditions. Levels of concentration several orders of magnitude greater than previously utilised levels are referred to as hyper- ionization. In Fig. 8 "hyper-ionization a" refers to ion concentrations approximately millions of times greater than those produced by prior art ionizers and "hyper-ionization b" refers to still higher concentrations in which substantially all the atmospheric oxygen in the vicinity is ionized (saturation levels). At saturation levels other atmospheric gas molecules (such as nitrogen) may be ionized, further increasing the ion concentration.

If a good earth is not available the clearing of smoke by the ionizer may be adversely affected. In order to ensure an effective clearing of smoke a very good earth may be provided by, for example, provision of a well earthed electrically conducting member. Such a member may be well earthed by connection to the earth terminal of a mains socket. If such an improved earth is provided there will be^" a tendency for the precipitating smoke particles to drift towards and precipitate onto said earth. This not only enhances precipitation but also enables some control over where the precipitated matter is deposited, facilitating disposal of said matter.

As an alternative, or in addition, to an improved earth, an anode may be provided, spaced part from the ionizer element. Negatively charged particles (such as smoke particles treated by high ion concentrations) will be attracted to the anode, so the anode will have an effect similar to an improved earth but still more pronounced.

Ion energetics and production are determined by factors including: i) concentration of discharge points per cm²; ii) active ionizer element surface area; iii) electrical current and voltage supply to the ionizer element; iv) earthing impedance; v) forces of attraction to anode; vi) positioning of earth or anode relative to ionizer element; vii) strategic positioning of ionizer element within premises.

Experiments have been conducted for a control having no ionizer plus four different systems incorporating embodiments of the present invention to investigate rates of extraction of airborne smoke particulates (see Fig. 9) .

Systems setups A to D correspond to the following systems: A. Ionizer stand-alone system; B. ionizer plus improved earth; C. ionizer plus anode; D. ionizer plus improved earth and anode.

Garden grade sulphur pellets were used for smoke generation and the experiments were performed at room temperature and pressure.

The experiments were conducted by creating smoke in a closed glass tank with a volume of 68,000 cm³.

In the control system the smoke did not dissipate substantially and was still thick after 15 minutes.

In system A clearing of smoke particles averaged 4.0 minutes. After one minute the initial rate of clearing was observed to decrease as clearing of particles (and particle motion) seemed to slow down. This is explained by earth-impedance build-up within the contained smoke cloud. As a result of this build-up precipitation slowed and the rate of removal (earthing) of smoke decreased.

In system B an improved earth made from sheets of high grade copper was used. The sheets were insulated on one side, the other cleaned and polished. The improved earth was wired to the earth pin of the same plug as provided power to the ionizing unit. This provided a very good earthing surface for the system.

There was a distinct increase in the rate of extraction of the smoke particles from the contained smoke cloud.

Strategic positioning of the improved earth relative to the ionizer element shortening the distance necessary for particles to travel to the earth speeds up the clearing process.

In system C it was observed that while some particulates continued to earth elsewhere there was a greater movement of airborne particulates toward the anode and a very significant build-up of the particulate was observable. Use of the anode was found to increase the rate of extraction of the smoke from the contained smoke-filled air.

In system D the series of tests was difficult to set up due to the restricted size of the container. However, it was apparent that the extraction of the smoke particulates was enhanced and a slight increase in the clearing of the smoke was observed.

It is evident from the experiments that use of an ionizer in accordance with the present invention can clear a significant amount of smoke in a relatively short time.

Use of an associated anode or earth may greatly increase the rate at which smoke is precipitated and positioning of the anode or earth has a considerable effect.

Smoke from fires usually follows a known distribution in the form of a convection current, see Fig. 10a. When treating air to remove smoke from fires it is desirable that the anode or earth is reasonably close to the ionizer element. It is also important that the smoke removal system causes precipitating smoke to drift away from, rather than towards, people in the vicinity. It is therefore envisaged that where practicable the ionizer and anode (or earth) would be positioned in order to take advantage of the normal path that smoke would take in a given space so that smoke particles would first pass the ionizer element 1 (see Fig. 10b) and then move and be precipitated onto an anode (or earth) 30.

The configuration shown in Fig. 10b is an example including the use of a drop down ionizer element. Clearly variations in the configuration of the ionizer element used and positioning of the anode (or earth) are possible. For example, anodes (or earths) which are ceiling mounted could be provided instead of, or in addition to, wall mounted versions. Further, an embodiment in which the ionizer element is in the form of a panel mounted on, and preferably substantially coplanar with, the ceiling is envisaged. Such an embodiment would be particularly suitable for use on aeroplanes (where a solution to the problem of rapid build up of smoke in a contained area is urgently needed) .

A further embodiment is one in which smoke is forced (for example by a fan) past an ionizer element and an anode (or earth) . Such a unit might have a similar appearance to the embodiment of Fig. 2.

Very high concentrations of negative ions may have effects and uses other than smoke precipitation.

Oxidisation, which is the process responsible for much corrosion of metals and spoiling of other substances may be regarded as the loss or sharing of electrons . By loading the air around a subject with high concentrations of negative ions (essentially oxygen atoms each having an excess electron) the loss of electrons from the surface of the subject may be stopped or greatly reduced. Indeed the negative ions may donate electrons to the object effectively reversing oxidisation which has occurred, and possibly liberating or expelling oxygen (or other contaminants) from the surface.

Inhibition of corrosion would be particularly effective if saturation levels of ionization were used, since this would eliminate the attraction between atmospheric oxygen and the electrons of the subject.

The anti-corrosion effect can be further enhanced by the addition of a negative charge to the surface of the subject. This would help to create an electrostatic barrier to inhibit oxygen contact with the metal surface, since negatively ionized oxygen atoms would be repelled from the negatively charged surface.

The combination of electric charge on the object and ionization of air nearing saturation levels, has a three-fold effect in that:

- the charge electrons supplied to the surface may replace lost electrons;

- like charges repel, so the ions and the charged surface will repel to form an electrostatic barrier;

- the oxygen ions that somehow get through the barrier, will donate electrons, reduce surface molecules and therefore inhibit oxidation or oxide formation.

Tests indicate that a measurable current occurs on a target metal surface. This current was found to result from negative ions in the air, created by the ionizer, releasing electrons onto the surface of metal.

In addition, ions (i.e. anions) can be induced to act as nucleophiles and to scavenge and neutralise many potentially corrosive substances.

Clearly the anti-corrosion effects are significant only at high ion concentrations and low (prior art) concentrations would have no appreciable effect. Tarnishing, as well as oxidisation, may be inhibited by high ion concentrations.

As a new approach to anti-corrosion, there are potentially a number of genuine uses for such a system. For example metallic artefacts in museums cannot be lacquered and they are kept within cases: it would be easy to build small ionization units into the cases to prevent oxidation of the metallic surfaces.

In addition to metallic objects, other items such as paintings and tapestries can be protected by application of an electrostatic charge over exposed surfaces in combination with ionization of surrounding air. Prevention of corrosion using ionization may allow other more cumbersome methods (such as storing artefacts in an inert or unreactive atmosphere) to be dispensed with and may allow display of items previously considered too delicate to expose to the atmosphere.

The aforementioned scavenging or neutralisation of potentially corrosive substances has two particular benefits. The first, more obvious, benefit is that corrosive substances which occur in the air (for example having been created by remote sources) can be neutralised in the vicinity of a subject to be protected.

The second benefit is that whereas in the past the cases or cabinets designed to enclose subjects have had to be formed of relatively expensive materials which produce no corrosive agents, it is now feasible to use inexpensive, e.g. plastics, materials which may give off small quantities of such substances. Clearly the other anti-corrosive functions of high ion levels also reduce the risk of damage from such substances.

Furthermore, the use of high ion concentrations will help to protect artefacts from smoke damage in the case of fire, especially where a good earth or anode is provided. Experiments have shown that where an anode is provided close to a neutral non-conductive subject (such as a painting or tapestry) substantially all the smoke is precipitated onto the anode and substantially no smoke is precipitated onto the subject. This effect would be still more pronounced if the negative surface charge on the subject were maintained.

Ionization apparatus in accordance with the present invention could also be used for the sterilisation and cleaning of air. As most airborne particulates, including bacterial, fungal and mould spores have a positive surface charge, it is possible to create an electrostatic attraction-repulsion system for the removal of such matter from the air.

While it is known that prior art ionizers can be used to precipitate particles, and, for example, bacteria out of the air, precipitated particles have previously been randomly deposited meaning that bacteria could then find their way back into the air, i.e. precipitated particles and bacteria were not permanently removed, only temporarily moved to a surface area. Also removal by use of low concentrations of ions would be very slow and only a relatively static body of air could be treated with any efficacy.

By combining ionization apparatus in accordance with the present invention with an improved earth or an anode, the ionization can provide effective removal of airborne particulates (including bacterial, mould, fungal and possibly other microbial matter) and the particulates can be attracted to a specific area for collection and disposal.

Systems are envisaged which would be designed to suit a number of different situations. For example small units could be fitted to the ends of beds for those who are immuno-suppressed and larger units could be situated above doors and windows, also within air conditioning systems.

Pollen consists of relatively large particles with a positive surface charge and could also be removed from the air by a system in accordance with the present invention.

It is known that particles less than 10 microns (10^"5m) in size can be extremely hazardous to health. Use of embodiments of ionization apparatus in accordance with the present invention could either precipitate such particles altogether (and preferably allow facilitated collection of precipitated matter) or at least cause several such particles to clump together so as to form a single larger and less dangerous particle. A further application of high concentrations of negative ions (or of an ionizer capable of producing large numbers of negative ions) can be found in reducing the risk of lightning strikes to certain objects. Discussion of the nature of lightning, and the reasons why a lightning bolt strikes in a given spot, is beyond the scope of this specification. However, lightning may be considered to stem from an excess negative charge finding a path to earth, and it is therefore apparent that lightning will be more likely to strike an anode than a cathode. Some objects vulnerable to lightning strikes produce a stream of positively charged particles, for example jet engines mounted on aircraft emit exhaust gas and chimneys emit smoke, and such emissions increase the objects' susceptibility to lightning strikes. This can be particularly hazardous in the case of lightning strikes upon aircraft.

The generation and emission of high concentrations of air anions, lending to negatively rather than positively charged emissions, can greatly reduce the charge of localised lightning strikes. It is therefore proposed that ions would be generated by ionizers provided at the front (input end) of jet engines and an exhaust stream of negatively charged emissions rather than positively charged emissions would therefore be created. The application of ionizers to lightning strike avoidance may be used in circumstances other than aircraft engines, for example chimneys or other structures, especially those which contain apparatus sensitive to voltage surges, may be protected in this way.

In such arrangements, and in particular in aircraft engines, the anti-corrosion effect of high concentrations of ions could be particularly beneficial.

Furthermore it is known that smoke can be detected by generating negative ions and detecting the drop in negative ion availability which is caused by the ions' interaction with smoke. It is envisaged that smoke production in an aircraft engine could be detected by producing high concentrations at the front of the engine and measuring ion concentrations at the rear of the engine. This could provide an important early warning of engine malfunction.

The use of high production ionizers in aircraft engines may also have a beneficial environmental effect. It is known that ozone can be manufactured by processes of electrostatic discharge in an oxygenated atmosphere. It has not, to date, been considered practicable to produce ozone at the altitudes at which ozone depletion is a problem, that is, at heights above about 12000m. Apparatus designed to produce large number of ions could be used to produce ozone by electrostatic discharge.

Aircraft often fly at heights of 12000 - 50000m. This, with the fact that hyper-ionization has the capacity to manufacture ozone, can provide a new option in the fight against ozone depletion.

Aircraft can be fitted with lightweight ion producing active surfaces, of a metallic, carbon fibre and/or graphite nature and either by supplying electrical energy from a wind-driven dynamo or direct from the aircraft's engine, ozone can be manufactured and released at the appropriate atmospheric level. To help minimise additional drag, and hence fuel consumption, the ionization surfaces can be situated within the tail or engine sections of the aircraft.

In addition, investigations of the chemistry of atmospheric pollution effects suggests that the production of high levels of air-anions, i.e. nucleophiles, may also have other beneficial effects upon primary and secondary pollutant reactants and products. One particular group of deleterious chemicals is, the halon group, e.g. CI and Br. These are known to have very high Ozone Depletion Potentials (ODP) . This is in part due to their long residence times in the stratosphere. It is know that the residence time of some of these chemicals can be reduced by making them several orders of magnitude more soluble by adding a hydroxyl group (OH) enabling the chemicals to be "washed" out of the air by precipitation. By generating high concentrations of ions it appears that "hydroxylation" of these chemicals can be enhanced, reducing their residence times in the stratosphere hence greatly reducing their ODP.

As some of the ozone depletion in the stratosphere occurs due to a free radical cascade reaction where many of the ions are exhibiting their tendency towards a more stable electrical state, a process which donates very high numbers of accessible electrons will have the effect of stabilising some of the free radicals and hence removing them from the chemical equation. At tropospheric levels the same process could be modified to assist in the removal or "de-ionizing" of various free radicals. By modifying the output of the ionizer and the target atoms this could be achieved without producing the ozone which is undesirable at this level. Thus in addition to lightning avoidance, corrosion reduction and smoke detection, use of high production ionization apparatus on aircraft may make a substantial contribution to the environment.

With hyper-ionization and preferably ion-saturation of air, the ability of free oxygen to ionize, convey and donate very large numbers of electrons is provided.

The electrical potential energy can be raised to a level sufficient to overcome the inherent earth impedance within a system. Hence a current can be induced on a conductive surface when sufficient ions radiate upon it. The rate of transfer of electrons is directly related to the concentration of ions produced in the air. Hyper-ionization induces concentrations of ions that are many orders of magnitude higher than has been produced previously.

It is believed that many or all processes of electron reduction or oxidation that may occur in air, or in surfaces in contact with air, can be manipulated by the use of hyper-ionization processes and technology. Combination effects of electron/ion attraction and repulsion between the ionizer element and natural or improved earth and/or anode can be used to manipulate changes in redox systems.

Modifications and improvements may be incorporated without departing from the scope of the invention. In particular, although preferred embodiments are hereinbefore described by way of example, the foregoing description is intended to include disclosure of mechanical and functional equivalents and variations which could clearly be seen to be potentially appropriate by a person skilled in the art.

Claims

1. An air ionizer adapted to produce ion concentrations at least of the order 10⁶ ions per cm³.

2. An air ionizer as claimed in Claim 1 adapted to produce ion concentrations in excess of 10⁷, 10⁸, 10⁹, 10¹⁰, 10ⁿ or 10¹² ions per cm³.

3. An air ionizer as claimed in either preceding claim adapted to produce said ion concentrations over a relatively large volume of air.

4. An air ionizer as claimed in Claim 3 wherein said relatively large volume of air is at least of the order of 60000 cm³.

5. An air ionizer as claimed in any preceding claim wherein said ionizer includes an ionizer element which may be stored in a contracted configuration and which may be deployed in an extended configuration for ion generation.

6. An air ionizer as claimed in Claim 5 wherein said ionizer element is a flexible member which is retained packed, preferably in folds or gathers, whilst stored in said contracted configuration and which, when released, drops into said extended configuration.

7. An air ionizer as claimed in any preceding claim including an ionizer element comprising a large number of conductive fibres with ends which form discharge points.

8. An air ionizer as claimed in any preceding claim including an ionizer element having an active emission surface with at least 100 discharge points per cm² and preferably with at least 500 or 1000 discharge points per cm².

9. An air ionizer as claimed in any of Claims 5 to 8 wherein the active surface area of said ionizer element is at least 100 cm² and is preferably at least of the order 10³, 10⁴, 10⁵, 10⁶, 10⁷ or 10⁸ cm².

10. An air ionizer as claimed in any preceding claim wherein said ionizer includes at least 10⁵ and preferably in excess of 10⁶, 10⁷, 10⁸, 10⁹, 10¹⁰ or 10¹¹ discharge points.

11. An air ionizer as claimed in any preceding claim wherein said ionizer is adapted to generate ions at a rate of at least 10¹² ions per second, and more preferably at a rate of at least 10ⁱ³, 10^1A, 10¹⁵, 10¹⁶, 10¹⁷' 10¹⁸, 10¹⁹, 10²⁰ or 10²¹ per second.

12. An air ionizer as claimed in any preceding claim wherein there is provided pulsing means to pulse the supply of current.

13. An air ionizer as claimed in Claim 12 wherein said pulsing means is adapted to pulse current at a frequency of at least 50 Hz and preferably more than 100 Hz.

14. An air ionizer as claimed in any preceding claim adapted to produce negative ions at a rate sufficient to precipitate smoke resulting from a fire from the air.

15. An air ionizing system for ionizing air and influencing the direction of drift of said ions or other charged particles, said system comprising an air ionizer as claimed in any preceding claim; and an attraction member adapted to attract said ions or charged particles.

16. An air ionizing system as claimed in Claim 15 wherein said attraction member is an electrically conductive earthed or charged member.

17. A method of clearing smoke from the air in the event of fire comprising the use of an air ionizer or an ionizing system as claimed in any preceding claim, in order to create an ion density in the vicinity of said smoke high enough to precipitate a substantial amount of said smoke.

18. A method of inhibiting oxidisation of a subject comprising the use of an air ionizer as claimed in any one of Claims 1 to 14 or the use of an air ionizing system as claimed in either one of Claims 15 or 16 to produce a negative ion density in the vicinity of the subject high enough to substantially inhibit the oxidation of said subject.

19. A method as claimed in Claim 18 comprising the further step of negatively charging at least part of the surface of said subject.

20. A method as claimed in either of Claims 18 or 19 wherein said subject is a metallic, and in particular a ferrous, object.

21. A method of cleaning air comprising passing said air to be cleaned through a region in which the air is ionized by an ionizer as claimed in any of Claims 1 to 14 or by an air ionizing system as claimed in either of Claims 15 or 16 .

22. A method of reducing the likelihood of an object being struck by lightning comprising ionization of air in the vicinity of said object by use of an ionizer as claimed in any one of Claims 1 to 14 or by an air ionizing system as claimed in either of Claims 15 or 16.

23. A method as claimed in Claim 22 wherein said object is an aircraft.

24. A method of detecting smoke in a system with gas flowing therethrough comprising the steps of using an ionizer as claimed in any one of Claims 1 to 14 to provide ions at an upstream part of said system and using ion detection means at a downstream part of said system to detect variations of the ion concentrations in the vicinity thereof which correspond to the existence of smoke at or between said upstream and downstream parts.

25. A method as claimed in Claim 24 wherein said system comprises at least part of a jet engine.

26. A method of producing ozone in the atmosphere comprising: mounting an ionizer as claimed in any one of Claims 1 to 14 on an aircraft; flying said aircraft in the atmosphere; and using said ionizer to produce ozone by electrostatic discharge.

27. A method of facilitating the removal of gases from the atmosphere comprising use of an ionizer as claimed in any one of Claims 1 to 14 to hydroxylate molecules of said gases, thereby increasing the solubility of said gases and facilitating their removal by precipitation.