Electric thrust-generating device

Abstract

An electric thrust-generating device comprises a cathode (2) and an anode (3) which are substantially planar, arranged substantially parallel and spaced from each other, with an interposed material or a dielectric medium (4) therebetween, the device being configured for connection to a voltage generator (5), for applying a voltage between the cathode (2) and the anode (3), and thereby determine a passage of electrons (e-) from the cathode (2) to the anode (3). At least the cathode (2) is micro- or nano-structured at the surface thereof facing the anode (3), in particular for the formation of aggregates of electrons (e-).

Description

[0001] "Electric thrust-generating device"

[0002] DESCRIPTION

[0003] Technical Field

[0004] The invention relates to electric thrust-generating devices, which can be used as propulsion systems, for example.

[0005] Prior art

[0006] As is well known, if one is in a medium such as the atmosphere, it is possible to obtain thrust through the well-known principle of conservation of momentum: for example, the air present in the atmosphere can be used to obtain thrust, as in the case of propeller planes or jets planes in which the exhaust gases are expelled at a great speed, thus producing a contrary thrust in the medium. In the absence of atmosphere, however, it can be advantageous to take advantage of the characteristics of the vacuum.

[0007] Space propulsion, which takes place in the absence of an atmosphere, is also based on the same principle of conservation of momentum, as particles, produced by combustion in the case of rockets, are ejected from the medium to obtain a thrust.

[0008] Electric space propulsion systems are known, which accelerate ions in order to gain a thrust on the vehicle.

[0009] The main limitation of this approach lies in the fact that, when the material that is ejected at a great speed to obtain the thrust is exhausted, the possibility of obtaining subsequent thrusts for positioning purposes also disappears, thus limiting the life of the vehicle (think, for example, of a satellite that needs to be repositioned).

[0010] In addition, the cost of spacecraft, such as satellites, is heavily influenced by the presence of propellant material that must be loaded into the vehicle. In fact, the propellant can represent 25% of the weight of the satellite and it is estimated that the cost per kg of mass to be carried into orbit can be in the order of about 20,000 euros. For example, in a satellite with a total weight of 1000 kg, the cost to bring the propellant into orbit can therefore reach the value of about 5 million euros.

[0011] Summary of the invention

[0012] In view of the above, this description aims at indicating a thrust generating device, electrically powered, of simple, economical and compact construction.

[0013] In summary, an electric thrust-generating device comprises a substantially planar cathode and anode, arranged substantially parallel and at a distance from each other, with an interposed material or dielectric medium (for example a polymer material, or the vacuum), the device being configured for connection to a voltage generator, to apply a voltage between the cathode and the anode, and thereby determine a passage of electrons from the cathode to the anode, wherein at least the cathode is micro- or nano-structured at the surface thereof facing the anode, in particular for the formation of electron aggregates (e‘).

[0014] As will be seen, thanks to these characteristics, the device described is able to generate thrusts suitable for example for application in the space environment, through a simple and compact structure, and without the need for the use of a propellant.

[0015] In various embodiments the device also comprises at least one temperature conditioning arrangement, such as a heating arrangement and / or a cooling arrangement. This feature makes it possible to increase the thrust effect that can be obtained by means of the device described.

[0016] In various embodiments, the interposed material or dielectric medium includes braking sites and / or for re-emission of electrons in their path between the cathode and the anode; as will be seen, in this way, the thrust effect obtainable by the device is further increased.

[0017] In preferential embodiments, the at least one temperature conditioning arrangement equipping the device comprises at least one electric heater, and at least one layer of electrically insulating - but substantially thermally conductive - material that is interposed between the electric heater and the cathode or anode. The presence of the electrically insulating but thermally conductive layer, for example made of silicone, guarantees in any way the heating effect that increases the thrust generated, without however causing the risk of damage to the structure, as it preserves the electrical insulation.

[0018] Preferably, the at least one conditioning arrangement comprises a temperature control system. In this way, in the case of the use of at least one electric heater, it can be easily checked that the working temperature of the heater has been reached and that it is maintained; similarly, in the case of the use of at least one cooling device, the corresponding working temperature can be controlled, in order to bring and maintain at least a portion of the device at a temperature suitable for its efficient operation.

[0019] In various embodiments, the dielectric material or medium interposed between the cathode and the anode comprises at least one layer of electrically insulating material, the structure of which creates or integrates braking sites for the electron in their path between the cathode and the anode. This feature makes it advantageous to exploit the same structure of the insulating material, to obtain the aforementioned braking sites, to the advantage of the simplicity of construction of the device.

[0020] Moreover, in various alternative embodiments, the interposed material or dielectric medium includes at least one layer of electrically insulating material, for example a polymeric material, to which at least one metal film or a plurality of metal micro- or nano-particles is / are is associated, which realizes / realize braking and / or re-emission sites of the electrons in their path between the cathode and the anode. In solutions of this type, the construction of the device is slightly more complicated than in the previous case, but with considerable advantages in terms of thrust generation.

[0021] In other possible embodiments, the interposed material or dielectric medium may include a vacuum, and in this case the device comprises an appropriate structure between the cathode and the anode, for the support of one of a metal film and a plurality of metal micro- or nano-particles that realizes / realize the aforementioned braking and / or re-emission sites for the electrons, also in this case with clear advantages in terms of generated thrust. Preferably, the above-mentioned support structure comprises a frame for a thin-film that supports the metal film or the plurality of metal micro- or nano-particles.

[0022] In various embodiments, the anode is also micro- or nano-structured, for example in a similar way to the cathode, in particular to further increase the braking of the electrons, particularly to the benefit of thrust generation.

[0023] In various embodiments, the cathode, and possibly also the anode, is structured in such a way as to present a plurality of tips or reliefs, preferably having a substantially pyramidal shape. This type of structuring facilitates the formation of electron aggregates, which proves useful for the purpose of generating thrust by the device.

[0024] The structuring of the anode and / or cathode can be achieved by means of a metal film deposited on a micro- or nano-structure previously obtained on a respective supporting layer made of an electrically insulating material, or by directly structuring a metal film on a respective supporting layer of electrically insulating material without its own micro- or nano-structuring. As can be seen, therefore, micro- or nano-structuring can be achieved in various ways, equally simple.

[0025] In possible embodiments, however, the sites of braking and / or re-emission of electrons can be obtained just as easily in the form of metal surface reliefs or micro- or nano-particles arranged at one face of a respective layer of dielectric material. The interposed material or dielectric medium may in any case include at least one metal film or a polymer filled with conductive particles at percolation level.

[0026] In various embodiments, the interposed dielectric material or medium may comprise a plurality of first layers of dielectric material, on a larger face of which a micro- or nano-structuring with a metallic film thereon. In embodiments of this type, the said first layers are superimposed in contact with each other, or separated from each other by a second electrically insulating layer or by a vacuum, in such a way that the micro- or nano-structuring of one of said first layers provided with the metal film faces the opposite major face, not provided with micro- or nanostructuring, of one of said first layer which is successive in the plurality. In solutions of this type, each metal film creates intermediate braking and re-emission sites for the electrons.

[0027] In other embodiments, the interposed dielectric material or medium includes both electron braking sites and electron re-emission sites, distinct from each other, for an increased thrust effect. In such embodiments, for example, the interposed dielectric material or medium may include one or more intermediate layers of electrically insulating material, wherein one major face of the layer faces the cathode, is substantially flat and bears a first metallic film or a plurality of metal micro- or nano-particles, and the other major face of the layer is opposite to the cathode and is provided with a micro- or nano-structuring bearing a second metal film, such that the first metal film or the plurality of micro- or nano-particles creates intermediate braking sites for electrons, and the second metal film creates intermediate re-emission sites for electrons.

[0028] In case of use of the device in the space environment, it may be convenient to equip the device with at least one of a cooling arrangement and a shield or similar shelter element, in order to cool or shield the device itself from solar radiation, in order to avoid overheating which might affect the correct functioning of the device itself.

[0029] The device is advantageously applied on spacecraft intended to operate in a vacuum, such as satellites.

[0030] Brief description of the drawings

[0031] Further purposes, characteristics and advantages will be clear from the detailed following description, made with reference to the attached schematic drawings, provided purely by way of non-exhaustive example, wherein:

[0032] - figure 1 is a schematic view of a thrust-generating device according to possible embodiment of the present description,

[0033] - figures 2 to 4 are schematic representations intended to illustrate possible arrangements of braking sites that can be used in a device according to possible embodiments of the present description,

[0034] - figures 5 and 6 are schematic views, respectively exploded and in partially sectioned perspective, of a multilayer structure that can be used in a device according to possible embodiments of the present description,

[0035] - figure 7 is a schematic view of a portion of a device according to possible embodiments of the present description,

[0036] - figures 8 and 9 are schematic views, respectively exploded and in partially sectioned perspective, of a multilayer structure that can be used in a device according to other possible embodiments of the present description, equipped with a heater,

[0037] - figure 10 is a detail on a larger scale of figure 9,

[0038] - figure 11 is a detail on a larger scale of figure 10,

[0039] - figures 12 and 13 are partially sectioned schematic views, respectively in perspective and exploded, of a multilayer structure that can be used in a device according to other possible embodiments of the present description, equipped with a heater,

[0040] - figure 14 is a schematic representation intended to exemplify a further possible embodiment of a device according to the present description,

[0041] - figure 15 is a schematic perspective view of a frame that can be used in a device according to other possible embodiments of the present description,

[0042] - figure 16 is a detail on a larger scale of figure 15,

[0043] - figure 17 is a partial and schematic cross-sectional view of a device using a frame of the type shown in figures 15-16,

[0044] - figure 18 is a schematic, partially sectioned perspective view of a structure of a device using a plurality of frames of the type shown in figures 15-16,

[0045] - figure 19 is detail on a larger scale of Figure 18,

[0046] - figure 20 is a view similar to that of figure 17, relating to a possible variant embodiment,

[0047] - figures 21 to 25 are schematic views aimed at showing further possible configurations of devices, and parts thereof, according to further possible embodiments of the present description,

[0048] - figures 26 and 27 are partially sectioned schematic views, respectively in perspective and exploded, of a multilayer structure used in a test device according to possible embodiments of the present description,

[0049] - figures 28 to 30 illustrate, in the form of graphs, experimental results relating to a device made in accordance with figures 26-27, figures 28-29 and figure 30, having forces which are expressed in Newtons [N] and milligrams, respectively,

[0050] - figures 31 and 32 are a macrophotograph and a related detail, respectively, to illustrate a dielectric layer (Kapton) on which aluminium nano-particles are deposited, used in a variant of the test device of figures 26-27,

[0051] - figure 33 illustrates, in the form of a graph, experimental results related to a device made according to the variant of figures 31-32, the figure having forces expressed in milligrams [mg],

[0052] - figure 34 is a schematic representation to illustrate the principle of operation of a device according to the present description, - figures 35 and 36 illustrate, by means of perspective views, possible applications of a device according to the present description,

[0053] - figure 37 is a graph illustrating experimental results from "Imaging lowdimensional nanostructures by very low voltage scanning electron microscopy: ultra-shallow topography and depth-tunable material contrast", Zarraoa, L. et al., and

[0054] - figures 38 to 44 are macro-photographs designed to illustrate the structural details of a device made according to possible embodiments of the present description.

[0055] Description of embodiments

[0056] The reference to "an embodiment" within this description indicates that a particular configuration, structure, or characteristic described in relation to the embodiment is included in at least one embodiment. Thus, phrases such as "in an embodiment" and the like, which may be present in different places in this description, do not necessarily refer to the same embodiment. In addition, particular conformations, structures or characteristics can be combined in any appropriate way in one or more embodiments, even if different from those depicted. The references used here are for convenience only and therefore do not define the frame of protection or the scope of the embodiments.

[0057] In figure 1 there is represented in a schematic way a basic structure of an electric thrust-generating device in accordance with possible embodiment. The basic structure of the device, designated as a whole by 1, comprises two electrodes, namely a cathode 2 and an anode 3, separated by an insulating layer 4 (of a thickness of the order of ten micrometers).

[0058] The device is designed for the connection of the cathode 2 and the anode 3 to a suitable voltage generator 5, configured for applying a voltage between the electrodes 2 and 3, in order to determine cause a passage of electrons from the cathode to the anode. The voltage generator 5 can be part of device 1 or be coupled thereto.

[0059] By applying a voltage between the electrodes by means of the voltage generator 5, an electron emission is obtained from cathode 2 and an electric current between the cathode 2 and the anode 3. The applied voltage is such that there is a passage of electrons between the cathode 2 and the anode 3, for example due to tunnelling effect, but without exceeding the breakdown voltage. In general terms, the required electric field is of the order of 108V / m. For example, as described in relation to the test device discussed below, voltages greater than 1 kV can be applied. The distance between the electrodes can generally depend on the applied voltage; in the case of the devices described herein, the distance between the anode and the cathode can be between 5 and 50 micrometers, preferably between 10 and 30 micrometers. The dimensional ratio between the lateral dimensions (any side of the perimeter in plan view) of the device and the thickness of the dielectric is between 50 and 10000, typically between 500 and 5000.

[0060] The voltage applied between electrodes 2, 3 can be a direct current at a constant voltage or modulated with a suitable oscillation frequency. This oscillation frequency can increase the resultant force of the device, obtained by operating the system in the vicinity of resonant frequencies of the overall circuit and / or of the electronic aggregates that will be described later.

[0061] If the insulating layer 4 between electrodes 2 and 3 is represented by vacuum, the electrons "e‘" will reach anode 3 without intermediate collisions. On the other hand, if the insulating layer 4 is represented by a dielectric, the motion of the electrons "e‘" will be distinguished by a sequence of collisions (i.e., numerous accelerations and decelerations), important for the operation of device 1, of for the generation of a thrust, in particular in the direction of anode the 3, as explained below.

[0062] As also explained below, the operation of the device described herein is generally based on the braking processes of the electrons emitted by the cathode on their way to the anode. Such braking processes can take place in the layer 4 comprised between the cathode 2 and the anode 3 and / or in the anode 3 itself.

[0063] For this purpose, according to an important aspect, intermediate braking sites of the electrons "e-" can be provided between the cathode 2 and the anode 3, arranged in an orderly or random manner. In various embodiments, the layer 4 can consist of a dielectric filled or structured with metal nanoparticles, for example gold nanoparticles, which obtains the aforementioned intermediate sites. In embodiments of this type, the metal nanoparticles operates as braking sites. Figures 2 and 3 show, schematically, non-limiting examples of nanoparticles 6 arranged in an orderly or disorderly manner, respectively, within a dielectric 4. Figure 4 illustrates some possible electron pathways EP, in the case of a random arrangement of the above-mentioned sites or nanoparticles 6. In figures 4-6, Ns is used to designate micro- or nano-structuring of the electrodes 2 and 3 (or of their respective electrically insulating supports, as explained below). In various embodiments, the structuring is aimed at the creation of reliefs or tips, in particular having a substantially pyramidal shape.

[0064] By structuring is meant herein at least one layer of uneven thickness, which therefore creates unevenness in the layer itself. For example, a layer of particles can be used in this way, as it achieves an inhomogeneity in the plane on which the particles are deposited, as shown in Figures 31 and 32. Another example is given by reliefs obtained by photolithography, as in the case shown in figure 42. The height of the reliefs of the structuring of the cathode and / or the anode is between 10 nm to 10 microns, preferably between 100 nm to 5 microns.

[0065] It is also preferable that the difference in height between one relief and another one in a device does not exceed 10% of the thickness of the dielectric (or of the first layer of dielectric, in case there are intermediate braking and re-emission layers, as explained below). The ratio of the maximum height of the reliefs of a structured electrode to the thickness of the dielectric is between 0.5 and 4000, preferably between 0.25 and 200.

[0066] In the case of the intermediate braking (and re-emission) sites, the ratio of the thickness of the braking particle to the amplitude of the empty zone surrounding it, is comprised between 0.1 and 200, preferably between 0.2 and 10. See, for example, figure 43, wherein a film of sputtered gold has empty areas of 10-20 nm in width and filled areas of comparable lateral extension, with a thickness of the order of a few nanometers, therefore a ratio of about 0.25-0.5. In addition, for the intermediate braking sites, it is preferable to limit the thickness of solid (metallic) zones to a few nanometers, for thicknesses comprised between 3 and 100 nm.

[0067] Note that, even in the absence of nanoparticles filled in the dielectric layer 4, the electrons will still encounter braking / scattering sites on their way between the cathode and the anode. In fact, the probability of passage through the dielectric due to tunneling effect of layers thicker than one or a few nanometers is low, and therefore the path of the electrons within the dielectric is characterized by distinguished by accelerations and brakings.

[0068] In this sense, Figures 3 and 4 are therefore illustrative of a device having a dielectric layer 4 comprising - in general - braking sites 6. Such braking sites may be metal nanoparticles or films within the dielectric, or be determined by the same lattice structure, crystalline or amorphous, of the dielectric (in the case of crystalline dielectrics, the braking sites could include possible defects in the crystalline or semicrystalline structure, or, in the case of amorphous dielectrics, any inhomogeneities or coordination defects). As it can be seen from the above indicated examples (as well as in the examples indicated thereafter), the dielectrics considered herein comprise solid materials.

[0069] As will be seen hereinafter (see the Test section), the nanoparticles or the films represent an advantageous choice as they provide more effective braking sites, for the purpose of the thrust generation effect, compared to a random interaction of electrons with the lattice, crystalline or amorphous, structure of the dielectric.

[0070] A possible realization of the aforementioned braking sites in a dielectric can be obtained by the deposition of micro- or nano-particles on a layer of dielectric material interposed between the two electrodes, or on layers of dielectric material superimposed in succession between the two electrodes, as shown for example in the exploded view of figure 5.

[0071] In said figure, reference numerals 10 and 11 designate two end support layers, formed in an electrically insulating material (for example a polymer), equipped with a surface micro- or nano-structuring Ns, for example consisting of a series of reliefs or substantially pyramidal tips. A metallic film, for example gold, is deposited on the structure Ns, which obtains the cathode 2 and / or the anode 3, respectively. The film can have a thickness of between 10 nm and 10 micrometers, preferably of between 50 and 500 nm (these thicknesses can also be used in the other embodiments described herein). Figure 5 shows the structuring Ns of the layer 11 only, to which the metal film that obtains the cathode 2 is superimposed, taking for granted that the layer 10 has a similar structure and a metal film that obtains the anode 3, having a similar thickness. Reference 12 and 13 designate two additional intermediate layers of electrically insulating material, for example having a thickness of between 100 nm and 30 micrometres, preferably of between 1 and 15 micrometres (these thicknesses can also be used in the other embodiments described here), intended to be attached to the layers 10 and 11. As a result of the overlapping, the layers 12 and 13 will be provided, on their respective faces facing the anode 3 or the cathode 2, with a surface negative micro- or nano- structure Ns', i.e. having a shape substantially complementary to the shape of the layers 10 and 11, respectively (also in this case the negative structuring Ns' of the layer 12 is visible, taking for granted that the layer 13 has a similar negative structure).

[0072] It should be noted that, in principle, the layers 10 and 11 could also be free of the structuring Ns, and that the micro- or nano-structured form of the electrodes 2, 3 could be obtained by suitable deposition of the metal films that constitute them.

[0073] Reference numerals 14 and 15 indicate two additional intermediate layers of electrically insulating material, preferably the same material as layers 12, and 13 and having substantially similar thickness, wherein between each of the pairs of insulating layers 12 and 14, 14 and 15, 15 and 13, there are the micro- or metal nano-particles 6 (schematized in the form of spheres only for the purpose of greater clarity) that create the above-mentioned intermediate braking sites for the electrons. In the example depicted, the particles 6 are arranged in a substantially orderly manner, but in other embodiments their arrangement may be random. A device 1 assembled in this way is shown in figure 6.

[0074] An ordered arrangement of particles 6 as exemplified in Figures 5-6 can be achieved by using, for example starting from the side of the cathode 2, successive depositions of dielectric layers on which thin metal layers or nano-particles are deposited, for example in gold, wherein the dielectric layers are surface-structured by any micro- or nano-working technique, such as photolithography, deposition by thermal evaporation through shadow mask, lift off. Once the surface structure has been created, the nano-particles or the metal layer are deposited thereon, and then the subsequent dielectric layer, for example by spin coating or PVD (Physical Vapour Deposition), PECVD (Plasma Enhanced Chemical Vapour Deposition), ALD (Atomic Layer Deposition) type deposition. The sequence continues up to the anode, which can also be smooth, if the last dielectric layer is not micro- or nano- structured with tips or other types of reliefs. In general, a metal layer is deposited onto the structured dielectric using any of the above mentioned thin-film techniques. Alternatively, it is possible to deposit a polymer highly charged with conductive particles in the percolation state by spin coating.

[0075] On the other hand, an un ordered arrangement of braking sites (such as micro- or nano-particles 6, for example) can be obtained without providing the structuring steps: for example, a simple deposition of an ultra-thin metal film, for example in gold, by sputtering, generates per se nano-particles with a random arrangement.

[0076] As exemplified in figure 7, in various embodiments, the structured layers (here designated by 10 and 11) on which the metal films obtaining the electrodes 3 and 2, respectively, are deposited, and the interposed dielectric layer or layers, which obtains the insulating layer 4, can be made such that the particles 6 are substantially aligned at respective tips of the structured layers, and hence to respective tips of the electrodes 2 and 3.

[0077] As mentioned, in various embodiments, the device 1 comprises at least one temperature conditioning arrangement.

[0078] In various preferential embodiments, including that in Figures 5-6, in operation, the device is subjected to heating, for example by having heating means associated or integrated thereto, such as a planar heater, most preferably of the resistive type. In various preferential embodiments, at least one layer of electrically insulating but thermally conductive material, for example a suitable silicone, is arranged between the heating means and the cathode. The heating arrangement preferably includes an active temperature control system. By the way, if the application is intended in an environment where the temperature may exceed 60°C, it is preferable - in addition to as an alternative - to provide a cooling or refreshing system, such as a planar Peltier junction,.

[0079] The heating means and at the least one layer of electrically insulating material are not shown in Figures 5-6, but an example of such an embodiment can be found in figures 8-11, relating to an alternative structure of the device 1, which integrates a planar resistive heater.

[0080] In figure 8 the device is shown in exploded view. In this figure, reference numeral 10' indicates a layer of electrically insulating material, for example 2 mm thick, on the upper surface of which there is a metal film, for example in gold or other metal, which obtains the anode 3. In this embodiment, therefore, the anode 3 is not structured, but is substantially flat. Reference numeral 11' indicates a layer of electrically insulating material, structured in a similar way to the layer 11 of figures 5-6, on which a corresponding metal film, for example in gold, is provided, which obtains the cathode 2. Between the two electrodes 2, 3 there is a series of intermediate layers 14' of electrically insulating material, for example similar to layer 14 of figures 5-6, provided on one face with corresponding micro- or nanoparticles 6, for example also made of gold. 15' indicates an additional intermediate layer of electrically insulating material, for example similar to layer 13 of figures 5-6, which is preferably (but not necessarily) free of particles 6.

[0081] Reference numeral 16 indicates a layer of electrically insulating but thermally conductive material, for example consisting of one or more layers of silicone, while reference numeral 17 indicates a resistive heater, here in the form of a coil. The thickness of the layer or layers 16 depends on the power of the heater 17, and can be approximately between 0.1 and 2 mm. Finally, with reference numeral 18, a support layer of electrically insulating material is indicated, with the heater 17 which is therefore interposed between the layers 16 and 18.

[0082] In various embodiments, the heater 17 can also be placed on the side of the anode 3, separated therefrom by an electrically insulating but thermally conductive layer similar to layer 16.

[0083] The block TCS schematically represents an active temperature control system, of any known design, configured to control the achievement of the working temperature of the conditioning arrangement, herein of the heater 17, and keep this temperature constant.

[0084] The device of figure 8 is shown in the assembled condition in figure 9 and in the corresponding detail of figure 10.

[0085] From figure 11 it is possible to note how, in various embodiments, the above- mentioned intermediate braking sites can be obtained in the form of micro- or nanosurface reliefs, for example in gold, on one face of each dielectric layer 14', for example with a periodic structure similar to a one-dimensional photonic crystal.

[0086] Figures 12 and 13 show another example of a device 1 equipped with a heater, of a different nature. In these figures, reference numerals 20 and 21 designates two electrodes of the heater 17, which consists of an electrically insulating sheet 22 (for example PET), but with a coating of an electrically resistive material (for example ITO) on the side thereof facing the electrodes 20 and 21. TCS designates the block representative of the aforementioned temperature control system.

[0087] Reference numeral 23 designates at least one electrical insulation layer, for example made of thermally conductive silicone, and reference numeral 24 designates at least one layer of dielectric material between the cathode 2 and the anode 3, for example having a thickness of between 0.1 and 50 micrometers, preferably of between 8 and 25 micrometers. Also in this case, two support layers 25 and 26 of electrically insulating material can be used for this purpose, with a micro- or nano-surface structure onto which the film or metal coating that obtains the cathode or anode, respectively, is affixed. Also in this case, the intermediate dielectric layer 24 will present on its two opposite major faces, following the superposition of layers 24-26, a negative micro- or nano- structuring Ns', substantially complementary to that of layers 25 and 26. The braking sites can be represented here by interactions of electrons with the dielectric structure (be it crystalline, semi-crystalline or amorphous, depending on the dielectric used) of layer 24 or by a metal film or metal nanoparticles included in the layer 24 (this layer 24 can be formed by two layers with the metal film or particles interposed).

[0088] Figures 8-11 and 12-13 exemplify the presence of a built-in heater in the device 1, but this is not an essential feature. As mentioned, in fact, in various embodiments, if device 1 is intended to be mounted in a position where too high temperatures can still be reached, for example above 90°C, the heater can be omitted, and it is on the contrary appropriate to provide a cooling arrangement, for example at least one element with Peltier junctions or other electric cooling element capable of removing excess heat. In the case of aeronautical or space applications, it may be appropriate to introduce a shield or similar protective element to shield the device 1 from direct solar radiation. For example, a gold-coated Kapton sheet can be used for this purpose, kept at a certain distance from the device 1, preferably a distance of 0.5 to 20 mm.

[0089] A device as shown in the figures can be provided with one or two heaters located at the cathode 2 and / or the anode 3.

[0090] In various embodiments, wherein the dielectric between the electrodes 2, 3 employs vacuum, a series of braking sites is preferably provided. A principle diagram in this sense is shown in figure 14, where reference numerals 2, 3 and 17 are used to schematize the aforementioned cathode, anode and heater, with their temperature control system TCS. On the other hand, reference numerals 30 are used to indicate the intermediate braking sites, which have been suitably configured.

[0091] Even in embodiments of this type, the electron emission from the cathode 2 is preferentially facilitated by heating thereof and by its micro- or nano-structuring, which facilitates the formation of electron aggregates.

[0092] In various embodiments, the intermediate braking sites 30, which can be maintained at a specific potential or else floating, may comprise thin films of dielectric material supported by frames obtained by micromachining.

[0093] In figures 15 and 16 there is exemplified a perforated frame 31 of electrically insulating material, i.e., a matrix of frames 32, each having a quadrangular profile, supporting at least one porous thin film, for example of between 1 and 20 micrometres thick, which in turn supports respective metal braking sites, for example in the form of micro- or nano-particles.

[0094] Such porous thin films can be made, for example, by means of anodic porous alumina (APA) having pores ordered in a substantially hexagonal structure and perpendicular to the film itself, or silicon oxidized in order to obtain nano-porous SiO2, or even a polymer whose porosity has been obtained by any known method.

[0095] Figure 17 is a schematic section of a portion of a frame 31, i.e., two adjacent frames 32. On the underside, the frames 32 support a respective nano-porous thin film 33, which in turn supports the braking sites, for example consisting of micro- or nano-metal particles 6, while on the upper side they support a track 22 belonging to a laminar heater 17. A resistive heater can therefore be supported by the frame 31, i.e. by the matrix of frames 32; in such a case, the material 31 of the frame may be substantially thermally conductive.

[0096] Figures 18-19 show a series of frames of the type indicated above with 31, superimposed between a cathode 2 and an anode 3. From the detail of figure 19 it can be noticed how the frames 32 have the function of supporting thin nano-porous layers 33, for example having a thickness of between 100 nm and 10 micrometers, which in turn support the metal nano-particles (not highlighted in the figure), having the function of intermediate braking and re-emission sites for the electrons. The function of the porosity of the substrate, i.e., of the matrix of frames 32 and the porous film 33, is not to create additional braking sites that could be less efficient than the metal ones represented by the nano-particles.

[0097] Figure 20 shows, with a view similar to that of figure 17, a possible variant embodiment, according to which the nano-porous film 33 supports respective metal nano-particles 6 on its two opposite major faces, in order to increase the number and / or the density of the braking and re-emission sites for the electrons.

[0098] Both in the case of a solid dielectric or vacuum, it is important to note that the electrons should not be considered as single particles interacting with the matter but as aggregates of electrons, as observed by Kenneth R. Shoulder (see, for example, US 5054046 A, "Method of and apparatus for production and manipulation of high density charge"). The presence of the tips on the cathode and the braking sites facilitates the formation of the aforementioned electron aggregates, which can have a diameter area comprised between 0.5 and 50 micrometers. Such phenomena of electronic collective coherence can disappear due to excessively high temperatures or excessively high currents, as will be seen later from the experimental data.

[0099] Figures 21-23 illustrate a further possible embodiment of a device 1, where reference numeral 40 is used to indicate dielectric layers which are micro- or nanostructured on a face only, i.e. provided with tips (for example substantially pyramidal), which layers 40 are superimposed in contact with each other, so that the structuring of one layer 40 is directed towards the unstructured face of the next layer 40. In this case a metal film 6' is provided on the surface of the layers 40 provided with the tips. On the other hand, reference numeral 42 designates an unstructured top dielectric layer, with the anode 3 consisting of a smooth layer of metal deposited on the face of the layer 42 opposite to the cathode 2. The cathode 2 consists of a metal film deposited on the tips of the lower structured layer 40.

[0100] In solutions of this type, the conductive layers 6' can operate as intermediate sites of electronic braking and re-emission, in particular by means of their respective tips, which are preferably aligned with each other for the various layers 40.

[0101] As already mentioned, in embodiments of this type, as well as in those described above, the tips obtained by surface structuring preferably have a substantially pyramidal shape.

[0102] A further principle diagram of a device 1 is shown in figure 23, where with 2, 3 and 17 the aforementioned cathode, anode and heater are schematized. Reference numeral 40 is used to indicate layers similar to those of figures 21 and 22, having a structured face on which a metal film 6' is deposited, that serves as an intermediate braking and re-emission site. The various layers 40 can be separated by an electrically insulating layer or by vacuum, so that the cathode and the anode are electrically isolated. The number of layers 40 can of course vary from the case exemplified.

[0103] Figures 24 and 25 schematically show a further possible simplified structure of a device 1, in which the slowing and re-emission functions of the intermediate sites are disjointed. In the example shown in these figures, the device 1 comprises a lower dielectric layer 45 structured on one of its faces, on which a thin metal film is deposited, which obtains the cathode 2, for example of between 50 nm and 10 micrometres thick. Above the cathode 2 there is an additional dielectric layer 46 which, on its face opposite to layer 45, is structured in a similar way to the latter, and has a corresponding metal film 6', for example having a thickness of between 5 and 100 nm, while the opposite face of the same layer 46 (i.e., the one facing the cathode 2) is preferably flat and has a thin metal coating or film 6", for example of between 5 and 100 nm thick. Finally, on top of layer 46 there is an additional dielectric layer 47, which has - on its face facing the layer 46 - a thin metal coating or film that obtains the anode 3.

[0104] In embodiments of this type, the film 6" acts as an intermediate slowing site for the electrons, while the film 6" (or the micro- or nano-particles that replace it) acts as an intermediate site of re-emission, in particular at the micro- or nano-tips of the surface structuring of the layer 46.

[0105] In solutions of this type, the various layers 45-47 are spaced apart, so that the insulation between the cathode and the anode also includes vacuum and / or an insulating or dielectric layer. The number of layers 46 can of course vary from the case exemplified, and the device can be equipped with a heater at least on the cathode side, similar to what has already been described above.

[0106] The material that obtains at least the layer 46, as an alternative to a pure dielectric with a film 6', can be a plastic filled with carbon black, or carbon nanotubes, or other electrically conductive charge.

[0107] Test

[0108] The experimentation was carried out with devices using dielectrics in the form of polymeric films, mainly PE, PP and Polymide (Kapton) having or not nanoparticles providing the discussed braking sites.

[0109] The structure of the devices whose experimental results are presented is illustrated in figures 26 and 27. A rigid electrically insulating support 26 provides support to the cathode 2, to present a pyramidal micro-structuring as already indicated above (of the type shown in figure 38). Two dielectric films 14 and 15 (Kapton) with a thickness of about 7.6 microns and 12.7 microns, respectively, are superimposed on the structured cathode 2. The anode 3 is smooth, i.e., not microstructured, and is obtained by sputtering gold on the second film of Kapton 15, on its face opposite to the cathode 2, with a thickness of about 100 nm. An additional electrically insulating layer 25, preferably elastic, covers the anode 3. The device 1 of which the experimental results are presented also implements a heater, placed on the side of the anode 3. In particular, an ITO heater 17 in the form of a coil is supplied on a plastic support 22 (made of PET) and separated from the layer 25 by a polyethylene layer 23 having a thickness of approximately 20 micrometres.

[0110] The floor area of the device, i.e., of the constituent layers, was about 14 cm2.

[0111] Tests were carried out to verify the direction of the force obtained, reversing the direction of the device with respect to the load cell used for the measurement: the force was always measured in the direction of the anode, as predicted by the theoretical model.

[0112] Any contributions of an electrostatic nature to the measured force are excluded by testing in the same experimental set-up devices with an area greater than that of the test device and with a dielectric thickness such as to prevent passage of current at the same applied voltage. Two other circumstances lead to the exclusion of electrostatic forces: the reversal of force by reversing the spatial orientation of the device, and the dependence of the force on temperature. To corroborate this last point, the capacity of the device at different temperatures was measured. The measured capacity was substantially constant over the temperature range of the device's use.

[0113] Numerous tests have been carried out, of which Tables 1 and 2 below show by way of example a sequence of four switch-ons, two at room temperature (23 °C) and two at 60°C (with active heater), carried out alternately (23° -60° -23° -60°).

[0114] The device's temperature T was monitored using a Fluke thermal imaging camera, model TiS75. In all cases, before switching on, thermostating of the system was waited, so as not to have thermal drifts. The voltage V was applied for between 10 and 30 seconds, during which time the average force F generated remained stable. The current I was monitored by measuring voltage drop on a resistance in series of a value of 1 Mohm. Voltage I on the shunt resistance was measured using an instrument Agilent 34401 A. The high voltage V was supplied by a power supply Keithley 2290E-S. The force F was measured with a load cell and read using ad hoc software: the system was calibrated for comparison using a scale Ohaus PA214C. The accuracy of the measurement can be conservatively estimated with +-1 mg. The current values should be understood as an estimate because, for currents of the order of tens of nA, the internal resistance of the measuring instrument and the ambient noise can affect the accuracy of the measurement.

[0115] Table 1 Table 2

[0116] As can be seen from the results, the device produces a higher force when the heater is switched on, operating at a temperature T around 60°C and a voltage of between 2 and 2.5 kV. Having brought the device to a much higher voltage V and current I, the second test cycle has a slightly lower performance than the first one. If, on the other hand, the range of 108V / m is not significantly exceeded (approximately no more than 30%, preferably no more than 10%), the behaviour of the device is repeatable and does not show degradation.

[0117] The data of the force F generated as a function of the current I are shown in figures 28 and 29 in the form of a graph, grouping tests I and II for each temperature. Force values are given in Newtons.

[0118] The linear trends, for which an interpretation is postponed to the next section, correctly predict the phenomenon up to about 35 nA in tests at 23 °C, while for tests at 60°C the saturation effect occurs earlier, around 20 nA, but the resulting forces are higher at the same current, if below the critical current.

[0119] Figure 30 also shows in the form of a graph the dependence of the force F on the voltage V. As can be seen, with the same voltage, greater force is obtained at a higher temperature, consistent with the model discussed below.

[0120] In a test device such as the one described above (figures 26-27), electron braking occurs primarily at the anode 3 and in the electron interactions with the dielectric structure in the dielectric layers 14 and 15 between the anode and the cathode. As discussed above, however, metal nano-particles can be added to the dielectric layers 14, 15 in order to provide additional braking and re-emission sites.

[0121] For this purpose, tests were also carried out with a device as described in relation to figures 26 and 27 , but having braking sites provided by micro- or nanoparticles of aluminium formed between the two layers of Kapton 14 and 15. Figures 31 and 32 illustrate a layer of Kapton (14) on which aluminium nanoparticles (6) are deposited that provide the braking and re-emission sites. The tests were carried out at a constant temperature of 67°C, i.e. with the heater 17 switched on.

[0122] Table 3 below, and the corresponding graph shown in figure 33, compare the experimental results obtained with devices with and without nanoparticles provided between the two Kapton films 14 and 15 of figures 26-27. The thrust generated is measured as a function of the voltage applied between the anode and the cathode and is expressed in milligrams.

[0123] From the graph of figure 33 it is evident that the addition of nanoparticles 6 providing electronic braking and re-emission sites results in a significantly greater force.

[0124] Table 3

[0125] Operating Principle

[0126] It is known that facing conductors, for example in the configuration of electrodes with flat and parallel faces, attract each other due to the effect of imbalance of the vacuum pressure between the inside and outside of the structure. This effect is known as the "Casimir effect" and has been experimentally verified. In this context and in this exposition, "vacuum" is to be understood as the space in which virtual particles and antiparticles are continuously created and annihilated, defined as a quantum vacuum. In the currently accepted view of particle physics, the various classes of particles that exist are the product of the quantization of specific fields. In this discussion, among the constituents of the quantum vacuum, only the electromagnetic field and the respective particles, i.e. the photons, the bosons that mediate the electromagnetic interactions between charged particles, are considered. The charged particles we are dealing with here are, as we have seen, electrons and positive charges due to the positive nuclei of the crystal lattice of the anode. However, the function of the latter is only to attract electrons, and will therefore not be described in detail.

[0127] The description of quantum vacuum used herein is therefore distinguished by the presence of the virtual photons, while the possible effect of all other fields is neglected.

[0128] The expression of the (attractive) force due to the Casimir effect is as follows hcji2A

[0129] F~ 240D4

[0130] Where "h" is Planck's constant divided by 2TT, and "c" is the speed of light in a vacuum, A is the area of the facing conductors, D is the distance between them. The Casimir effect described by the above equation can be defined as the static Casimir effect.

[0131] In this discussion, the concept of dynamic Casimir effect from electron acceleration is introduced.

[0132] Other types of dynamic Casimir effect are known, obtained for example by varying the dielectric constant of the medium, the conductivity of the conductors, the reciprocal motion of the conductors, both the distance and the rotation.

[0133] For an overview of the dynamic Casimir effect, see, for example, Dodonov, V. "Fifty Years of the Dynamical Casimir Effect" Physics 2020, 2, 67-104.

[0134] The electrons in the facing conductors are subjected to the force mediated by the virtual photons of the vacuum, both the one between the facing electrodes and the one outside them. However, the pressure of the virtual photon gas inside, i.e. between the two electrodes, is lower with respect the pressure outside, as not all modes of photon oscillation are allowed inside. The only photons allowed inside the cavity are those with

[0135] 2D

[0136] 1~~ where " " is the wavelength of the photon, "D" is the distance between the conductive plates, and "N" is a non-zero positive integer. The calculation of the energy density of the vacuum both inside and outside the two conductors turns out to be delicate as it easily leads to divergences. However, the difference in energy is finite and allows for calculating the force whose expression is given above.

[0137] If an electronic current is generated between the two conductors by applying a certain voltage (of the order of kV), an initial acceleration of the electrons from the cathode to the anode is obtained, and subsequently an even more significant deceleration when the electrons reach the anode.

[0138] The acceleration from the cathode to the anode is given by the relation eV a = - — meD as it is obtained with simple algebraic steps, where "a" is the acceleration, "e" the charge of the electron, "V" the applied voltage, "me" the mass of the electron, and "D" is the distance between the electrodes between which there may be a dielectric or a vacuum. A gas should be avoided, the ionization of which would cause other effects not relevant for the device object of the invention (the two conductors facing each other will tend to attract each other by virtue of the electrostatic attraction, but this obvious effect is not of interest in the present discussion, for the reasons explained in the previous experimental part, and due to the fact that the electrostatic effect is substantially null for the purpose of generating a thrust in a given direction).

[0139] In general, it is necessary to apply a field of the order of 108V / m to obtain field emission. For example, a dielectric thickness of 20 micrometers will cause there to be a threshold voltage of about 2 kV to trigger the phenomena described.

[0140] The deceleration is similarly given by where "f" represents the braking length of the electrons. f is the depth to which the electrons penetrate the anode (or the intermediate braking sites) during braking until they assume a kinetic energy close to that of the other electrons of the electrode. The same goes for the intermediate braking sites.

[0141] The value of f depends not only on the material and the shape and thickness of the anode, but also on the applied voltage. Braking at the anode or at the braking sites occurs in the first atomic layers.

[0142] A body subject to an acceleration undergoes in the opposite direction to acceleration a reduction of the event horizon whose modulus is (defined by some authors as Rindler's horizon, hence the choice of the letter R) c2

[0143] Re = ' - a where "c" is the speed of light in a vacuum and "a" is acceleration.

[0144] The concept of Rindler's horizon (see, for example, Rindler, W. (1960). "Hyperbolic Motion in Curved Space Time". Physical Review. 119 (6): 2082- 2089) describes the effect by which any accelerated body undergoes a contraction, in the opposite direction to that of acceleration, of the points in space with which it can interact. For the relatively small accelerations due to the electric field between the electrodes, the Re value is too large to have measurable practical implications.

[0145] On the contrary, the great acceleration due to braking in a very confined space, indicatively comprised between 10'8and 10'12m depending on the energy of the electron, when it impacts on the braking sites or on the anode, can have appreciable effects.

[0146] In order to get an estimate, by combining the above equations, it is immediately obtained for the electrons during the acceleration phase between the cathode and the anode, in the absence of an intervening dielectric. With / ?e(C) it is indicated the event horizon experienced by electrons during the acceleration phase from the cathode to the anode.

[0147] For example, for a voltage of 4 kV applied over a distance D of 20 micrometers, the value of Re is about 2.56 mm.

[0148] Although this value is very small compared to cosmological scales, it is, as mentioned, still too large to have measurable effects. If, on the other hand, one takes into account the braking of the electrons themselves when they reach the anode, the situation changes.

[0149] In general, due to Coulomb repulsion, the charge on a conductor is distributed over the surface. Specifically, the atoms that make up the anode are not all, on average, unbalanced towards a positive charge of the same value, but the positive charge is distributed on the surface, in the first atomic layers, the most superficial ones. The result is very fast braking.

[0150] During braking on the anode, the electrons therefore see an event horizon of where the dependence of f on the applied voltage V is now explicit. "ReAN) " indicates the length of the event horizon that forms beyond the anode during braking.

[0151] From the point of view of electrons, there is therefore an imbalance between the event horizon in the direction of the anode and that in the direction of the cathode, i.e. between the part of space with which it is possible to interact beyond the anode and that with which it is possible to interact between the anode and the cathode and beyond the cathode.

[0152] The electrons thence undergo a dynamic Casimir effect and are subjected to a net force in the direction of the anode.

[0153] In figure 34, eacc e eaec indicate an electron in the acceleration phase and an electron in the braking phase on the anode 2, respectively, a(f) indicates the braking acceleration that produces the corresponding event horizon Re(AN), Re(C) indicates the event horizon experienced by the electrons during the cathode-to-anode acceleration phase.

[0154] Vacuum pressure on accelerated charges passing through a dielectric under the action of an electric field.

[0155] As seen above, an electron that is accelerated experiences a contraction of the event horizon (or Rindler horizon) in the opposite direction to that of the acceleration. where "c" is the speed of light in a vacuum and "a" is the acceleration.

[0156] Since the space is pervaded by virtual photons to which a certain wavelength A can be associated, for an accelerated charge there will be a maximum wavelength with which it can interact λMAX= 2Rein the direction of motion, in the opposite direction to that of acceleration.

[0157] The acceleration of the electric field is given by as can be obtained with simple algebraic steps, where a is the acceleration, e is the charge of the electron, V the applied voltage, methe mass of the electron, D is the distance between the electrodes between which there may be a dielectric or a vacuum.

[0158] The deceleration is similarly given by where f represents the braking length of the electrons. f is the depth to which the electrons penetrate the anode (or the intermediate braking sites in the dielectric) during braking, until they take on a kinetic energy close to that of the other electrons in the electrode.

[0159] The density distribution of the virtual photons as a function of temperature and frequency is given by

[0160] The vacuum pressure can be calculated by integrating the above expression on all frequencies vcit is a suitable cut-off frequency whose actual value will not be relevant in this discussion, as will be clearer in the next steps (normally the Compton frequency of the electron is used as the cut-off frequency).

[0161] The accelerated particle will then be able to interact with all photons in the direction and orientation (positive or negative direction) of acceleration, but only with those with a wavelength less thanMAX=2R in the same direction and in the opposite orientation (positive or negative direction).

[0162] Moving on to frequencies, during the deceleration phase the electron will only be able to interact with virtual photons having a frequency greater than

[0163] There will then be an imbalance of the vacuum pressure acting on the electron given by

[0164] Limiting ourselves to the case of low frequencies, the distribution approximates with

[0165] The expression is valid in the approximation of photons with energy hv « kT, as in the case of interest and as it occurs immediately by developing in Taylor series the exponential function that appears in .p(v, T) non-approximated.

[0166] Integration is trivial

[0167] Therefore, taking into account the value of vmincalculated using the expressions already mentioned that link it to the event horizon, we obtain

[0168] An additional factor of division by 3 has been inserted, which takes into account the fact that the observed phenomenon occurs only in one direction, and therefore the pressure to which the electron is actually subjected must be divided over the degrees of freedom. The calculation of the pressure in the acceleration phase is clearly analogous but in the orientation (positive or negative direction) and is

[0169] The resulting pressure is therefore

[0170] The second side in square brackets, which accounts for the pressure towards the cathode, is quantitatively much smaller than the first side (pressure towards the anode) and will generally be omitted.

[0171] In the case of taking into account the fact that the electrons passing through the dielectric make many small jumps made up of accelerations and abrupt braking, the value of V applied between the electrodes must be divided by the number of jumps n.

[0172] Depending on the energy of the incident electrons and the material of which the anode and the dielectric are made, the penetration fin the collisions ranges from fractions of a nanometer to tens or hundreds of nanometers.

[0173] As discussed in relation to Table 4 presented in the following section "Estimation of the value of the braking or penetration distance in the anode f(V)", the ratio f(V) / V can be, as a first approximation, considered constant in the range of the voltages of interest. The contribution to the pressure due to the single electron therefore depends only on the temperature T. It can therefore be said that the total thrust, i.e. generated by all the electrons passing through the dielectric, is in the first approximation linearly dependent on the current.

[0174] Under conditions of high acceleration, the momentum conservation requires that an interaction between the momentum of the material particles and space takes place, in particular by means of the virtual photons in the current description of the quantum vacuum. Momentum conservation results in

[0175] PT=Pd+ Pvwhere "PT" is the total momentum, "Pd" is the device momentum, and "Pv" is the vacuum momentum. The initial momentum is zero, and therefore the final impulse PT= 0 must also be zero, and so Pd= — Pv. The momentum that the electrons transferred to the virtual photons in the vacuum results in a net push on the device.

[0176] Note that, in evaluating the conservation of momentum, one must take into account the contribution attributable to fields not considered in the previous discussion, possibly massless. Among the massless fields that are included in the momentum balance equations is the electromagnetic field (see, for example, David J. Griffiths, “Resource Letter EM-1 : Electromagnetic Momentum” in Am. J. Phys. 80, 7, 2012, for a discussion of the momentum of the electromagnetic field). In the momentum conservation equations one must therefore consider (at least) the momentum of the photons emitted in the acceleration and deceleration processes of the electrons in their path between the cathode and the anode and in the asymmetry of the interaction with the electromagnetic field in the deceleration and acceleration processes, as described above.

[0177] The above discussion aims to give a qualitative description of a phenomenon whose nature is still a source of debate in the scientific community. In fact, the possibility of exchanging a momentum by exploiting the vacuum is, although a possibility with interesting applications, still to be clarified from a theoretical point of view.

[0178] A more rigorous and in-depth treatment of the underlying theory is beyond the aims of this description, and will be provided elsewhere.

[0179] For further information on the issue, the following documents (and the references cited therein) can be consulted:

[0180] "Frontiers of propulsion science, " Marc G. Millis and Eric W. Davis, American Institute of Aeronautics and Astronautics, 2009

[0181] "Quantum vacuum contribution to the momentum of dielectric media", A. Feigel, Phys. Rev. Lett. 92 (2004) 020404,

[0182] "Lorentz-invariant description of the Feigel Process for the Extraction of Momentum from a vacuum", ESA report available at https: / / www.esa.int / gsp / ACT / doc / ARI / ARI%20Studv%20Report / ACT-RPT-

[0183] PHY-ARI-041201 -Koln Feigel.pdf, “Momentum Transfer between Quantum Vacuum and Anisotropic Medium”, Jian Qi Shen, Progress of Theoretical Physics, Vol. 119, No. 3, March 2008.

[0184] In the last reference cited, note in particular how the generation of an anisotropy can generate the type of momentum transmission from ordinary matter to vacuum. Although in the dissertation of J. Qi Shen different conditions are considered from those considered herein, this reference gives foundation to a mechanism of momentum exchange with the vacuum at the basis of the operation of a device as described here. As further references, especially concerning the application of massless thrust generating devices in spacecraft and considerations on the conservation of momentum and energy, the following documents can be consulted for example:

[0185] “Propulsion Through Electromagnetic Self- Sustained Acceleration”, V. Petkov, arXiv:physics / 9906059,

[0186] “Inertial frames and breakthrough propulsion physics”, M. G. Millis, Acta Astronautica 138 (2017) 85-94, and

[0187] “Spacedrives and Conservation Laws”, R. Sedwick et al., JOURNAL OF SPACECRAFT AND ROCKETS Vol. 55, No. 4, July-August 2018.

[0188] The references cited testify an intense research activity in devices whose operation can be traced back to the operation of a device as described herein, in particular, of a device capable of exploiting the interaction between matter and vacuum and therefore based on the possibility of exploiting the energy of the vacuum (see, e.g., M. G. Millis, chapter 5 of the above reference for an estimate of this energy).

[0189] From the previous discussion it is clear that the greatest contribution to the thrust of the device comes from the braking of the electrons, and not so much from their acceleration. In fact, in the devices obtained by the Applicant, it is precisely the contribution due to the braking of electrons that is exploited to obtain a thrust.

[0190] In the case of collisions (and therefore a succession of accelerations and decelerations) the electrons will not release all their energy in a single solution when they reach the anode, but will release it in a succession of impact processes, which take place in a space of the order of the nanometer, inside the dielectric or the braking sites. Each braking will give rise to a thrust due to the dynamic Casimir effect from electronic acceleration, which in general will involve a multitude of particles, both material and virtual with a reciprocal exchange of momentum.

[0191] The device according to the invention finds a particularly advantageous application in the field of space propulsion, given that it allows to obtain an electric propulsion without mass emission.

[0192] Space propulsion is based, regardless of the medium used, on the principle of conservation of momentum, classically defined as p=mv, where "m" is the mass of the object and v its speed. If, for convenience, a reference system is chosen in which the satellite is initially stationary, the total initial momentum will be zero, PT=0. By operating any mass emission propulsion system (chemical rockets, electric propulsion, etc.) k particles of mass m are ejected at speed v. Applying the conservation of the momentum, the final total momentum must also be zero, so

[0193] Ps= —kmv and so the satellite will acquire a velocity vs=Ps / M where M is the mass of the satellite.

[0194] If one wants to create a propulsion system without mass emission, it is therefore necessary to transfer the momentum differently. In the atmosphere, air can be used as a propellant, as do propeller planes or jets in which exhaust gases are expelled at great speed. In the absence of atmosphere, however, it can be advantageous to exploit the characteristics of the vacuum. Even in the absence of matter in a vacuum processes (called virtual) occur, characterized by the creation / annihilation of particles and corresponding antiparticles. Normally this particle gas (quantum vacuum) pervades the space in a homogeneous and isotropic way and its presence is therefore undetectable. However, it is possible to create the conditions to cause an anisotropy of the quantum vacuum, as happens for example in the Casimir effect. The device that is the subject of the invention transfers part of the electron momentum to the virtual photons of the vacuum, obtaining a net thrust without mass emission.

[0195] Figure 35 exemplifies a possible positioning of some devices 1 on a satellite, schematized by a cube 100. In the example, the satellite 100 is equipped with a device 1 on each of its visible sides (the same number can be provided on the non- visible faces). According to the case of figure 36, on the other hand, several devices 1 are provided on the same side of the satellite 100, for example to facilitate rotational movements thereof.

[0196] Additional Considerations

[0197] Estimation of the value of the braking distance or penetration into the anode f(V)

[0198] Figure 37 shows a graph from the paper "Imaging low -dimensional nanostructures by very low voltage scanning electron microscopy: ultra-shallow topography and depth-tunable material contrast", named Zarraoa, L., Gonzalez, M.U. & Paulo, A.S., Sci Rep 9, 16263 (2019) (https: / / doi.org / 10.1038 / s41598-019- 52690-9). The graph shows the braking, i.e., the distance travelled in a gold or silicon anode, respectively, before losing almost all kinetic energy, for different energies of the incident electrons.

[0199] Using the data made available by the aforementioned article, the data relating to a gold anode are reported in Table 4 below. Table 4 also shows the ratio of anode penetration to applied voltage, which must be minimal to maximize strength.

[0200] TABLE 4

[0201] On the basis of these data, it seems preferable, for the application proposed herein, to use low voltages, in general not exceeding 10 kV, unless multiple braking sites are used.

[0202] The trend of the available data for voltages below 1000 V is almost linear. To estimate the penetration depth for voltages below 100 V, the relation f(V)=r V with r=0.005 nm / V is used.

[0203] Presence of a dielectric

[0204] If there is a dielectric between the electrodes 2 and 3, tunneling the entire dielectric in a single jump is very unlikely. On the other hand, the motion will most likely distinguished by continuous accelerations and decelerations, with acceleration phases of the order of the nanometer and decelerations on lengths of two or three orders of magnitude lower.

[0205] For this reason, for the practical implementation of the proposed device, it is preferable to a) use dielectrics with a high relative dielectric constant, b) decrease the distance between electrodes 2, 3, and c) increase the applied voltage.

[0206] These expedients can increase the probability of an avalanche discharge, or other parasitic discharges not due to the tunnel effect, in some area of the device, i.e., phenomena that cancel out the desired effect almost completely. For this reason, a more homogeneous charge distribution with a high peak density is generally preferable.

[0207] A particularly advantageous combination, according to the experiments carried out, is at voltages between 1 and 10 kV, a dielectric thickness between 8 and 70 micrometers, and relatively low relative dielectric constant values Er, generally comprised between 1 and 4, typical of polymers such as polyethylene, polypropylene, polyamide (Kapton).

[0208] Cathode and anode shape

[0209] As previously indicated, it is particularly advantageous to obtain at least the cathode 2 with a multitude of micro- or nano-tips. The effect of this structuring is to improve the emission of electrons by the cathode 2, making this emission more homogeneous: it is in fact necessary that there not occurs a punctual avalanche discharge, but that the electrons "e‘" reach the anode 3 by tunneling from the entire surface, in a homogeneous way.

[0210] In general, it is preferable for the conductive surfaces to be thin, in order to avoid shielding of the event horizons. In the specific case of the anode 3 it is also important to maintain a reduced thickness, as the braking of the electrons "e‘" must take place in a space as small as possible: it is in fact from the virtual Casimir cavity that a part of the propulsive force is derived beyond the anode.

[0211] To minimize the braking path, and thus maximize deceleration, it is particularly useful to obtain the anode as thin as possible, for example using a graphene sheet, preferably covered with a layer of gold 3-10 nm thick or gold nanoparticles 3-10 nm in diameter, or a superconducting layer a few nanometers thick.

[0212] The possible use of superconducting electrodes, in addition to ensuring maximum efficiency in the transport of current, can be useful to increase the effect, as the superconducting electrodes are closer to the hypothesis with which the expression of the Casimir effect of perfectly conductive surfaces is normally obtained.

[0213] It is also possible that too thick metal layers can shield the effect, and it is therefore preferable for this reason to obtain thin electrodes, preferably with a thickness between 2 and 120 nanometers, and in general no more than 10 micrometers.

[0214] It can also be advantageous to obtain the anode in micro- or nano- structured form in order to increase the braking effect.

[0215] As indicated, in order to obtain the tips of the cathode (and possibly the anode) it is preferable for this purpose to structure an electrically insulating material, e.g., a polymer, and then cover the pointed structure thus obtained with a thin layer of conductor, e.g., gold or copper or nickel or aluminum.

[0216] As already mentioned, the tips on the cathode have the function of facilitating the emission of the electrons, and in particular of aggregates of electrons. Any tips on the anode have the function of concentrating the positive charge, and thus increasing the braking effect of the electrons.

[0217] In possible embodiments, it may be useful to obtain the layer that covers the tips using graphene, by virtue of the high electrical conductivity and the reduced thickness, preferably covered in turn with 1-3 nm of gold or copper, or other metal. For example, it is also possible to obtain a single monoatomic layer of graphene. The tips could also be covered with a superconducting thin film.

[0218] Gold is a material that is particularly suitable for making the anode, but other metals can also be used. In general terms, it is preferable to use materials with high electrical conductivity. On the other hand, it is less advantageous to use semiconductor materials such as silicon, as the braking of electrons is less effective.

[0219] The number of tips per unit anode area should preferably be high.

[0220] Temperature

[0221] As seen above, it can be particularly advantageous to heat the device, to improve the field emission by the cathode and to increase the vacuum pressure. However, heating must not impair the insulating properties of the dielectric. In general, the temperature should be between 30 and 80°C, preferably between 50 and 70°C. To achieve this effect, it is also possible to use the same cathode as a resistive heater.

[0222] As seen above, it is also possible to insert an additional conductive layer which is suitably electrically but not thermally insulated from the device, used as a resistive heater. As mentioned, in the experiment, a planar ITO heater was integrated into the device, with gold electrodes and covered with a layer of thermally conductive but electrically insulating silicone.

[0223] Examples of electrodes

[0224] Figures 38-44 exemplify some types of possible surface structures that can be used for the anode and / or the cathode. The corresponding images are obtained by scanning electronic microscope (SEM).

[0225] Figure 38 illustrates the case of silicon micro-tips, prepared by the Applicant, which can be used directly or after their transfer by moulding on plastic and then coated with a metal layer, e.g., Al or Au.

[0226] However, it is important that the density of tips per unit area is as high as possible, in order to avoid excessive current densities that can lead to deterioration of the tip itself, as shown in figure 39, which shows the case of silicon micro-tips covered in gold.

[0227] Figure 40 shows the case of pyramidal micro-excavations on a polypropylene film coated with gold. The advantage of this manufacturing technique lies in having the metal deposit directly on the insulating film, deposited under vacuum and therefore without potential air bubbles, as can occasionally happen with silicon or polymer micro-pyramids coated with a conductive layer and pressed on a dielectric film. Figure 41 illustrates another particularly advantageous conformation, represented by ordered carpet of carbon nanotubes.

[0228] Depending on the type of nanotubes, the diameter can range from 0.5 to 1.5 nm for single-wall nanotubes up to more than 100 nm for multi -wall nanotubes. The compact arrangement with an orderly carpet as shown in figure 36 is particularly suitable for obtaining an electrode with many highly conductive tips. It is preferable to cover the surface of the nanotube anode with a metal, preferably gold, with a thickness of between 15 and 50 nanometers, as the braking effect determined by gold is greater than in the case of carbon.

[0229] In order to obtain the tips of the aforementioned structures, various polymers can also be used, the surface of which is treated via plasma, or injection molding or hot embossing of the mold can be used. In the latter case, however, the pyramidal structures may result to be substantially truncated, with a less relevant effect on field emission: more pointed structures such as those reported above are therefore to be preferred.

[0230] The micro-tips can also be obtained by photolithography as shown in figure 42, or by gold-coated photoresist by sputtering.

[0231] Figure 43 shows an example of gold nanoparticles (clear parts in the figure) below the percolation level, obtained by sputtering. This type of coating is suitable for use as an intermediate braking layer.

[0232] Figure 44 shows an example of a gold film deposited by sputtering, in which the particles (clear parts in the figure) have reached the percolation level. This type of film can be used both as an electrode and as an intermediate braking means, although for intermediate braking it is preferable to use films whose conductive particles are below the percolation level, as in figure 43: in this case, in fact, a possible avalanche discharge that locally deteriorates the dielectric (breakdown) is less likely to compromise the operation of the device.

[0233] Form the description above the characteristics of the present invention are clear, as well as its advantages.

[0234] It is clear that numerous variants are possible for the person skilled in the field to the device described as an example, without however departing from the scope of the invention as defined by the claims that follow. Used symbols k number of particles m mass of particles v speed vssatellite speed

[0235] Pssatellite momentum

[0236] M satellite mass h Planck's constant divided by 2 π c speed of light in vacuum

[0237] A area of facing conductors

[0238] D distance between facing conductors

[0239] F force λ photon wavelength

[0240] N nonzero positive integer

[0241] A acceleration e electron charge

[0242] V applied voltage meelectron mass f generic braking length, for each impact

[0243] Reevent horizon, also known as the Rindler horizon a(f) braking acceleration f(V) braking length as a function of voltage V

[0244] I current

[0245] KBBoltzman's constant

[0246] PTtotal momentum

[0247] Pddevice momentum

[0248] Pvvacuum momentum

[0249] T temperature

[0250] P pressure

Claims

CLAIMS1. An electric thrust-generating device, comprising a cathode (2) and an anode (3) which are substantially planar, arranged substantially parallel and spaced from each other, with an interposed material or a dielectric medium (4) therebetween, the device being configured for connection to a voltage generator (5), for applying a voltage between the cathode (2) and the anode (3), and thereby determine a passage of electrons (e-) from the cathode (2) to the anode (3), wherein at least the cathode (2) is micro- or nano-structured at the surface thereof facing the anode (3), in particular for the formation of aggregates of electrons (e‘).

2. The device according to Claim 1, further comprising at least one temperature-conditioning arrangement (16-18; 17, 20-23; 17, 22, 32), such as a heating arrangement and / or a cooling arrangement.

3. The device according to Claim 1 or Claim 2, where the interposed dielectric material or medium (4) comprises sites (6) for the braking and / or re-emission of electrons (e‘) in the path thereof between the cathode (2) and the anode (3).

4. The device according to Claim 2, wherein the at least one temperatureconditioning arrangement (16-18; 20-23; 17, 22, 32) comprises at least one electric heater (17) and at least one layer or element made of an electrically insulating material which is substantially thermally conductive (16; 23; 32), that is setbetween the electric heater (17) and the cathode (2) or the anode (3).

5. The device according to Claim 2, wherein the at least one temperatureconditioning arrangement (16-18; 17, 20-23; 17, 22, 32) comprises a system (TCS) for temperature control, in particular of the temperature of at least one of an electric heater (17) and an electric cooler.

6. The device according to Claim 3, wherein the interposed dielectric material or medium (4) comprises at least one layer of electrically insulating material (14, 15; 24) having a structure that obtains or integrates sites for the braking of electron (e‘) in the path thereof between the cathode (2) and the anode (3).

7. The device according to Claim 3, wherein the interposed dielectric material or medium (4) includes at least one layer of electrically insulating material (12-15; 14'- 15'; 40; 46) to which at least one metal film (6', 6"), or else a plurality of metal micro- or nano-particles (6), is / are associated, which obtains / obtain sites for thebraking and / or re-emission of electrons (e‘) in their path between the cathode (2) and the anode (3).

8. The device according to Claim 3, wherein the interposed dielectric material or medium (4) comprises vacuum, and the device (1) further comprises a supporting structure (31-33) between the cathode (2) and the anode (3), for supporting one of a metal film and a plurality of metal micro- or nano-particles (6) that obtains / obtain sites for the braking and / or re-emission of electrons (e‘) in the path thereof between the cathode (2) and the anode (3), where preferably the supporting structure (31-33) comprises a frame (31, 32 ) for a thin film (33) that supports the metal film or the plurality of metal micro- or nano-particles (6).

9. The device according to any of Claims 1-8, wherein the anode (2) is also micro- or nano- structured at the surface thereof facing the cathode (3), in particular for increasing braking of electrons (e‘).

10. The device according to any of Claims 1-9, wherein at least one of the cathode (2) and the anode (3) is micro- or nano-structured so as to present a plurality of tips or reliefs, preferably having a substantially pyramidal shape.

11. The device according to any of Claims 1-10, where at least one of the cathode (2) and the anode (3) comprises at least one of:- a metal film deposited on a micro- or nano-structuring (Ns) of a respective supporting layer ( 10, 11; I T; 25, 26; 45) of electrically insulating material,- a micro- or nano-structured metal film on a respective supporting layer of electrically insulating material free of micro- or nano-structuring.

12. The device according to Claim 6, wherein the sites for the braking and / or re-emission of electrons (e‘) are in the form of metal surface reliefs or else metal micro- or nano-particles (6) on a face of a respective layer of dielectric material (14').

13. The device according to Claim 6, wherein:- the interposed dielectric material or medium (4) comprises a plurality of first layers (40) of dielectric material having two opposite major faces, on one major face there being provided a micro- or nano-structuring with a metal film (61) thereon,- the first layers (40) of the plurality are superimposed in contact with eachother, or else separated from each other by a second electrically insulating layer or by vacuum, in such a way that the micro- or nano-structuring of one of said first layers (40) provided with the metal film (6') is oriented towards the opposite major face free of micro- or nano-structuring of a successive one of said first layers (40) of the plurality, where in particular each metal film (6') obtains intermediate sites for the braking and re-emission of electrons (e‘).

14. The device according to any of Claims 1-1 3, wherein the interposed dielectric material or medium (4) includes both electron braking sites and electron re-emission sites.

15. The device according to Claim 14, wherein the interposed dielectric material or medium (4) includes one or more intermediate layers of electrically insulating material (46), each having a first face and a second face opposite to each other, wherein:- the first face is oriented towards the cathode (3), is substantially flat, and bears a first metal film (6") or a plurality of metal micro- or nano-particles,- the second major face is opposite the cathode (3) and is provided with a micro- or nano-structuring bearing a second metal film (6'), wherein the first metal film (6") operates as an intermediate braking site for electrons, and the second metal film (6") or the plurality of metal micro- or nanoparticles operates as an intermediate site for re-emission of electrons (e‘), where preferably, in case of a plurality of said intermediate layers, (46), they are spaced apart from each other.

16. The device according to Claim 14, wherein the interposed dielectric material or medium (4) comprises at least one metal film or a polymer filled with conductive particles at the percolation level.

17. The device according to Claim 1, comprising at least one of a cooling arrangement and a shield or similar protection element, to shield the device itself against direct sunlight.

18. An electric device, in particular a thrust generator, comprising a cathode (2) and an anode (3) substantially planar, arranged substantially parallel and spaced from each other, with an interposed material or a dielectric medium (4)therebetween, the device being configured for connection to a voltage generator (5), for applying a voltage between the cathode (2) and the anode (3), and thereby determine a passage of electrons (e‘) from the cathode (2) to the anode (3), wherein:- at least the cathode (2) is micro- or nano-structured at the surface thereof facing the anode (3), in particular for formation of electron aggregates (e‘), and / or- the interposed dielectric material or medium (4) includes sites (6) for braking and / or re-emitting electrons (e‘) in the path thereof between the cathode (2) and the anode (3), and / or- the device comprises at least one temperature-conditioning arrangement, such as a heating arrangement (17; 20-22; 17-22) and / or a cooling arrangement.

19. A space vehicle, such as a satellite, comprising an electric device according to one or more of Claims 1-18.

Images