GB2399216A

GB2399216A - A radio frequency ultraviolet light source

Info

Publication number: GB2399216A
Application number: GB0305092A
Authority: GB
Inventors: James Lodovico Moruzzi
Original assignee: Quay Technologies Ltd
Current assignee: Quay Technologies Ltd
Priority date: 2003-03-06
Filing date: 2003-03-06
Publication date: 2004-09-08
Anticipated expiration: 2023-03-06
Also published as: GB0305092D0; GB2399216B

Abstract

An ultraviolet light source comprising a radio frequency energy generator 60 connected to two separate electrodes 30 and 32, the electrodes arranged to excite at least one ultraviolet bulb 10 with RF energy. At least one of the electrodes, preferably both, are optically transparent, and are arranged so as to substantially surround the bulb. This is achieved by forming the electrodes of an optically transparent material, or of an electrically conductive grid/mesh. The UV light source is particularly suitable for use in the sterilisation of substances; the promotion of photochemical reactions; and the promotion of molecular dissociation in liquids. Also disclosed is an electrodless ultraviolet bulb containing a vapour which emits UV radiation on excitation, and provided with a spur or protrusion shaped for receipt of means for cooling the vapor (see figures 11 and 12).

Description

23972 l UV light source

Technical Field

The present invention is in the field of ultraviolet (UV) light sources, particularly those suitable for use in sterilization apparatus.

Background to the Invention

It is known to use ultraviolet (UV) radiation in sterilization systems for use in the purification of water and the sanitisation of a variety of items. The UV radiation and any ozone produced by the UV radiation with oxygen in the air acts to kill bacteria and germs. It is also known to use ultraviolet (UV) radiation for a variety of other uses including those involving the promotion of photochemical reactions and of molecular dissociation.

Known systems employ microwave energy to excite the source of UV radiation. One problem such systems is that it is difficult to efficiently provide sufficient excitation energy to the UV source and difficult to effectively transfer that energy to the substance or entity to be treated. It is therefore difficult to arrange systems for high energy, high throughput industrial purposes.

There is now described an ultraviolet light source which enables efficient, high throughput UV treatment to be conducted. The ultraviolet light source comprises an UV bulb that is excited by a radio frequency excitation system.

The radio frequency excitation system comprises two separate optically transparent electrodes in electrical connection with a radio frequency generator. The electrodes are arranged to effectively transfer exciting radio frequency energy to the bulb.

The ultraviolet light sources of the present invention have been found to provide for good efficacy (e.g. enhanced sterilising capability) and low power consumption, particularly when the bulb is excited in pulsed fashion.

POT Patent Applications No.s WO 00/32244 and WO 01/09924 (in the name of the Applicant) describe ultraviolet light sources excited by a microwave energy generator.

Summary of the Invention

According to one aspect of the present invention there is provided an ultraviolet light source comprising a radio frequency energy generator; in electrical connection with said generator, a first optically transparent electrode; in electrical connection with said generator but separate from said first electrode, a second electrode; and an ultraviolet bulb, wherein said first and second electrodes are arranged to excite said ultraviolet bulb with radio frequency energy from the generator.

The radio frequency generator may have any suitable form. Suitably, it generates radio frequency energy in the range from 5 to 50 MHz, for example 13.57, 27.12 and 40.68 MHz.

The generator and electrodes are generaHy arranged to excite a resonant circuit for excitation of the bulb. Once excited, the bulb emits ultraviolet radiation.

In general terms, the resonant circuit includes capacitative and inductance elements. In one aspect, the first and second separated electrodes form act as a capacitor and the inductor is present within the radio frequency generator. In another aspect, the capacitor is present within the radio frequency generator and the electrode(s) act as an inductor (e.g. being shaped as an inductive coil).

Suitably, the ultraviolet bulb has an operating temperature, which maximises the chosen bulb characteristics. Typical operating temperatures are from 1 0 C to 900 C, for example 40 C to 200 C and the operating temperature will be selected and optimised according to the purpose of use.

The first and second electrodes both connect to the generator, but are otherwise distinct (e.g. located physically distant to one another).

In one aspect, the first optically transparent electrode partially surrounds the ultraviolet bulb. Preferably, the first electrode generally or wholly surrounds the ultraviolet bulb. By 'generally surrounds' it is meant that the bulb is surrounded to the extent that it is in essence, excitable as if it were wholly surrounded. By way of an example, in one embodiment a tubular bulb is wholly surrounded (i.e. along its whole length) by a cylindrical first electrode and in a related embodiment the same tubular bulb is generally surrounded by a first electrode in the form of a broken cylinder (e.g. 340 cylinder with 20 slit cutaway along its length).

By optically transparent electrode it is meant an electrode that is substantially transparent to the ultraviolet radiation employed herein, typically having a transparency of greater than 50%, preferably greater than 90% to UV radiation.

Optical transparency may in aspects, be achieved by the use of optically transparent materials to form the electrode(s). Alternatively, the electrode may be physically shaped (e.g. in a mesh pattern) such that the required transparency is achieved even when the constituent materials of the mesh are non-optically transparent.

Suitably, the first electrode has the form of a hollow cylinder and the second electrode has the form of a solid cylinder locating along the axis defined by said hollow cylinder. That is to say, the second electrode lies along the central axis defined by the cylindrical form of the first electrode.

In another aspect, the first and second electrodes in combination partially surround the ultraviolet bulb and both electrodes are optically transparent.

Preferably, the first and second electrodes in combination generally or wholly surround the ultraviolet bulb and both electrodes are optically transparent. The term 'generally surround' has the meaning as described above. In this aspect, both electrodes in combination act such as to wholly or generally surround the bulb.

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Suitably, both of the first and second electrodes have semi-cylindrical form. In particular, both semi-cylindrical electrodes are arranged in near mating fashion such as to define a cylindrical region to receive the ultraviolet bulb.

Suitably, both of the first and second electrodes have planar form. Square or rectangular electrode forms are for example, envisaged.

Suitably, both of the first and second electrodes have cylindrical form. In particular, the first and second cylindrical electrodes have different diameters and may be arranged in concentric fashion to receive a cylindrical ultraviolet bulb in the region defined there between.

The first and second electrodes generally comprise metallic or other conducting material. Suitably, both electrodes comprise meshed material (e.g. metallic mesh material).

In one aspect, the ultraviolet light source comprises a single ultraviolet bulb.

Suitably, the single ultraviolet bulb nests within a region defined by the first and second electrodes. It will be appreciated that a distance will generally exist between the bulb and the electrodes, and the term 'nests' should be read in the light of this appreciation.

In one aspect, either of the first and second electrodes is deposited on the bulb.

The ultraviolet bulb may have any suitable shape and size, including elongate forms such as a cigar-shape. The bulb size can be tailored. Typical bulb diameters are from 5 to 200mm, for example 22mm.

Embodiments are envisaged in which plural bulbs are employed. The bulb may be similar in type e.g. of similar size and operating temperature or combinations of different bulb types may be employed. The number of bulbs employed is tailored to the purpose of use. Typically from 2 to 25 bulbs are employed, such as from 3 to 18 bulbs.

Various forms of arrangement of the plural bulbs are envisaged including random or informal arrangements.

Suitably, the plural ultraviolet bulbs are uniformly arranged within a region defined by the first and second electrodes. Preferably, the plural ultraviolet bulbs form an arrangement selected from the group consisting of a side-by- side arrangement, a series arrangement, an array arrangement and a cluster arrangement.

Suitably, the ultraviolet light source additionally comprises an enclosure for enclosing the first electrode, the second electrode and the ultraviolet bulb in combination. That is to say, each of these elements is enclosed.

In one aspect, the enclosure controls the flow of ultraviolet radiation there from.

The control function typically includes the prevention of the release of harmful or unnecessary ultraviolet radiation frequencies. The material of the enclosure may be selected to preferentially allow different wavelengths of UV radiation to escape. The exact nature of the enclosure and its control function can be tailored to fit the purpose of use.

Suitably, the enclosure is in the form of a sleeve.

Suitably, the enclosure comprised a UV-transparent material. Preferably, the enclosure comprises quartz.

Suitably, the electrodes or any enclosure therefor are coated with a coating, which assists in controlling the flow of ultraviolet and/or radio frequency energy therefrom. The coating may be applied to either or both of the inner or outer surfaces of the enclosure. Partial coatings are also envisaged.

Suitably, a system for cleaning the electrodes or any enclosure therefor (e.g. a quartz tube) is incorporated herein. Suitable cleaning systems include those based upon fluid flow, such as flow of water, air or gas. Cleaning agents such as detergents may be employed as necessary.

Suitably, the ultraviolet light source additionally comprises a housing for the enclosure. Preferably, the housing has an inlet and an outlet and the housing is shaped to guide fluid flow from the inlet past the enclosure (e.g. along a protective sleeve enclosure) to the outlet. Preferably, the fluid comprises air or a liquid such as water. Suitably, the ultraviolet light source additionally comprises a pump for pumping fluid from the inlet, past the enclosure to the outlet. Alternatively, gravity may be utilised to encourage fluid flow.

The choice of materials for use in the housing and any fluid flow piping arrangements can be important. Typically, the materials will be selected which are resistant to corrosion and which do not leach contaminants to the system.

Seal materials are also carefully selected with typical seal materials including Chemraz (trade name), Teflon (trade name), encapsulated Viton (trade name) and GORE-TEX (trade name).

Suitably, the radio frequency generator generates pulses of radio frequency energy to excite the ultraviolet bulb. In another aspect, continuous radio frequency generators may also be employed.

In general, the ultraviolet light bulb herein requires pulsing at relatively high power levels at a relatively short pulse width.

Suitably, the radio frequency excitation system can be pulsed with pulse widths ranging from 100 milliseconds to 0.5 microseconds, preferably from 10 milliseconds to 5 microseconds.

Suitably, the radio frequency excitation system has a pulse period of from 200 milliseconds to 1.0 microseconds, preferably from 5 milliseconds to 50 microseconds.

Optimisation of both pulse width and pulse period is preferred.

Suitably, the peak operating energy of the bulb is from 40 watts to 100, 000 watts, preferably from 40 watts to 30,000 watts.

In aspects herein, the bulb may be excited by both a continuous (i.e. nonpulsed) radio frequency excitation system and a pulsed radio frequency excitation system. In aspects, the ultraviolet light source additionally comprises a continuous radio frequency excitation system, which may be separate from or integral with the pulsed radio frequency excitation system.

Suitably, the energy consumption of pulsed excitation is significantly lower than that of continuous excitation. Typically, the pulsed energy for excitation is directly dependent on the pulse duty cycle (pulse width / pulse period).

Suitably, the peak energy value of pulsed excitation is significantly higher than that of the peak energy value of continuous excitation. Typical peak energy ratios are from 1:10 to 1:100 for continuous-pulsed energy systems. In one example, the lamp is excited at steady state by a continuous 100 watt energy source and pulsed at up to 3,000 watts by a pulsed excitation source.

In aspects, the ultraviolet light source may be arranged for the emission of either monochromatic or polychromatic ultraviolet radiation.

The dominant wavelength of the ultraviolet light source may be selected according to the particular application for which the light source is to be used.

In one aspect, the dominant wavelength of the ultraviolet light source is from 240nm to 31 Onm, particularly 254nm. Such wavelengths have been found to be particularly useful for sterilization, purification or sanitisation applications.

In another aspect, the dominant wavelength of the ultraviolet light source is from 140 to 260nm, preferably from 150 to 220nm, most preferably from 160 to 200nm, particularly 182nm or 185nm. Such wavelengths have been found to be particularly useful for use in promoting molecular dissociation reactions.

In a further aspect, the dominant wavelength of the ultraviolet light source is from 310 to 400nm, preferably from 320 to 380nm, most preferably from 330 to 370nm, particularly 346nm. Such wavelengths have been found to be particularly useful for use in promoting certain photochemical reactions.

The ultraviolet light produced by the ultraviolet light source herein may additionally be channelled as a light source of high intensity. Suitable uses would include lighting within buildings and lighting for vehicles such as cars, lorries and buses.

Suitably, the ultraviolet bulb has no electrode. That is to say it is an electrode- less bulb such as one comprising a partially evacuated tube comprising an element or mixtures of elements in vapour form. Mercury is a preferred element for this purpose, but alternatives include mixtures of inert (e.g. xenon, argon and mixtures thereof) gases with mercury compounds, sodium and sulphur. Halides, such as mercury halide are also suitable herein. Amalgams are also suitable herein including indium / mercury amalgam.

Inevitably, such electrode-less bulbs emit a spectrum of wavelengths, dependent on the chemical nature of the core element or elements.

Embodiments employing multiple lamps of different spectrum characteristics are envisaged herein.

According to another aspect of the present invention there is provided an ultraviolet light source assembly comprising a first optically transparent electrode, electrically connectable to a radio frequency energy generator; a second electrode, separate from said first electrode and electrically connectable to said radio frequency energy generator; and an ultraviolet bulb, wherein said first and second electrodes are arranged to excite said ultraviolet bulb with radio frequency energy receivable from the generator.

In one aspect, the first electrode generally or wholly surrounds the ultraviolet bulb.

In another aspect, the first and second electrodes in combination generally or wholly surround the ultraviolet bulb and both are optically transparent.

According to another aspect of the present invention there is provided a method of sterilising a substance comprising employing the ultraviolet light source described herein to apply radio frequency energy to an ultraviolet bulb to produce ultraviolet radiation of dominant wavelength of from 240nm to 310nm; and exposing the substance to said ultraviolet radiation.

The sterilising method aspect herein is suitable for use in sterilising a variety of substances including water for human consumption; waste water and sewage; metallic and non-metallic objects including medical instruments; air in buildings such as hospitals, offices and homes; and in prolonging the shelf-life of foodstuffs (e.g. fruit and vegetables) by killing bacteria on the surface thereof.

The sterilising method aspect herein is suitable in one aspect for use in air conditioning systems for use in vehicles such as cars, lorries and buses. The system will be sized and shaped to fit within the airconditioning system of the I vehicle and will typically therefore have a size less than the size it would possess when used in large scale air and water treatment applications.

According to another aspect of the present invention there is provided a method of promoting the dissociation of a molecular entity comprising employing the ultraviolet light source described herein to apply radio frequency energy to an ultraviolet bulb to produce ultraviolet radiation of dominant wavelength of from 140 to 260nm; and exposing the molecular entity to said I ultraviolet radiation.

In one aspect, the molecular entity is borne in a fluid such as air or a liquid and the fluid flows past the enclosure. A specific example of this is in the clean up: of ballast seawater from the holds of ships wherein contaminants in the ballast water are dissociated by application of ultraviolet radiation.

A further specific example of molecular dissociation applications based on fluid flow is in the dissociation of organic material, such as Total Oxidisable Carbon (TOC) in rinse water for use in the electronics, semiconductors pharmaceuticals, beverage, cosmetics and power industries. The process involves the production of OH radicals which oxidise any hydrocarbon molecules in the rinse water. Optionally, other oxidants may be employed such as ozone and hydrogen peroxide. Typically, polishing deionization beds, featuring nuclear-grade resin materials are placed downstream of the TOC reduction units to remove any ionised species and restore the resistivity of the water.

In another aspect, the molecular entity is borne on a surface and the ultraviolet radiation is applied to the surface to eliminate any bacterial contaminants by disinfection. The molecular entity may, for example be a contaminant on the surface which is rendered harmless by its molecular dissociation.

In one example, the surface is of a food product such as a meat, dairy, fish, fruit or vegetable product and the ultraviolet radiation is applied to the surface; to dissociate any contaminants such as chemical residues including pesticides.

In another example, the surface is an industrially-produced product such as a packaging product for example, a medical packaging product, a foil bag, cup or lid, or a glass or plastic bottle, and the ultraviolet radiation is applied to the surface to dissociate any contaminants arising from the industrial process.

In a further example, the surface is the surface of any equipment used in the manufacture of food products or industrially produced products such as the surface of any reactors or conveyors.

According to another aspect of the present invention there is provided a method of promoting a photochemical reaction in a substance comprising employing the ultraviolet light source described herein to apply radio frequency energy to an ultraviolet bulb to produce ultraviolet radiation of dominant wavelength of from 310 to 400nm; and exposing the substance to said ultraviolet radiation.

In one aspect, the substance is borne in a fluid such as air or a liquid and the substance-bearing fluid flows past the enclosure.

In another aspect, the substance is borne on a surface and the ultraviolet radiation is applied to the surface.

Preferably, the substance is selected from the group consisting of surface treatment materials including paints, toners, varnishes (e.g. polyurethane varnishes), stains and laminating materials.

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Laminating is for example, used in the production of various electronic components, data storage devices including compact discs and packaging materials including blister packages.

In another method aspect herein, the exposure of a biological substance to wavelengths of less than 200nm or from 300-400nm has been found to help to prevent DNA recovery. This may for example, be of use in the elimination of biological contaminants and pests e.g. insects.

In the method aspects herein, the radio frequency energy suitably has a pulse width of from 100 milliseconds to 0.5 microseconds, preferably from 10 milliseconds to 5 microseconds. Suitably, the radio frequency energy has a pulse period of from 200 milliseconds to 1.0 microseconds, preferably from 5 milliseconds to 50 microseconds. Optimisation of both pulse width and pulse cycle is preferred.

In another aspect, the Applicants have found that in use, it is desirable to provide a pronounced degree of cooling to at least part of the ultraviolet bulb.

This applies whether the bulb is excited by a radio frequency source, as described herein, or by a microwave energy source, for example as described in POT Patent Applications No.s WO 00/32244 and WO 01/09924 (also in the name of the Applicant).

The desirability for cooling arises because the peak operating temperature of a bulb is typically higher than the optimum temperature for emission of ultraviolet radiation required for sterilization purposes. In one example, the operating temperature of a particular bulb is 100 C whereas the optimum temperature for emission of ultraviolet radiation is 40 C.

It can be costly and involve practical difficulties to cool the entire bulb (e.g. by a fan cooling system). The Applicants have therefore developed a solution in which only a part of the bulb is made available to a cooling system.

According to another aspect of the present invention there is provided an electrodeless ultraviolet bulb comprising a housing; and within said housing a vapour form material which emits ultraviolet radiation on excitation by an energy source, wherein said housing is provided with a spur shaped for receipt of cooling means for cooling the vapour form material in said spur.

The housing may have essentially any suitable form but is often elongate, for example of elongate cylindrical form.

The housing comprises an optically transparent material such as glass or quartz.

The ultraviolet bulb has no electrode. Typically, the housing is a partially evacuated tube comprising an element or mixtures of elements in vapour form that emit ultraviolet radiation on excitation by an energy source. Mercury is a preferred element for this purpose, but alternatives include mixtures of inert gases (e.g. xenon, argon and mixtures thereof) with mercury compounds, sodium and sulphur. Halides, such as mercury halide are also suitable herein.

Amalgams are also suitable herein including indium / mercury amalgam.

The housing is provided with a spur that shaped for receipt of cooling means for cooling the vapour form material found within the spur. By spur it is meant an element of the housing that branches off from the main housing for example, in the sense that it disturbs the overall geometry of the main housing.

In one example, the housing is an elongate tube (e.g. cylindrical or cigar- shaped) and the spur comprises a side arm (or dog leg) branching of at a right angle to the elongate axis.

The spur is sized and shaped to receive a cooling means. The cooling means can provide cooling by any suitable means including conductive and convective. In one aspect, the cooling means is a heat sink. In another aspect, where the bulb is used in a sterilization apparatus for sterilising a fluid (e.g. water or air) the cooling is arranged to be provided by that fluid.

Within the spur area it can be advantageous for the vapour pressure of the vapour form material to be reduced (e.g. to around 6 millibar pressure of mercury). In aspects, the vapour form material is cooled to such a temperature that it condenses out as a liquid or solid (e.g. vapour form mercury would typically condense out to liquid mercury when cooled to 40 C).

The ultraviolet electrodeless bulb with spur as described above, may be used with any suitable energy generator.

According to another aspect of the present invention there is provided an ultraviolet light source comprising an energy generator; in electrical connection with said generator, a first optically transparent electrode; in electrical connection with said generator but separate from said first electrode, a second electrode, wherein said first and second electrodes are arranged to excite said ultraviolet bulb with radio frequency energy from the generator; an electrodeless ultraviolet bulb comprising a housing and within said housing a vapour form material which emits ultraviolet radiation on excitation by an energy source, wherein said housing is provided with a spur shaped for receipt of cooling means for cooling the vapour form material in said spur.

In aspects, both the first and second electrodes are optically transparent.

The energy generator may be a radio frequency energy generator or a microwave energy generator (e.g. a magnetron).

The ultraviolet light source incorporating the spurred ultraviolet bulb may also be used in a sterilization apparatus and in accord with any of the method of use aspects described herein.

Brief description of the drawings

Preferred embodiments of the ultraviolet light source in accord with the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a schematic, sectional representation of a steriliser apparatus incorporating a first ultraviolet light source herein; Figures 2a and 2b are schematic, sectional representations of steriliser apparatus incorporating second and third ultraviolet light sources herein; j Figure 3 is a schematic, sectional representation of a steriliser apparatus incorporating a fourth ultraviolet light source herein; ; Figure 4 is a schematic, sectional representation of a steriliser apparatus incorporating a fifth ultraviolet light source herein; Figure 5a is a schematic, sectional representation of a sixth ultraviolet light source herein; Figure 5b is a schematic, perspective view of the enclosure arrangement of the sixth ultraviolet light source of Figure 5a; Figure 6a is a schematic, sectional representation of a seventh ultraviolet light source herein; Figure 6b is a schematic, perspective view of the enclosure arrangement of the seventh ultraviolet light source of Figure 6a; Figure 7 is a schematic, sectional representation of an eighth ultraviolet light source herein; Figure 8 is a schematic, sectional representation of a ninth ultraviolet light source herein; Figure 9 is a schematic, cross-sectional representation of a tenth ultraviolet light source herein; Figure 10 is a schematic representation of a suitable pulsed radio frequency energy wave herein; Figure 11 is a schematic, sectional representation of a first ultraviolet light source herein comprising a spurred electrodeless bulb; Figure 12 is a schematic, sectional representation of a second ultraviolet light source herein comprising a spurred electrodeless bulb; Figure 13 is a schematic, cross-sectional representation of an eleventh ultraviolet light source herein; Figure 14 is a schematic, cross- sectional representation of a twelfth ultraviolet light source herein; Figure 15 is a schematic, plan representation of a thirteenth ultraviolet light source herein; and Figure 16 is a side-view of a wiper system for use with an ultraviolet light source herein.

Detailed description of the invention

The present invention is here described by means of examples, which constitute possible embodiments of the invention.

Figure 1 shows an ultraviolet light source comprising an ultraviolet bulb 10 enclosed by cylindrical enclosure 20. The cylindrical walls of the enclosure 20 are comprised of quartz material, which is transparent to UV radiation. First 30 and second 32 semi-cylindrical mesh optically transparent electrodes are provided within the enclosure 20 and locate proximal to the inner wall thereof.

In combination, the electrodes 30, 32 act such as to surround the bulb 10. The ends of the cylindrical enclosure 20 have blocking end flanges 22, 24 provided thereto. The electrodes 30, 32 connect via electrical contact points 40, 42 to radio frequency generator 60.

In use, the radio frequency generator acts as a pulsed radio frequencyexcitation system to excite a resonant circuit via the electrodes 30, 32 and thus to provide pulsed radio frequency excitation energy to the ultraviolet bulb 10 which emits ultraviolet radiation.

The enclosure 20 locates within tubular housing 70. The housing 70 has a fluid inlet 72 and a fluid outlet 74 provided thereto. In use, fluid flows from the inlet 72 past the enclosure 20 and towards the outlet 74. As the fluid flows past the enclosure 20 it is irradiated with UV radiation produced by the ultraviolet bulb 10. The radiation itself passes through the UV transparent walls of the enclosure 20 to contact the fluid. In one aspect, the fluid is water and the dominant wavelength of emitted UV radiation is 254nm.

Figures 2a and 2b show related ultraviolet light sources herein. Both comprise ultraviolet mercury discharge bulb 11 Oa, 11 Ob enclosed by cylindrical enclosure 120a, 120b. The cylindrical walls of the enclosure 120a, 120b form a sleeve comprised of quartz material, which is transparent to UV radiation. The enclosure 120a, 120b has air or nitrogen circulating therein. First end 122a, 122b of the cylindrical enclosure is squared off. The second end is provided with blocking flange 124a, 124b.

First 130a, 130b and second 132a, 132b semi-cylindrical mesh optically transparent electrodes are provided within the enclosure 120a, 120b and locate proximal to the inner wall thereof. In combination, the electrodes 130a,130b; 132a, 132b act such as to surround the bulb 11 Oa, 11 Ob. The electrodes 130a,130b; 132a, 132b connect via electrical contact points 140a,140b; 142a, 142b to radio frequency generator 160a, 160b.

In use, the radio frequency generator 160a, 160b acts as a pulsed radio frequency excitation system to excite a resonant circuit via the electrodes 130a,130b; 132a, 132b and thus to provide pulsed radio frequency excitation energy to the ultraviolet bulb 11 Oa, 11 Ob which emits ultraviolet radiation.

The enclosure 120a, 120b is within tubular housing 170a, 170b. The housing 170a, 170b has a fluid inlet 172a, 172b and a fluid outlet 174a, 174b provided thereto. In use, fluid flows from the inlet 172a, 172b past the enclosure 120a, 120b and towards the outlet 174a, 174b. As the fluid flows past the enclosure 120a, 120b it is irradiated with UV radiation produced by the ultraviolet bulb 11 Oa, 11 Ob. The radiation itself passes through the UV transparent walls of the enclosure 120a, 120b to contact the fluid. In one aspect, the dominant wavelength is 254nm.

In variations, the systems of Figures 1; 2a and 2b may be provided with cooling systems to enable the cooling of the bulb.

Figure 3 shows a cabinet ultraviolet light source herein suitable for use in treating objects herein. Ultraviolet mercury discharge bulb 210 is enclosed by cylindrical enclosure 220. The cylindrical wails of the enclosure 220 are comprised of quartz material that is transparent to UV radiation. The enclosure 220 has cooling air or nitrogen circulating therein. First end 222 of the cylindrical enclosure is squared off. The second end is provided with blocking flange 224.

First 230 and second 232 semi-cylindrical mesh optically transparent electrodes are provided within the enclosure 220 and locate proximal to the inner wall thereof. In combination, the electrodes 230, 232 act such as to surround the bulb 210. The electrodes 230, 232 connect via electrical contact points 240, 242 to radio frequency generator 260.

In use, the radio frequency generator 260 acts as a pulsed radio frequency excitation system to excite a resonant circuit via the electrodes 230, 232 and thus to provide pulsed radio frequency excitation energy to the ultraviolet bulb 210 which emits ultraviolet radiation.

The enclosure 220 is within housing 270, which has an entry door 280 provided thereto. In use, items to be treated are placed in the housing 270.

The items are irradiated with pulsed UV radiation produced by the ultraviolet lamp 210. The radiation itself passes through the UV transparent wails of the enclosure 220 to contact the items. Optionally, the housing 270 may be provided with UV transparent shelves for the items. An inner reflective lining, for example an aluminium foil lining, may also be provided to the housing 270.

Figure 4 shows an ultraviolet light source comprising an ultraviolet bulb 310 1 enclosed by cylindrical enclosure 320. The cylindrical walls of the enclosure 320 are comprised of quartz material that is transparent to UV radiation. The quartz tube enclosure 320 is provided with a cleaning system comprising wiper 380 that is mounted for movement on track 382. The track 382 is arranged parallel to the enclosure 320 and the movement of the wiper 380 is powered by motor 384.

First 330 and second 332 semi-cylindrical mesh optically transparent; electrodes are provided within the enclosure 320 and locate proximal to the inner wall thereof. In combination, the electrodes 330, 332 act such as to surround the bulb 310. The ends of the cylindrical enclosure 20 have blocking end flanges 322, 324 provided thereto. The electrodes 330, 332 connect via electrical contact points 340, 342 to radio frequency generator 360.

In use, the radio frequency generator acts as a pulsed radio frequency excitation system to excite a resonant circuit via the electrodes 330, 332 and thus to provide pulsed radio frequency excitation energy to the ultraviolet bulb 310 which emits ultraviolet radiation.

The enclosure 320 is within stainless steel housing 370. The housing 370 has a fluid inlet 372 and a fluid outlet 374 provided thereto. In use, fluid flows from the inlet 372 past the enclosure 320 and towards the outlet 374. As the fluid flows past the enclosure 320 it is irradiated with UV radiation produced by the ultraviolet bulb 310. The radiation itself passes through the UV transparent walls of the enclosure 320 to contact the fluid.

In variations, another form of wiper arrangement may be employed which comprises plural (e.g. two) helical blades (similar to cylindrical lawn mower blades) arranged along the length of the quartz enclosure sleeve 320. As fluid flows along the outside of the enclosure 320 these blades will rotate and if a suitable material is placed on the Inner edge of each blade cleaning of the quartz sleeve 320 will be promoted.

It may be appreciated that lamps comprising plural bulbs in any suitable arrangement may be employed in variations of the ultraviolet light sources shown in Figures 1 to 4.

Figure 5a shows an ultraviolet light source comprising plural ultraviolet bulbs 410a, 410b arranged in a circular arrangement and enclosed by cylindrical enclosure 420. The cylindrical walls of the enclosure 420 are comprised of quartz material, which is transparent to UV radiation.

A cylindrical mesh optically transparent electrode 430 (of typical length 1000mm and typical diameter from 40 to 500mm) is provided within the enclosure 420 and locates proximal to the inner wall thereof. This cylindrical electrode 430 surrounds the bulbs 41 Oa, 41 Ob, which are located interior to the cylinder 430. A solid central electrode 432 is also provided within the enclosure 420 and lies along the central axis defined by the cylindrical electrode 430 (and indeed, at the centre of the circular arrangement of bulbs 410a, 410b). The relative spatial relationship of the electrodes 430, 432 may be better understood by making reference to Figure 5b.

The electrodes 430, 432 (which together act as a capacitor) connect via electrical contact points 440, 442 to radio frequency generator 460. In use, the radio frequency generator acts as a pulsed radio frequency excitation system to excite a resonant circuit via the electrodes 430, 432 and thus to provide pulsed radio frequency excitation energy to the ultraviolet bulb 410 which emits ultraviolet radiation.

Figure 6a shows an ultraviolet light source comprising plural ultraviolet bulbs 510a, 510b arranged in a circular arrangement and enclosed by cylindrical enclosure 520. The cylindrical walls of the enclosure 520 are comprised of quartz material, which is transparent to UV radiation.

Two semi-cylindrical mesh optically transparent electrodes 530, 532 (of typical length 1000mm and typical diameter from 40 to 500mm) are provided within the enclosure 520 and locate proximal to the inner wall thereof. In combination, the semi-cylindrical electrodes 530, 532 surround the bulbs 510a, 510b, which are located interior to the 'cylindrical space' defined by the electrodes 530, 532 in combination. The relative spatial relationship of the electrodes 530, 532 may be better understood by making reference to Figure fib.

The electrodes 530, 532 (which together act as a capacitor) connect via electrical contact points 540, 542 to radio frequency generator 560. In use, the radio frequency generator acts as a pulsed radio frequency excitation system to excite a resonant circuit via the electrodes 530, 532 and thus to provide pulsed radio frequency excitation energy to the ultraviolet bulbs 510a, 510b which emit ultraviolet radiation.

Figure 7 shows an ultraviolet light source comprising a single hollow cylindrical ultraviolet bulb 610 centrally located within and enclosed by cylindrical enclosure 620. The cylindrical walls of the enclosure 620 are comprised of quartz material, which is transparent to UV radiation.

Two semi-cylindrical mesh optically transparent electrodes 630, 632 (of typical length 1000mm and typical diameter from 10 to 40mm) are provided within the enclosure 620 and locate proximal to the inner wall thereof. In combination, the semi-cylindrical electrodes 630, 632 surround the bulb 610 that locates interior to the 'cylindrical space', defined by the electrodes 630, 632 in combination.

The electrodes 630, 632 (which together act as a capacitor) connect via electrical contact points 640, 642 to radio frequency generator 660. In use, the radio frequency generator acts as a pulsed radio frequency excitation system to excite a resonant circuit via the electrodes 630, 632 and thus to provide pulsed radio frequency excitation energy to the ultraviolet bulb 610 which emits ultraviolet radiation.

Figure 8 shows an ultraviolet light source comprising a single, elongate rectangular form ultraviolet bulb 710 centrally located within and enclosed by elongate, rectangular form enclosure 720. The walls of the enclosure 720 are comprised of quartz material, which is transparent to UV radiation.

Two elongate flat mesh optically transparent electrodes 730, 732 are provided within the enclosure 720 and locate proximal to the top and bottom inner walls thereof. In combination, the semi-cylindrical electrodes 730, 732 surround the bulb 710 that locates interior to the 'elongate rectangular space', defined by the electrodes 730, 732 in combination.

The electrodes 730, 732 (which together act as a capacitor) connect via electrical contact points 740, 742 to radio frequency generator 760. In use, the radio frequency generator acts as a pulsed radio frequency excitation system to excite a resonant circuit via the electrodes 730, 732 and thus to provide pulsed radio frequency excitation energy to the ultraviolet bulb 710 which emits ultraviolet radiation.

Figure 9 shows an ultraviolet light source comprising a single hollow cylindrical ultraviolet bulb 810 centrally located within and enclosed by cylindrical enclosure 820. The cylindrical walls of the enclosure 820 are comprised of quartz material, which is transparent to UV radiation. The bulb 810 is comprised of concentrically mounted quartz tubes 811, 812 with vapour form filling (e.g. mercury) filling the space defined therebeween.

Two concentrically mounted, cylindrical mesh optically transparent electrodes 830, 832 are provided within the enclosure 820. The first electrode locates outside the (outer wall 811 of) bulb 810 and the second electrode locates inside the (inner wall 812 of) bulb 810. In combination, the cylindrical electrodes 830, 832 surround the bulb 810 that is'sandwiched'within the tubular region defined by the electrodes 830, 832 in combination.

The electrodes 830, 832 (which together act as a capacitor) connect via electrical contact points 840, 842 to radio frequency generator 860. The radio frequency generator acts as a pulsed radio frequency excitation system to excite a resonant circuit via the electrodes 830, 832 and thus to provide pulsed radio frequency excitation energy to the cylindrical ultraviolet bulb 810 which emits ultraviolet radiation. In use, fluid to be sterilised would be supplied to the volume lying outside of the cylindrical enclosure 820.

In a variation of the ultraviolet light source of Figure 9, the cylindrical enclosure 820 has a much smaller diameter such that it may be located inside (and coaxial with) the second electrode. In this variation, in use, fluid to be sterilised would be supplied to the volume lying inside the cylindrical enclosure 820.

It may be appreciated that the steriliser apparatus of Figures 1 to 4 incorporates an ultraviolet light source most similar in arrangement to that of Figures 6a and 6b. It will also be appreciated that ultraviolet light sources of the type shown in any of Figures 5a to 9 may be used in variations of the steriliser apparatus of Figures 1 to 4. ! Figure 10 shows a suitable pulsed radio frequency energy waveform herein, as would be produced by the radio frequency generator of any of Figures 1 to 4 using known pulsing circuitry. The defining characteristics of the waveform are the pulse width (X) which is typically short; the pulse period (Y) which is typically much longer; and the peak operating energy (intensity) of the radio frequency wave (Z). It will be appreciated that continuous (i.e. non-pulsed) radio frequency energy may also be used herein in combination with the pulsed radio frequency energy to excite the bulb of the ultraviolet light source of the invention.

Figure 11 shows an ultraviolet light source for use in treatment of fluid substances comprising ultraviolet mercury discharge lamp 1010 enclosed by cylindrical enclosure 1020. The cylindrical walls of the enclosure 1020 are comprised of quartz material that is transparent to UV radiation. A conducting; mesh (e.g. copper or stainless steel) optically transparent waveguide 1030 is provided to the inner surface of the waveguide. The enclosure 1020 has air or nitrogen circulating therein. First end of the cylindrical enclosure has blocking end flange 1022 provided thereto. The second end is provided with coupling flange 1024 that couples with airtight chamber 1050 containing waveguide, 1040 and magnetron 1060. The magnetron 1060 acts as a pulsed microwave; energy source to feed pulsed microwaves into brass waveguide 1040 and thence to the ultraviolet lamp 1010 that is excited thereby.

The enclosure 1020 is within tubular housing 1070. The housing 1070 has a fluid inlet 1072 and a fluid outlet 1074 provided thereto. The fluid may be for example, water or air. In use, fluid flows from the inlet 1072 past the enclosure 1070 and towards the outlet 1074. As the fluid flows past the enclosure 1020 it is irradiated with UV radiation produced by the ultraviolet lamp 1010. The radiation itself passes through the UV transparent walls of the enclosure 1020 to contact the fluid, thereby treating the fluid.

The bulb 1010 may be seen to be provided with a spur 1016 in the form of a side arm branching of at a right angle from the elongate axis defined by the bulb 1010. The tip 1018 of the spur 1016 protrudes into the housing 1070 such that it experiences the fluid flowing through the housing 1070. Generally, the fluid will be at about room temperature, which is much lower than the typical operating temperature of the bulb 1010 (e.g. 100 C). The mercury in the tip: 1018 of the spur 1016 is therefore cooled to the point where it condenses out as a liquid.

Figure 12 shows an ultraviolet light source comprising an ultraviolet bulb 1110 consisting of a mercury discharge bulb and enclosed by cylindrical enclosure 1120. The cylindrical walls of the enclosure 1120 are comprised of quartz material, which is transparent to UV radiation. First 1130 and second 1132; semi-cylindrical optically transparent mesh electrodes are provided within the enclosure 1120 and locate proximal to the inner wall thereof. In combination, the electrodes 1130, 1132 act such as to generally surround the bulb 1110.

The ends of the cylindrical enclosure 1120 have blocking end flanges 1122, 1124 provided thereto. The electrodes 1130, 1132 connect via electrical contact points 1140, 1142 to radio frequency generator 1160.

In use, the radio frequency generator acts as a pulsed radio frequency excitation system to excite a resonant circuit via the electrodes 1130, 1132 and thus to provide pulsed radio frequency excitation energy to the ultraviolet bulb 1110 which emits ultraviolet radiation.

The enclosure 1120 locates within tubular housing 1170. The housing 1170; has a fluid inlet 1172 and a fluid outlet 1174 provided thereto. In use, fluid flows from the inlet 1172 past the enclosure 1120 and towards the outlet 1174.

As the fluid flows past the enclosure 1120 it is irradiated with UV radiation produced by the ultraviolet bulb 1110. The radiation itself passes through the UV transparent walls of the enclosure 1120 to contact the fluid. In one aspect, ! the fluid is water and the dominant wavelength of emitted UV radiation is 254nm. I The bulb 1110 may be seen to be provided with a spur 1116 in the form of a side arm branching of at a right angle from the elongate axis defined by the bulb 1110. The tip 1118 of the spur 1116 extends beyond the second electrode 1132 to contact the inner surface of the quartz sleeve enclosure 1120 such, that it experiences the fluid flowing through the housing 1170. Generally, the; fluid will be at about room temperature, which is much lower than the typical operating temperature of the bulb 1110 (e.g. 100 C) . The mercury in the tip 1118 of the spur 1116 is therefore cooled to the point where it condenses out as a liquid.

Figure 13 shows a fluid sterilization apparatus including an ultraviolet light source comprising a single hollow cylindrical ultraviolet bulb 1210 centrally located within and enclosed by first and second concentricallyarranged, outer and inner cylindrical enclosures 1220,1222. The cylindrical walls of each enclosure 1220, 1222 are comprised of quartz material, which is transparent to UV radiation. The bulb itself 1210 is comprised of concentrically mounted quartz tubes 1211,1212 with vapour form filling (e.g mercury / xenon mixture) filling the space defined there between.

Two concentrically mounted, cylindrical mesh optically transparent electrodes 1230,1232 are provided within the enclosure 1220. The first electrode locates outside the (outer wall 1211 of) bulb 1210 and the second electrode locates inside the (inner wall 1212 of) bulb 1210. In combination, the cylindrical electrodes 1230, 1232 surround the bulb 1210 that is in essence, 'sandwiched' within the tubular region defined by the electrodes 1230, 1232 in combination.

A cylindrical housing 1270 is provided exterior to and concentric with the outer enclosure 1220.

The electrodes 1230,1232 (which together act as a capacitor) connect via electrical contact points 1240, 1242 to radio frequency generator 1260. The radio frequency generator acts as a pulsed radio frequency excitation system to excite a resonant circuit via the electrodes 1230, 1232 and thus to provide pulsed radio frequency excitation energy to the cylindrical ultraviolet bulb 1210 which emits ultraviolet radiation.

It will be appreciated that the apparatus of Figure 13 provides two fluidreceiving volumes. The first volume 1272 is defined as the region enclosed between the exterior cylindrical housing 1270 and the outer enclosure 1220.

The second volume 1274 is defined as the region within the inner enclosure. In use, fluid (e.g. air of water) is flowed through either or both of the fluid receiving volumes 1272,1274. ; As fluid flows through either volume 1272,1274 it is irradiated with UV radiation produced by the ultraviolet bulb 1210. The radiation itself passes through the UV transparent walls of the relevant enclosure 1220, 1222 to contact the fluid. In one aspect, the fluid is water and the dominant wavelength! of emitted UV radiation is 254nm.

Figure 14 shows an ultraviolet light source comprising plural ultraviolet bulbs 1310a,1310b arranged in a circular arrangement and enclosed by cylindrical enclosure 1320. The cylindrical walls of the enclosure 1320 are comprised of quartz material, which is transparent to UV radiation.

Two sets 1330a-d, 1332a-d of four part-cylindrical optically transparent mesh electrodes are arranged in ABAB... type series proximal to and concentric with the inner wall of the enclosure 1320. It may be seen that, in combination, the electrodes generally surround the circular arrangement of bulbs 1310a, 1310b, which are located interior to the 'cylindrical space' defined by the electrodes 1330a-d, 1332a-d in combination.

The sets of electrodes 1330a-d, 1332a-d (each relevant pair of which, together act as a capacitor) connect via electrical contact points 1340ad, 1342a-d via circuitry 1344, 1346 to radio frequency generator 1360. It will be appreciated that the first set of electrodes 1330a-d connects to the generator via circuitry 1344, which is distinct from that circuitry 1346 which connects the second set of electrodes to the generator 1360.

In use, the radio frequency generator acts as a pulsed radio frequency excitation system to excite resonant circuits via the electrodes 1330a-d, 1332a- d and thus to provide pulsed radio frequency excitation energy to the ultraviolet bulbs 131 Oa, 131 Ob which emit ultraviolet radiation. : Figure 15 shows an ultraviolet light source comprising a cylindrical ultraviolet bulb 1410. In use, the bulb 1410 would generally be further enclosed by a cylindrical quartz enclosure (not shown, but e.g. of a type as generally described hereinbefore).

An electrode 1430 is helically coiled around the exterior of the bulb 1420. The ends of the electrode 1430 connect via electrical contact points 1440, 1442 to radio frequency generator 1460, which includes capacitor 1464. The coiled electrode 1430 acts as an inductor and, in combination with the capacitor 1464 of the generator 1460, enables a resonant circuit to be set up.

In use, the radio frequency generator 1460 acts as a pulsed radio frequency excitation system to excite a resonant circuit via the electrodes 1430 and thus I to provide pulsed radio frequency excitation energy to the ultraviolet bulb 1410 which emits ultraviolet radiation.

Many of the ultraviolet light sources described herein utilise a quartz tube form enclosure for the ultraviolet bulb. When used as part of a fluid sterilization apparatus in which fluid is flowed past the enclosure, the Applicant has found; that it is advantageous to keep the outer walls of the enclosure clean and thereby ensure effective transmission of ultraviolet radiation to the fluid flowing past. The apparatus of Figure 4 includes a wiper 380 form cleaning system for the enclosure 320.

Figure 16 shows a cylindrical quartz enclosure 1520 suitable for use with any ultraviolet light source herein provided with a rotationally mounted wiper 1580. I In more detail, the wiper 1580 comprises end-pieces 1585, 1586 mounted for rotation about central axis X-X' and a single, helical form wiper blade 1588 helically wound around the enclosure and in wiping contact with the outer wall thereof. Overall, the wiper 1580 thus be appreciated to take the form of an Archimedean screw (or screw Auger). ! In use (e.g. in an apparatus as shown in Figure 4), fluid flows past the enclosure 1520 and such fluid flow acts on the helical wiper blade 1588 to cause rotational movement of the wiper 1580 about its rotational axis. As such rotation occurs, the blade 1588 sweepingly contacts the enclosure 1520 thereby cleaning its outer wall.

Claims

Claims 1. An ultraviolet light source comprising a radio frequency energy

generator; in electrical connection with said generator, a first optically transparent electrode; in electrical connection with said generator but separate from said first electrode, a second electrode; and an ultraviolet bulb, wherein said first and second electrodes are arranged to excite said ultraviolet bulb with radio frequency energy from the-generator.
2. An ultraviolet light source according to claim 1, wherein the first electrode generally or wholly surrounds the ultraviolet bulb.
3. An ultraviolet light source according to claim 2, wherein the first electrode has the form of a hollow cylinder and the second electrode has the form of a solid cylinder locating along the axis defined by said hollow cylinder.
4. An ultraviolet light source according to claim 1, wherein the first and second electrodes in combination generally or wholly surround the ultraviolet bulb and both electrodes are optically transparent.
5. An ultraviolet light source according to claim 4, wherein both of the first and second electrodes have semi-cylindrical form.
6. An ultraviolet light source according to claim 4, wherein both of the first and second electrodes have planar form.
7. An ultraviolet light source according to claim 4, wherein both of the first and second electrodes have cylindrical form.
8. An ultraviolet light source according to any of claims 1 to 7, wherein both of the first and second electrodes comprise meshed material.
9. An ultraviolet light source according to any of claims 1 to 8, comprising a single ultraviolet bulb.
10. An ultraviolet light source according to claim 9, wherein said single ultraviolet bulb nests within a region defined by the first and second electrodes.
11. An ultraviolet light source according to claim 10, wherein the single ultraviolet bulb has an elongate form.
12. An ultraviolet light source according to any of claims 1 to 8, comprising plural ultraviolet bulbs.
13. An ultraviolet light source according to claim 12, comprising from 2 to 25, preferably from 3 to 18 bulbs.
14. An ultraviolet light source to either of claims 12 or 13, wherein said plural ultraviolet bulbs are uniformly arranged within a region defined by the first and second electrodes.
15. An ultraviolet light source according to claim 14, wherein said plural ultraviolet bulbs form an arrangement selected from the group consisting of a side-by-side arrangement, a series arrangement, an array arrangement and a cluster arrangement.
16. An ultraviolet light source according to any of claims 1 to 15, additionally comprising an enclosure for enclosing the-first electrode, the second electrode and the ultraviolet bulb in combination.
17. An ultraviolet light source according to claim 16, wherein said enclosure is in the form of a sleeve.
18. An ultraviolet light source according to either of claims 16 or 17, wherein the enclosure comprised a UV-transparent material.
19. An ultraviolet light source according to claim 18, wherein the enclosure comprises quartz.
20. An ultraviolet light source according to any of claims 16 to 19, additionally comprising a system for cleaning the enclosure.
21. An ultraviolet light source according to any of claims 16 to 20, additionally comprising a housing for the enclosure.
22. An ultraviolet light source according to claim 21, wherein the housing has an inlet and an outlet and the housing is shaped to guide fluid flow from the inlet, past the enclosure to the outlet.
23. An ultraviolet light source according to either of claims 21 or 22, additionally comprising a pump for pumping fluid from the inlet, past the enclosure to the outlet.
24. An ultraviolet light source according to any of claims 1 to 23, wherein the radio frequency generator generates pulses of radio frequency energy.
25. An ultraviolet light source according to claim 24, wherein the radio frequency generator generates radio frequency energy with a pulse width of from 100 milliseconds to 0.5 microseconds.
26. An ultraviolet light source according to either of claims 24 or 25, wherein the radio frequency generator generates radio frequency energy with a pulse period of from 200 milliseconds to l.O microseconds.
27. An ultraviolet light source according to any of claims 1 to 26, wherein the peak operating energy of the ultraviolet bulb is from 40 watts to 100,000 watts.
28. An ultraviolet light source according to any of claims 1 to 27, arranged for the emission of either monochromatic or polychromatic ultraviolet radiation.
29. An ultraviolet light source according to any of claims 1 to 7, wherein the dominant wavelength of the ultraviolet bulb is from 240 to 310nm.
30. An ultraviolet light source according to any of claims 1 to 29, wherein the ultraviolet bulb has no electrode.
31. An ultraviolet light source assembly comprising a first optically transparent electrode, electrically connectable to a radio frequency energy generator; a second optically transparent electrode, separate from said first electrode and electrically connectable to said radio frequency energy generator; and an ultraviolet bulb, wherein said first and second electrodes are arranged to excite said ultraviolet bulb with radio frequency energy receivable from the generator.
32. An ultraviolet light source assembly according to claim 31, wherein the first electrode generally surrounds the ultraviolet bulb.
33. An ultraviolet light source according to claim 31, wherein the first and second electrodes in combination generally surround the ultraviolet bulb.
34. A method of sterilising a substance comprising employing the ultraviolet light source according to any of claims 1 to 30 to apply radio frequency energy to an ultraviolet bulb to produce ultraviolet radiation of dominant wavelength of from 240nm to 310nm; and exposing the substance to said ultraviolet radiation.
35. A method according to claim 34, wherein the substance is selected from the group consisting of water for human consumption; waste water and sewage; metallic and non-metallic articles; medical instruments; air in buildings; and foodstuffs.
36. A method of promoting the dissociation of a molecular entity comprising employing the ultraviolet light source according to any of claims 1 to 30 to apply radio frequency energy to an ultraviolet bulb to produce ultraviolet radiation of dominant wavelength of from 140 to 260nm; and exposing the molecular entity to said ultraviolet radiation.
37. A method according to claim 36, wherein the molecular entity is borne in a fluid such as air or a liquid and the substance-bearing fluid flows past the enclosure.
38. A method according to either of claims 36 or 37, wherein the molecular entity is an organic material.
39. A method according to claim 38, for the dissociation of Total Oxidisable Carbon (TOC) in water.
40. A method according to claim 36, wherein the molecular entity is borne on a surface and the ultraviolet radiation is applied to said surface.
41. A method according to claim 40, wherein the surface is of a product selected from the group consisting of food products, packaging products and the surfaces of any equipment employed in the manufacture thereof.
42. A method of promoting a photochemical reaction in a substance comprising employing the ultraviolet light source according to any of claims 1 to 30 to apply radio frequency energy to an ultraviolet bulb to produce ultraviolet radiation of dominant wavelength of from 310 to 400nm; and exposing the substance to said ultraviolet radiation.
43. A method according to claim 42, wherein the substance is borne in a fluid such as air or a liquid and the substance-bearing fluid flows past the enclosure.
44. A method according to claim 42, wherein the substance is borne on a surface and the ultraviolet radiation is applied to the surface.
45. An electrodeless ultraviolet bulb comprising a housing; and within said housing a vapour form material which emits ultraviolet radiation on excitation by an energy source, wherein said housing is provided with a spur shaped for receipt of cooling means for cooling the vapour form material in said spur.
46. An ultraviolet bulb according to claim 45, wherein the housing is partially evacuated and comprises an element or mixtures of elements in vapour form.
47. An ultraviolet bulb according to either of claims 45 or 46, wherein the housing is of elongate form.
48. An ultraviolet bulb according to claim 47, wherein the spur comprises a side arm at a right angle to the elongate axis.
49. An ultraviolet bulb according to any of claims 45 to 48, wherein the cooling means is a heat sink.
50. An ultraviolet light source comprising an energy generator; in electrical connection with said generator, a first optically transparent electrode; in electrical connection with said generator but separate from said first electrode, a second optically transparent electrode, wherein said first and second electrodes are arranged to excite said ultraviolet bulb with radio frequency energy from the generator; and an electrodeless ultraviolet bulb according to any of claims 45 to 49.
51. An ultraviolet light source according to claim 50, wherein the energy generator is a radio frequency energy generator or a microwave energy generator.
52. An ultraviolet light source according to either of claims 50 or 51, additionally comprising an enclosure for enclosing the first electrode, the second electrode and at least part of the ultraviolet bulb in combination.
53. An ultraviolet light source according to claim 52, additionally comprising; a housing for the enclosure.
54. An ultraviolet light source according to claim 53, wherein the housing has an inlet and an outlet and the housing is shaped to guide fluid flow from the inlet, past the enclosure to the outlet.
55. An ultraviolet light source according to claim 54, wherein the spur protrudes into the housing such that it may be cooled by said fluid flow.