Aerosol Generation System

Abstract

The aerosol-generating system (1, 2, 3) comprises an aerosol-generating substrate (26), an inductor (29) for generating a primary electromagnetic field (42), a primary susceptor (28) configured to be inductively heated by the primary electromagnetic field (42) and to heat only the aerosol-generating substrate (26), and a secondary susceptor (40) configured to generate only a secondary electromagnetic field (44). The secondary electromagnetic field (44) is generated under the influence of the primary electromagnetic field (42) and acts in opposition to the primary electromagnetic field (42).

Description

[Technical field]

[0001] The present disclosure relates generally to aerosol generation systems, and more particularly to aerosol generation systems for heating an aerosol-generating substrate to generate an aerosol for inhalation by a user. [Background technology]

[0002] In recent years, devices that generate aerosols for inhalation by heating, rather than burning, an aerosol-generating substrate have become popular with consumers. Such devices can provide heat to the aerosol-generating substrate using one of several different techniques.

[0003] One such approach is to provide an aerosol-generating device that employs an induction heating system. In such a device, an induction coil (also called an inductor) is provided in the device and a susceptor is provided, for example, in the aerosol-generating substrate. When a user activates the device, electrical energy is supplied to the inductor, which generates an alternating electromagnetic field. The susceptor couples with the electromagnetic field, generating heat, which is transferred, for example by conduction, to the aerosol-generating substrate, generating vapor, which typically cools and condenses to form an aerosol for inhalation by a user of the device.

[0004] Such an approach has the potential to provide greater control over heating and therefore aerosol generation. However, a drawback of using induction heating systems is that the electromagnetic field generated by the inductor can leak, and therefore this drawback needs to be addressed. Summary of the Invention [Means for solving the problem]

[0005] According to a first aspect of the present disclosure, an aerosol-generating substrate; an inductor for generating a primary electromagnetic field; a primary susceptor configured to be inductively heated by a primary electromagnetic field and configured to heat only the aerosol-generating substrate; a secondary susceptor configured to generate only a secondary electromagnetic field acting in opposition to the primary electromagnetic field, the secondary electromagnetic field being generated under the influence of the primary electromagnetic field; An aerosol generating system is provided, comprising:

[0006] The aerosol-generating system, and more specifically the primary susceptor, is configured to heat the aerosol-generating substrate without burning it to generate a vapor by evaporating at least one component of the aerosol-generating substrate, which vapor cools and condenses to form an aerosol for inhalation by a user of the aerosol-generating device. In particular, the primary susceptor is heated by the primary electromagnetic field due to eddy currents and / or magnetic hysteresis losses resulting in the conversion of energy from electromagnetic to thermal, and the aerosol-generating substrate is heated solely by the heat transferred from the primary susceptor.

[0007] Generally speaking, a vapor is a substance that is in the gas phase below its critical temperature, meaning that it can be condensed into a liquid by increasing the pressure without decreasing the temperature. An aerosol, on the other hand, is a suspension of fine solid particles or liquid droplets in air or another gas. However, it should be noted that in this specification, the terms "aerosol" and "vapor" may be used interchangeably, particularly with respect to the form of inhalable medium that is generated for inhalation by the user.

[0008] The primary electromagnetic field is attenuated by a secondary electromagnetic field that acts in opposition to the primary electromagnetic field, thereby reducing electromagnetic leakage from the aerosol-generating system without the need for complex electromagnetic shielding structures. The purpose of the secondary susceptor is to attenuate the primary electromagnetic field. The secondary susceptor does not heat the aerosol-generating substrate.

[0009] The aerosol generation system may comprise a housing. The housing may define a device boundary, and the secondary electromagnetic field may be configured to attenuate the primary electromagnetic field to form a net electromagnetic field boundary that is at least partially, and possibly completely, within the device boundary. By configuring the aerosol generation system to form a net electromagnetic field boundary that is at least partially, and possibly completely, within the device boundary, exposure of a user of the aerosol generation system to the electromagnetic field may be reduced.

[0010] The secondary susceptor may have a lower electrical resistivity than the primary susceptor. The low electrical resistivity (in other words, high electrical conductivity) of the secondary susceptor ensures that the current induced in the secondary susceptor by the primary electromagnetic field does not cause substantial heating of the secondary susceptor and thus other components of the aerosol generation system in close proximity to the secondary susceptor. In contrast, the high electrical resistivity of the primary susceptor ensures that the primary susceptor is efficiently heated by the primary electromagnetic field. The primary susceptor may include a first material, and the secondary susceptor may include a second material having a lower electrical resistivity than the first material. In one example, the first material may include aluminum, and the second material may include copper. Alternatively or additionally, the low electrical resistivity of the secondary susceptor may be achieved based on the geometric characteristics of the primary susceptor and the secondary susceptor, for example, the secondary susceptor may have a greater thickness than the primary susceptor. In this case, the primary and secondary susceptors may comprise the same material.

[0011] The aerosol generating system may further comprise an electromagnetic shield that may be disposed between the inductor and the secondary susceptor. The electromagnetic shield may comprise a ferrimagnetic, non-conductive material. Examples of suitable materials for the electromagnetic shield include, but are not limited to, ferrite, nickel zinc ferrite, and mu metal. The electromagnetic shield may comprise a laminated structure and thus may comprise multiple layers. The layers may comprise the same material or may comprise multiple different materials, for example, selected to provide desired shielding properties. The electromagnetic shield may reduce electromagnetic coupling between the primary electromagnetic field and the secondary susceptor, thereby ensuring that a maximum amount of energy is transferred from the inductor to the primary susceptor.

[0012] The inductor may include a helical induction coil and the primary susceptor may be disposed inside the helical induction coil. In the context of this disclosure, the term "helical induction coil" includes induction coils having any suitable cross-sectional shape relative to the winding axis of the coil, including, but not limited to, circular, elliptical, square, and rectangular.

[0013] The primary susceptor may comprise a plurality of first susceptor disks arranged inside the induction coil. This arrangement may ensure that the electromagnetic coupling between the primary electromagnetic field and the plurality of first susceptor disks is enhanced, thereby efficiently heating the aerosol-generating substrate. In other embodiments, the primary susceptor may be strip or plate-shaped, rod-shaped, U-shaped, E-shaped, I-shaped, pin-shaped, or tubular, for example with a circular, rectangular, or square cross section.

[0014] The secondary susceptor may include at least one susceptor disk (e.g., a copper disk) disposed at an axial end of the helical induction coil. In some embodiments, the secondary susceptor may include a pair of susceptor disks (e.g., copper disks) disposed at both axial ends of the helical induction coil. The susceptor disk, or each of the susceptor disks, may have an opening therein and may include a susceptor ring. Such a configuration may facilitate the generation of electrical currents in the susceptor disks under the influence of the primary electromagnetic field, and thus the generation of the secondary electromagnetic field.

[0015] The secondary susceptor may include a susceptor mesh (e.g., a copper mesh) that may surround at least a portion of the helical induction coil. Such a configuration may facilitate the generation of electrical currents in the susceptor mesh under the influence of the primary electromagnetic field, and thus the generation of the secondary electromagnetic field.

[0016] The secondary susceptor may partially or completely surround the inductor (e.g., a helical induction coil), the primary susceptor, and the aerosol-generating substrate. For example, the secondary susceptor may comprise a cup-shaped susceptor element or a pair of cup-shaped susceptor elements, e.g., disposed at both axial ends of the helical induction coil. In embodiments in which the secondary susceptor completely surrounds the inductor (e.g., a helical induction coil), the primary susceptor, and the aerosol-generating substrate, the secondary susceptor may comprise one or more openings that allow air and steam to flow through the aerosol-generation system and that allow the inductor to be electrically connected to a power source and controller.

[0017] In some embodiments, the secondary susceptor may comprise a housing. In such a configuration in which the housing acts as the secondary susceptor, there is no need to provide an additional component (e.g., a susceptor disk or susceptor mesh) that acts as the secondary susceptor. This may advantageously help to simplify the construction of the aerosol generation system, thereby reducing the size and / or weight of the system.

[0018] The primary susceptor and the aerosol-generating substrate may be integrated into a planar body having a major surface, and the inductor may comprise a pair of coil plates disposed on opposite sides of the planar body, each having a first surface facing a corresponding major surface of the planar body. Each coil plate may include a planar inductive coil, such as a helically wound coil having a winding axis perpendicular to the surface on which the coil plate lies. The planar coil may lie in a planar plane, and thus the planar coil may be a flat coil. Such a configuration may facilitate manufacture of the aerosol-generating system.

[0019] Each of the coil plates may have a second surface facing opposite the first surface, and the secondary susceptor may include a pair of susceptor plates, each of which may be disposed adjacent the second surface of a respective coil plate. The electromagnetic shield may include a pair of electromagnetic shield members, one of which may be disposed between each coil plate and an adjacent susceptor plate. Each electromagnetic shield member may include a ferrite plate. Such a configuration may simplify the construction of the aerosol generation system.

[0020] The aerosol generating system may further comprise an air gap layer that may be disposed between each coil plate and the adjacent electromagnetic shielding member. Such a configuration may improve the shielding effect and / or help to reduce heat transfer to other components of the aerosol generating system. This may improve user comfort, for example by reducing the temperature of an exterior surface of the aerosol generating system.

[0021] Each gap layer may include an insulating material, which may include ceramic or foam glass. The use of insulating materials may help to further reduce heat transfer to other components of the aerosol generation system.

[0022] The secondary susceptor may act as a conductor, and the aerosol generating system may include a self-oscillating circuit formed by the inductor and the secondary susceptor. For example, each planar coil may include a first electrode that may be connected to a power supply and a controller, and a second electrode that may be connected to an adjacent susceptor plate, for example, by a rivet or soldered connection. The second electrodes, and thus the susceptor plates, may be connected to each other by a center tap, thereby forming a self-oscillating circuit.

[0023] The aerosol generation system may comprise an aerosol generation device incorporating the inductor.The aerosol generation device may comprise a cavity having a longitudinal axis.

[0024] In embodiments in which the inductor includes a helical induction coil, the helical induction coil may extend around the cavity such that a longitudinal axis of the helical induction coil and a longitudinal axis of the cavity are substantially parallel.

[0025] In embodiments in which the inductor includes a pair of coil plates, the coil plates may be positioned on opposite sides of the cavity, with a first surface of each coil plate facing the cavity.

[0026] The inductor may comprise any suitable material, for example, a Litz wire or a Litz cable.

[0027] The aerosol-generating substrate may comprise a non-liquid aerosol-generating substrate, such as any type of solid or semi-solid material. Exemplary types of aerosol-generating substrates include powders, granules, pellets, shreds, strands, particles, gels, strips, loose-leaf, cut-leaf, cut-filler, porous materials, foamed materials, or sheets. The non-liquid aerosol-generating substrate may comprise a plant-derived material, in particular tobacco. The plant-based aerosol-generating material may advantageously comprise reconstituted tobacco.

[0028] The aerosol-generating substrate may include an aerosol former. Examples of aerosol formers include polyhydric alcohols such as glycerin or propylene glycol and mixtures thereof. Typically, the aerosol-generating substrate may include an aerosol former content of about 5% to about 50% on a dry weight basis. In some embodiments, the aerosol-generating substrate may include an aerosol former content of about 10% to about 20% on a dry weight basis, and in some cases about 15% on a dry weight basis.

[0029] Upon heating, the aerosol-generating substrate may release volatile compounds, which may include flavor compounds such as nicotine or tobacco flavorings.

[0030] The inductor may be configured to operate with a varying electromagnetic field having a magnetic flux density, during use, of between about 20 mT and about 2.0 T at the point of greatest density.

[0031] The aerosol generation system may include a power supply and controller that may be configured to operate at high frequencies. The power supply and controller may be configured to operate at frequencies between about 100 kHz and 900 kHz, optionally between about 350 kHz and 450 kHz, and optionally about 400 kHz. The power supply and controller may be configured to operate at higher frequencies, for example in the MHz range, depending on the type of inductively heatable susceptor (particularly the primary susceptor) used.

[0032] The aerosol-generating system may comprise an aerosol-generating article comprising an aerosol-generating substrate and a primary susceptor. The aerosol-generating article may be generally cylindrical or generally plate-shaped.

[0033] The aerosol-generating article may include a breathable shell, and the aerosol-generating substrate and the primary susceptor may be disposed inside the breathable shell. The breathable shell may include an electrically insulating, non-magnetic breathable material that is highly breathable to allow air to flow therethrough while being resistant to high temperatures. Examples of suitable breathable materials include cellulose fibers, paper, cotton, and silk. The breathable material may also act as a filter.

[0034] The plate-shaped aerosol-generating article may comprise a substantially planar aerosol-generating substrate and a substantially planar primary susceptor. The substantially planar aerosol-generating substrate may comprise two substantially planar layers of aerosol-generating material and the substantially planar primary susceptor may be disposed between the two substantially planar layers of aerosol-generating material. [Brief description of the drawings]

[0035] [Figure 1] FIG. 1 is a schematic diagram of a first example of an aerosol generation system. [Diagram 2] Figures 2a-2c are partial schematic diagrams of the aerosol generation system of Figure 1 showing the attenuation of the primary electromagnetic field by the secondary electromagnetic field (the orientation and size of the triangular symbols are intended to indicate the direction and strength of the electromagnetic field, respectively). [Diagram 3] FIG. 2 is a schematic diagram of a second example of an aerosol generation system. [Figure 4] FIG. 13 is a partial schematic diagram of a third example of an aerosol generation system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0037] Referring initially to Figure 1, a first example of an aerosol generating system 1 is shown diagrammatically. The aerosol generating system 1 comprises a first example of an aerosol generating device 10 and an aerosol generating article 24. The aerosol generating device 10 has a proximal end 12 and a distal end 14 and comprises a device housing 16. The device housing 16 comprises a power source 18 and a controller 20. The power source 18 and the controller 20 may be configured to operate at radio frequency. The power source 18 typically comprises one or more batteries, which may be, for example, inductively rechargeable.

[0038] The aerosol-generating device 10 is generally cylindrical and comprises a generally cylindrical cavity 22, for example in the form of a heating section, at the proximal end 12 of the aerosol-generating device 10. The cylindrical cavity 22 is configured to receive a correspondingly shaped generally cylindrical aerosol-generating article 24 housing an aerosol-generating substrate 26 and a primary inductively heatable susceptor 28, for example in the form of a first susceptor disk 28a formed of aluminium. The aerosol-generating article 24 may comprise a non-metallic, breathable outer shell 24a for housing the aerosol-generating substrate 26 and the first susceptor disk 28a and for allowing air to flow through the aerosol-generating article 24. The aerosol-generating article 24 is a disposable article and may, for example, house tobacco as the aerosol-generating substrate 26.

[0039] The aerosol generating device 10 comprises an inductor 29 in the form of a helical induction coil 30 having a circular cross section and extending around the cylindrical cavity 22. In other non-illustrated embodiments, the helical induction coil may have a non-circular cross section, for example an elliptical, square or rectangular cross section. The induction coil 30 may be energized by a power source 18 and a controller 20. The controller 20 comprises, among other electronic components, an inverter configured to convert direct current from the power source 18 into alternating high frequency current for the induction coil 30.

[0040] The aerosol generating device 10 includes one or more air inlets 32 in the device housing 16 that allow ambient air to flow into the cylindrical cavity 22. The aerosol generating device 10 also includes a mouthpiece 34 having an air outlet 36. The mouthpiece 34 is removably attached to the device housing 16 at the proximal end 12 to provide access to the cylindrical cavity 22 for purposes of inserting or removing an aerosol-generating article 24.

[0041] As will be appreciated by those skilled in the art, when the induction coil 30 is energized during use of the aerosol generating system 1, an alternating, time-varying primary electromagnetic field 42 is generated, as shown diagrammatically by a triangular symbol in Fig. 2a. The primary electromagnetic field 42 couples with the primary susceptor 28 and generates eddy currents and / or magnetic hysteresis losses in the first susceptor disk 28a, causing them to heat up. As shown diagrammatically in Fig. 2a, the primary electromagnetic field 42 has an electromagnetic field boundary 90 that is external to a boundary 92 of the aerosol generating device 10, e.g., defined by the exterior of the device housing 16.

[0042] The first susceptor disk 28a is in direct or indirect contact with the aerosol-generating substrate 26 such that when the first susceptor disk 28a is inductively heated by the primary electromagnetic field 42 generated by the induction coil 30, heat may be transferred from the first susceptor disk 28a to the aerosol-generating substrate 26, for example by conduction, radiation, and convection, to heat the aerosol-generating substrate 26 without burning it, thereby generating vapor. Evaporation of the aerosol-generating substrate 26 is facilitated by adding air from the surrounding environment through the air inlet 32. The vapor generated by heating the aerosol-generating substrate 26 exits the cylindrical cavity 22 through the air outlet 36, where it cools and condenses to form an aerosol that can be inhaled by a user of the device 10 through the mouthpiece 34. The flow of air through the cylindrical cavity 22, i.e., from the air inlet 32, through the cavity 22 and out the air outlet 36 of the mouthpiece 34, may be assisted by negative pressure created by the user inhaling air from the air outlet 36 side of the device 10.

[0043] In addition to the primary susceptor 28 (i.e., the first susceptor disk 28a in the illustrated example), the aerosol generating system 1, and more particularly the aerosol generating device 10, comprises a secondary susceptor 40. In the illustrated example, the secondary susceptor 40 comprises a pair of second susceptor disks 40a arranged at both axial ends of the helical induction coil 30. The second susceptor disk 40a may be ring-shaped, as shown in FIG. 1. The second susceptor disk 40a may be advantageously formed from a material (e.g., copper) having a lower electrical resistivity than the material (e.g., aluminum) from which the first susceptor disk 28a is formed.

[0044] The second susceptor disk 40a is configured to generate a secondary electromagnetic field 44 under the influence of the primary electromagnetic field 42 generated by the induction coil 30, as shown diagrammatically by a triangular symbol in FIG. 2b. More specifically, the primary electromagnetic field 42 is absorbed by the second susceptor disk 40a and induces a current in the second susceptor disk 40a, which generates a secondary electromagnetic field 44 acting in opposition to the primary electromagnetic field 42 (e.g., at 180 degrees as shown in FIG. 2b). By acting in opposition to the primary electromagnetic field 42, the secondary electromagnetic field 44 attenuates the primary electromagnetic field 42 such that the resulting net electromagnetic field 46 has a net electromagnetic field boundary 94 that is at least partially within the device boundary 92 of the aerosol generating device 10, as shown diagrammatically by a triangular symbol in FIG. 2c. As a result, exposure of a user of the aerosol generating system 1 to electromagnetic fields may be reduced compared to an aerosol generating device not employing a secondary susceptor 40.

[0045] Referring now to Figure 3, there is shown a second example of an aerosol generation system 2 similar to the first example of an aerosol generation system 1 described above in relation to Figures 1 and 2, and corresponding components are identified using the same reference numbers.

[0046] The aerosol generating system 2 comprises a second example of an aerosol generating device 50 which is similar to the first example of an aerosol generating device 10 described above, and also comprises an aerosol generating article 24 as described above.

[0047] The aerosol generating device 50 includes a secondary susceptor 40 in the form of a susceptor mesh 52, e.g., made of copper, that at least partially surrounds the helical induction coil 30. In the illustrated example, the susceptor mesh 52 includes a generally cylindrical mesh portion 54 and a generally circular mesh portion 56 disposed at an axial end of the induction coil 30.

[0048] The susceptor mesh 52 is configured to generate a secondary electromagnetic field 44 under the influence of the primary electromagnetic field 42 generated by the induction coil 30. More specifically, the primary electromagnetic field 42 is absorbed by the susceptor mesh 52 and induces currents in the susceptor mesh 52, which generates a secondary electromagnetic field 44 that acts in opposition to the primary electromagnetic field 42. The secondary electromagnetic field 44 attenuates the primary electromagnetic field 42 as described in connection with FIG. 1 such that a resulting net electromagnetic field 46 has a net electromagnetic field boundary 94 that is at least partially within a device boundary 92 of the aerosol generating device 50.

[0049] The aerosol generating device 50 may also include an electromagnetic shield 60 that may be disposed between the induction coil 30 and the susceptor mesh 52. The electromagnetic shield 60 is typically formed of a ferrimagnetic, non-conductive material, such as ferrite. In the embodiment shown in FIG. 3, the electromagnetic shield layer 60 includes a generally cylindrical shield portion 62, for example in the form of a generally cylindrical sleeve disposed radially outward of the induction coil 30 so as to extend circumferentially around the induction coil 30. The electromagnetic shield 60 also includes a first circular shield portion 64 disposed at an axial end of the induction coil 30. The electromagnetic shield 60 may also include a second circular shield portion 66 that may be disposed at a second axial end of the induction coil 30.

[0050] Referring now to Figure 4, there is shown a portion of a third example of an aerosol generation system 3 which is similar to the first and second examples of aerosol generation systems 1, 2 described above in relation to Figures 1 to 3, and corresponding components are identified using the same reference numbers.

[0051] The aerosol generating system 3 comprises a third example of an aerosol generating device 70 which shares some similarities with the first and second examples of aerosol generating devices 10, 50 described above, only a portion of which is shown in Figure 4. In the aerosol generating device 70, the inductor 29 comprises a pair of coil plates 72 arranged on either side of a cavity 74 adapted to receive a plate-shaped aerosol-generating article 76. The plate-shaped aerosol-generating article 76 comprises an aerosol-generating substrate 26 with a planar body 77 having a main surface 78, and a primary susceptor 28, e.g. a planar susceptor arranged between two layers of aerosol-generating material.

[0052] Each coil plate 72 includes a helically wound planar coil 80, which may be formed as a multi-layer printed circuit board with each planar coil 80 formed as a copper trace. Each coil plate 72 has a first surface 72a that faces a corresponding major surface 78 of the planar body 77. In some embodiments, the first surface 72a may be coated with a thermally conductive material, for example, so that heat loss from the planar coil 80 can reach the aerosol-generating substrate 26 and contribute to its heating. The planar coil 80 (a flat coil in the illustrated example) is configured to generate a primary electromagnetic field 42, similar to the helical induction coil 30 described above. Each planar coil 80 includes a first electrode 80a that is connected to the power supply 18 and the controller 20. Each planar coil 80 also includes a second electrode 80b, which may be connected by a center tap (not shown in FIG. 4), which is well known in the art and does not require further description.

[0053] The aerosol generating device 70 comprises a secondary susceptor 40 in the form of a pair of susceptor plates 82, each of which is disposed adjacent to the second surface 72b of a respective coil plate 72. The susceptor plates 82 are configured to generate a secondary electromagnetic field 44 under the influence of a primary electromagnetic field 42 generated by the coil plate 72. More specifically, the primary electromagnetic field 42 is absorbed by the susceptor plate 82 and induces a current in the susceptor plate 82, which generates a secondary electromagnetic field 44 that acts in opposition to the primary electromagnetic field 42 generated by the coil plate 72. The secondary electromagnetic field 44 attenuates the primary electromagnetic field 42 as described in relation to Figures 1-3, such that the resulting net electromagnetic field 46 has a net electromagnetic field boundary 94 that is at least partially within a device boundary 92 of the aerosol generating device 70.

[0054] The aerosol generating device 70 may also include substantially planar electromagnetic shielding members 84, one of which is disposed between each coil plate 72 and an adjacent susceptor plate 82. Each electromagnetic shielding member 84 is typically formed of a ferrimagnetic, non-conductive material, and in the illustrated example, each electromagnetic shielding member 84 comprises a ferrite plate. Each electromagnetic shielding member 84 may be spaced apart from an adjacent coil plate 72 by an air gap layer 86, which may include an insulating material such as ceramic or foam glass to prevent unwanted heat transfer within the aerosol generating device 70, for example from the coil plate 72 to other components of the aerosol generating device 70.

[0055] Although exemplary embodiments have been described in the preceding paragraphs, it should be understood that various modifications can be made to these embodiments without departing from the scope of the appended claims, and thus the breadth and scope of the claims should not be limited to the exemplary embodiments described above.

[0056] Any combination of the above-described features in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or clearly contradicted by context.

[0057] Unless the context clearly dictates otherwise, throughout this specification and the claims, the words "comprise", "including", and the like are to be construed in an inclusive sense, i.e., "including but not limited to," as opposed to an exclusive or exhaustive sense.

Claims

1. An aerosol generating system comprising: an aerosol-generating substrate (26); and an inductor (29) for generating a primary electromagnetic field (42); a primary susceptor (28) configured to be inductively heated by the primary electromagnetic field (42) and to heat only the aerosol-generating substrate (26); a secondary susceptor (40) configured to generate only a secondary electromagnetic field (44) acting counter to the primary electromagnetic field (42), the secondary electromagnetic field (44) being generated under the influence of the primary electromagnetic field (42); Equipped with The aerosol generation system (1, 2, 3) comprises a housing (16) defining a device boundary (92), and the secondary electromagnetic field (44) is configured to attenuate the primary electromagnetic field (42) to form a net electromagnetic field boundary (46) that is at least partially within the device boundary (92).

2. The aerosol generating system of claim 1 , wherein the secondary susceptor (40) has a lower electrical resistivity than the primary susceptor (28).

3. 3. The aerosol generating system of claim 1, further comprising an electromagnetic shield (60, 84) disposed between the inductor (29) and the secondary susceptor (40) and comprising a ferrimagnetic, non-conductive material.

4. 4. The aerosol generation system of claim 1, wherein the inductor (29) comprises a helical induction coil (30), and the primary susceptor (28) is disposed inside the helical induction coil (30).

5. 5. The aerosol generating system of claim 4, wherein the secondary susceptor (40) comprises at least one susceptor disk (40a) disposed at an axial end of the helical induction coil (30).

6. 6. The aerosol generation system of claim 4 or 5, wherein the secondary susceptor (40) comprises a susceptor mesh (52) surrounding at least a portion of the helical induction coil (30).

7. 5. The aerosol generating system of claim 1, wherein the secondary susceptor (40) at least partially surrounds the inductor (29), the primary susceptor (28), and the aerosol-generating substrate (26) and comprises a cup-shaped susceptor element or a pair of cup-shaped susceptor elements.

8. 4. The aerosol generating system of claim 1, wherein the primary susceptor (28) and the aerosol-generating substrate (26) are integrated into a planar body (77) having a main surface (78), and the inductor (29) comprises a pair of coil plates (72) arranged on either side of the planar body (77), each having a first surface (72a) facing the corresponding main surface (78) of the planar body (77).

9. 9. The aerosol generation system of claim 8, wherein each of the coil plates (72) has a second surface (72b) facing opposite the first surface (72a), and the secondary susceptor (40) comprises a pair of susceptor plates (82), each positioned adjacent to the second surface (72b) of the respective coil plate (72).

10. The aerosol generating system of claim 9 when dependent on claim 3, wherein the electromagnetic shield (60) comprises a pair of electromagnetic shield members (84), one of the electromagnetic shield members (84) being disposed between each coil plate (72) and the adjacent susceptor plate (82).

11. 11. The aerosol generating system of claim 10, wherein each electromagnetic shielding member (84) comprises a ferrite plate.

12. 12. The aerosol generating system of claim 10 or 11, further comprising an air gap layer (86) disposed between each coil plate (72) and the adjacent electromagnetic shield member (84).

13. 13. The aerosol generating system of claim 12, wherein each void layer (86) comprises a thermal insulating material.

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