Patent Description:
Smoking articles such as cigarettes, cigars and the like burn tobacco during use to create tobacco smoke. Attempts have been made to provide alternatives to these articles by creating products that release compounds without combusting. Examples of such products are so-called "heat not burn" products or tobacco heating devices or products, which release compounds by heating, but not burning, material. The material may be, for example, tobacco or other non-tobacco products, which may or may not contain nicotine.

<CIT> (<NUM>-<NUM>-<NUM>) discloses an induction coil arrangement for use with apparatus for heating smokable material to volatilise at least one component of the smokable material.

A first aspect of the present invention provides an inductor for use in an aerosol provision device, the inductor comprising: an electrically-conductive element; wherein the element comprises an electrically-conductive non-spiral first portion coincident with a first plane, an electrically-conductive non-spiral second portion coincident with a second plane that is spaced from the first plane, and an electrically-conductive connector that electrically connects the first portion to the second portion.

In an exemplary embodiment, the second plane is parallel to the first plane.

In an exemplary embodiment, the first portion is a first partial annulus and the second portion is a second partial annulus.

A second aspect of the present invention provides an inductor for use in an aerosol provision device, the inductor comprising: an electrically-conductive element; wherein the element comprises an electrically-conductive first partial annulus coincident with a first plane, an electrically-conductive second partial annulus coincident with a second plane that is spaced from the first plane, and an electrically-conductive connector that electrically connects the first partial annulus to the second partial annulus.

In an exemplary embodiment, the first portion or first partial annulus is a first circular arc, and the second portion or second partial annulus is a second circular arc.

In an exemplary embodiment, when viewed in a direction orthogonal to the first plane, the first and second portions or partial annuli extend in opposite senses of rotation from the electrically-conductive connector.

In an exemplary embodiment, when viewed in a direction orthogonal to the first plane, the first portion or first partial annulus overlaps, only partially, the second portion or second partial annulus.

In an exemplary embodiment, when viewed in a direction orthogonal to the first plane, the first portion or first partial annulus at least partially overlaps the electrically-conductive connector.

In an exemplary embodiment, the first and second planes are flat planes.

In an exemplary embodiment, a distance between the first and second planes measured in a direction orthogonal to the first and second planes is less than <NUM> millimetres. In an exemplary embodiment, the distance between the first and second planes is less than <NUM> millimetre.

In an exemplary embodiment, the first and second portions or partial annuli together define at least <NUM> turns about an axis that is orthogonal to the first and second planes.

In an exemplary embodiment, the element comprises further electrically-conductive non-spiral portions or electrically-conductive partial annuli that are coincident with respective spaced-apart planes.

In an exemplary embodiment, the spaced-apart planes are parallel to the first plane.

In an exemplary embodiment, a total number of turns, about an axis, defined by all of the electrically-conductive non-spiral portions or partial annuli of the element together is between <NUM> and <NUM>. In an exemplary embodiment, the total number of turns is between <NUM> and <NUM>. In an exemplary embodiment, the total number of turns is between <NUM> and <NUM>.

In an exemplary embodiment a distance between each adjacent pair of the portions or partial annuli of the element is equal to, or differs by less than <NUM>% from, a distance between each other adjacent pair of the portions or partial annuli of the element.

In an exemplary embodiment, each of the first and second portions or partial annuli has a thickness, measured in a direction orthogonal to the first plane, of between <NUM> micrometres and <NUM> micrometres. In an exemplary embodiment, the thickness is between <NUM> micrometres and <NUM> micrometres. In an exemplary embodiment, the thickness is between <NUM> micrometres and <NUM> micrometres.

A third aspect of the present invention provides an inductor for use in an aerosol provision device, the inductor comprising a coil having a pitch of less than <NUM> millimetres.

In an exemplary embodiment, the pitch is less than <NUM> millimetre.

A fourth aspect of the present invention provides an inductor arrangement for use in an aerosol provision device, the inductor arrangement comprising: an electrically-insulating support having opposite first and second sides; and the inductor according to the first or second aspect of the present invention, wherein the first portion or first partial annulus is on the first side of the support, and the second portion or second partial annulus is on the second side of the support.

In an exemplary embodiment, the inductor arrangement has a through-hole that is radially-inward of, and coaxial with, the first and second portions or partial annuli.

In an exemplary embodiment, the electrically-conductive connector of the inductor extends through the support.

In an exemplary embodiment, the support has a thickness of between <NUM> millimetres and <NUM> millimetres. In an exemplary embodiment, the support has a thickness of between <NUM> millimetres and <NUM> millimetre. In an exemplary embodiment, the support has a thickness of between <NUM> millimetres and <NUM> millimetres.

In an exemplary embodiment, the inductor arrangement comprises a printed circuit board, wherein the support is a non-electrically-conductive substrate of the printed circuit board and the first and second portions or partial annuli are tracks on the substrate.

A fifth aspect of the present invention provides an inductor assembly for use in an aerosol provision device, the inductor assembly comprising plural inductors according to any one of the first, second and third aspects of the present invention or comprising plural inductor arrangements according to the fourth aspect of the present invention.

A sixth aspect of the present invention provides a magnetic field generator for use in an aerosol provision device, the magnetic field generator comprising one or more inductors according to any one of the first, second and third aspects of the present invention or one or more inductor arrangements according to the fourth aspect of the present invention or the inductor assembly according to the fifth aspect of the present invention.

A seventh aspect of the present invention provides a magnetic field generator for use in an aerosol provision device, the magnetic field generator comprising one or more inductors and an apparatus that is operable to pass a varying electrical current through the one or more inductors, wherein the one or more inductors and the apparatus are configured to cause the generation of a magnetic field having a magnetic flux density of at least <NUM> Tesla. In an exemplary embodiment, the magnetic flux density is at least <NUM> Tesla.

In an exemplary embodiment, the, or each, inductor is according to any one of the first, second and third aspects of the present invention, or the magnetic field generator comprises one or more inductor arrangements according to the fourth aspect of the present invention and the one or more inductors of the magnetic field generator are of the respective one or more inductor arrangements.

An eighth aspect of the present invention provides an aerosol provision device, comprising: a heating zone for receiving at least a portion of an article comprising aerosolisable material; and a magnetic field generator according to the sixth or seventh aspect of the present invention, wherein the magnetic field generator is configured to be operable to generate a varying magnetic field for use in heating at least part of the aerosolisable material of the article when the article is in the heating zone.

In an exemplary embodiment, the, or each, inductor of the magnetic field generator at least partially encircles the heating zone.

In an exemplary embodiment, the aerosol provision device comprises a susceptor that is heatable by penetration with the varying magnetic field to thereby cause heating of the heating zone.

In an exemplary embodiment, the magnetic field generator is configured to be operable to generate plural respective varying magnetic fields independently of each other, for use in heating respective parts of the aerosolisable material of the article independently of each other.

A ninth aspect of the present invention provides an aerosol provision system, comprising the aerosol provision device according to the eighth aspect of the present invention and the article comprising aerosolisable material, wherein the article comprising aerosolisable material is at least partially insertable into the heating zone.

As used herein, the term "aerosolisable material" includes materials that provide volatilised components upon heating, typically in the form of vapour or an aerosol. "Aerosolisable material" may be a non-tobacco-containing material or a tobacco-containing material. "Aerosolisable material" may, for example, include one or more of tobacco per se, tobacco derivatives, expanded tobacco, reconstituted tobacco, tobacco extract, homogenised tobacco or tobacco substitutes. The aerosolisable material can be in the form of ground tobacco, cut rag tobacco, extruded tobacco, reconstituted tobacco, reconstituted aerosolisable material, liquid, gel, a solid, an amorphous solid, gelled sheet, powder, beads, granules, or agglomerates, or the like. "Aerosolisable material" also may include other, non-tobacco, products, which, depending on the product, may or may not contain nicotine. "Aerosolisable material" may comprise one or more humectants, such as glycerol or propylene glycol.

In some examples, the aerosolisable material is in the form of an "amorphous solid". Any material referred to herein as an "amorphous solid" may alternatively be referred to as a "monolithic solid" (i.e. non-fibrous), or as a "dried gel". It some cases, it may be referred to as a "thick film". In some examples, the amorphous solid may consist essentially of, or consist of, a gelling agent, an aerosol generating agent, a tobacco material and/or a nicotine source, water, and optionally a flavour. In some examples, the gel or amorphous solid takes the form of a foam, such as an open celled foam.

A susceptor is material that is heatable by penetration with a varying magnetic field, such as an alternating magnetic field. The heating material may be an electrically-conductive material, so that penetration thereof with a varying magnetic field causes induction heating of the heating material. The heating material may be magnetic material, so that penetration thereof with a varying magnetic field causes magnetic hysteresis heating of the heating material. The heating material may be both electrically-conductive and magnetic, so that the heating material is heatable by both heating mechanisms.

Induction heating is a process in which an electrically-conductive object is heated by penetrating the object with a varying magnetic field. The process is described by Faraday's law of induction and Ohm's law. An induction heater may comprise an electromagnet and a device for passing a varying electrical current, such as an alternating current, through the electromagnet. When the electromagnet and the object to be heated are suitably relatively positioned so that the resultant varying magnetic field produced by the electromagnet penetrates the object, one or more eddy currents are generated inside the object. The object has a resistance to the flow of electrical currents. Therefore, when such eddy currents are generated in the object, their flow against the electrical resistance of the object causes the object to be heated. This process is called Joule, ohmic, or resistive heating.

In one example, the susceptor is in the form of a closed circuit. It has been found that, when the susceptor is in the form of a closed circuit, magnetic coupling between the susceptor and the electromagnet in use is enhanced, which results in greater or improved Joule heating.

Magnetic hysteresis heating is a process in which an object made of a magnetic material is heated by penetrating the object with a varying magnetic field. A magnetic material can be considered to comprise many atomic-scale magnets, or magnetic dipoles. When a magnetic field penetrates such material, the magnetic dipoles align with the magnetic field. Therefore, when a varying magnetic field, such as an alternating magnetic field, for example as produced by an electromagnet, penetrates the magnetic material, the orientation of the magnetic dipoles changes with the varying applied magnetic field. Such magnetic dipole reorientation causes heat to be generated in the magnetic material.

When an object is both electrically-conductive and magnetic, penetrating the object with a varying magnetic field can cause both Joule heating and magnetic hysteresis heating in the object. Moreover, the use of magnetic material can strengthen the magnetic field, which can intensify the Joule heating.

In each of the above processes, as heat is generated inside the object itself, rather than by an external heat source by heat conduction, a rapid temperature rise in the object and more uniform heat distribution can be achieved, particularly through selection of suitable object material and geometry, and suitable varying magnetic field magnitude and orientation relative to the object. Moreover, as induction heating and magnetic hysteresis heating do not require a physical connection to be provided between the source of the varying magnetic field and the object, design freedom and control over the heating profile may be greater, and cost may be lower.

Referring to <FIG>, there is shown a schematic cross-sectional side view of an example of an aerosol provision system. The system <NUM> comprises an aerosol provision device <NUM> and an article <NUM> comprising aerosolisable material <NUM>. The aerosolisable material <NUM> may, for example, be of any of the types of aerosolisable material discussed herein. In this example, the aerosol provision device <NUM> is a tobacco heating product (also known in the art as a tobacco heating device or a heat-not-burn device).

In some examples, the aerosolisable material <NUM> is a non-liquid material. In some examples, the aerosolisable material <NUM> is a gel. In some examples, the aerosolisable material <NUM> comprises tobacco. However, in other examples, the aerosolisable material <NUM> may consist of tobacco, may consist substantially entirely of tobacco, may comprise tobacco and aerosolisable material other than tobacco, may comprise aerosolisable material other than tobacco, or may be free from tobacco. In some examples, the aerosolisable material <NUM> may comprise a vapour or aerosol forming agent or a humectant, such as glycerol, propylene glycol, triacetin, or diethylene glycol. In some examples, the aerosolisable material <NUM> comprises reconstituted aerosolisable material, such as reconstituted tobacco.

In some examples, the aerosolisable material <NUM> is substantially cylindrical with a substantially circular cross section and a longitudinal axis. In other examples, the aerosolisable material <NUM> may have a different cross-sectional shape and/or not be elongate.

The aerosolisable material <NUM> of the article <NUM> may, for example, have an axial length of between <NUM> and <NUM>. For example, the axial length of the aerosolisable material <NUM> may be greater than <NUM>, or <NUM>, or <NUM>, or <NUM>. For example, the axial length of the aerosolisable material <NUM> may be less than <NUM>, or <NUM>, or <NUM>, or <NUM>.

In some examples, such as that shown in <FIG>, the article <NUM> comprises a filter arrangement <NUM> for filtering aerosol or vapour released from the aerosolisable material <NUM> in use. Alternatively, or additionally, the filter arrangement <NUM> may be for controlling the pressure drop over a length of the article <NUM>. The filter arrangement <NUM> may comprise one, or more than one, filter. The filter arrangement <NUM> could be of any type used in the tobacco industry. For example, the filter may be made of cellulose acetate. In some examples, the filter arrangement <NUM> is substantially cylindrical with a substantially circular cross section and a longitudinal axis. In other examples, the filter arrangement <NUM> may have a different cross-sectional shape and/or not be elongate.

In some examples, the filter arrangement <NUM> abuts a longitudinal end of the aerosolisable material <NUM>. In other examples, the filter arrangement <NUM> may be spaced from the aerosolisable material <NUM>, such as by a gap and/or by one or more further components of the article <NUM>. In some examples, the filter arrangement <NUM> may comprise an additive or flavour source (such as an additive- or flavour-containing capsule or thread), which may be held by a body of filtration material or between two bodies of filtration material, for example.

The article <NUM> may also comprise a wrapper (not shown) that is wrapped around the aerosolisable material <NUM> and the filter arrangement <NUM> to retain the filter arrangement <NUM> relative to the aerosolisable material <NUM>. The wrapper may be wrapped around the aerosolisable material <NUM> and the filter arrangement <NUM> so that free ends of the wrapper overlap each other. The wrapper may form part of, or all of, a circumferential outer surface of the article <NUM>. The wrapper could be made of any suitable material, such as paper, card, or reconstituted aerosolisable material (e.g. reconstituted tobacco). The paper may be a tipping paper that is known in the art. The wrapper may also comprise an adhesive (not shown) that adheres overlapped free ends of the wrapper to each other, to help prevent the overlapped free ends from separating. In other examples, the adhesive may be omitted or the wrapper may take a different from to that described. In other examples, the filter arrangement <NUM> may be retained relative to the aerosolisable material <NUM> by a connector other than a wrapper, such as an adhesive. In some examples, the filter arrangement <NUM> may be omitted.

The aerosol provision device <NUM> comprises a heating zone <NUM> for receiving at least a portion of the article <NUM>, an outlet <NUM> through which aerosol is deliverable from the heating zone <NUM> to a user in use, and heating apparatus <NUM> for causing heating of the article <NUM> when the article <NUM> is at least partially located within the heating zone <NUM> to thereby generate the aerosol. In some examples, such as that shown in <FIG>, the aerosol is deliverable from the heating zone <NUM> to the user through the article <NUM> itself, rather than through any gap adjacent to the article <NUM>. Nevertheless, in such examples, the aerosol still passes through the outlet <NUM>, albeit while travelling within the article <NUM>.

The device <NUM> may define at least one air inlet (not shown) that fluidly connects the heating zone <NUM> with an exterior of the device <NUM>. A user may be able to inhale the volatilised component(s) of the aerosolisable material by drawing the volatilised component(s) from the heating zone <NUM> via the article <NUM>. As the volatilised component(s) are removed from the heating zone <NUM> and the article <NUM>, air may be drawn into the heating zone <NUM> via the air inlet(s) of the device <NUM>.

In this example, the heating zone <NUM> extends along an axis A-A and is sized and shaped to accommodate only a portion of the article <NUM>. In this example, the axis A-A is a central axis of the heating zone <NUM>. Moreover, in this example, the heating zone <NUM> is elongate and so the axis A-A is a longitudinal axis A-A of the heating zone <NUM>. The article <NUM> is insertable at least partially into the heating zone <NUM> via the outlet <NUM> and protrudes from the heating zone <NUM> and through the outlet <NUM> in use. In other examples, the heating zone <NUM> may be elongate or non-elongate and dimensioned to receive the whole of the article <NUM>. In some such examples, the device <NUM> may include a mouthpiece that can be arranged to cover the outlet <NUM> and through which the aerosol can be drawn from the heating zone <NUM> and the article <NUM>.

In this example, when the article <NUM> is at least partially located within the heating zone <NUM>, different portions 11a-11e of the aerosolisable material <NUM> are located at different respective locations 110a-110e in the heating zone <NUM>. In this example, these locations 110a-110e are at different respective axial positions along the axis A-A of the heating zone <NUM>. Moreover, in this example, since the heating zone <NUM> is elongate, the locations 110a-110e can be considered to be at different longitudinally-spaced-apart positions along the length of the heating zone <NUM>. In this example, the article <NUM> can be considered to comprise five such portions 11a-11e of the aerosolisable material <NUM> that are located respectively at a first location 110a, a second location 110b, a third location 110c, a fourth location 110d and a fifth location 110e. More specifically, the second location 110b is fluidly located between the first location 110a and the outlet <NUM>, the third location 110c is fluidly located between the second location 110b and the outlet <NUM>, the fourth location 110d is fluidly located between the third location 110c and the outlet <NUM>, and the fifth location is fluidly located between the fourth location 110d and the outlet <NUM>.

The heating apparatus <NUM> comprises plural heating units 140a-140e, each of which is able to cause heating of a respective one of the portions 11a-11e of the aerosolisable material <NUM> to a temperature sufficient to aerosolise a component thereof, when the article <NUM> is at least partially located within the heating zone <NUM>. The plural heating units 140a-140e may be axially-aligned with each other along the axis A-A. Each of the portions 11a-11e of the aerosolisable material <NUM> heatable in this way may, for example, have a length in the direction of the axis A-A of between <NUM> millimetre and <NUM> millimetres, such as between <NUM> millimetres and <NUM> millimetres, between <NUM> millimetres and <NUM> millimetres, or between <NUM> millimetres and <NUM> millimetres.

The heating apparatus <NUM> of this example comprises five heating units 140a-140e, namely: a first heating unit 140a, a second heating unit 140b, a third heating unit 140c, a fourth heating unit 140d and a fifth heating unit 140e. The heating units 140a-140e are at different respective axial positions along the axis A-A of the heating zone <NUM>. Moreover, in this example, since the heating zone <NUM> is elongate, the heating units 140a-140e can be considered to be at different longitudinally-spaced-apart positions along the length of the heating zone <NUM>. More specifically, the second heating unit 140b is located between the first heating unit 140a and the outlet <NUM>, the third heating unit 140c is located between the second heating unit 140b and the outlet <NUM>, the fourth heating unit 140d is located between the third heating unit 140c and the outlet <NUM>, and the fifth heating unit 140e is located between the fourth heating unit 140d and the outlet <NUM>. In other examples, the heating apparatus <NUM> could comprise more than five heating units 140a-140e or fewer than five heating units, such as only four, only three, only two, or only one heating unit. The number of portion(s) of the aerosolisable material <NUM> that are heatable by the respective heating unit(s) may be correspondingly varied.

The heating apparatus <NUM> also comprises a controller <NUM> that is configured to cause operation of the heating units 140a-140e to cause the heating of the respective portions 11a-11e of the aerosolisable material <NUM> in use. In this example, the controller <NUM> is configured to cause operation of the heating units 140a-140e independently of each other, so that the respective portions 11a-11e of the aerosolisable material <NUM> can be heated independently. This may be desirable in order to provide progressive heating of the aerosolisable material <NUM> in use. Moreover, in examples in which the portions 11a-11e of the aerosolisable material <NUM> have different respective forms or characteristics, such as different tobacco blends and/or different applied or inherent flavours, the ability to independently heat the portions 11a-11e of the aerosolisable material <NUM> can enable heating of selected portions 11a-11e of the aerosolisable material <NUM> at different times during a session of use so as to generate aerosol that has predetermined characteristics that are time-dependent. In some examples, the heating apparatus <NUM> may nevertheless also be operable in one or more modes in which the controller <NUM> is configured to cause operation of more than one of the heating units 140a-140e, such as all of the heating units 140a-140e, at the same time during a session of use.

In this example, the heating units 140a-140e comprise respective induction heating units that are configured to generate respective varying magnetic fields, such as alternating magnetic fields. As such, the heating apparatus <NUM> can be considered to comprise a magnetic field generator, and the controller <NUM> can be considered to be apparatus that is operable to pass a varying electrical current through inductors <NUM> of the respective heating units 140a-140e. Moreover, in this example, the device <NUM> comprises a susceptor <NUM> that is configured so as to be heatable by penetration with the varying magnetic fields to thereby cause heating of the heating zone <NUM> and the article <NUM> therein in use. That is, portions of the susceptor <NUM> are heatable by penetration with the respective varying magnetic fields to thereby cause heating of the respective portions 11a-11e of the aerosolisable material <NUM> at the respective locations 110a-110e in the heating zone <NUM>.

In some examples, the susceptor <NUM> is made of, or comprises, aluminium. However, in other examples, the susceptor <NUM> may comprise one or more materials selected from the group consisting of: an electrically-conductive material, a magnetic material, and a magnetic electrically-conductive material. In some examples, the susceptor <NUM> may comprise a metal or a metal alloy. In some examples, the susceptor <NUM> may comprise one or more materials selected from the group consisting of: aluminium, gold, iron, nickel, cobalt, conductive carbon, graphite, steel, plain-carbon steel, mild steel, stainless steel, ferritic stainless steel, molybdenum, silicon carbide, copper, and bronze. Other material(s) may be used in other examples.

In some examples, such as those in which the susceptor <NUM> comprises iron, such as steel (e.g. mild steel or stainless steel) or aluminium, the susceptor <NUM> may comprise a coating to help avoid corrosion or oxidation of the susceptor <NUM> in use. Such coating may, for example, comprise nickel plating, gold plating, or a coating of a ceramic or an inert polymer.

In this example, the susceptor <NUM> is tubular and encircles the heating zone <NUM>. Indeed, in this example, an inner surface of the susceptor <NUM> partially delimits the heating zone <NUM>. An internal cross-sectional shape of the susceptor <NUM> may be circular or a different shape, such as elliptical, polygonal or irregular. In other examples, the susceptor <NUM> may take a different form, such as a non-tubular structure that still partially encircles the heating zone <NUM>, or a protruding structure, such as a rod, pin or blade, that penetrates the heating zone <NUM>. In some examples, the susceptor <NUM> may be replaced by plural susceptors, each of which is heatable by penetration with a respective one of the varying magnetic fields to thereby cause heating of a respective one of the portions 11a-11e of the aerosolisable material <NUM>. Each of the plural susceptors may be tubular or take one of the other forms discussed herein for the susceptor <NUM>, for example. In still further examples, the device <NUM> may be free from the susceptor <NUM>, and the article <NUM> may comprise one or more susceptors that are heatable by penetration with the varying magnetic fields to thereby cause heating of the respective portions 11a-11e of the aerosolisable material <NUM>. Each of the one or more susceptors of the article <NUM> may take any suitable form, such as a structure (e.g. a metallic foil, such as an aluminium foil) wrapped around or otherwise encircling the aerosolisable material <NUM>, a structure located within the aerosolisable material <NUM>, or a group of particles or other elements mixed with the aerosolisable material <NUM>. In examples in which the device <NUM> is free from the susceptor <NUM>, the susceptor <NUM> may be replaced by a heat-resistant tube that partially delimits the heating zone <NUM>. Such a heat-resistant tube may, for example, be made from polyether ether ketone (PEEK) or a ceramic material.

In this example, the heating apparatus <NUM> comprises an electrical power source (not shown) and a user interface (not shown) for user-operation of the device. The electrical power source of this example is a rechargeable battery. In other examples, the electrical power source may be other than a rechargeable battery, such as a non-rechargeable battery, a capacitor, a battery-capacitor hybrid, or a connection to a mains electricity supply.

In this example, the controller <NUM> is electrically connected between the electrical power source and the heating units 140a-140e. In this example, the controller <NUM> also is electrically connected to the electrical power source. More specifically, in this example, the controller <NUM> is for controlling the supply of electrical power from the electrical power source to the heating units 140a-140e. In this example, the controller <NUM> comprises an integrated circuit (IC), such as an IC on a printed circuit board (PCB). In other examples, the controller <NUM> may take a different form. The controller <NUM> is operated in this example by user-operation of the user interface. The user interface may comprise a push-button, a toggle switch, a dial, a touchscreen, or the like. In other examples, the user interface may be remote and connected to the rest of the aerosol provision device <NUM> wirelessly, such as via Bluetooth.

In this example, operation of the user interface by a user causes the controller <NUM> to cause an alternating electrical current to pass through the inductor <NUM> of at least one of the respective heating units 140a-140e. This causes the inductor <NUM> to generate an alternating magnetic field. The inductor <NUM> and the susceptor <NUM> are suitably relatively positioned so that the varying magnetic field produced by the inductor <NUM> penetrates the susceptor <NUM>. When the susceptor <NUM> is electrically-conductive, this penetration causes the generation of one or more eddy currents in the susceptor <NUM>. The flow of eddy currents in the susceptor <NUM> against the electrical resistance of the susceptor <NUM> causes the susceptor <NUM> to be heated by Joule heating. When the susceptor <NUM> is magnetic, the orientation of magnetic dipoles in the susceptor <NUM> changes with the changing applied magnetic field, which causes heat to be generated in the susceptor <NUM>.

The device <NUM> may comprise a temperature sensor (not shown) for sensing a temperature of the heating chamber <NUM>, the susceptor <NUM> or the article <NUM>. The temperature sensor may be communicatively connected to the controller <NUM>, so that the controller <NUM> is able to monitor the temperature of the heating chamber <NUM>, the susceptor <NUM> or the article <NUM>, respectively, on the basis of information output by the temperature sensor. In other examples, the temperature may be sensed and monitored by measuring electrical characteristics of the system, e.g., the change in current within the heating units 140a-140e. On the basis of one or more signals received from the temperature sensor, the controller <NUM> may cause a characteristic of the varying or alternating electrical current to be adjusted as necessary, in order to ensure that the temperature of the heating chamber <NUM>, the susceptor <NUM> or the article <NUM>, respectively, remains within a predetermined temperature range. The characteristic may be, for example, amplitude or frequency or duty cycle. Within the predetermined temperature range, in use the aerosolisable material <NUM> within the article <NUM> located in the heating chamber <NUM> is heated sufficiently to volatilise at least one component of the aerosolisable material <NUM> without combusting the aerosolisable material <NUM>. Accordingly, the controller <NUM>, and the device <NUM> as a whole, is arranged to heat the aerosolisable material <NUM> to volatilise the at least one component of the aerosolisable material <NUM> without combusting the aerosolisable material <NUM>. The temperature range may be between about <NUM> and about <NUM>, such as between about <NUM> and about <NUM>, or between about <NUM> and about <NUM>. In other examples, the temperature range may be other than one of these ranges. In some examples, the upper limit of the temperature range could be greater than <NUM>. In some examples, the temperature sensor may be omitted.

Further discussion of the form of each of the heating units 140a-140e will be given below with reference to <FIG>. However, what is notable at this stage is that the size or extent of the varying magnetic fields as measured in the direction of the axis A-A is relatively small, so that the portions of the susceptor <NUM> that are penetrated by the varying magnetic fields in use are correspondingly small. Accordingly, it may be desirable for the susceptor <NUM> to have a thermal conductivity that is sufficient to increase the proportion of the susceptor <NUM> that is heated by thermal conduction as a result of the penetration by the varying magnetic fields, so as to correspondingly increase the proportion of the aerosolisable material <NUM> that is heated by operation of each of the heating units 140a-140e. It has been found that it is desirable to provide the susceptor <NUM> with a thermal conductivity of at least <NUM> W/m/K, optionally at least <NUM> W/m/K, and further optionally at least <NUM> W/m/K. In this example, the susceptor <NUM> is made of aluminium and has a thermal conductivity of over <NUM> W/m/K, such as between <NUM> and <NUM> W/m/K, for example approximately <NUM> W/m/K or <NUM> W/m/K. As noted above, each of the portions 11a-11e of the aerosolisable material <NUM> may, for example, have a length in the direction of the axis A-A of between <NUM> millimetre and <NUM> millimetres, such as between <NUM> millimetres and <NUM> millimetres, between <NUM> millimetres and <NUM> millimetres, or between <NUM> millimetres and <NUM> millimetres.

In this example, the heating apparatus <NUM> is configured to cause heating of the first portion 11a of the aerosolisable material <NUM> to a temperature sufficient to aerosolise a component of the first portion 11a of the aerosolisable material <NUM> before or more quickly than the heating of the second portion 11b of the aerosolisable material <NUM> during a heating session. More specifically, the controller <NUM> is configured to cause operation of the first and second heating units 140a, 140b to cause the heating of the first portion 11a of the aerosolisable material <NUM> before or more quickly than the heating of the second portion 11b of the aerosolisable material <NUM> during the heating session. Accordingly, during the heating session, the position at which heat energy is applied to the aerosolisable material <NUM> of the article <NUM> is initially relatively fluidly spaced from the outlet <NUM> and the user, and then moves towards the outlet <NUM>. This provides the benefit that during a heating session aerosol is generated from successive "fresh" portions of the aerosolisable material <NUM>, which can lead to a sensorially-satisfying experience for the user that may be more similar to that had when smoking a traditional combustible factory-made cigarette.

Moreover, in some examples, the controller <NUM> is configured to cause a cessation in the supply of power to the first heating unit 140a, during at least part of a period (or all of the period) for which the controller <NUM> is configured to cause operation of the second heating unit 140b. This provides the further benefit that aerosol generated in a given portion of the aerosolisable material <NUM> need not pass through another portion of the aerosolisable material <NUM> that has previously been heated, which could otherwise negatively impact the aerosol. For example, aerosol passing through previously-heated or spent aerosolisable material can result in the aerosol picking-up components that provide the aerosol with "off-notes".

In some examples in which the heating apparatus <NUM> has more than two heating units, such as the example shown in <FIG>, during the heating session the heating apparatus <NUM> may also be configured to cause heating of at least one further portion 11b-11e of the aerosolisable material <NUM> to a temperature sufficient to aerosolise a component of the further portion 11b-11e of the aerosolisable material <NUM> before or more quickly than the heating of a still further portion 11c-11e of the aerosolisable material <NUM> that is fluidly closer to the outlet <NUM>. That is, the controller <NUM> may be configured to cause suitable operation of the heating units to cause the heating of the at least one further portion 11b-11e of the aerosolisable material <NUM> before or more quickly than the heating of the still further portion 11c-11e of the aerosolisable material <NUM>. For example, in the device of <FIG>, the heating apparatus <NUM> may be configured to cause:.

It will be understood that, for a given duration of heating session, the greater the number of heating units and associated portions of the aerosolisable material <NUM> there are, the greater the opportunity to generate aerosol from "fresh" or unspent portions of the aerosolisable material <NUM> extending along a given axial length. Alternatively, for a given duration of heating each portion of the aerosolisable material <NUM>, the greater the number of heating units and associated portions of the aerosolisable material <NUM> there are, the longer the heating session may be. It should be appreciated that the duration for which an individual heating unit may be activated can be adjusted (e.g. shortened) to adjust (e.g. reduce) the overall heating session, and at the same time the power supplied to the heating element may be adjusted (e.g. increased) to reach the operational temperature more quickly. There may be a balance that is struck between the number of heating units (which may dictate the number of "fresh puffs"), the overall session length, and the achievable power supply (which may be dictated by the characteristics of the power source).

Referring to <FIG>, there is shown a flow diagram showing an example of a method of heating aerosolisable material during a heating session using an aerosol provision device. The aerosol provision device used in the method <NUM> comprises a heating zone for receiving at least a portion of an article comprising aerosolisable material, an outlet through which aerosol is deliverable from the heating zone to a user in use, and heating apparatus for causing heating of the article when the article is at least partially located within the heating zone to thereby generate the aerosol. The aerosol provision device may, for example, be that which is shown in <FIG> or any of the suitable variants thereof discussed herein.

The method <NUM> comprises the heating apparatus <NUM> causing, when the article <NUM> is at least partially located within the heating zone <NUM>, heating <NUM> of a first portion 11a of the aerosolisable material <NUM> of the article <NUM> to a temperature sufficient to aerosolise a component of the first portion 11a of the aerosolisable material <NUM> before or more quickly than heating <NUM> of a second portion 11b of the aerosolisable material <NUM> of the article <NUM> to a temperature sufficient to aerosolise a component of the second portion 11b of the aerosolisable material <NUM>, wherein the second portion 11b of the aerosolisable material <NUM> is fluidly located between the first portion 11a of the aerosolisable material <NUM> and the outlet <NUM>.

It will be understood from the teaching herein that the method <NUM> could be suitably adapted to comprise the heating apparatus <NUM> also causing heating of at least one further portion 11b-11e of the aerosolisable material <NUM> to a temperature sufficient to aerosolise a component of the further portion 11b-11e of the aerosolisable material <NUM> before or more quickly than the heating of a still further portion 11c-11e of the aerosolisable material <NUM> that is fluidly closer to the outlet <NUM>, as discussed above.

Referring to <FIG>, there is shown a flow diagram showing another example of a method of heating aerosolisable material during a heating session using an aerosol provision device. The aerosol provision device used in the method <NUM> comprises a heating zone for receiving at least a portion of an article comprising aerosolisable material, an outlet through which aerosol is deliverable from the heating zone to a user in use, and heating apparatus for causing heating of the article when the article is at least partially located within the heating zone to thereby generate the aerosol. The heating apparatus comprises a first heating unit, a second heating unit, a third heating unit and a controller that is configured to cause operation of the first, second and third heating units. The aerosol provision device may, for example, be that which is shown in <FIG> or any of the suitable variants thereof discussed herein.

The method <NUM> comprises the controller <NUM> controlling the first, second and third heating units 140a, 140b, 140c independently of each other to cause, when the article <NUM> is at least partially located within the heating zone <NUM>: the first heating unit 140a to heat <NUM> a first portion 11a of the aerosolisable material <NUM> of the article <NUM> to a temperature sufficient to aerosolise a component of the first portion 11a of the aerosolisable material <NUM> (e.g. before or more quickly than the second portion 11b); the second heating unit 140b to heat <NUM> a second portion 11b of the aerosolisable material <NUM> of the article <NUM> to a temperature sufficient to aerosolise a component of the second portion 11b of the aerosolisable material <NUM> (e.g. before or more quickly than the third portion 11c); and the third heating unit 140c to heat <NUM> a third portion 11c of the aerosolisable material <NUM> of the article <NUM> to a temperature sufficient to aerosolise a component of the third portion 11c of the aerosolisable material <NUM>, wherein the second portion 11b of the aerosolisable material <NUM> is fluidly located between the first portion 11a of the aerosolisable material <NUM> and the outlet <NUM>, and the third portion 11c of the aerosolisable material <NUM> is fluidly located between the second portion 11b of the aerosolisable material <NUM> and the outlet <NUM>.

When the aerosol provision device used in the method <NUM> comprises sufficient heating units, it will be understood from the teaching herein that the method <NUM> could be suitably adapted to comprise the heating apparatus <NUM> also controlling fourth and fifth heating units 140d, 140e independently of each other to cause, when the article <NUM> is at least partially located within the heating zone <NUM>: the fourth heating unit 140d to heat a fourth portion 11d of the aerosolisable material <NUM> of the article <NUM> to a temperature sufficient to aerosolise a component of the fourth portion 11d of the aerosolisable material <NUM>; and the fifth heating unit 140e to heat a fifth portion 11e of the aerosolisable material <NUM> of the article <NUM> to a temperature sufficient to aerosolise a component of the fifth portion 11e of the aerosolisable material <NUM>, wherein the fourth portion 11d of the aerosolisable material <NUM> is fluidly located between the third portion 11c of the aerosolisable material <NUM> and the outlet <NUM>, and the fifth portion 11e of the aerosolisable material <NUM> is fluidly located between the fourth portion 11d of the aerosolisable material <NUM> and the outlet <NUM>.

One of the heating units 140a-140e of the heating apparatus <NUM> will now be described in more detail with reference to <FIG>. These Figures respectively show a schematic cross-sectional side view of an inductor arrangement <NUM> of the heating unit and a schematic perspective view of an inductor <NUM> of the inductor arrangement <NUM>.

The inductor arrangement <NUM> comprises an electrically-insulating support <NUM> and the inductor <NUM>. The support <NUM> has opposite first and second sides 172a, 172b, and parts <NUM>, <NUM> of the inductor <NUM> are on the respective first and second sides 172a, 172b of the support <NUM>.

More specifically, the inductor <NUM> comprises an electrically-conductive element <NUM>. The element <NUM> comprises an electrically-conductive non-spiral first portion <NUM> that is coincident with a first plane P<NUM>, and an electrically-conductive non-spiral second portion <NUM> that is coincident with a second plane P<NUM> that is spaced from the first plane P<NUM>. In this example, the second plane P<NUM> is parallel to the first plane P<NUM>, but in other examples this need not be the case. For example, the second plane P<NUM> may be at an angle to the first plane P<NUM>, such as an angle of no more than <NUM> degrees or no more than <NUM> degrees or no more than <NUM> degrees. The inductor <NUM> also comprises a first electrically-conductive connector <NUM> that electrically connects the first portion <NUM> to the second portion <NUM>. The first portion <NUM> is on the first side 172a of the support <NUM>, and the second portion <NUM> is on the second side 172b of the support <NUM>. The electrically conductive connector <NUM> passes through the support <NUM> from the first side 172a to the second side 172b. The electrically conductive connector <NUM> may have the structure of plating (e.g., copper plating) on the surface of a through hole provided in the support <NUM>.

The support <NUM> can be made of any suitable electrically-insulating material(s). In some examples, the support <NUM> comprises a matrix (such as an epoxy resin, optionally with added filler such as ceramics) and a reinforcement structure (such as a woven or non-woven material, such as glass fibres or paper).

The inductor <NUM> can be made of any suitable electrically-conductive material(s). In some examples, the inductor <NUM> is made of copper.

In some examples, the inductor arrangement <NUM> comprises, or is formed from, a PCB. In such examples, the support <NUM> is a non-electrically-conductive substrate of the PCB, which may be formed from materials such as FR-<NUM> glass epoxy or cotton paper impregnated with phenolic resin, and the first and second portions <NUM>, <NUM> of the inductor <NUM> are tracks on the substrate. This facilitates manufacture of the inductor arrangement <NUM>, and also enables the portions <NUM>, <NUM> of the element <NUM> to be thin and closely spaced, as discussed in more detail below.

In this example, the first portion <NUM> is a first partial annulus <NUM> and the second portion <NUM> is a second partial annulus <NUM>. Moreover, in this example, each of the first and second portions <NUM>, <NUM> follows only part of a respective circular path. Therefore, the first portion or first partial annulus <NUM> is a first circular arc, and the second portion or second partial annulus <NUM> is a second circular arc. In other examples, the first and second portions <NUM>, <NUM> may follow a path that is other than circular, such as elliptical, polygonal or irregular. However, matching the shape of the first and second portions <NUM>, <NUM> to the shape (or at least an aspect of the shape, such as outer perimeter) of respective adjacent portions of the susceptor <NUM> (whether provided in the device <NUM> or the article <NUM>) helps lead to improved and more consistent magnetic coupling of the inductor <NUM> and the susceptor <NUM>. Moreover, in examples in which the first and second portions <NUM>, <NUM> are respective circular arcs, providing that the radii of the circular arcs are equal also can help lead to the generation of a more consistent magnetic field along the length of the inductor <NUM>, and thus more consistent heating of the susceptor <NUM>.

The inductor arrangement <NUM> has a through-hole <NUM> that is radially-inward of, and coaxial with, the first and second portions <NUM>, <NUM> or partial annuli. In the assembled device <NUM>, the susceptor <NUM> and the heating zone <NUM> extend through the through-hole <NUM>, so that the portions <NUM>, <NUM> of the element <NUM> together at least partially encircle the susceptor <NUM> and the heating zone <NUM>. In examples in which the susceptor <NUM> is replaced by plural susceptors, each of the plural susceptors may be located so as to extend through the through-holes <NUM> of one or more inductor arrangements <NUM> of the respective heating units 140a. In some examples, the or each susceptor does not extend through the through-holes <NUM>, but rather is adjacent (e.g. axially) the associated element <NUM>.

In examples in which the heating apparatus <NUM> is free from a susceptor, as discussed above, the heating zone <NUM> may still nevertheless extend through some or all of the through-holes <NUM> of the inductor arrangements <NUM> of the respective heating units 140a. In some such examples, the article <NUM> comprises one or more susceptors, such as a metallic foil (e.g. aluminium foil) wrapped around or otherwise encircling the aerosolisable material <NUM> and/or a susceptor, such as in the form of a pad, at one end of the article <NUM> axially adjacent the aerosolisable material <NUM> of the article <NUM>. In some examples, the susceptor of an article <NUM> comprising liquid or gel or otherwise flowable aerosolisable material may comprise a susceptor (e.g. metallic) in, or coated on, a (e.g. ceramic) wick. In some examples, portions 11a-11e of the aerosolisable material <NUM> have the same respective forms or characteristics, or have different respective forms or characteristics, such as different tobacco blends and/or different applied or inherent flavours. In some such examples, the article <NUM> may comprise plural susceptors, each of which is arranged and heatable to heat a respective one of the portions 11a-11e of the aerosolisable material <NUM>. In some examples, the portions 11a-11e of the aerosolisable material <NUM> are isolated from each other. In other examples, there may be plural heating zones, each of which is located between a pair of the inductor arrangements <NUM>. Some or all of the plural heating zones may not extend through the through-holes <NUM>. The plural heating zones may be for receiving respective articles <NUM> comprising aerosolisable material <NUM>. The aerosolisable material <NUM> of the respective articles <NUM> may be of the same or different respective forms or characteristics. In some examples, the through-holes <NUM> may be omitted.

As may best be understood from further consideration of <FIG>, when viewed in a direction orthogonal to the first plane P<NUM>, and thus in the direction of an axis B-B of the inductor <NUM>, the first and second portions <NUM>, <NUM> extend in opposite senses of rotation from the first electrically-conductive connector <NUM>. For example, were one to view the inductor <NUM> of <FIG> in the direction of the axis B-B from left to right as <FIG> is drawn, then the first portion <NUM> of the inductor <NUM> would extend in an anticlockwise direction from the connector <NUM>, whereas the second portion <NUM> of the inductor <NUM> would extend in a clockwise direction from the connector <NUM>.

Moreover, in this example, when viewed in the direction orthogonal to the first plane P<NUM>, the first portion <NUM> or first partial annulus overlaps, albeit only partially, the second portion <NUM> or second partial annulus. In this example, the first and second portions <NUM>, <NUM> together define about <NUM> turns about the axis B-B that is orthogonal to the first and second planes P<NUM>, P<NUM>. In other examples, the number of turns may be other than <NUM>, such as another number that is at least <NUM>. For example, the number of turns may be between <NUM> and <NUM>, or between <NUM> and <NUM>. In other examples, the number of turns may be less than <NUM>, although decreasing the number of turns per support <NUM> may lead to an increase in the axial length of the inductor assembly <NUM>.

Furthermore, when viewed in the direction orthogonal to the first plane P<NUM>, the first portion <NUM> or first partial annulus, as well as the second portion <NUM> or second partial annulus, at least partially overlaps the first electrically-conductive connector <NUM>. This is facilitated by the inductor arrangement <NUM> comprising, or being formed from, a PCB (or more generally, a planar substrate layer). In particular, in such examples, the first electrically-conductive connector <NUM> takes the form of a "via" that extends through the support <NUM>. Even in examples in which the inductor arrangement <NUM> is not formed from a PCB, the connector <NUM> still may extend through the support <NUM>. This overlapped arrangement enables the inductor <NUM> to occupy a relatively small footprint, when viewed in the direction orthogonal to the first plane P<NUM>, as compared to a comparative example in which the first and second portions <NUM>, <NUM> are connected by a connector <NUM> that is spaced radially outwards of the first and second portions <NUM>, <NUM>. Furthermore, this overlapped arrangement enables the width of the through-hole <NUM> to be increased, as compared to a comparative example in which the first and second portions <NUM>, <NUM> are connected by a connector <NUM> that is spaced radially inwards of the first and second portions <NUM>, <NUM>. Nevertheless, in some examples, the connector <NUM> may be radially-inward or radially-outward of the first and second portions <NUM>, <NUM>. This may be effected by the connector <NUM> being formed by a "through via" that extends through the support <NUM>. Through vias tend to be cheaper to form than blind vias, as they can be formed after the PCB has been manufactured.

It will be noted that, in this example, the inductor arrangement <NUM> comprises two further supports <NUM>, <NUM>, and the element <NUM> comprises two further electrically-conductive non-spiral portions <NUM>, <NUM> that are coincident with two respective spaced-apart planes P<NUM>, P<NUM> that are parallel to the first plane P<NUM>. In other examples, one or each of the spaced-apart planes P<NUM>, P<NUM> may be at an angle to the first plane P<NUM>, such as an angle of no more than <NUM> degrees or no more than <NUM> degrees or no more than <NUM> degrees. The second and third electrically-conductive non-spiral portions <NUM>, <NUM> are on opposite sides of the second support <NUM>, and are electrically connected by a second electrically-conductive connector <NUM>. The third and fourth electrically-conductive non-spiral portions <NUM>, <NUM> are on opposite sides of the third support <NUM>, and are electrically connected by a third electrically-conductive connector <NUM>. The second and third electrically-conductive connectors <NUM>, <NUM> are rotationally offset from the first electrically-conductive connector <NUM>. In arrangements in which the supports <NUM>, <NUM> and <NUM> are formed as a PCB, the connectors <NUM> and <NUM> may be formed as "blind vias", while connector <NUM> may be formed as a "buried via".

In this example, the first, second, third and fourth portions or partial annuli <NUM>, <NUM>, <NUM>, <NUM> together define a total of about <NUM> turns about the axis B-B that is orthogonal to the first and second planes P<NUM>, P<NUM>. In other examples, the total number of turns may be other than <NUM>, such as another number that is between <NUM> and <NUM>. For example, the total number of turns may be between <NUM> and <NUM>, or between <NUM> and <NUM>. Having a relatively small total number of turns is thought to increase the voltage that will be available in the susceptor <NUM> (whether provided in the device <NUM> or the article <NUM>) for forcing electrical current along or around the susceptor <NUM>.

It will be noted that the inductor <NUM> also comprises first and second terminals <NUM>, <NUM> at opposite ends of the inductor <NUM>. These terminals are for the passage of electrical current through the inductor <NUM> in use.

In this example, each of the first, second and third supports <NUM>, <NUM>, <NUM> has a thickness of about <NUM> millimetres. In some examples, one or more of the supports <NUM>, <NUM>, <NUM> may have a thickness other than <NUM> millimetres, such as another thickness lying in the range of <NUM> millimetres to <NUM> millimetres. For example, each of the thicknesses may be between <NUM> millimetres and <NUM> millimetre, or between <NUM> millimetres and <NUM> millimetres. In some examples, the thicknesses of the respective supports <NUM>, <NUM>, <NUM> are equal to each other, or substantially equal to each other. In other examples, one or more of the supports <NUM>, <NUM>, <NUM> may have a thickness that differs from a thickness of one or more of the other supports <NUM>, <NUM>, <NUM>.

In this example, each of the portions <NUM>, <NUM>, <NUM>, <NUM> of the inductor <NUM> has a thickness, measured in a direction orthogonal to the first plane P<NUM>, of about <NUM> micrometres. In some examples, one or more of the portions <NUM>, <NUM>, <NUM>, <NUM> of the inductor <NUM> may have a thickness other than <NUM> micrometres, such as another thickness lying in the range of <NUM> micrometres to <NUM> micrometres. For example, each of the thicknesses may be between <NUM> micrometres and <NUM> micrometres, or between <NUM> micrometres and <NUM> micrometres.

In examples in which the inductor arrangement <NUM> is made from a PCB, the thickness of the material of the inductor <NUM> may be determined by "plating-up" the material on the substrate, prior to construction of the PCB. Some standard circuit boards have a 1oz layer of electrically-conductive material, such as copper, on the substrate. A 1oz layer has a thickness of about <NUM> micrometres. By plating-up to a 4oz layer, the thickness is increased to about <NUM> micrometres. Increasing the thickness makes the structure of the inductor arrangement more robust and reduces system losses due to a commensurate reduction in ohmic losses. Increasing the volume of material of the inductor <NUM> will increase the heat capacity of the inductor <NUM>, reducing the temperature gain for a given input of heat. This may be beneficial, as it can be used to help ensure that the temperature of the inductor <NUM> itself in use does not get so high as to cause damage to the structure of the inductor arrangement <NUM>. In some examples, the thicknesses of the respective portions <NUM>, <NUM>, <NUM>, <NUM> of the inductor <NUM> are equal to each other, or substantially equal to each other. This can lead to a more consistent heating effect being produced by the different portions of the inductor <NUM>. In other examples, one or more of the portions <NUM>, <NUM>, <NUM>, <NUM> of the inductor <NUM> may have a thickness that differs from a thickness of one or more of the other portions <NUM>, <NUM>, <NUM>, <NUM> of the inductor <NUM>. This may be intentional in some examples, so as to provide an increased heating effect produced by certain portion(s) of the inductor <NUM> as compared to the heating effect produced by other portion(s) of the inductor <NUM>.

In this example, each of the planes P<NUM>-P<NUM> is a flat plane, or a substantially flat plane. However, this need not be the case in other examples.

The first and second planes P<NUM>, P<NUM> are spaced apart by a distance D<NUM> in the direction of an axis B-B of the inductor <NUM>, as shown in <FIG>. In this example, the distance D<NUM> between the first and second planes P<NUM>, P<NUM> measured in a direction orthogonal to the first and second planes P<NUM>, P<NUM> is less than <NUM> millimetres, such as less than <NUM> millimetre. In other examples, the distance D<NUM> may be between <NUM> millimetre and <NUM> millimetres, or more than <NUM> millimetres, for example.

The combination of the first electrically-conductive connector <NUM> and the first and second portions <NUM>, <NUM> of the electrically-conductive element <NUM> can be considered to be, or to approximate, a helical coil. Indeed, the full inductor <NUM> can be considered to be, or to approximate, a helical coil.

Given the distances D<NUM>, D<NUM>, D<NUM> between adjacent pairs of the planes P<NUM>, P<NUM>, P<NUM>, P<NUM>, the coil of this example can be considered to have a pitch of less than <NUM> millimetres, such as less than <NUM> millimetre. In other examples, the pitch may be between <NUM> millimetre and <NUM> millimetres, or more than <NUM> millimetres, for example. Optionally, a distance between each adjacent pair of the portions <NUM>, <NUM>, <NUM>, <NUM> of the element <NUM> is equal to, or differs by less than <NUM>% from, a distance between each other adjacent pair of the portions <NUM>, <NUM>, <NUM>, <NUM> of the element <NUM>. This can lead to the generation of a more consistent magnetic field along the length of the inductor <NUM>, and thus more consistent heating of the susceptor <NUM>.

The smaller the pitch, the greater the ratio of magnetic field strength to mass of susceptor <NUM> (whether provided in the device <NUM> or the article <NUM>) to which the energy is being applied. However, this needs to be balanced against the negative effects of the "proximity effect". In particular, as the pitch is reduced, losses due to the proximity effect increase. Therefore, careful pitch selection is required to reduce the losses in the inductor <NUM> while increasing the energy available for heating the susceptor <NUM>. It has been found that, in some examples, when the inductors <NUM> and the controller <NUM> are suitably configured, they cause the generation of a magnetic field having a magnetic flux density of at least <NUM> Tesla. In some examples, the magnetic flux density is at least <NUM> Tesla.

Relatively small pitches are enabled through the manufacture of the inductor arrangement <NUM> from a PCB. Given the present teaching, the skilled person would be able to conceive of other ways of manufacturing induction coils with a similarly small pitch. However, manufacture of the inductor arrangement <NUM> from a PCB is likely also to be cheaper than some other ways of manufacturing induction coils, such as by winding Litz wire.

While the inductor arrangement <NUM> of the example shown in the Figures has three supports <NUM>, <NUM>, <NUM> and an inductor <NUM> comprising four portions <NUM>, <NUM>, <NUM>, <NUM>, this need not be the case in other examples. In some examples, the inductor <NUM> may have more or fewer than four portions, such as only three portions <NUM>, <NUM>, <NUM> or only two portions <NUM>, <NUM>. In some examples, the inductor arrangement <NUM> may have more or fewer than three supports, such as only two supports <NUM>, <NUM> or only one support <NUM>. Indeed, in some examples, the number of supports in the inductor arrangement <NUM> may be only one, and the number of portions of the inductor <NUM> may be only two, and those two portions <NUM>, <NUM> of the inductor <NUM> would be on opposite sides of the single support <NUM>. It will be understood that the number of electrically-conductive connectors <NUM>, <NUM>, <NUM> would have to be correspondingly adjusted depending on the number of two portions <NUM>, <NUM>, <NUM>, <NUM> present in the inductor <NUM>. In some examples, the inductor <NUM> may be provided without any supports between the portions <NUM>, <NUM>, <NUM>, <NUM> of the inductor <NUM>. In such examples, it is desirable for the inductor <NUM> to be of sufficient strength to be self-supporting.

The inductor arrangements <NUM> of the respective heating units 140a-140e, or the inductors <NUM> thereof, may be provided in an inductor assembly or a magnetic field generator <NUM> for inclusion in an aerosol provision device, such as the device <NUM> of <FIG> or any of the variants thereof discussed herein. The inductors <NUM> of the inductor assembly, magnetic field generator <NUM> or device <NUM> may be spaced apart by a distance selected so as to enable heating of a majority or otherwise desired amount of the aerosolisable material <NUM>, while avoiding or reducing interference between the inductors <NUM>. As noted herein, the relatively small pitch of the inductors has been found to result in the generation of a varying magnetic field that is relatively concentrated, so that others of the inductors <NUM> can be placed relatively closely without suffering too much from interference. Adjacent inductors <NUM> may be spaced apart by a distance of between <NUM> millimetres and <NUM> millimetres, such as a distance of between <NUM> millimetres and <NUM> millimetres or a distance of between <NUM> millimetres and <NUM> millimetres. Other distances may be employed in other examples.

Once all, substantially all, or many of the volatilisable component(s) of the aerosolisable material <NUM> in the article <NUM> has/have been spent, the user may remove the article <NUM> from the heating chamber <NUM> of the device <NUM> and dispose of the article <NUM>.

In some examples, the article <NUM> is sold, supplied or otherwise provided separately from the device <NUM> with which the article <NUM> is usable. However, in some examples, the device <NUM> and one or more of the articles <NUM> may be provided together as a system, such as a kit or an assembly, possibly with additional components, such as cleaning utensils.

Claim 1:
An inductor for use in an aerosol provision device (<NUM>), the inductor comprising:
an electrically-conductive element (<NUM>);
wherein the element (<NUM>) comprises an electrically-conductive non-spiral first portion (<NUM>) coincident with a first plane (P<NUM>), an electrically-conductive non-spiral second portion (<NUM>) coincident with a second plane (P<NUM>) that is spaced from the first plane (P<NUM>), and an electrically-conductive connector (<NUM>) that electrically connects the first portion (<NUM>) to the second portion (<NUM>).