DEVICE AND METHOD FOR FORMING A TEMPERATURE GRADIENT
The invention relates to a device (1) for forming a temperature gradient, having at least one gas-tight working chamber (9) having a cathode (8) and an anode (7), wherein an inhomogeneous electric field can be generated when an electric voltage is applied between the cathode (8) and anode (7) in the working chamber (9), as well as a working gas between the cathode (8) and anode (7). According to the invention, a distance between the cathode (8) and anode (7) is less than 5000 nm in order to enable a heat transport from the anode (7) to the cathode (8) with the working gas. The invention further relates to a method for producing a device (1) to form a temperature gradient. The invention also relates to a method for forming a temperature gradient between a cathode (8) and an anode (7) in a working chamber (9) by means of a working gas in the working chamber (9), to which an inhomogeneous electric field is applied.
The invention relates to a device for forming a temperature gradient, comprising at least one gastight working space having a cathode and an anode, wherein an inhomogeneous electric field can be produced when an electric voltage is applied between the cathode and the anode in the working space, as well as a working gas located between the cathode and the anode.
Furthermore, the invention relates to a method for producing a device for forming a temperature gradient, wherein the device is formed with at least one gastight working space having a cover plate with a cathode and a base plate having an anode and having a working gas located therebetween so that an inhomogeneous electric field can be produced when an electric voltage is applied between the anode and the cathode in the working space.
In addition, the invention relates to a method for forming a temperature gradient between a cathode and an anode in a working space by means of a working gas located in the working space, to which working gas an inhomogeneous electric field is applied.
A device for forming a temperature gradient which is based on the application of an inhomogeneous electric field is known from DE 10 2008 021 086 A1 as an electrostatic heat pump. A method with which a temperature gradient is formed by means of an inhomogeneous electric field is also theoretically known from the same document. However, it has been shown that, when the teaching from the aforementioned document is applied, a temperature gradient cannot be formed as theoretically predicted and also that no heat can be transferred according to the teaching.
It is therefore the object of the invention to disclose a device of the type named at the outset with which a temperature gradient can be achieved and heat can be transferred.
Furthermore, it is an object of the invention to disclose a method for producing a device of the type named at the outset with which a device can be produced with which a temperature gradient can be formed in an electrostatic manner.
A further object is to disclose a method for forming a temperature gradient of the type named at the outset, which method produces a temperature gradient between the anode and the cathode.
The first object is attained according to the invention in that, for a device of the type named at the outset, a distance between the cathode and the anode is less than 5000 nm to enable a heat transport from the anode to the cathode with the working gas.
Since a force acts on the molecules or atoms (molecules and atoms are hereinafter used synonymously, since atoms can also be used in place of molecules and vice versa) of the working gas in the inhomogeneous electric field, which force effects an acceleration of the molecules in the direction of the cathode, a kinetic (thermal) energy of the molecules increases with increasing displacement in the direction of the cathode. During an impact with the cathode, the molecules release a part of their kinetic energy to the cathode, which is thus heated. The molecules are subsequently reflected by the cathode and move away from the cathode in an opposing direction, in the direction of the anode. During a movement of the molecules from the cathode in the direction of the anode, the molecules are slowed down by the electric field and lose kinetic energy. An energy difference of the molecules between the cathode and the anode is equal to that energy which is necessary to displace the molecules against the electric field by the distance between the anode and the cathode. The molecules thus cool down before they impact the anode, for which reason thermal energy is released to the molecules from the anode during a contact of the molecules with the anode. At the same time, the anode is cooled in this manner. The molecules are subsequently reflected from the anode in the direction of the cathode, wherein they once again absorb energy on the path to the cathode via the electric field. The inventors have recognized that a temperature gradient can only be formed when molecules of the working gas oscillate between the anode and the cathode in an inhomogeneous electric field as a result of a molecular motion. Therefore, a distance between the anode and the cathode must be small enough so that the molecules oscillate between the anode and the cathode because of the molecular motion and so that they only interact with few other molecules between the anode and the cathode, wherein energy could be released to other molecules or could be absorbed by these molecules. That means that the molecules of the working gas essentially only interact with the anode and the cathode. Preferably, a gas pressure in the working space is smaller than an ambient pressure in order to be able to reduce an interaction between gas molecules. In this regard, a gas pressure of less than 500 mbar, preferably between 40 mbar and 100 mbar, in particular approximately 60 mbar, has proven to be advantageous. Preferably, a positive electric voltage is applied between the cathode and the anode. However, proper functioning is also ensured if a polarity of the applied voltage is reversed, since the molecules or atoms are always accelerated in the direction of the higher field strength. The terms anode and cathode used to describe the invention therefore do not anticipate the polarity of the applied voltage. A strength of the electric voltage, that is, a potential difference between the cathode and the anode, results from the dimensions of the working space used as well as from the desired field strengths. Anode and cathode refer to those surfaces or regions of the working space at which electrons or an electric field enter or exit the working space from a solid body, for example a metal or a dielectric.
It is advantageous that a distance between the cathode and the anode is less than five times, preferably less than double, a free path length of the molecules or atoms of the working gas. The interaction between molecules can thus be further reduced.
Preferably, a distance between the cathode and the anode is less than a free path length of the molecules or atoms of the working gas. This makes it possible for the movement of the molecules between the cathode and the anode to be achieved purely as a result of the molecular motion of the molecules and for molecules to oscillate independently in order to transfer energy. A Knudsen number of the working space, which number indicates a ratio of the free path length of the working gas to the distance between the anode and the cathode, is then approximately one or greater than one.
Expediently, the distance between the cathode and the anode is smaller than 2000 nm, preferably smaller than 1000 nm, in particular approximately 500 nm. An effect for forming a temperature gradient can thus, as described above, also be achieved in the case of gas pressures that are achievable with a low design cost of the working space. For this purpose, a distance between 200 nm and 800 nm in particular has proven to be especially advantageous.
Advantageously, the working space is delimited by a cover plate and a base plate which are at least partially composed of a dielectric. Since high electric field strengths are applied to the working space, typically between 107 V/m and 109 V/m, in particular approximately 108 V/m, at the anode and between 108 V/m and 1010 V/m, in particular approximately 109 V/m, at the cathode, dielectrics have proven especially successful.
To facilitate a production, it is advantageous that the dielectric comprises a polymer, in particular a Parylene and/or a photoresist. These materials have proven to be especially advantageous for satisfying the requirements in both electrical terms and also in mechanical terms. Especially the SU-8, a negative resist used in microsystems engineering, has proven to be advantageous for forming structures of the indicated dimensions.
For the embodiment of the electric field, it is advantageous that the cover plate is coated at least partially with an electrically conductive material, preferably a metal, in particular gold, at a contact surface to the working space. This has also proven to be advantageous in respect of a heat transfer from the working space to the cover plate.
However, it can also be provided that the cover plate is not gold-plated, in order to save cost in the production. In this case, electric voltage is transferred to the anode via an essentially planar metal electrode which is worked into the cover plate. In an embodiment of this type, the anode is designed as a dielectric which connects the metal electrode with the working space. This especially has advantages in respect of production imprecisions that could lead to a direct contact between the anode and the cathode. If the anode is designed as a dielectric, a direct contact between the anode and the cathode does not result in any impermissibly large current flows. Furthermore, an undesired distortion of the electric field is avoided.
Advantageously, the base plate and the cover plate respectively comprise a substrate, preferably a silicon substrate, which is connected to the dielectric via an electrically conductive planar electrode. This material is particularly well-suited to conducting a heat transferred via the temperature gradient, so that the device can in particular be used as an electrostatic heat pump.
It has proven successful that the cathode is formed as a wire electrode which in particular is formed from gold. By means of a cathode that is formed as a wire electrode and an anode embodied in a planar manner, an inhomogeneous electric field can be formed in a particularly simple manner, which field is necessary for the effect described above.
Preferably, the at least one working space has a roughly semicircular cross section. An inhomogeneous field can thus be formed between an anode having a roughly semicircular cross section and a cathode that is preferably arranged equidistant to the anode as a wire electrode. Because of the equal distance of the anode to the cathode, an electric field of this type is particularly well-suited to forming a temperature gradient according to the method described above and to transferring heat.
It is advantageous if the at least one working space is embodied in a hemispherical shape or in a roughly pyramidal shape. Calculations and trials have shown that this geometry enables an improved method because of paths on which the molecules or atoms move. Advantageously, the wire electrode which forms the cathode then leads, on a planar boundary area of the hemispherical working space or the roughly pyramidal working space, roughly diagonally across this boundary area of the working space. Of course, other geometric forms of the working space are also possible, such as for example truncated cones or truncated pyramids.
For a particularly beneficial design of the electric field, it is advantageous that a cross section of the cathode is less than 3%, preferably less than 1%, in particular less than 0.5%, of a cross section of the working space. This enables, in the case of a planar embodiment of the anode and a positioning of the cathode, which is preferably embodied as a wire electrode, equidistant to the anode, an inhomogeneous field which completely fills the working space. The working space is thus utilized particularly efficiently.
For a practical application of the device in which a heat flow of several watts is transferred, it has proven successful that multiple working spaces are arranged next to one another, wherein the individual working spaces are spatially connected to one another by bridges. Since only a small amount of energy can be transferred due to the dimensions of each working space, advantageously multiple working spaces are arranged next to one another to also be able to transfer larger amounts of energy. The bridges, which are hollow spaces filled with working gas, also prevent a temperature difference between the anode and the cathode from leading to a heat flow from the cathode to the anode via the base plate and the cover plate. If the working spaces are embodied in a hemispherical shape or in a roughly pyramidal shape, it is advantageous to arrange the working spaces next to one another on two planes so that these planes are arranged in multiple rows and columns in the form of a grid. Particularly in the case of pyramidal working spaces, there thus results a high utilization of the available space on a plane.
Expediently, the working spaces arranged next to one another comprise a shared anode. Potential differences between working spaces positioned next to one another which could lead to undesired current flows can thus be avoided. Even if the anodes of the individual working spaces are formed separately, it is advantageous if the anodes of the individual working spaces are electrically connected to one another.
Preferably, the cathodes of the working spaces arranged next to one another are electrically connected to one another. On the one hand, this is advantageous in respect of a production; on the other hand, an electric field with a gradient between the cathodes is thus avoided, so that the temperature gradient is only generated between the anode and the cathode. Provided that working spaces embodied in a hemispheric shape or in a roughly pyramidal shape are used, this can be achieved particularly easily in that the cathodes are embodied as wire electrodes which are arranged roughly diagonally on a planar area through the individual working spaces. Thus, one wire electrode forms the cathode of multiple working spaces in a particularly simple manner.
To achieve large temperature differences, it is advantageous that multiple working spaces are arranged serially above one another in multiple layers, wherein heat can be transferred between the layers. As a result, temperature differences of the individual layers are added and a total temperature difference of the entire device can be configured via the number of layers. Since, with one layer, only a small temperature difference is achievable as a function of a selected field strength, a working gas used, and the dimensions of the working space, multiple layers must be placed on top of one another such that the temperature differences are added. To transfer heat between the individual layers, the layers are preferably connected via a thermally conductive material, in particular a silicon substrate.
With multiple layers arranged on top of one another, it is advantageous that the cathodes of the individual layers and the anodes of the individual layers are electrically connected to one another respectively. Exceedingly high direct current voltages in the device are thus avoided which, for example, could lead to an arcing.
The second object is achieved according to the invention in that, in a method for producing a device of the type named at the outset, the cover plate is arranged at a distance of less than 5000 nm to the base plate.
As described above, the effect according to the invention is only achieved and a temperature gradient is only formed in a method according to the invention if the molecules or atoms of the working gas essentially do not transfer heat to other molecules of the working gas, but rather transport heat from the anode to the cathode. This is enabled with a small distance of the base plate to the cover plate, wherein preferably a pressure of the working gas is small enough so that only little interaction can occur between individual molecules. In this respect, a pressure that is lower than an ambient pressure, preferably less than 500 mbar, in particular preferably between 40 mbar and 100 mbar, particularly 60 mbar, has proven to be advantageous.
Preferably, the cover plate is produced using a stamping die produced in a galvanizing process. Since the cover plate preferably comprises a structuring with dimensions within a nanometer range so that the inhomogeneous electric field can be formed, a high-precision production method is necessary to be able to produce corresponding structures. In this respect, a method has proven to be useful in which a stamping die comprising a negative mold of the structures that are to be produced is produced in the galvanizing process. The cover plate is then stamped using the produced stamping die so that the structures are formed in the cover plate. To stamp the cover plate with the stamping die, a hot stamping method is preferably used in which the cover plate is brought to a deformation temperature and the stamping die is then pressed into the cover plate in a power-controlled manner and/or a path-controlled manner, wherein the cover plate is stamped. The cover plate is subsequently cooled until it has solidified, and the stamping die is removed from the cover plate.
To form an advantageous inhomogeneous electric field, the stamping die which is used preferably comprises a galvanic structure with a roughly semicircular cross section, wherein a radius of the roughly semicircular cross section is less than 5000 nm, preferably less than 1000 nm, in particular preferably between 100 nm and 800 nm, particularly roughly 350 nm. The stamping die preferably comprises a polymer layer applied to a base plate, in particular a layer which is composed of Parylene or photoresist. To form the galvanic structure, at least one wire electrode is arranged on a surface of the stamping die, preferably on the polymer layer, in a first step. In a further step metal, preferably gold, is deposited on the wire electrode in a galvanic process by application of an electric voltage. In this manner, a galvanic structure is formed around the at least one wire electrode, which structure comprises the roughly semicircular cross section starting from the wire electrode as a central point. The cross section of the structure, which determines dimensions of the working space via the stamping of the cover plate, can be influenced via the amount of metal that is deposited on the wire electrode.
Advantageously, the stamping die that is used comprises a metallization layer having a metallization layer thickness of less than 1000 nm, preferably less than 500 nm, in particular preferably between 50 nm and 300 nm, particularly approximately 100 nm. Particularly if multiple working spaces are produced next to one another, it is advantageous to also provide the galvanic structure with a full-area metallization layer before the stamping of the cover plate. Bridges between the individual working spaces are thus formed during the stamping of the cover plate, which bridges prevent or at least reduce a heat backflow from the cathode to the anode. The metallization layer is preferably composed of gold or potassium.
To form the base plate and the cover plate, an electrically conductive planar electrode is preferably applied to a substrate. This has proven to be particularly advantageous for the electric field required in the method according to the invention.
Expediently, a dielectric is applied to the planar electrode. Because of the high electric field strengths, this is advantageous for achieving the desired formation of the electric field.
To achieve a particularly suitable contacting, a contact surface between the cover plate and the working space is coated with a metal, in particular gold. A thusly produced planar metallization of the contact surface then forms the anode, which is embodied as a planar electrode. If multiple working spaces are arranged next to one another, the anodes of the individual working spaces are connected via the planar metallization. Gold exhibits favorable properties in respect of electrical conductivity, chemical resistance and thermal conduction, for which reason gold is preferably used on the anode.
However, it can also be provided that the contact surface between the working space and the cover panel, which forms the anode, is designed as a dielectric. This has advantages in the event of a direct contact between the anode and the cathode occurring due to imprecisions during the production. If the anode is designed as a dielectric, high currents and field distortions are avoided in the case of a direct contact. The production can also be simplified by this measure, in which the face of the anode is not coated.
To form a device which comprises multiple working spaces arranged next to one another and on top of one another to be able to produce large temperature differences, multiple base plates and cover plates are stacked on top of one another. It can thereby be provided that one plate can be embodied on a top side as a base plate and one plate on a bottom side as a cover plate in order to design a production process in a simpler manner and to improve a heat transfer from one layer to a next layer.
To simplify the production, it is advantageous if roughly flat planar electrodes are applied to an essentially plate-shaped substrate layer on two sides, which electrodes form electrodes of working spaces positioned on top of one another. Those parts via which an electric voltage is conducted from outside the device into the region of the working space are thereby referred to as electrodes. However, these electrodes do not need to lead directly into the working space, since the electric field is also formed when the electrodes lead to a region bordering the working space, for example to a dielectric. Preferably the electric voltage that generates the electric field is applied to these electrodes in the method. This simplifies the production and reduces costs in the production. The substrate layer is thereby advantageously composed of a dielectric, whereby high currents inside the substrate layer from an electrode of a layer to the electrode of the layer positioned thereabove are prevented. A thickness of the substrate layer which defines a distance between the cathode and the anode is thereby determined as a function of a desired maximum current inside the plate and of a conductance of the dielectric selected. Typically, currents inside the substrate layer are less than 10−5 A, in particular less than 10−10 A, preferably smaller than 10−15 A. Because the substrate layer in this embodiment assumes both a structural function concerning a gastight separation of working spaces positioned on top of one another and also an electric function concerning the supply of an electric potential to working spaces positioned on top of one another, the production can occur in a particularly cost-effective manner.
It can also be preferred that the cathode is formed by a wire electrode produced in a lift-off process. The lift-off process has proven successful for producing structures within the nanometer range. A sacrificial layer, usually a photoresist, is thereby deposited on a substrate in a first step. The sacrificial layer is then structured using an inverse pattern of the eventual structure. This preferably occurs in a hot-stamping process or by means of photolithography.
After the structuring, metal, preferably gold, is deposited across the entire area on the structured surface, wherein the metal is deposited on the substrate in the region of the structuring. In a final step, the sacrificial layer is removed in a wet-chemical manner, for example using a solvent, wherein the metal that was deposited on a top side of the sacrificial layer is lifted and removed. Thus, only the metal in the regions of the structuring remains, where metal is in direct contact with the substrate. In this manner, the wire electrodes within the nanometer range can be produced particularly precisely and cost-effectively.
The third object is attained in that, in a method for forming a temperature gradient of the type named at the outset, molecules or atoms of the working gas carry out a molecular motion and thereby oscillate between the cathode and the anode, wherein these molecules or atoms absorb energy at the anode and release energy at the cathode.
Because the molecules or atoms oscillate independently between the anode and the cathode due to the molecular motion, energy can be inputted into the molecules through the electric field during a movement in the direction of the cathode, whereby a kinetic (thermal) energy of the molecules is increased. At the cathode, the molecules release energy to the cathode, whereby the cathode is heated. The molecules are then reflected in the direction of the anode. In a subsequent motion in the direction of the anode, the kinetic (thermal) energy of the molecules decreases, since these molecules are moved against the electric field, whereby the molecules can absorb energy at the anode before they are once again reflected in the direction of the cathode. Only by means of an independent oscillation of the molecules as the result of the molecular motion does the method become effective and lead to the formation of a temperature gradient between the anode and the cathode, whereby heat is transferred by means of an electrostatic process.
Preferably, molecules or atoms of the working gas essentially only interact with the anode and the cathode of the working space. This prevents an undesired heat transfer between molecules among one another, whereby the effect described above would appear to a considerably lesser extent, since molecules could already be cooled before arriving at the cathode. Preferably, the dimensions of the working space and the thermodynamic states of the working gas are chosen such that a molecule on the path between the anode and the cathode only strikes another molecule with a very low probability. This can be influenced particularly easily by a distance from the anode to the cathode in the working space and a pressure of the working gas.
Advantageously, a working space is used which comprises a distance between the anode and the cathode which is less than five times, preferably less than double, a free path length of the molecules or the atoms of the working gas. With an embodiment of this type of the working space, the method for forming the temperature gradient can be achieved particularly advantageously, since little interaction takes place between molecules.
Particularly preferably, a working space is used which comprises a distance between the anode and the cathode which is less than the free path length of the molecules or the atoms of the working gas. In this manner, a movement of the molecules between the anode and the cathode is guaranteed as a result of the molecular motion. A Knudsen number of the working space, which indicates a ratio of the free path length of the working gas to the distance between the anode and the cathode, is then approximately one or slightly greater than one.
It has proven successful that the molecules or atoms of the working gas are accelerated from the anode in the direction of the cathode by the electric field. Energy is thus inputted into the molecules, which release this energy to the cathode to transfer heat and to form the temperature gradient.
It is advantageous that molecules or atoms of the working gas are decelerated at the cathode, wherein energy is released from the molecules or the atoms to the cathode. A temperature gradient between the anode and the cathode is thereby formed which enables a heat flow.
It is advantageous if a working gas is used which does not comprise a dipole moment. Due to the electric field, a working gas without a dipole moment is polarized and the molecules of the working gas are aligned according to the electric field and are accelerated by the electric field. Because the dipole moment of the working gas is induced by the electric field, a polarization of the molecules is retained even after an impact of the molecules with the anode or the cathode. In contrast to a working gas which comprises a dipole moment, an alignment of the molecules as in the case of a working gas with a static dipole moment does not occur. Preferably, a working gas is used which has a high polarizability and a high mass in order to maximize a transferable heat flow per volume. In this regard, particularly gases or molecules that can be brought into the gas phase, such as argon, xenon, C60, C60F60, iodine, SF6, and UF6 have proven successful.
Expediently, corresponding processes take place in multiple working spaces positioned on top of one another, wherein a temperature difference between a bottommost working space and a topmost working space is formed which is larger than the temperature difference that can be produced with a single working space. In this manner, a greater temperature difference is formed than that which would be possible with a single layer, whereby heat flows of several megawatts can be transferred.
Additional features, advantages and effects of the invention follow from the exemplary embodiment illustrated below. The drawings which are thereby referenced show the following:
The anode 7 at which electrons enter or exit the working space 9 depending on a polarization of the applied voltage is formed by the dielectric 4 in the device 1, which is illustrated in
To form a temperature gradient and to transfer heat with the device 1 from
With a method according to the invention, it is possible to form a temperature gradient by means of an electrostatic field. For example, a temperature difference of approximately 1.5 K to 3.5 K can be achieved with a device as illustrated schematically in
Claims
1. Device for forming a temperature gradient, comprising at least one gastight working space (9) having a cathode (8) and an anode (7), wherein an inhomogeneous electric field can be produced when an electric voltage is applied between the cathode (8) and the anode (7) in the working space (9), as well as a working gas located between the cathode (8) and the anode (7), characterized in that a distance between the cathode (8) and the anode (7) is less than 5000 nm in order to enable a heat transport from the anode (7) to the cathode (8) with the working gas.
2. Device according to claim 1, characterized in that a distance between the cathode (8) and the anode (7) is less than five times, preferably less than double, a free path length of the molecules or atoms of the working gas.
3. Device according to claim 1 characterized in that a distance between the cathode (8) and the anode (7) is less than a free path length of the molecules or atoms of the working gas.
4. Device according to claim 1, characterized in that the distance between the cathode (8) and the anode (7) is less than 2000 nm, preferably less than 1000 nm, in particular approximately 500 nm.
5. Device according to claim 1, characterized in that the working space (9) is delimited by a cover plate (3) and a base plate (2) which are at least partially composed of a dielectric (4).
6. Device according to claim 5, characterized in that the dielectric (4) comprises a polymer, in particular a Parylene, and/or a photoresist.
7. Device according to claim 5, characterized in that the base plate (2) and the cover plate (3) respectively comprise a substrate, preferably a silicon substrate, which is connected to the dielectric (4) via an electrically conductive planar electrode (6).
8. Device according to claim 1, characterized in that the cathode (8) is formed as a wire electrode (15) which is in particular composed of gold.
9. Device according to claim 1, characterized in that the at least one working space (9) has a roughly semicircular cross section.
10. Device according to claim 1, characterized in that the at least one working space (9) is embodied in a hemispherical shape or in a roughly pyramidal shape.
11. Device according to claim 1, characterized in that a cross section of the cathode (8) is less than 3%, preferably less than 1%, in particular less than 0.5%, of a cross section of the working space (9).
12. Device according to claim 1, characterized in that multiple working spaces (9) are arranged next to one another, wherein the individual working spaces (9) are spatially connected to one another by bridges (13).
13. Device according to claim 12, characterized in that the working spaces (9) arranged next to one another comprise a shared anode (7).
14. Device according to claim 12, characterized in that the cathodes (8) of the working spaces (9) arranged next to one another are electrically connected to one another.
15. Device according to claim 1, characterized in that multiple working spaces (9) are arranged serially on top of one another in multiple layers, wherein heat is transferable between the layers.
16. Device according to claim 15, characterized in that the cathodes (8) of the individual layers and the anodes (7) of the individual layers are respectively electrically connected to one another.
17. Method for producing a device (1) for forming a temperature gradient, wherein the device (1) is formed with at least one gastight working space (9) having a cover plate (3) with a cathode (8) and a base plate (2) with an anode (7) and a working gas located therebetween so that an inhomogeneous electric field can be produced when an electric voltage is applied between the anode (7) and the cathode (8) in the working space (9), characterized in that the cover plate (3) is arranged with a distance of less than 5000 nm to the base plate (2).
18. Method according to claim 17, characterized in that the cover plate (3) is produced using a stamping die (14) produced in a galvanizing process.
19. Method according to claim 18, characterized in that the stamping die (14) that is used comprises a galvanic structure (18) with a roughly semicircular cross section, wherein a radius of the roughly semicircular cross section is less than 5000 nm, preferably less than 1000 nm, in particular preferably between 100 nm and 800 nm, particularly approximately 350 nm.
20. Method according to claim 18, characterized in that the stamping die (14) that is used comprises a metallization layer (19) with a metallization layer thickness (20) of less than 1000 nm, preferably less than 500 nm, in particular preferably between 50 nm and 300 nm, in particular approximately 100 nm.
21. Method according to claim 17, characterized in that an electrically conductive planar electrode (6) is applied to a substrate to form the base plate (2) and the cover plate (3).
22. Method according to claim 21, characterized in that a dielectric (4) is applied to the planar electrode (6).
23. Method according to claim 17, characterized in that roughly flat planar electrodes (6) are applied to an essentially plate-shaped substrate layer (5) on two sides, which electrodes form electrodes of working spaces (9) positioned on top of one another.
24. Method according to claim 17, characterized in that the cathode (8) is formed by a wire electrode (15) produced in a lift-off process.
25. Method for forming a temperature gradient between a cathode (8) and an anode (7) in a working space (9) by means of a working gas located in the working space (9), to which gas an inhomogeneous electric field is applied, characterized in that molecules or atoms of the working gas carry out a molecular motion and thereby oscillate between the cathode (8) and the anode (7), wherein these molecules absorb energy at the anode (7) and release energy at the cathode (8).
26. Method according to claim 25, characterized in that molecules or atoms of the working gas essentially only interact with the anode (7) and the cathode (8) of the working space (9).
27. Method according to claim 25, characterized in that a working space (9) is used which comprises a distance between the anode (7) and the cathode (8) which is less than five times, preferably less than double, a free path length of the molecules or atoms of the working gas.
28. Method according to claim 25, characterized in that a working space (9) is used which comprises a distance between the anode (7) and the cathode (8) which is less than the free path length of the molecules or atoms of the working gas.
29. Method according to claim 25, characterized in that molecules or atoms of the working gas are accelerated from the anode (7) in the direction of the cathode (8) by the electric field.
30. Method according to claim 25, characterized in that molecules or atoms of the working gas are decelerated at the cathode (8), wherein energy is released by the molecules or atoms to the cathode (8).
31. Method according to claim 25, characterized in that a working gas is used which does not comprise a dipole moment.
32. Method according to claim 25, characterized in that corresponding processes take place in multiple working spaces (9) positioned on top of one another, wherein a temperature difference between a bottommost and a topmost working space (9) is formed which is greater than the temperature difference that can be produced with a single working space (9).
Type: Application
Filed: Mar 4, 2013
Publication Date: Mar 12, 2015
Inventors: Rudolf HIRSCHMANNER (Feldbach), Siegfried MAIERHOFER , Gerald BÖHM
Application Number: 14/383,297
International Classification: F25B 21/00 (20060101);